# Handling differences due to mechanical vs A-LSD R33/R34 GTR?



## Addicted2Boost (Nov 15, 2007)

Ive searched a fair bit and still couldn't come across a definite clear answer on this, if anyone can give info on this would be great!

Whats the exact difference in handling/behaviour of the R33/R34 GTRs due to the driveline, the mechanical diff of the standard car vs the rear Active LSD on the Vspec models?

I know how the A-LSD functions, but never been in a car, EVO etc with an A-LSD and both my previous and current R34 GTR were non-vspec and always found the rear to come out so easily, heavily biased RWD car feel not dissimilar to an S15. In my previous one, had 310kw @ hubs and even launching in the rain, would never see anything about 30% front torque and alot of owners seemed to agree that was its limit? But like Dino's post his R34 GTR on speedhunters a Vspec as below sees near 50% to the front. Is this also a clear difference on the Vspec models?

[URL="http://cdn.speedhunters.com/wp-content/uploads/2013/01/Dino-GTR-Project-39.jpg"]http://cdn.speedhunters.com/wp-content/uploads/2013/01/Dino-GTR-Project-39.jpg[/URL]

With my 2nd GTR, wanting to keep its near stock power and learning to actually drive properly on a track, have done the brakes, then do chassis braces, suspension linkages, coilovers (currently S-tune suspension) etc.... wondered about the advantages/dis-advantages of the A-LSD and better ETS system on the Vspec on a track. 

And with using stuff like the Tarzan G-box or Midori Spec ETS controller/g sensor upgrade the changes it makes, again what would be the differences, advantages or dis etc?


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## Steve (Sep 21, 2001)

Come to Castle Comb on the 22nd April and I'll show / demostrate the difference


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## tonigmr2 (Sep 12, 2002)

I think I read somewhere the vspec adjusts every 1/100th of a second and a non vspec every 1/10 of a second. Most drivers would not know the difference If that's true IMHO!


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## SklyaFett (Oct 18, 2005)

If the car is not locking full 50/50 split on a lose service the 4wd system is not working properly.
Let steve show you the difference, hes the best driver on here. Hes faster than Mr Vettel lol.


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## R32 Combat (Jan 29, 2004)

A good ET-S controller will fix your needs.


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## SklyaFett (Oct 18, 2005)

R32 Combat said:


> A good ET-S controller will fix your needs.


Shameless plug lol. But r32 combat has a good point.


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## Addicted2Boost (Nov 15, 2007)

I would happily give the car to someone to show the difference. Unfortunately there arnt many R34 GTR owners here in NZ to compare. 

With both my R34s only showing 30% though, first one with 69km on the clock, surely wouldnt be faulty? So im guessing most of you guys see a near full 50% lock on the front?

I am very keen on replacing G-sensor, so say this torque transfer to the front was improved same as a Vspec etc, then just regarding the rear Active LSD, is there a huge real world difference on the track? Would a non vspec with same modified suspension, brakes and other handling upgrades be as quick and easily get it quick as a V-spec for the average driver? It almost makes me want to sell my GTR to get a Vpsec for the A-LSD


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## SklyaFett (Oct 18, 2005)

Iv do a document on my pc at home mate that tells you all the differences from vspec to non vspec. It's much more than just the diff. The 4wd works different also. I will post it up as soon as I can. But tbh mos people won't or can't feel it anyway and on track it would make no difference to there track times. Some tuners think the standard car handles better on UK roads, and I would tend to believe them. Don't see your cars for vspecs.
Jeff


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## Addicted2Boost (Nov 15, 2007)

Cool thanks mate, that would be really useful. Although ive read some places where they've crashed their cars with the rear coming loose so easily in the non-specs, perhaps just their driving, whatever the case, even my old R34 I was told that the new owner wrote the whole thing off onto a small country ditch only after a few months of taking ownership  which was very tail happy


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## Steveline (Oct 6, 2010)

Sounds to me like your transfer plates are worn out, the screen dose NOT prove the four wheel drive system is actually functioning mechanically, and also dose NOT display the front torque as a percentage! I think it would be worth a visit to RIPS to check out his 4 wheel drive dyno!


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## bluesky (Mar 12, 2006)

My R34GTR is standard and it sticks to the road like glue so as steveline says possibly a fault?


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## Addicted2Boost (Nov 15, 2007)

Steveline said:


> Sounds to me like your transfer plates are worn out, the screen dose NOT prove the four wheel drive system is actually functioning mechanically, and also dose NOT display the front torque as a percentage! I think it would be worth a visit to RIPS to check out his 4 wheel drive dyno!


I know that it is in Nm or kg-m, but for the longest time just assumed it as a percentage and never re-thought about it as have read in places from Nissan re: the attessa that it sends up to 50% of the available torque to the front so assumed this... hmm in this case, does it mean that it can measure the amount of torque? So if u have a modified car, it should be reading more? 

My old GTR the fronts were working fine, was quite a low KM stock, unmolested version that i purchased and when modified i did have it on a 4WD dynapack dyno etc. (would only read 30 peak) Launching my current stock R34 hard (other than PFC, cat back only) u can definitely feel when the fronts start to grip etc, but was concerned its only sending 20nm as per graph. 

I would be interested to know that if this is gauge is infact no indication of the 4wd actually working nor how much power its getting, is the dyno the only way? Does the GTR indeed do a 50/50 split front and rear when attessa fully engaged? At what point do the clutch packs slip when u add more power? 

Anyone still know about the A-LSD vs Mechanical LSD. *SklyaFett* were u able to find some info on this?


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## akasakaR33 (Oct 10, 2005)

What no one has mentioned is the A-LSD's ability to split torque in varying proportions LEFT AND RIGHT between the rear wheels - no mechanical diff available for the non-Vspec cars, can do this. This is a big factor as to why the 33 was so fast at Nur vs the 32.

