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Thrust race fork

Sydneykid
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Sydneykid Grand Master

Sydneykid

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Hi guys, any one ever broken a thrust race fork on a GTST? One of our circuit race cars broke one on the weekend. Didn't have a very big clutch in it either. It also broke the pivot "mushroom", can't tell which happened first, but both are broken.

If anyone else has broken either the fork or the pivot "mushroom", did you replace it/them with something better/stronger? I had a look at the GTR one and it looks the same, bit hard to tell as it is in the gearbox though.

Any help/input would be greatly appreciated.

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GTS-t VSPEC Grand Master

GTS-t VSPEC

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Hi Sydneykid, Mates have had a GTR break two in it's PPG box. PPG make a steel fork which is meant to be much stronger, but is almost $1000, which seems quite expensive, but seeing as they break the factory ones then there is no choice. This car has 500rwhp, so I'm not sure if your's is up in that same power level. When they break they have caused other damage to the box.

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Sydneykid Grand Master

Sydneykid

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Hi GTS-t VSPEC, I think power output is pretty much irrelevant but the resistance to compression from a high clamp pressure plate is an issue. This car had a very mild clutch and pressure plate, so even that reasoning doesn't seem to fit.

RPM can also be relevant in that it can make thrust races fail and this damages the fork, but the race made no noises at. So I doubt the source in this case is thrust race failure.

It's about to get the usual OS Giken twin plate installed (while the box is out) so I figured I'd check around and see if anyone else had this problem and knew of a fix. I don't want to pull the box out again if it breaks another one. Not if there is an answer anyway.

Thanks for the input.

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Sydneykid Grand Master

Sydneykid

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Hi Guys, it certainly wasn't being driven very harshly at the time it broke, I was doing a cool down lap with very gentle gearchanges. Plus I am very light on gearboxes and clutches, too much mechanical sympathy the "drivers" reckon.

I'll keep checking around, we have a couple more days before the OS twin plate will be ready as the clamping pressures need setting up. If I don't hear that it is a common problem (ie; freak accident), I will stick a new one in and move on.

Thanks for the input.

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gtrken Grand Master

gtrken

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Paul you tosser ( j/k ), your talking about the gear change forks ( selector forks ).

Sydneykid is talking about the fork that is attached to the thrust bearing which pushs on the clutch.

Yes , Nismo do a thicker one for the GTR cos they break with triples in them.

I have a complete HKS triple for a GTR including the thicker ( and longer to decrease leg pressure )clutch fork for sale if interested.

Cheers

Ken

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Sydneykid Grand Master

Sydneykid

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Hi guys, OK did some research overnight. It seems the R32 pivot is a bit weak and susceptible to breakage. Nissan recognised this and released an upgraded one for the R33 S1 (S11's and R34's have pull type pressure plates). The original R32 ones break with standard clamping pressures, heavy duty and multi plate clutches would certainly be a problem.

So, any of you R32 owners out there, next time you change the clutch I would strongly suggest upgrading to an R33 S1 pivot. Cost is peanuts compared to pulling the gearbox back out again.

Thanks to the guys for your input, hope it saves someone else from the same problem.

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