m73m95

I'm wondering how big of a problem this really is...

Maybe there are a few "bad" years of forks from Porsche? A change in suppliers or something? There has to be quite a few people with heavy PPs, and either only a few have had problems, or no one talks about it. Its strange that Josh has broken 2 of them, in the exact same spot. One of them was even heat treated. Then Cole has broken one, only on the other side of the fork, but same location on the fork itself.

I'm thinking about making a few new ones out of some good cold roll plate. The stock unit is Forged (Not cast like I originally thought), but either way, the tensile strength is 45k psi. The difference is hardness. A good cold roll will have the same tensile strength, but will also be more ductile=Less brittle.

I don't have access to a CNC, so the plate version won't be as pretty... but it would be just as strong, and cheaper to produce...Unless one of you has access to a CNC. Then the billet unit would be the way to go.

Cole

Fwiw, I have a spare fork here if anyone needs one to work with. I bought it before welding up my broken one.

tman

I'm not sure why you guys insist on running those heavy pressure plates, especially with all the clutch fork problems.

Rogue_Ant

Agreed tman... I purchased this pressure-plate before I was aware of any fork problems. Believe me, it is something I've regretted.
In fact, with the proper clutch disc material, I don't see the need for anyone to ever go beyond a KEP stg I.

tman

Easier on your left leg also.

azmi951

I had the KEP2 now I run a KEP1.

Here are some pictures of a new OE fork and an old one I had. look at the differences.

A.Wayne

Try indexing your clutch pedal ..........

Thom

Surprised no one has mentioned clutch pedal travel adjustment already - too little travel means too much assistance and increasing the risk to increase excessive load on the fork/PP when pushing down the pedal too far. Things get worse when jumping on the pedal like a nutter.

If David did 70k miles, a friend 40k miles and I 14k miles then maybe the problem doesn't come from the hardware.

333pg333

Well I was trying to decide what pp to use. Kep2 or the one that Southbend supplied. Guess I'll try the Southbend one. Think we'll reinforce the Blaszak fork just the same though. A bit concerning and thanks for posting Josh.

Rogue_Ant

Yep, adjusted it so that it properly dis-engages the clutch.

I think your meaning too much travel? I suppose there is a possibility that too much travel causes the fork to pull too much on the PP, exceeding the torque capacity of the fingers... BUT, the problem I have with that theory, is the slave is self adjusting. The stroke length on the slave is always the same (assuming you don't artificially limit it by lessening the clutch pedal travel). So the only conclusion would be that for a normal slave stroke, the PP is exceeding the capacity of the fork.

Regardless, one common theme is that the majority of people that have broken the fork are running an aftermarket pressure plate. Furthermore, the majority of them are running the KEP stg 2.

Also, it appears that the fork is not evenly applying pressure to the TB. On both of my forks that broke, the right finger has a deeper wear groove then the left - and it was the right finger the broke both times. On Cole's pictures, it is the left finger which has more wear - and it was the left finger that broke...
Perhaps the bellhousing isn't perfectly cast, causing the fork pin alignment to be off, resulting in the fork fingers to be unevenly loaded. (?)

Again, with a stock pressure plate, a little bit of uneven load is within the tolerance of the fork. But, when we throw in a heavy pressure plate, this uneven load eventually breaks the fork.

Patrick at this point, I definitely would suggest going with the SB PP. I don't want people to have the same headache as I've had.

Thom

I adjusted the pedal travel so that I could feel the disengaging point when the pedal is very close to the firewall. In that case I know that the PP will be pulled backwards to a minimum extent, thus meaning the fork works less hard than with more PP travel.
Well, my understanding is that PP stiffness is not linear and increases with travel.

Inversely, setting the clutch biting point "too high" means than whenever you push the pedal past the biting point then you apply extra, unnecessary load to the fork/PP.

A long pedal travel isn't the most comfortable way to change gears, but I'd rather beef up my left leg than replace clutch forks every once in a while.

A.Wayne

when indexing , the pedal goes down just far enuff to dis-engage......

Rogue_Ant

The PP most likely follows Hooke's law (spring). And, yes the more travel, the more force required.

Yes, I do know how to adjust a clutch, but good info for those that do not.

Conversely, you can "under-adjust" the clutch that will allow the car to shift, but is still dragging... This can cause more stress/wear on the synchros and transmission, and make high rpm shifting difficult.

I do not want a dragging clutch, so a proper slave throw is whats needed - and a fork that can handle the added stress of a heavier PP, or resort to using a lighter PP.

Thom

So, how have you had the pedal travel adjusted?
How high/low have you had the biting point?

If the biting point is in the first half of the pedal travel then I would say it may result in strain on the fork excessive to the point of breaking it in the long term.

Mine is set to disengage at about 2 thirds of the pedal travel, perhaps even lower.

333pg333

What about the idea that welding onto forged can weaken it?
Isn't forged stronger than billet?