This is why I find extremely hard to believe any claims that a mechanical diff is better (and I have seen some posts where people are trying to convince others to ditch their A-LSDs for a mechanical one). I have a non-Vspec car (albeit 33 - the 34 had revised electronics BTW), and so if anyone wants to trade their active diff, computer etc. with mine (OS Giken!) for free, then happy to do so. (although to be honest, I find that when I take my car onto the track, the diff really doesn't seem to matter unless you are one of the top, professional level drivers - which I am sure all you believe yourself to be LOL).

Also, as Toni pointed out - the computer for the V-spec calculates at 1/1000 sec while the non vspec computer calculates at 1/100 I think. The programming is also different, as you can see from the charts (the V-spec will also be calculating the YAW rate of the car).

But, as Steveline pointed out, I think it's quite possible that your transfer is worn out too. So when people say that G-sensor or Tarzan box or Skylab or other Electrical ETS controller can fix your problems - well that will only be true if there is nothing wrong MECHANICALLY wrong with your car.

ALSO - such products only "fix" the front/rear speed/proportionality of the power to the drivetrain. While some products urge you to give up the A-LSD and go mechanical so you can fit their product, I would say don't give up left/right variability while you are at it!


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## akasakaR33 (Oct 10, 2005)

PS - Midori Seibi here in Japan has just released another digital upgrade - this time only for V-Specs. Namely, it's a digital YAW rate sensor, so that the Left/Right calculations can be done more quickly and accurately.


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## tyndago (Oct 24, 2002)

akasakaR33 said:


> What no one has mentioned is the A-LSD's ability to split torque in varying proportions LEFT AND RIGHT between the rear wheels - no mechanical diff available for the non-Vspec cars, can do this. This is a big factor as to why the 33 was so fast at Nur vs the 32.


Not true. The A-LSD does not vary right to left. The lockup is hydraulic/mechanical with a single solenoid controlling it. A-LSD can vary/open the rear, which when open its easier to turn in and turn, and then on power locks up the diff and the car wants to go straight. I have a picture of a rear diff that shows the fluid lines, but I can't find it right now. It uses the TPS as a big input to the A-LSD.

Some older ATTESA info - Nissan Skyline GT-R s in the USA Blog: ATTESA Information

HKS Torque Split Controller Instructions - Nissan Skyline GT-R s in the USA Blog: HKS ETC and EDA Drag Adapter Instructions

We put an A-LSD in an R32, the theory is solid, but I didn't have enough time or back to back to tell you how much I think it really makes a difference. I also don't think I am good enough a driver to let you know. Nissan Skyline GT-R s in the USA Blog: R32 A-LSD










The R34 Super Taikyu car had a unique ATTESA system. A-LSD, but modified. It had variable torque split, wet/dry ABS, and it used the HICAS yaw rate sensor as an input into the ATTESA system. The HICAS was locked out, on the car but locked.


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## tyndago (Oct 24, 2002)

Addicted2Boost said:


> . In my previous one, had 310kw @ hubs and even launching in the rain, would never see anything about 30% front torque and alot of owners seemed to agree that was its limit? But like Dino's post his R34 GTR on speedhunters a Vspec as below sees near 50% to the front. Is this also a clear difference on the Vspec models?



The figure on the gauge on the dash, it might as well read in pigs heads/feet. It is a calculated figure based on pressure to the transfercase. There is no actual measurement, really doesn't mean anything. 

*So what I am saying is ignore it. *

The center differential or clutch locks up with hydraulic pressure from the ATTESA pump. The more pressure, the more lockup, the more power sent to the front wheels. The reason it isn't locked up all the time is drag, and the car would not want to turn. There are plates in the clutch, and slippage that occurs. If someone has done lots of burnouts, or ran an R33/R34 on a dyno without dropping the front driveshaft, you can burn the transfer in one session. Check the fluid, see if it smells burned. You can also pull the shifter assembly out, and look for any "bluing" on the clutch drum. If it got hot, there is a good chance it started to turn blue. Good sign of needing a new transfer. R32/R33 are the same. R34 is different. 

A video showing inside the transfer.





Nissan Skyline GT-R ATTESA System Transfercase - YouTube


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## tyndago (Oct 24, 2002)

R32/R33 transfercase compared to R34.


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## R32 Combat (Jan 29, 2004)

tyndago said:


> The figure on the gauge on the dash, it might as well read in pigs heads/feet. It is a calculated figure based on pressure to the transfercase. There is no actual measurement, really doesn't mean anything.


We put a mechanical pressure gauge on the piston on the back of the transfer box and compared the actual pressure with what the front torque gauge said.
You have have hydraulic pressure and no front torque gauge pressure in one instance.


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## tyndago (Oct 24, 2002)

R32 Combat said:


> We put a mechanical pressure gauge on the piston on the back of the transfer box and compared the actual pressure with what the front torque gauge said.
> You have have hydraulic pressure and no front torque gauge pressure in one instance.


Right, pressure is really want you want to measure. So if you try and read anything, read that.

In the case of fail safe on R33/R34, the gauge reads 0, but there is pressure to the transfer. This is how you burn out the transfercase. Ask me, I have learned that $1000 lesson.


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## R32 Combat (Jan 29, 2004)

I think it would be interesting to read rate of pressure change on R32/33/34 to see if there was a difference. As far as I know, all the solenoids run at 200Hz, as does the one for the diff on V-Specs so they should all be the same.
If you know the coefficient of friction between the friction/pressure plate you can easily work out the front torque. As standard, I think it's more than the engine produces. I did a few cals a while ago.


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## tyndago (Oct 24, 2002)

R32 Combat said:


> I think it would be interesting to read rate of pressure change on R32/33/34 to see if there was a difference. As far as I know, all the solenoids run at 200Hz, as does the one for the diff on V-Specs so they should all be the same.
> If you know the coefficient of friction between the friction/pressure plate you can easily work out the front torque. As standard, I think it's more than the engine produces. I did a few cals a while ago.


