# Gearbox failers v C-clip failers (big bhp cars)



## mattysupra (Oct 31, 2008)

Been reading about failed gearbox's and it seems the fix is replacing the C-clips. I am talking about big BHP cars here. Im close to buying a R35 but would be looking for around a 850bhp one so want to make sure i know what to upgrade on the gearbox. 

Is there any 'known' failers of boxes after the C-Clip is changed for a uprated one? 

Is there other issues that still need sorting? 

What about using the launch, is it o.k to use at free will after c-clip upgrade?


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## Turbotwo (Jan 28, 2011)

I`m no expert,but at 850 bhp i think you ought to consider more than the c-clips for long term durability..1st gear upgrade,clutches,clutch baskets (sportsman clutch kit might do the trick for example)..have a look at the Dodson upgrades and cars in the projects section,there`s some gearbox info there amongst the builds.

Here`s a good page to look through. Gearboxes | Transmissions 

http://dodsonmotorsport.com/index.p...ategory_id=19&option=com_virtuemart&Itemid=30 Sportsman.


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## Stevie76 (Dec 17, 2009)

+1....1st gear as a minimum probably....best to give SVM a call and they can advise the best route. Not heard of any circlip related failures following dodson upgrades.

I would also think about uprated clutch pack etc at that power. Launching is ok after the upgrades I think but unless doing 1/4 miles it's not worth it...over stressing the box and shafts etc for no real benefit...at 850bhp nothing on the road is going to come near you launched or not.


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## CarPlanetRacing (Jan 13, 2010)

at 850bhp, we would recommend at the minimum;

Front and Rear Circlip Retainers
Uprated Clutch Plates
Uprated Clutch Piston/Basket + Seals
Uprated FWD Propshaft

If you are using the car for drag racing, then there is a strong recommendation to upgrade 1st or Full Gear Set, dependant on tyres used etc.

The circlip issue can occur on standard cars as we have seen, and the risk of failure we believe is heightened when more loading is put on the 4WD Gear (more power, more extreme driving).

Beyond the circlips, the other areas of failure (or faults) on the GT-R Drivetrain, are issues with the stock Clutch Piston/Basket Rubber Seal failing (where pressure is lost, losing drive on that particular clutch pack), Clutch plate slip (due to high torque, or insufficient clamping force on the pack), and also issues with excessive wear / play at the front bellhousing (where the bearings become loose through wear on the alloy bellhousing).
Also we have seen a few FWD propshafts snap too, we have uprated propshafts for big power cars

We can help with *any* transmission related services, we have seen pretty much any type of failure on the GT-R on stock and modified cars.

Also, cooling upgrades for your GTR at that power level would be a good idea.


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## Radical1 (Feb 8, 2011)

I was at Litchfields last week and they said there is ABSOLUTELY no need to change the c-clip on my car (custom cobb so 580 bhp'ish). I can't see any evidence of forum members gearbox failures and most seem to be tuned. Litchfield said they can repair pretty much any gearbox issue anyway so surely it's a waste of moey taking preventive measures when the risks are tiny (on <650bhp cars anyway).


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## mickv (May 27, 2009)

Agreed. Iain said the same to me. For mild stage 1/2 tunes it's overkill to replace circlips. Lots of LC starts might make it more sensible, but that assumes you have an LC worth using, which most of us don't. I might be more nervous about it if I had a tweaked MY2011 and was using LC regularly as a failure could make a real mess of the box with possibly no warranty cover. But I'll worry about that if I ever trade up.


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## Radical1 (Feb 8, 2011)

I don't even know how to launch mine and don't want to know either
I'll leave launching to the "17 year old RS drivers at the lights", really can't be ar*ed with that stuff. I agree with clarkson on that front, LC is a total waste of time not to mention gearbox stress ! I can cpount on one hand how many times I've booted it in first gear, it's more fuin with a bit of wheelspin/snaking anyway !


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## TAZZMAXX (Mar 9, 2010)

From what I've read LC can save possibly 0.2 seconds. Great. Does anyone think they are that good that they will notice? If you are going to rip your car like that on ordinary road driving you have to accept the consequences. Launch control? No thanks.


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## Zed Ed (Oct 24, 2007)

mattysupra said:


> Been reading about failed gearbox's and it seems the fix is replacing the C-clips. I am talking about big BHP cars here. Im close to buying a R35 but would be looking for around a 850bhp one so want to make sure i know what to upgrade on the gearbox.
> 
> Is there any 'known' failers of boxes after the C-Clip is changed for a uprated one?
> 
> ...


Why do you want 850 bhp?


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## JapFreak786 (Aug 29, 2003)

ah so you want a R35 now do you hey  - something more family oriented is it? lol - i'll be giving you a call on saturday night hopefully mate


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