# GTR33 OS Giken Close Ratio Gear Set, std 5speed, Advice?



## saffarco (Dec 20, 2012)

Nice day everybody,

I'm interested on OS G close ratio gear sets, want some support. Car is used as a street racer with 600whp and PTE6466 .84 turbo, normally rolling from 40kmh to 700m distance.

1/ What's better and why, 1-3 + input shaft _OR _1-5 + input shaft?
2/ Does the 1-5 come with 4th gear _OR _I get the 1-5 and put my stock gear?
3/ Do I need some other parts to do a proper swap? 
4/ Who supplies the gear set with a good price?
5/ What would you recommend please?

I'd appreciate your support..
Ali


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## lightspeed (Jul 11, 2002)

I built mine up with OS 1-4, billet centreplate, new bearings and synchros and had the gears REM finished.

4th gear is the input shaft effectively. Select 4th and the input shaft is locked to the main shaft and drives straight through at 1.00 ratio - most efficient gear in the box, lay shaft is bypassed.

OS 5th is lower ratio and good for top end acceleration but limits top speed to 180mph-ish. Stock 5th will run to over 200mph with a high rpm motor.
Stock 5th also better for motorway cruising.

You shouldn't need much else if yours is a late model 33 gearbox - early one may need some synchro parts and possibly reverse gear components. I built mine from a 32 box which needed a ton of parts from Nissan. I was lucky enough to pick up my new gearset and most of the synchros from Yahoo Auctions Japan for a bargain price.

I would definitely put new synchros and shift pawls whilst it's apart.


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## Clark Motorsport (Feb 11, 2014)

Not much I can add to that Lightspeed! 

Regarding the 5th gear you can use a 1-4 Kit (OS) and use just a stasndard Nissan 5th gear giving the said 200mph top speed. If your box has never been re-built using the OEM modified 3rd-5th kit then you will need said syncros and baulk rings to make this work.

The OS Giken center plate is worth considering if you run 600hp as the torque pulls the two shafts apart the Billet OS keeps this in place.

Really strong kit as you would expect from OS Giken

Rich


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## JTJUDGE (Nov 21, 2011)

How much does the 1-5 OS kit cost Inc fitting ?


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## muzzer2002 (Oct 10, 2007)

i was round about 4.5k to have mines suplied and fitted


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## JTJUDGE (Nov 21, 2011)

Hhmm 6spd getrag is a a better/cheaper option then


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## muzzer2002 (Oct 10, 2007)

im not sure tbh u need the getrag , the cross member then muck about with props irc then a 34 clutch as well am sure it prob work out about the same


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## saffarco (Dec 20, 2012)

Thanks for the replays folks..
I believe I'll need 1-4 OS + input shaft. Will keep 5th stock for top speed.



> Regarding the 5th gear you can use a 1-4 Kit (OS) and use just a stasndard Nissan 5th gear giving the said 200mph top speed. If your box has never been re-built using the OEM modified 3rd-5th kit then you will need said syncros and baulk rings to make this work.


My box never been opened, when you say "make this work" does that mean that to fit the 1-4 + input shaft OS kit I will need syncros and baulk rings? Sorry but I'm not into transmissions that much.. One of the main objectives of the thread is to know what's needed to make the kit works (parts etc..), if somebody could list me the parts I would appreciate it..


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## nightcrawler (May 7, 2010)

whats the maintenance for the OS? does it need to be rebuilt every now and then even for fast street cars? getrag kit will cost around £5k including nismo clutch from nengun/rhdhapan if im not mistaken, so i guess OS is cheaper depending on its maintenance?


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## saffarco (Dec 20, 2012)

Alright, I think I found the cheapest of what I need from rhdjapan?

OS Giken Close Gear Kit 3-Speed Nissan RB26DETT + Input Shaft - RHDJapan

OS Giken Strengthened MT Center Plate RB26DETT - RHDJapan

Around $3,000 shipped. Now looking for what do I need else...


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## saffarco (Dec 20, 2012)

hi guys,
I have by now the OS 1-5 gearset + inputshaft + center plate. I also have baulk rings, countershaft bearings, needle bearings and some other stuffs. I'm looking now for the synchros which I can source. Could you guys please help me what do you I need else? I think there are other types of bearings and seals I read somewhere ... Any help would be appreciated..


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## FRRACER (Jun 23, 2013)

muzzer2002 said:


> im not sure tbh u need the getrag , the cross member then muck about with props irc then a 34 clutch as well am sure it prob work out about the same


Easier to fit the getrag than to strip your old box and rework that.


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## scoooby slayer (Jun 13, 2009)

ive had a route 6 3 speed which is virtually identical gearing to os 3 speed, and id much prefer a getrag 6 speed personally. 

1st gear was massive on my route 6 to big imo.


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## saffarco (Dec 20, 2012)

Hello everybody, 
I started working on the 1-5 OS kit. I have a problem currently, I would appreciate if someone could help. My mechanic is saying that there is a difference between the synchro sizes, see pics below. Anybody knows where can have these? I bought all stock synchros from rhdjapan, this one though I don't know where to get from. I'm assuming this is a GTR33 box I hope I'm not wrong, we installed everything except this synchro I'm asking about. The new shaft is on the left without a synchro, the stock shaft is on the right with the synchro. The stock synchro doesn't fit the new shaft.


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## lightspeed (Jul 11, 2002)

Maybe your old box was Auto Gallery Yokohama modified?

They machine the gears and use multi part synchros for a better shift.


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## Clark Motorsport (Feb 11, 2014)

Yes you need ALL of the later baulk rings and syncros to suit. From 1st to 5th.