It would be interesting to datalog the pressure differences. I can tell you from years of working with the cars, and standing beside the dragstrip, watching R32,R33, R34 come off the line, that an R32 system is something you see work. You notice the rear wheel spin, then about 5-10 feet out, you see the fronts come in and the rear slip go away. The R33 and R34 you never really notice, it just goes, or spins all 4 pretty quickly. 

There is however a downside to too much front torque, and that is you spit parts out of the front diff.









This one, the mechanic did not put any fluid into. At about 110 mph, having it come apart like this wasn't fun. 

http://www.gtrusablog.com/2013/04/broken-front-differential-oil-pan-on.html


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## R32 Combat (Jan 29, 2004)

All the GTR's have a feature that applies hydraulic pressure that is proportional to TPS (over a set voltage) when the car is stationary. Over a set speed, this feature is turned off.

This only works over a certain TPS voltage. If you put a pressure gauge on the hydraulic line, start the engine and rev it, you can see the pressure rise and fall. The gauge on the dash doesn't show anything. This is Nissans rapid start function.

Another reason for keeping the ATTESA!!


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## tyndago (Oct 24, 2002)

R32 Combat said:


> All the GTR's have a feature that applies hydraulic pressure that is proportional to TPS (over a set voltage) when the car is stationary. Over a set speed, this feature is turned off.
> 
> This only works over a certain TPS voltage. If you put a pressure gauge on the hydraulic line, start the engine and rev it, you can see the pressure rise and fall. The gauge on the dash doesn't show anything. This is Nissans rapid start function.
> 
> Another reason for keeping the ATTESA!!


I have never seen or heard of this. Interesting. Doesn't work very well in the R32.


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## R32 Combat (Jan 29, 2004)

We discovered it on the R32.:squintdan

I'll PM you what we did.


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## tyndago (Oct 24, 2002)

akasakaR33 said:


> What no one has mentioned is the A-LSD's ability to split torque in varying proportions LEFT AND RIGHT between the rear wheels - no mechanical diff available for the non-Vspec cars, can do this. This is a big factor as to why the 33 was so fast at Nur vs the 32.


Put up a couple of hydraulic circuit diagrams of the R34 ATTESA ETS Pro system. You can see it has no way to vary torque split side to side.
Nissan Skyline GT-R s in the USA Blog: R34 GT-R ATTESA ETS-PRO Hydraulic Diagram


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## Addicted2Boost (Nov 15, 2007)

Wow, tons of great info. Thanks for that guys, appreicated. Thanks *tyndago* for your input in response to my private message and posting information on this thread for everyone.

So i guess, regarding the ATTESSA, torque to the front is dependant largly on the condition of the clutch packs in the transfer casse etc, and the 1/1000th vs 1/100th difference can be addressed by using aftermarket G-sensors that send more signal, earlier etc? 

As for the A-LSD, along with its obvious advantages, but as most people have said, possibly could do without being just a track hobbyist? Wonder is if its less of a handful with the active rear at speed? For V-spec owners that track their cars, is it still comparable to a lively RWD like the S15 etc? I myself nearly kissed the wall on a wet track whilst exiting a hairpin...too much gas too early...along with that being a total newbie!


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## tyndago (Oct 24, 2002)

Addicted2Boost said:


> So i guess, regarding the ATTESSA, torque to the front is dependant largly on the condition of the clutch packs in the transfer casse etc, and the 1/1000th vs 1/100th difference can be addressed by using aftermarket G-sensors that send more signal, earlier etc?
> 
> As for the A-LSD, along with its obvious advantages, but as most people have said, possibly could do without being just a track hobbyist? Wonder is if its less of a handful with the active rear at speed? For V-spec owners that track their cars, is it still comparable to a lively RWD like the S15 etc? I myself nearly kissed the wall on a wet track whilst exiting a hairpin...too much gas too early...along with that being a total newbie!


If you are a novice driver, I don't think you would notice much difference in the ATTESA system. Its fastest in the R34, but I don't think people can tell the difference between 1/100th and 1/1000th in real life. Most the issues with the GT-R's handling center around other things, not just or only the all wheel drive system.

The biggest thing you should work on is the steering wheel gasket. Get that thing good, and the car will be great. Then you can start to add in other aftermarket parts to make it all work. 

In the wet, well all bets are off. The all wheel drive system can give you more grip, but mostly what it allows you to do it hit things harder when you do make a big mistake.


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## Addicted2Boost (Nov 15, 2007)

Steering wheel gasket? Interesting, never theard of doing that before, nor do i understand the purpose? U dont mean a steering wheel hub/quick release system right, rather the acutal gasket, being way way down the steering column?


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## tyndago (Oct 24, 2002)

Addicted2Boost said:


> Steering wheel gasket? Interesting, never theard of doing that before, nor do i understand the purpose? U dont mean a steering wheel hub/quick release system right, rather the acutal gasket, being way way down the steering column?


That is the soft squishy part between the steering wheel and the seat. 

Its a joke. Improving the driver will pick up 10s and 10s of seconds of time. A fast driver in a slow car is fast. A slow driver in a fast car is slow. 

Spend some time in driver improvement courses. Learn the car and the tracks, and you will be fast.


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## Addicted2Boost (Nov 15, 2007)

LOL.... my bad... hahaha...... umm yes and yes, will be upgrading that every session. hence why im doing NO power mods and doing everything backward this time round  

Thanks for your time in all the info/input


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## akasakaR33 (Oct 10, 2005)

tyndago said:


> Not true. The A-LSD does not vary right to left. The lockup is hydraulic/mechanical with a single solenoid controlling it. A-LSD can vary/open the rear, which when open its easier to turn in and turn, and then on power locks up the diff and the car wants to go straight. I have a picture of a rear diff that shows the fluid lines, but I can't find it right now. It uses the TPS as a big input to the A-LSD.
> 
> Some older ATTESA info - Nissan Skyline GT-R s in the USA Blog: ATTESA Information
> 
> ...


