Upgraded Clutch Squeak

[Rybot]

I seem to be going for gold on the reoccurring trans issues, don't I?

Clutch pedal still feels solid through the revs 6 months down the line.
That's good!
Actual OEM Subaru replacement release bearing is now squealing again.
That's bad!
Nothing else transmission related seems broken, yet.
That's good!
It's now getting into the colder months when I have less motivation to work on the car, especially this caliber of work.
That's bad!

So yeah, 6 months is all I got from this release bearing before it started failing.

I took a look at another thread talking about quality release bearings.
One was a Rock Auto SKF N4111. No idea if that'd help or fix anything.

I've already got the Velox fork and pivot ball.

I need either a stronger replacement, different geometry pressure plate with the same clamping force so as to mitigate excessive ToB wear, or a properly lubed ToB.

Any ideas @humfrz, @Ultramaroon?

You think the heavier clamping load of the pressure plate is causing a crazy amount of wear?

FYI, I've only driven it like 4k miles or less since the install, but it did get me through a season of AutoX.

[Tcoat]

If you replaced the TOB with the old original part number then it makes sense you had the issue return. Need to ensure you got the new part number. If it was the new number that you need to dig deeper.

[Rybot]

Originally Posted by Tcoat

If you replaced the TOB with the old original part number then it makes sense you had the issue return. Need to ensure you got the new part number. If it was the new number that you need to dig deeper.

Do you mean the new SU00307349?

If it's only a Toyota part number, then I probably didn't get one.

I had to panic buy two from a Subaru dealership back in July since I didn't think my ToB, at the time only 2 months installed, would be as hashed and broken as it was.

I can double check part numbers later, but I highly doubt it's the "new" one.

[humfrz]

Originally Posted by Rybot

Do you mean the new SU00307349?

If it's only a Toyota part number, then I probably didn't get one.

I had to panic buy two from a Subaru dealership back in July since I didn't think my ToB, at the time only 2 months installed, would be as hashed and broken as it was.

I can double check part numbers later, but I highly doubt it's the "new" one.

Well, that's a bummer ......

OK, as @Tcoat suggests, check and see if the new and improved TOB was installed.

We can go from there.


humfrz

[RallySTI]

Originally Posted by Rybot

Do you mean the new SU00307349?

If it's only a Toyota part number, then I probably didn't get one.

I had to panic buy two from a Subaru dealership back in July since I didn't think my ToB, at the time only 2 months installed, would be as hashed and broken as it was.

I can double check part numbers later, but I highly doubt it's the "new" one.

Subaru Part number is 30502-AA150 and will have a white dot on one of the ears of the bearing.

[Rybot]

Originally Posted by RallySTI

Subaru Part number is 30502-AA150 and will have a white dot on one of the ears of the bearing.

I was just looking at that and saw two different numbers for 2017 BRZs from a random parts site.

The 30502AA051 is the old one, I think, looking at amazon history and reviews dating back in 2016.

Was this revised bearing meant to mitigate premature failure?
I'm not precisely sure what or why my bearings keep failing, but when they start making this noise, once removed, they aren't the easiest things to rotate.

I'm assuming there's too much force on the face causing excessive pressures on the moving surfaces which in turn exacerbates the wear.

[RallySTI]

The Subaru TSB says that the grease has been improved and doesn't allude to any other design changes.

If the grease is wearing out or the body of the release bearing is melting from heat then I would think the revision should help this issue.

Do you have free play at the top of your pedal travel ?

[Rybot]

Originally Posted by RallySTI

The Subaru TSB says that the grease has been improved and doesn't allude to any other design changes.

If the grease is wearing out or the body of the release bearing is melting from heat then I would think the revision should help this issue.

Do you have free play at the top of your pedal travel ?

If by free play you mean smooth pedal travel until I reach my catch point, yes.

If by free play you mean a loose pedal until I hit any resistance, no.

I've raised and lowered my catch point many times due to all these issues.
I even switched out the slave cylinder to see if that'd help back when I was having pressure plate issues.

[RallySTI]

Originally Posted by Rybot

If by free play you mean a loose pedal until I hit any resistance, no.

This !

With out this the bearing is slightly loaded against the diaphragm spring and causes premature wear.

Try adjusting the clutch pedal, you will want to turn the threaded rod clockwise. This will give you some free play. About a half inch of free play is good.

[Rybot]

Originally Posted by RallySTI

This !

With out this the bearing is slightly loaded against the diaphragm spring and causes premature wear.

Try adjusting the clutch pedal, you will want to turn the threaded rod clockwise. This will give you some free play. About a half inch of free play is good.

