Hello all,

So, with my ACT Extreme clutch kit for the last few years, it has managed to snap 2 clutch forks already. I am assuming the high-pressure plate is just too much pressure for the OEM clutch fork for an FC. I can't seem to find any aftermarket or reinforced clutch forks for FC, so it appears that my only option is to downgrade my pressure plate to a softer one.

After reading some older threads, it seems like the softest ACT clutch kit (street/strip) can still break the OEM clutch fork! With my engine making 250-300 lb-ft (as measured by my butt dyno), which clutch kit out there can hold up to 300 lb-ft without snapping the OEM clutch fork again??

Thank you all for your help!

 

if you're breaking them that easily then you aren't giving the proper care to the piviots and slides of the bearing and pivot.

 

next step is twin plate, they have more clamping, but pedal effort is like stock

 

Proper care? Please translate that as I wasn't aware of maintenances needed for transmissions aside from making sure the hydraulics are holding pressure to move everything. Perhaps you meant proper installation in the first place? That is one thing I can't verify as I always leave the motor and transmission for my mechanic with his shop and tools. For better or worse, I'm now with a new mechanic since I've moved to another town, so I'll definitely be more watchful this time on how the fork, pivot bolt, and the clutch put back in together.

 

I never have problem with that I think that there is some problem with the installation and/or adjustments on the pedal or slave cylinder pin that excess pressure is present at the moment you presss the clucth pedal. I use factory master cylinder pump and slave cylinder with steel braided clutch hose. I lubricate with moly-graph grase the pivot points on the fork, pin and release bearing. This help to avoid any unnecesary friction.

 

I use the ACT Stage 1 clutch, it's worked great for almost a year. My slave cylinder broke shortly after but I should have replaced that anyway. New slave/master cylinders, stainless line. Molybdenum grease on everything. If you have to replace your clutch, make sure you do it right and don't miss a thing. Especially the pilot bearing/seal.

 

Thanks for the inputs, everyone. The transmission is now out and it turned out the fork was indeed broken. The snapped-off fork finger also managed to partially chew up my flywheel. Luckily, I have a two-piece flywheel where I can just swap out the friction plate only, instead of replacing the entire flywheel.

Another interesting tidbit was my mechanic's discovery that the broken fork was made of cast iron, while the newly-acquired fork was made out of stainless steel (also made by Mazda). Previously, I've tried to look up any "upgraded" or reinforced clutch fork for the FC, but came up with nothing aside from some FD guys fabricating their own reinforced forks. So, I thought I was going to get another OEM iron fork. Did Mazda actually address the cast fork issue accordingly? Either way, I'm hoping the new SS fork will last longer than the old/original fork, especially now I've "downgraded" to the ACT stage 1 kit with a softer pressure plate.

 

All the shift forks I've seen are stamped steel, not stainless, definitely NOT cast.
I'd like to see a pic of the "OEM Mazda cast fork".

 

The way the original fork snapped (i.e. clean separation with no obvious bending) appears to be similar to cast iron when it cracks, so that's how we concluded the fork to be made of cast material. Obviously, I'm not going to alloy test the broken fork, hence why I brought up my question about if Mazda changed the manufacturing process to its OEM part, similar to what some car manufacturers do after certain recalls.

And yes, the new fork isn't "stainless" by any means. That was just me mentally rolling steel in with other SS stuff I ever deal with =)

 

the FD has a cast fork, the FC and all previous rotary powered cars and trucks had a stamped steel fork. i haven't ever seen one break(FC or earlier, the FD forks do tend to crack like you describe), if you have been having this problem before, something else is wrong. was the transmission nose cone for the bearing clean and lubed? alot of lazy turd mechanics just slabber on some more grease and put it on the dirty nose, eventually causing the TO bearing to grab and seize.

 

If looking for a replacement clutch, should look at a used os given twin disc. I scored one one the forums shipped to my door for $350. With only .04 thickness used on each disc..