Sean -I would be the first to acknowledge you have more knowledge about anything Skyline GT-R out there than anyone else in the English speaking world.

And perhaps I should not have said it apportions torque left and right - rather, it should have been, the A-LSD can change the amount of torque going to each wheel by way of varying pressure on the clutch plates. 

However, in all of the Japanese materials I have read, the A-LSD is described as being able to "vary the rear left-right torque distribution, hence allowing yaw control."

http://history.nissan.co.jp/GT-R/9901GT-RFC/MECHANZM/mec_fr.html
***8220;ú***381;Y�FGTR/***402;�***402;J***402;j***402;Y***402;***8364;




















Nevertheless, however you define it, I think you would agree that there is SOMETHING going on that a mechanical diff cannot do. If you are saying that the active nature allows for a gradual (or instant, depending on conditions) lock up vs an on/off mechanical diff, I would say that is partially right. I would think that, while this alone is an advantage, the added advantage of varying torque between the rear wheels would also be something Nissan thought of. I can ask next time I talk to Watanabe-san.

Anyway - the point here is, the OP was concerned with Front/Rear torque distribution, I wanted to make the point that there is also the Active LSD issue (however it works).

Aki


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## tyndago (Oct 24, 2002)

akasakaR33 said:


> However, in all of the Japanese materials I have read, the A-LSD is described as being able to "vary the rear left-right torque distribution, hence allowing yaw control."
> Nevertheless, however you define it, I think you would agree that there is SOMETHING going on that a mechanical diff cannot do. If you are saying that the active nature allows for a gradual (or instant, depending on conditions) lock up vs an on/off mechanical diff, I would say that is partially right. I would think that, while this alone is an advantage, the added advantage of varying torque between the rear wheels would also be something Nissan thought of. I can ask next time I talk to Watanabe-san.


It does do something, but I needed to read up some more on yaw control. I know of the single hydraulic path, and the clutches on each side

Clemson Vehicular Electronics Laboratory: Active Yaw Control

There is a natural differential action, and by controlling the lockup, the loaded and unloaded sides can vary in speed. Locking up the clutches will straighten the car up, opening it up will let the car turn more. 

With the GT-R Vspec being active vs a passive diff, it can unlock more with a set throttle input and G-load. However, what it is missing, from what I am seeing in the service manual is steering input, and a yaw rate sensor. 

The R34 Super Taikyu car had a yaw rate sensor, that was added to the ATTESA system, and used the steering angle input to ATTESA. It was a specially programmed ECU, and interesting as it will actually make the A-LSD work, vs being something that is mostly passive. I have all the wiring diagrams that show how to add those inputs, however without the right ATTESA ECU, those inputs aren't going to do anything. 

However, then there would be a real feedback loop. The system would know when you are turning in, or straightening up, and then with the yaw rate sensor can actually do something real about the A-LSD lockup or opening. They did it that way on the race car for a reason. Seems like the A-LSD on the street car was just more of a gimmick.


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## Steveline (Oct 6, 2010)

The Yaw rate controller is branded Mitsubishi, and is mounted on the shelf in the boot above the fuel tank, along with the other electronics! i don't have a picture handy but its on the right hand side towards the back! Having driven a couple Evo's I would imagine this would be a significant upgrade over non V-spec cars! Unfortunately I don't think i've actually driven my GTR with a fully functioning four wheel drive system yet, so cant really comment, other than to say it seamed very tail happy! But thats also to do with 500+ BHP


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## tyndago (Oct 24, 2002)

Steveline said:


> The Yaw rate controller is branded Mitsubishi, and is mounted on the shelf in the boot above the fuel tank, along with the other electronics! i don't have a picture handy but its on the right hand side towards the back! Having driven a couple Evo's I would imagine this would be a significant upgrade over non V-spec cars! Unfortunately I don't think i've actually driven my GTR with a fully functioning four wheel drive system yet, so cant really comment, other than to say it seamed very tail happy! But thats also to do with 500+ BHP


The Yaw rate sensor is hooked to the HICAS. It is not an input to the ATTESA. However as I said, on the Super Taikyu race car, they locked out the HICAS, and used the steering angle input, and yaw rate as an input into the ATTESA system. That way the A-LSD actually works.


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## SklyaFett (Oct 18, 2005)

Ok as promised though a bit late, the document I have on my PC about the differences on V-spec and none V-spec.

What is ATTESA/ATTESA-ETS/ATTESA-ETS Pro and differences between v-spec & non-vspec ?

Short Answer:
ATESSA E-TS PRO is Nissans 4WD system which transfers power and braking force where it is needed for best performance. Torque is split between front and rear wheels while braking force is split independently to all four wheels utilising ABS. In ordinary driving conditions torque is delivered purely to the rear wheels, however when the car is pushed the computer engages the front wheels and calculates the amount of power split between front and rear.

Long Answer:
The Nissan Skyline GT-R is predominately a rear wheel drive (RWD) car. All power, be it a V-Spec model or not, is transferred to the rear wheels. The 4WD control system is called ATTESA. In true Japanese style, this acronym stands for "Advanced Total Traction Engineering System for All wheel drive". This system is used by Nissan on a majority of their 4WD cars and off roaders (Shogun, Pajero, etc.). There is a further refined variation of this system, known as ATTESA-ETS. Where ETS stands for "Electronic Torque Split". This is used in the GTR. Then, there is an updated version again, known as the ATTESA-ETS Pro. The Pro spec version is used on the V-Spec varient (it stands for Victory specification, in honour of the many Nissan motorsport victories, BTW). There are other versions (ATTESA-ETS Pro ELITE, used in motorsport and not commercially available, as there are undoubtably others).

