Bad pressure plate

[07gts197]

What are the common signs of a bad pressure plate? From googling here and other boards it looks like it can include difficulty getting into 1st and reverse, some difficulty shifting and a high engagement point. Anyone here have any firsthand experience with this?

A little background if you havent read my other threads, my original clutch grenaded itself and I had Ford replace it with an Exedy Mach 350. That was back in 2013. Since then, I dont remember before this, getting into 1st, 2nd and 4th especially has been getting harder to do. If Im rolling I can slide right into 1st no problem. Otherwise I have to put it into 3rd then 1st. Also sometimes if Im stop and go traffic so Im still in 1st, if I push the clutch in it wont let me shift out of 1st. And to make it even more strange I get locked out of 2nd at low rpms like when shifting 1-2 in a parking lot.

So does it sound clutch related?

 

[702GT]

If you put an inertially heavier pressure plate (higher clamping force) in an OEM clutch system you are demanding higher psi requirements from the Master Cylinder to move the pressure plate. The OEM unit by design is built to deliver a rated psi tolerance, like anything else beyond its intended design you could have issues. There are 2 kinds of hydralic leaks possible in the clutch system. External and Internal. External usually happens between the Master and the Slave, though rare. Internal happens within the Master, when the plunger seals leak-by causing hydralic pressure to drop. This leak can be caused by a multitude of issues. Either the psi requirements are beyond its ability to provide, or the seals have worn or failed to seal in the increased pressure demand.

'13 GT500 MC should be a go-to upgrade when increasing hydralic pressure demands in the clutch system. Beyond that, pressure plate failure is typically associated with "riding the clutch" either by foot floating on the pedal or the hydralic systems inability to fully disengage the pressure plate from the clutch, causing uneven wear on both materials. In less common instances, the pressure plate fingers may also deform and over time not allow the pressure plate to fully disengage from the clutch disc. Usually something found on a PP that's been re-used and just had the clutch disc replaced.

 

[07gts197]

As long as Ive had the clutch its acted funny. Its like I have to dump the clutch every time I take off. Its quite annoying.

Also I swapped to a 13 gt500 clutch master cylinder less than 1k miles ago. It made the clutch engage even higher than before.

 

[702GT]

The GT500 MC will raise the engagement point because of the difference in dimension between the OE GT and GT500. The GT500 MC being a bit longer and slightly higher volume. If you're still having difficulty getting into gears with the pedal fully depressed, there are only two things I can think of clutch related to rule out;

- Hydraulic line ballooning (check the entire length of the clutch line, if it has ballooned you'll know, it'll look like a blister on the clutch line, or the line will be deformed "swollen" in a length. Not a common occurrence.)
- Hydraulic leak (would be a visual leak, check either end of the clutch line for signs of fluid. Even more rare would be a break in the slave body itself, would see low brake reservoir in either case.)

If your engagement point is high on the pedal, that means the pressure plate is engaging/disengaging with minimal slave throw. If you follow that logic, it means that the Master/Slave and components therein are working properly. If you follow the mechanical movement of the pressure plate, as the PP wears and components near failure, your engagement point will actually drop. The only wear item to really be concerned with is the finger diaphragm (the black metal fingers usually weighted that the slave bearing pushes against to actuate the PP). The PP itself will out-live the clutch disc, as it's essentially a brake disc that clamps the clutch material to the flywheel. I really don't think you have a pressure plate problem, given that you have high engagement yet difficulty getting into gears.

The fact that you stated, if you're rolling you don't have trouble moving into gears, to me suggests worn or failing synchronizers. I would rule out a bent/damaged shift fork, as that typically shows as difficulty moving through all gears and/or being completely unable to enter a gear or more, ever. Synchronizers for specific gears can be damaged/worn/failed and only affect that gear. Unfortunately the only way to confirm in early stages of synchro problems is to just go ahead and rebuild the tranny. Alternatively, only time will reveal bad synchro's, as they get worse you'll start grinding through those bad synchro's as you change gears.


Just my $0.02, based on the description of issues you've given, I think your issues are in the tranny not the clutch.

 

[46addict]

The issues you're describing are just like mine, and we have the same aftermarket brand clutch. From the consensus of the responses in my thread, and the synchro test TSB you posted, I'm leaning towards the master cylinder.

 

[07gts197]

For me that cant be the case because I have a new unit. Maybe a remote fluid resivour would help, I dont know.

 

[RocketcarX]

The Exedy clutch is the problem, put an OEM clutch back in it and forget it. I had the Mach 500 and hated it, i have no idea why people love these clutches so much.

 

[07gts197]

Id believe it after all the research Ive done. I dont need a clutch just this moment and now this is my dd so no doing crazy things to it right now lol but this is good to know thanks. That would explain a lot too.