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## saffarco (Dec 20, 2012)

Clark Motorsport said:


> Yes you need ALL of the later baulk rings and syncros to suit. From 1st to 5th.


You have a PM. I would appreciate your support


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## MIKEGTR (Jul 8, 2005)

OS 1-5 is the best mod I've done on my car.
The long first gear is perfect for big turbo cars and is great for launches and keeping the car on boost


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## saffarco (Dec 20, 2012)

MIKEGTR said:


> OS 1-5 is the best mod I've done on my car.
> The long first gear is perfect for big turbo cars and is great for launches and keeping the car on boost


Great. I have been thinking to increase my turbine housing size (currently 0.84) since as you mentioned that the long ratios help spooling and having big turbos. What's your turbo set up and what power you have please? On my PTE6466 0.84 I guess it would be fun to drive though. 

For my issue above, my bad I missed getting the 4th gear synchro (32604-40P61).


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## jdmchrist (Apr 27, 2009)

How many whp you are going for? And which clutch are you gonna use?

I got an rb30 with a pte 6266 gen2 and looking for drivetrain option at the moment.


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## saffarco (Dec 20, 2012)

jdmchrist said:


> How many whp you are going for? And which clutch are you gonna use?
> 
> I got an rb30 with a pte 6266 gen2 and looking for drivetrain option at the moment.


Now making 617whp/466lb.ft @1.5 bar with Gen2 6466 .84 T4 divided turbo, 50mm wg and trust ex manifold. My clutch is OS twin plate. I'm looking for 700whp with methanol, will be using OS triple plate clutch.

I still have issues with the transmission parts, it's not as they say a direct replacement. I installed all parts and all synchros, but the gears don't rotate "my mechanic said".


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## cobrAA (Jun 1, 2008)

Didn't they provided a guide with the os gearset with all the parts needed to fit ?

I wanted to buy this kit this weekend for my R32 GTR but if theres a lack of support regarding parts, I will forget it lol !


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## cobrAA (Jun 1, 2008)

..And I'm also curious. whats the point of the input shaft ? I rarely heard of a 4th gear breaking. is it common ?


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## saffarco (Dec 20, 2012)

cobrAA said:


> Didn't they provided a guide with the os gearset with all the parts needed to fit ?
> 
> I wanted to buy this kit this weekend for my R32 GTR but if theres a lack of support regarding parts, I will forget it lol !


For an r32, would need TONs of parts. You can search and find all parts need. OS don't provide a guide.


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## cobrAA (Jun 1, 2008)

oh really ? that means, i would be better off buying a built box then lol.. I don't understand why it would be that much different tho..

I had my box rebuilt once and we simply bought a 300zx kit and we found everything we needed. All we are doing is replacing the gear, are the syncro different from an oem r32 ?


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## saffarco (Dec 20, 2012)

cobrAA said:


> oh really ? that means, i would be better off buying a built box then lol.. I don't understand why it would be that much different tho..
> 
> I had my box rebuilt once and we simply bought a 300zx kit and we found everything we needed. All we are doing is replacing the gear, are the syncro different from an oem r32 ?


You would need the late r33 gearbox parts in order to fit the OS kit in your r32, and some other parts as well. The OS kit is not designed to fit on the r32 directly. You can search and see, there are a lot of topics covering this. Synchros are different yes. 

Buying a built gearbox is much more expensive than fitting the OS kit.


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## lightspeed (Jul 11, 2002)

Better to buy a cheap 33 box as a starter than convert an early 32 box.
I know as I did the latter. Loads of small improvements in the 33 box means many of the major components are different.


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## R390LM (Mar 7, 2010)

saffarco said:


> Nice day everybody,
> 
> I'm interested on OS G close ratio gear sets, want some support. Car is used as a street racer with 600whp and PTE6466 .84 turbo, normally rolling from 40kmh to 700m distance.
> 
> ...



get a hollenger and call it a day ! :bowdown1:


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## R390LM (Mar 7, 2010)

lightspeed said:


> Better to buy a cheap 33 box as a starter than convert an early 32 box.
> I know as I did the latter. Loads of small improvements in the 33 box means many of the major components are different.


JZA80 supra 6sp box and build from there. gear set swap the covers and bell housing done.


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## DirtyTorquer (Sep 3, 2013)

R390LM said:


> JZA80 supra 6sp box and build from there. gear set swap the covers and bell housing done.


And that works with the transfer box or are you just talking for a pure RWD application?


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## R390LM (Mar 7, 2010)

DirtyTorquer said:


> And that works with the transfer box or are you just talking for a pure RWD application?



remove the bell housing or make your own adapater plate to use the stock Toyota one. Next split the box open make sure you use wood when hammering it open and pull the cover off. get things checked out before putting back together.


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## DirtyTorquer (Sep 3, 2013)

Not exactly what I was asking dude. I am fully aware how to open up a gearbox and either a custom bell housing or plate adapter for the bell housing, but what about the GT-R transfer box? If someone were to go RWD then there are plenty of other gearbox options out there of sufficient torque handling capabilities. My question was with your initial comment, are you talking about this conversion working with the GT-R 4wd system or just having a RWD GT-R? My apologies if I was not clear in my question.


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## Dan ep3 turbo (Sep 29, 2013)

R390LM said:


> remove the bell housing or make your own adapater plate to use the stock Toyota one. Next split the box open make sure you use wood when hammering it open and pull the cover off. get things checked out before putting back together.



What would be the point of that when it's basically a r34 getrag box?


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