The difference between the two GTR versions is that the Pro version has control over the torque split between the left/right rear wheels (via the A-LSD rear diff) - in addition to the standard versions front/rear lockup (which is performed via an electically pumped, fluid filled, transfer case arrangement). There are also other differences in how the torque transfer is performed front/rear. Namely to do with the ramp speed of the pump (which affects the progression of the lock up) as well the monitoring of various extra sensors.

The sensors used by ATTESA-ETS are a three dimensional G-sensor and the ABS wheel speed sensors. The V-Spec variant will take into account deceleration and vertical G's in it's torque split bias, whereas the standard non-vspec GTR will not. Both versions will take note of road speed differences (via the ABS sensors) and cross reference them with the G-sensor input. If ATTESA detects a loss of traction at the rear, it will proceed to gradually lock up the transfer case (by increasing the pressure of the fluid with the electric pump) until it achieves a full 50/50 lock. Depending upon the quality of the fluid, the state of the pump, the state of the clutch pack arrangements in the transfer case, you might not get a 100% lock (ergo a 50/50 split) and this is usually the case on older cars that have been thrashed. Basically, put the car onto some wet grass/dirt, Vspec or not, and dump the clutch at 8000 RPM in 1st gear. If you don't get 100% lockup within a second (a full 50/50 split) your ATTESA system might need some attention. As Vspec or not, your transfer case should be locked. More on the differences between Vspec and non-Vspec. The Vspec cars will take into account the vertical G's, so if the front of the car is dipping (due to a decline in the road) or under heavy braking, 10% is immediately transfered to the fronts (your torque transfer gauge should show this). Also on the Vspec, if you are in a hard turn, with the rears braking traction (drift) ATTESA should detect that you are in a moderate to high G sustained corner and not take action (the normal ATTESA-ETS will in this case). The Pro version will limit torque split to the fronts until such a time as your input from the steering wheel indicates that you wish to terminate the slide (by counter steering) at which point it will immediately transfer gradual lock (in correlation to the speed of your steering input, via the HICAS computer). The system is very complex, but there is more to it than the usual dealer story that 'there isn't much difference'. The truth of the matter is that most people will never push the car hard enough to find the differences, in conjunction with the fact that a lot of second hand GTR's have 'loose' transfer cases and the 4WD system has suffered. ATTESA requires that all the wheels and tyres are identical. The same grip level and rolling diameter. One of the common mistakes that people make is using different tyres (grip levels) and different sizes (your fronts and rears should be the same size, width and height) as any small changes will drastically affect how ATTESA interprets its input. Tyre choice is also crucially important. If you use crap tyres, don't be surprised to see the 4WD system doing strange things and the handling suffering as a consequence.


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## R32 Combat (Jan 29, 2004)

I do not agree with everything you have said.



> The difference between the two GTR versions is that the Pro version has control over the torque split between the left/right rear wheels (via the A-LSD rear diff) - in addition to the standard versions front/rear lockup (which is performed via an electically pumped, fluid filled, transfer case arrangement). There are also other differences in how the torque transfer is performed front/rear.




How can pressure, delivered via 1 pipe, control the torque split between the left/right rear wheels?



> Namely to do with the ramp speed of the pump (which affects the progression of the lock up) as well the monitoring of various extra sensors.


The pressure is maintained using a pressure switch and relief valve. The system has to move upto 4cc of fluid at a pressure of 1.6MPa.


> The sensors used by ATTESA-ETS are a three dimensional G-sensor and the ABS wheel speed sensors.


The ATTESA ET-S used 3 G-Sensors, a standalone sensor for the ABS and a longitudinal/lateral sensor.



> The V-Spec variant will take into account deceleration and vertical G's in it's torque split bias, whereas the standard non-vspec GTR will not.


Why do you need to measure vertical G? There are already 2 sensors for measuring deceleration. 



> Both versions will take note of road speed differences (via the ABS sensors) and cross reference them with the G-sensor input. If ATTESA detects a loss of traction at the rear, it will proceed to gradually lock up the transfer case (by increasing the pressure of the fluid with the electric pump) until it achieves a full 50/50 lock.


Not true. Read this.












> Depending upon the quality of the fluid, the state of the pump, the state of the clutch pack arrangements in the transfer case, you might not get a 100% lock (ergo a 50/50 split) and this is usually the case on older cars that have been thrashed. Basically, put the car onto some wet grass/dirt, Vspec or not, and dump the clutch at 8000 RPM in 1st gear. If you don't get 100% lockup within a second (a full 50/50 split) your ATTESA system might need some attention.


If you do that, you will have high front torque before you pull away.



> The Vspec cars will take into account the vertical G's, so if the front of the car is dipping (due to a decline in the road) or under heavy braking, 10% is immediately transfered to the fronts (your torque transfer gauge should show this).


The ATTESA transmits front torque when braking at high engine RPM's to use engine braking to balance the car.



> Also on the Vspec, if you are in a hard turn, with the rears braking traction (drift) ATTESA should detect that you are in a moderate to high G sustained corner and not take action (the normal ATTESA-ETS will in this case).


The amount of front torque is proportional to G and wheel speed. You will get front torque, but you are busy looking at the road not the gauge.


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## SklyaFett (Oct 18, 2005)

As I said mate. It's just a document iv got on my PC. But are you saying the a-lsd does not work? The v-spec system or at least the way it works must be a bit different. Is the software the same, and its just the diff and suspension that's different on the v-specs?
Jeff


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## tyndago (Oct 24, 2002)

SklyaFett said:


> As I said mate. It's just a document iv got on my PC. But are you saying the a-lsd does not work? The v-spec system or at least the way it works must be a bit different. Is the software the same, and its just the diff and suspension that's different on the v-specs?
> Jeff


I said it above. The A-LSD does work, but it is more or less a "dumb" diff. It controls lockup with throttle, but there is no real feedback to actually control yaw. UNLESS its setup like the Super Taikyu cars. 

