rocketrider2

Well I just had it happen a couple of days ago in morning rush hour traffic. Heard a metalic twang and felt the cluth pop under my foot. Clutch pedal went to the floor. Had the car flatbedded over to the Indy I use. Borescope revealed broken clutch fork. They are going to disassemble at the beginning of the week to see if they can discover the failure. Car has 71K miles and has been on a stage 4 upgrade since 30K miles. I changed the clutch, pressure plate and put in a light weight fly wheel back then. When they replace the broken fork I am putting back in the dual mass flywheel and having the the GT3 mod done to the slave cylinder.
I just cant ever remember reading of a clutch fork failure on here...

Lane

John D II

I have not heard of one either...

rocketrider2

Well it turns out it wasnt the clutch fork but the release bearing literally shattered.
I have not heard of that one either. Is there a stronger alternatiive to the stock bearing?
Any input is appreciated.

Thanks
Lane

pete95zhn

Well you're not the first one, just check 997 GT3 forum and Mobonic's build thread, there's more story of a similar issues with pics. Seems to be more common with 997 GT3's.

Well you can use Cup car's hydraulic PP, but it's pushing, not pulling, so the whole clutch assy must be changed to something like this.

blockhed

or go into the gt2/3 set up works great

pete95zhn

Which is the excatly same than 997 GT3...

rocketrider2

OK so the release/throw out bearing shattered. The bearing was part of the Sachs light weight flywheel, clutch and pressure plate package that I purcased from Imgaine Auto and the same one EVOMS sells.
So here is what I want to do, I am returning back to the stockdual mass flywheel. Will the upgraded Sachs pressure plate and clutch work with the stock flywheel. If so do I need the Sachs bearing or the stock bearing?
If the stock flywheel cant work with the Sachs parts what pressure plate/clutch would you suggest. The car is running upgrade K24 turbos with the stage 4 tune and all the associated parts.
Thanks for the help!

Lane

pete95zhn

LWFW is thinner, so the release bearing for LWFW has longer "claws" than the one meant for dual mass FW. Otherwise the PP and clutch are OK. The problem IMO is not in the release bearing itself, but in stronger PP, which increases the force to release bearing's claws. OTH it might be a material problem with a certain set of bearing's claws because most reports are from 997s and upgrades made recently.
One more thing to note is that Sachs release bearing has 34mm ID ( The guide tube tube is 31.8mm OD ) and Porsche OEM release bearing 32mm ID. There might be problems with this -At least I had- when release bearing has a change to move around turbo's (also shorter than GT3/2's) guide tube and clutch fork may slip away from release bearing's claws. Which means you don't have a clutch anymore. So I recommend to stick with OEM release bearing and check that the guide tube (around transmission's main shaft) is changed to a correct one if a LWFW is installed to a turbo's transmission.

rocketrider2

Pete thanks for the heads up. So just to make sure I am getting this right:

1- I can use the upgraded clutch and pressure plate with the stock dual mass flywheel.
2- I will need to use the OEM bearing to fit the stock fly wheel.
3- Also I will need to get the longer stock bolts to remount everything back on to the stock flywheel, the bolts for the LWFW are too short.

To my knowledge nothing else was changed in the transmission when I had the Sachs LWFW, PP and clutch installed. That being the case everything else in there should be ok

Thanks
Lane

Kevin

Lane, it's not recommended to use the same clutch disk when you move back to the dual mass.

The shattered T/O bearings often have previous wear to the pad surfaces where the fork rides. I have seen wear damage to the fork and off-centered wear on the T/O bearing. This causes uneven force or a twisting action. Failure of the T/O arms will occur. If the factory lube was not used on the metal to metal pad surfaces, the fork pads mushroom. Breakage of the ear is the result.

FYI, if you have close to 35 to 40K on your existing clutch, you might want to replace everything.

rocketrider2

Kevin thanks for jumping in. As a matter of fact I asked my Indy to call you because I consider you the resident expert on these cars.
Do you have clutch and pressure plate you recommend? I want to retain the stock flywheel, the noise from the light weight one just wore me out...lol.
We will most likely order everything we need through you. Just let me know the parts and models of everything, even down to the correct lube to use.

Thanks
Lane