As far as I'm aware, a release bearing is designed to sit against the pressure plate and spin with it. The spring behind the clutch fork puts very light pressure on the bearing ensuring it shores up the dead space. I don't want a dead/loose pedal. I'd rather a smooth travel until it hit the catch point.

Adjusting the pedal in the footwell like that doesn't modify the actual slave cylinder's resting location on the fork to then adjust the release bearing's preload on the pressure plate. It just modifies the location of the pedal catch point during the pedal travel.

I could be wrong, but I've been under that footwell enough to think that's how it works.

[Rybot]

Welp. The part number I installed is 30502AA051, which I think is the old number, as I suspected.

I already ordered the new one and clips. I just need to find some time and motivation to drop the trans again. I'm also pretty sure I cross threaded one of the slave cylinder bolts...

We'll see.

[Ultramaroon]

With respect to clutch pedal free play at the top, the main point to consider is how the self-adjusting mechanism works.

The piston in the master cylinder must be allowed to fully extend. At the end of its travel it opens a port to allow fluid exchange between the reservoir and the rest of the system.

It works just like a brake master cylinder except in reverse. As the clutch wears, the TOB is pushed further away from the pressure plate. The fluid flows back into the reservoir.

This adjustment can be tested simply by pulling the clutch fork forward by hand. If it gives, then that port is open. The clutch pedal will have to be pumped a couple times to extend the pushrod out of the slave cylinder. Either that or wait a few minutes for the piston to extend on its own.

[RallySTI]

Originally Posted by Rybot

As far as I'm aware, a release bearing is designed to sit against the pressure plate and spin with it. The spring behind the clutch fork puts very light pressure on the bearing ensuring it shores up the dead space. I don't want a dead/loose pedal. I'd rather a smooth travel until it hit the catch point.

Adjusting the pedal in the footwell like that doesn't modify the actual slave cylinder's resting location on the fork to then adjust the release bearing's preload on the pressure plate. It just modifies the location of the pedal catch point during the pedal travel.

I could be wrong, but I've been under that footwell enough to think that's how it works.

I wanted a chance to drive my BRZ to give you some more insight on the free pedal. I drove my wife's outback all weekend and the free play is very noticeable in that pedal. Same release bearing as the Twins BTW.

The over center spring makes the free play less noticeable, however if you press on the pedal with slight pressure you can feel when the bearing and fork load against the diaphragm spring. This was about .5-.75 " of the top play in the pedal stroke. The movement at the bearing is much less.

I checked to see if I could move the fork with the slave cylinder still installed. I was able to move the fork side to side and very slightly front to back.

I would imagine that this is normal as you do not want any heavy tension on the fork as this would indicate that the bearing is loaded against the diaphragm spring. If the bearing is loaded against the diaphragm spring it will cause it to wear prematurely and also will not allow the pressure plate to exert its full clamping force.

I am not sure if the ACT clutch has the same diaphragm spring height as the OE clutch, I would assume it is. The pressure plate design on the ACT is much different than the OE or EXEDY pressure plate. If the diaphragm spring height is taller than the OE this would make the required pedal adjustments differ from OE.

Have you tried to thread the master cylinder rod into the clevis slightly ( half to full turn) to see if this helps the chirping go away? You would need to compress the slave cylinder by hand after the adjustment to reset the piston in the slave.

A fun fact is the 2.5L non turbo Subaru's all share this same release bearing and the release load of the clutch on those models is higher than the factory clutch on the BRZ.

[TRAKRAVN]

Hey all,

Thanks so much for this lengthy and informative thread. Ive been searching for quite a bit about the exact same issues I’ve had, and all this info will hopefully be of great help.

I am hoping that because the symptoms as described are identical to my situation, that my fix will also be something simple like some retainer clips that decided they didn’t want to play anymore.

I haven’t purchased any replacement parts yet, but am preparing to drop the trans again to see what’s going on. In trying to prepare for the job I’d of course like to get as much ready to go before hand as possible.

I am planning on getting replacement clips, and a new *NEW style* TOB.

Do you recommend still replacing the hydraulic components still(slave/master)?

Also, I have seen recommendations to replace front bearing cover with TOB sleeve/shaft part. (Not sure on exact name). What are your thoughts on doing this all at once to hopefully never have to drop the transmission again (If that part is installed with the others it will bring every part in that area to either new, or installed a few months back with the original new PP/TOB/FW/Clutch etc.

Thanks in advanced, and again for this great thread @Ultramaroon @humfrz and @Rybot