"There is a natural differential action, and by controlling the lockup, the loaded and unloaded sides can vary in speed. Locking up the clutches will straighten the car up, opening it up will let the car turn more. 

With the GT-R Vspec being active vs a passive diff, it can unlock more with a set throttle input and G-load. However, what it is missing, from what I am seeing in the service manual is steering input, and a yaw rate sensor. 

The R34 Super Taikyu car had a yaw rate sensor, that was added to the ATTESA system, and used the steering angle input to ATTESA. It was a specially programmed ECU, and interesting as it will actually make the A-LSD work, vs being something that is mostly passive. I have all the wiring diagrams that show how to add those inputs, however without the right ATTESA ECU, those inputs aren't going to do anything. 

However, then there would be a real feedback loop. The system would know when you are turning in, or straightening up, and then with the yaw rate sensor can actually do something real about the A-LSD lockup or opening. They did it that way on the race car for a reason. Seems like the A-LSD on the street car was just more of a gimmick."


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## akasakaR33 (Oct 10, 2005)

All I know now, is that Midori Seibi has just come out with a Digital Yaw Rate sensor, not for HICAS, but for the V-Spec A-LSD.

For those who can read the description - 
yaw rate sensor??????????????????? - ???????? | GT-R?????? ???????

Basically it says that the digital sensor replaces the OEM analog one, hence ensuring faster, more accurate response by the A-LSD. Better traction too.


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## tyndago (Oct 24, 2002)

akasakaR33 said:


> All I know now, is that Midori Seibi has just come out with a Digital Yaw Rate sensor, not for HICAS, but for the V-Spec A-LSD.
> Basically it says that the digital sensor replaces the OEM analog one, hence ensuring faster, more accurate response by the A-LSD. Better traction too.


Odd. These pages are out of the R34 GT-R Service Manual supplement. I know what I have seen on R34's. I am not aware of an early and late change, as you can see here - Yaw rate is part of HICAS. No Yaw rate in the ATTESA ETS- PRO system.



















ATTESA ETS-PRO


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## akasakaR33 (Oct 10, 2005)

Sean, I do admit that is odd. Let me do some searching in Japanese. I will also call around. Perhaps Nissan engaged in some creative advertising, who knows?

Aki


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## Addicted2Boost (Nov 15, 2007)

Thanks for all the info from various sources, really enjoying this thread. From all the info, it seems that my want for a "vspec" has subsided somewhat, and seems like the issue of torque to the front is the same and the Vpsec and the A-LSD seems its more of a 'gimmick' especially for an amature driver. 

After all even the MCR R34 GTR (based on vspec) had a hard time against a pure RWD rx7 equiped with a mechanical diff. 

Nissan GT-R R35 Vs Mazda RX-7 Vs Skyline GT-R R34 MCR - YouTube


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## akasakaR33 (Oct 10, 2005)

Well I still need to call around, BUT just thought of something - if the Yaw rate signal is going only into the HICAS - then that ALSO implies that the V-Spec HICAS, and non V-Spec HICAS, are different in operation.

OR, it could simply be that the signal is fed first into the HICAS, which then sends it along to the ATTESSA computer - so that in a V-Spec car, you have both systems working together. That would be ANOTHER difference between V-spec an non V-spec BNR34s.

Practically, if the HICAS is the same, then Midori would obviously market it as for ALL R34s, not just V-Spec models. So logically, either the HICAS is different, or the yaw rate sensor is specific to the V-Spec models. Further, the Japanese description says nothing about HICAS operation and their digital yaw sensor.

Does anyone know if the HICAS is also different in V-Spec cars?


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## tyndago (Oct 24, 2002)

akasakaR33 said:


> OR, it could simply be that the signal is fed first into the HICAS, which then sends it along to the ATTESSA computer - so that in a V-Spec car, you have both systems working together. That would be ANOTHER difference between V-spec an non V-spec BNR34s.
> Does anyone know if the HICAS is also different in V-Spec cars?


According to what I have seen on cars, and what is in the service manual supplement the HICAS on the regular and VSpec cars is the same.

However as you can see above, on the ETS Pro there is the control for the A-LSD, but no yaw rate, and no steering input.

NISMO, when they made the modifications to the R34's for racing, took the HICAS steering input, and the yaw rate input and fed it into the ATTESA ECU. It did require rewiring, it did require a unique ATTESA ECU. 

See for the A-LSD to act as yaw control, you have to know that that car is yawing. You have to know how it is moving around that fixed yaw point. You also need to know how much steering input is being fed into the car. 

The way the factory A-LSD works in the R33/R34 GT-R is from TPS input. If you are off throttle the thing is more or less open. An open diff corners easily. The two rear wheels can spin at different speeds. Start to lock it up, and you are going to straighten the car up. If its fully locked, like a 4WD truck, or a welded differential then the rear is not want to have any differential action. Its going to buck, its going to spin both tires, its going to make the car want to keep going straight. 

So as you are headed into a corner, you lift throttle to slow down, the diff opens up. Turns in nice, and now you start to feed throttle in on the way to the apex. Once you go wide open, or somewhere between there, the A-LSD starts to lock up the diff, and the car straightens up. Since there is no real feedback, its still a dumb differential. 

However if it had steering input and a yaw rate, it would see that when you are cornering and on it part throttle, that the rear end is starting to step out in a steady g load. The car will be yawing around, so it will lock or unlock the diff to help keep the car inline with the steering input. 

Torque Vectoring and Active Differential


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## akasakaR33 (Oct 10, 2005)

Sean-I finally called around, and yes you are correct. It means that someone at Midori didn't do their homework lol...


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## freakazoid3 (Jan 19, 2008)

^^Better late then never LOL :chuckle: some good info he never the less! :thumbsup:


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## R32 Combat (Jan 29, 2004)

akasakaR33 said:


> Sean-I finally called around, and yes you are correct. It means that someone at Midori didn't do their homework lol...


Really? How so?


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## tyndago (Oct 24, 2002)

R32 Combat said:


> Really? How so?


I'm always right- never wrong. Ha ha. 

This was about the Yaw rate sensor. Midori was selling an aftermarket one, and saying it worked with the ATTESA.

The factory cars don't use the Yaw sensor as an input. I know that the Super Taikyu cars did use the Yaw rate sensor as an input into ATTESA, but it required rewiring. 



> All I know now, is that Midori Seibi has just come out with a Digital Yaw Rate sensor, not for HICAS, but for the V-Spec A-LSD.
> 
> For those who can read the description -
> yaw rate sensor??????????????????? - ???????? | GT-R?????? ???????
> ...


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## K66 SKY (Jan 25, 2005)

tyndago said:


> *This one, the mechanic did not put any fluid into. *


Talking about Differential fluids, _(After doing a quick search on here)_...It seems that some Owners on here are using ever so slightly different viscosity oils in their GT-R's?!

So, What ones should we really be using for maximum life/ultimate performance on our Road cars and should we be using different weighted oils for the V-Spec and non-V-Spec model GT-R's?

Lastly, What's the most likely fault that makes this Blue BCNR33 understeer so badly after its had aftermarket Mechanical front & Rear Diff's fitted....






Sorry for all the questions but I hope someone can clear this up once and for all. 

Cheers!


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## tyndago (Oct 24, 2002)

K66 SKY said:


> So, What ones should we really be using for maximum life/ultimate performance on our Road cars and should we be using different weighted oils for the V-Spec and non-V-Spec model GT-R's?
> 
> Lastly, What's the most likely fault that makes this Blue BCNR33 understeer so badly after its had aftermarket Mechanical front & Rear Diff's fitted....


Fluids. I like Redline. I use Shockproof in the front and rear. I like my diffs to last, and it gives you a real shockload advantage. It can make the rear diff bind up a little at low speed, but I did find by setting my car to rwd it didn't bind the same under low speed high steering angle. 

Nissan's recommendations on fluid types.

Front Differential (F160) - GL5 85-90 1 liter - (1 quart)
Transmission fluid - Don't try and fill it though the gear shifter. Though the gear shifter is the transfer case . GL4 75-90 4.1 liters (4.3 quarts)
Transfercase - Nissan Automatic Fluid Type D 1.8 liters (1.9 quarts)
Rear Differential(R200) - LSD GL5 80-90 1.5 liter(1.5 quarts)

There are also two more separate hydraulic systems in the car. The power steering/HICAS, and the ATTESA system. Each use ATF. Each has its own reservoir. 

Nissan Skyline GT-R s in the USA Blog: Preparing a NISMO Nissan Skyline GT-R for a Track Day : Fluids

As far as why that car understeers. It is the reason there is an ATTESA system. A locked 4 wheel drive system really doesn't want to turn. It wants to keep both wheels/all wheels going at the same speed all the time. When this happens, the car really doesn't want to change direction. 

The more open the center diff is, with an open front diff, the better the car turns in. However under power the unloaded wheel/s will spin. This is why as you feed in power, the ATTESA system locks up the center differential. 

There are 1 way, 1.5 way, and 2 way front differentials. They probably put something pretty aggressive in it, and now the car will not turn. 

Some guys aren't "tuners" they are just parts putters. They put this part or that part on a car thinking it will make the car better. If they don't understand what they are putting, how can they expect the car to react the way they want it to?


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## K66 SKY (Jan 25, 2005)

Thanks for the reply Tyndago!

I did wonder when I read on the forum that some Owners were using exactly the same LSD oil for both the front and rear diff's. 

One of the other things that still kind of bothers me is the Diff oil temperature. I know from past experience _(thanks to my old Carlton GSi)_ that these can rocket up sharply after just a few laps on a Track. Seeing as my non-V-Spec Import R33 was designed to be used in Japan at much lower speeds than here in the UK, Do you think it would be advisable to upgrade to the larger aluminium Greddy/Trust vented Diff covers to both increase the oil capacity and try to keep the Diff oil cooler for slightly longer? Or do you think that these are a complete waste of time and the only way is to copy what Middlehurst's done by fitting extra leccy pumps and oil coolers??


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## tyndago (Oct 24, 2002)

K66 SKY said:


> Thanks for the reply Tyndago!
> 
> I did wonder when I read on the forum that some Owners were using exactly the same LSD oil for both the front and rear diff's.
> 
> One of the other things that still kind of bothers me is the Diff oil temperature. I know from past experience _(thanks to my old Carlton GSi)_ that these can rocket up sharply after just a few laps on a Track. Seeing as my non-V-Spec Import R33 was designed to be used in Japan at much lower speeds than here in the UK, Do you think it would be advisable to upgrade to the larger aluminium Greddy/Trust vented Diff covers to both increase the oil capacity and try to keep the Diff oil cooler for slightly longer? Or do you think that these are a complete waste of time and the only way is to copy what Middlehurst's done by fitting extra leccy pumps and oil coolers??


NISMO did something interesting on the R35 Super Taikyu, all wheel drive car. They only added a front diff cooler. Since the front diff on the R35, like the R32,R33, and R34 are part of the oil pan, keeping the front diff cool can help keep the oil cool, and vice versa. 

Super Taikyu Nissan GT-R Brakes and Cooling | Nissan GT-R : Since 2007

These are some of my advanced notes from talking to Mr. Tamura years ago about setting up an R32 for the circuit.

Set up car like a front wheel drive car 

He has different attesa EPROMs for different types of circuits , suggested Field ETS controller as simple alternative 
Attesa system relies on the factory ECU to sense engine load and when you change the engine load mapping , it affects the attesa system response 
He uses LSD type front diff for some short circuits 
He used Trust type large capacity front differential cover 
He recommends rear diff cooler for heavy circuit use 

Nissan Skyline GT-R s in the USA Blog: Nissan Skyline GT-R Advanced Notes

On the Super Taikyu R34, they mostly ran open front diff. They had a transfercase cooler, and a rear diff cooler. They had run the front diff cooler on the car before, but from talking to Suzuki from Shift, he said they seldom use a front diff cooler. 

I don't have a lot of data from front diff temperatures, or even transfer or rear diff temperatures. 

With that said, I have driven an R33 GT-R across the US, from California to Florida and back. No diff coolers, cruising at 80mph. Not a problem.


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## K66 SKY (Jan 25, 2005)

tyndago said:


> *With that said, I have driven an R33 GT-R across the US, from California to Florida and back. No diff coolers, cruising at 80mph. Not a problem.*


My mate James has been trying to talk me into going with him and his BMW M3 on a trip to the Nürburgring, ever since I got my Skyline. Last time we done such a journey in 2005, The loud pedals got mashed deep into the carpets as often as safely possible and 150mph+ was the norm on occasions. Something in the back of my mind _(I really dunno why unless its something I heard from Andy Middlehurst on the Nissan GT-R video)_ is telling me that treating my Import in the same way as my old Carlton would not be a good idea without improving the cooling for these vital Differential fluids first?!

Years ago, A fellow Autobahnstormers Club member called Joe built a white Lotus Carlton to compete in the Silver State Classic at the 160mph class, What he told us about his very high Diff oil temps _(Mr Ellis ended up fitting aftermarket oil pump and oil cooler to stop the high speeds/high temps from melting his cars Differential)_ led us to see just how hot ours got under normal road and Track use. Anyway _(without boring everybody whose not into Vauxhall's/Opel's)_...another symptom of mine was that the hotter my old GSi 3000's Diff got, the less willing the factory LSD seemed to want to lock up afterwards. Changing the GM OE oil to a slightly thicker BMW recommended type of LSD oil seemed to improve this mechanical fault. 

Ok, I know that what I'm going on about there is not specifically about my Skyline..._(but thanks to you I now know that the V-Spec's and non-V-Spec's require exactly the same fluids here)_...but If my Carlton's Differential oil could get so hot that the lock-up could become a bit loose and somewhat unpredictably vague after extremely hard and prolonged use....Surely the standard model non-V-Spec GT-R that's capable of much higher speeds can do the same as the Diff oil temperature rises. 

And its at these sustained high temperatures, Who knows exactly what damage this could do to the Factory GT-R's LSD??


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## tyndago (Oct 24, 2002)

K66 SKY said:


> is telling me that treating my Import in the same way as my old Carlton would not be a good idea without improving the cooling for these vital Differential fluids first?!
> 
> Years ago, A fellow Autobahnstormers Club member called Joe built a white Lotus Carlton to compete in the Silver State Classic at the 160mph class,..another symptom of mine was that the hotter my old GSi 3000's Diff got, the less willing the factory LSD seemed to want to lock up afterwards. Changing the GM OE oil to a slightly thicker BMW recommended type of LSD oil seemed to improve this mechanical fault. Differential oil could get so hot that the lock-up could become a bit loose and somewhat unpredictably vague after extremely hard and prolonged use....Surely the standard model non-V-Spec GT-R that's capable of much higher speeds can do the same as the Diff oil temperature rises.
> 
> And its at these sustained high temperatures, Who knows exactly what damage this could do to the Factory GT-R's LSD??


The GT-R uses an R200 rear end. Its a pretty proven rear end. Used in most of Nissan's line up. I would say 99% of the people out there don't need to put much concern into the diff. Good fluid, change it more than once in the cars life, should be good to go. 

In a straight line, there isn't much "differential action", so other than just regular loads, a diff shouldn't get that hot. Now if we go to a race track where you are going corner to corner with much "differential action" then the diff is going to get hot. Depending on the type of LSD, a clutch type especially gets hot. Some diffs are viscous, so the hotter they get, the less LSD action you get. 

The transfercase uses clutches. It can get hot. But again, if you are going straight, not much lockup/slip. 

Going off topic a bit, I did the Big Bend Open road race(119 miles) in a GMC Typhoon. Big heavy AWD SUV. 125 mph class, teched to 150 mph. We didn't run any coolers, but 125 mph average really wasn't "that fast". Would I put coolers on it if we were going harder? I might. Would have to see data to see if it was worth it.

From what I am hearing, unless you hit Nurburgring hard, the coolers might just be more complexity and expense vs just changing the fluid more often.


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## K66 SKY (Jan 25, 2005)

tyndago said:


> *Some diffs are viscous, so the hotter they get, the less LSD action you get.*


You are spot on there Tyndago, My Carlton's Factory LSD was indeed the viscous type...



Thanks again for all of your advice here!:thumbsup:


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## tyndago (Oct 24, 2002)

K66 SKY said:


> Do you think it would be advisable to upgrade to the larger aluminium Greddy/Trust vented Diff covers to both increase the oil capacity and try to keep the Diff oil cooler for slightly longer?


I was thinking I didn't answer this. I think extra capacity on a diff, like the Greddy parts are a good thing. Not a lot of downside to them. The OEM diffs use just a small amount of fluid, so these increase capacity around 50%. Good idea.


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## K66 SKY (Jan 25, 2005)

tyndago said:


> *I was thinking I didn't answer this. *


You kind of did for me when you said this bit below Tyndago....



tyndago said:


> *keeping the front diff cool can help keep the oil cool, and vice versa*


You made me feel much better about ordering this Greddy finned cover from RHDJapan last week. Just waiting for it to turn up now!


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