Clutch Masters hydro bearing failure!

Getting it converted back for now. Definitely the safe option at this point. I can't afford to miss work and call a tow truck every 300 miles. My factory TOB was only barely starting to squeal and I'll be putting a new one in now. I'll jeep my eye on that Tilton setup though for sure.

 

Can confirm, it does not leak and actually works better than the original shockingly. Got one as part of the group buy. The rest of it on the other hand.... just shoot me

 

Welp my bad apparently I didn't use the vehicle search function. They do still have them.

 

Mine leaked in 10k miles or whatever I stated in the first post. I recall someone had theirs leak then they resealed it and it leaked again

 

been 15k mi and mine doesn’t leak

why?

 

Don't know, you got a lunch one.

 

Okay. can anyone tell me what the air gap is for the CM hydraulic t.o.b./slave is? Also, the non t.o.b. gap.

I bought the LC Engineering Pro Clutch kit and CM told me it was there kit. I know the clutch is gonna be harder to operate and so the hydraulic kit would really help with that. But I am @ a stand still on this.

I contacted Kevin Gomez(I think) @ CM and he said they are constant contact and no shimming necessary. But I think I agree with gear cruncher.

some on here have had very good success with them and some not so much. Help me out on if I should pull the trigger or not.
Brian

 

Supposedly the CM only goes in one way and the instructions say to adjust pedal bite via master cyl rod to 50%

other option is 3rd gen trans or the DIY on installing a Tilton, unless Tilton someday plans to make a kit

 

I never adjusted the gap and it’s not required per the FSM, seems to be working fine.

 

These universal hydraulic piston-style throwout bearings do require some sort of air gap adjustment. The OE fork style TOB's probably don't. If I remember right, the clutchmaster TOB was supposedly advertised as designed with a spacer machined to the appropriate height for the 1GR/RA60F combo so the air gap was fixed and did not need to be adjusted upon install. It would've been nice if they (CM) actually provided a spec on what that gap needed to be so the end users could double check this and possibly shim if needed.

What Clutchmasters made ZERO mention of, and I'm not sure why, was the need to add some sort of pedal stop to limit piston travel. Tilton stresses this point very clearly and they even disclaim that their TOB does not have any form of internal travel stop so a pedal stop is necessary. Well the CM doesn't have an internal travel stop either, but for some reason they never mention the need to limit piston travel via pedal stop. I have a feeling some of the failures that have popped up on here happened because of this.

 

would pedal bite adjustment be a factor?
Their instructions say set it to 50%, via the adjustment rod/nut

 

2 of these have failed on friends trucks in the last month. same thing.. not even a year or 10k miles on either.. hell.. probably not even 5k miles on either.

 

how/in what manner did they fail?

 

TOB seal went out on both and puked all the fluid out of the bell housing.

 

Selling mine NIB not installing this POS. I've seen enough. I don't wanna deal with pulling trans multiple times because of a shit product.

 

For me to lower the clutch bite closer to the floor, I have to reduce the amount of thread showing at the top of the pedal rod.
Instructions say get it to 50%.
I might be close. 40% I think.
It seems to change at times. I'll try bleeding another liter of fluid.

Maybe this is normal. I suspect the pressure plate may be bent, and the flywheel surface not straight.

If I adjust the bite too high, it seems to not shift well. Too low, and it starts to squeak.
At 40%, it squeaks sometimes a bit, and the slightest poke at the top of the clutch pedal stops it.
That tells me once I get it to 50% it should quiet down.
Because that is so close, and I've missed the mark so many times, I will probably turn the rod 1/4 turn rather than rushing it and overshoot. And be patient.

At this point I've been contorted under the dash playing with the adjustment at least 10 times.

It's about as fun as permanently living in a McDonald's PlayPlace



hopefully going Stage 2 URD + HW flywheel later will make things magical
but I doubt it will make up for needing a regear

 

Count me in as another CM failure. It's obvious why -

The inner ring is the freely-spinning part of the bearing, and the outer ring is fixed to the piston. The inner ring is so small it fits THROUGH the clutch fingers, and the fingers only contact on the outer ring, turning the piston with the pressure plate. The failure is not a matter of adjustment/preload, the bearing is outright the wrong size



That being said, this is with the OEM pressure plate. Aftermarket pressure plates may have longer fingers that actually contact the correct part of the bearing. Maybe that explains why some people have these fail in less than 8k miles (people with OEM pressure plates) and others have 10s of thousands of miles without issue (those with aftermarket pressure plates)

 

That's scary.

What does that mean? How does it function? I'm guessing the outer race remains stationary, that the rubber seal is in the middle, and that hydraulic pressure from your foot/clutch pedal sending DOT4 (held sealed by the seal) pushes only the inner piston race out?
If yes, that pic makes it look like either:
1. it barely has any pressure plate fingers to grab onto
2. might shoot straight past them into an immediate failure

I wonder why mine didn't. Installed an Exedy kit.
However, it squeaks sometimes, and the bite is always chasing. I've gotten tired of adjusting under the pedal.
They say set it to 50%. I don't even know the best way to do that. Driving? Or truck lifted in the air?
Warm/hot operating temp, and expect it to act different when cold? Probably.

The squeak is intermittent and goes away with a quick light kick at the top of the pedal.
Maybe something else is causing it?
Such as my flywheel (used) or stock equivalent pressure plate, if there is any bending or uneven spots. On one side, I think that's possible. I went through a hell of a time moving/towing a lot of weight, up hills, in traffic, backing up, etc. + bigger tires w/ stock gears
on the other side, supposedly a stock clutch is supposed to be able to handle that

when I go to put in the URD hwfw + stg2PP hopefully the fingers work with the hydrobearing
I'll definitely take a close look at the bearing while I'm in there to see how it looks
Another thing I don't get is why whenever I pressure bleed the clutch, fluid comes out looking dark/dirty. I don't think it's supposed to that recently. Pedal master cyl is new.
Like I have seen cars with brake fluid 1-2yo look cleaner than my fluid after a month.

 

I annotated some pictures to help illustrate. The entire bearing rides on the piston. The way the bearing is built, the outer ring (I called it a 'lip' in my last post) is stationary relative to the piston, and its the inner ring that rotates with the pressure plate. The inner ring is smaller than the pressure plate fingers, so its the outer ring that contacts the fingers, causing the outer ring and piston to turn with the pressure plate.



Here is the whole assembly together:


Its hard to see, but the piston seal that actually holds the hydraulic pressure is under the piston; the wiper seal that is visible at the front of the cylinder is not what hold the hydraulic pressure, it just keeps debris out. As the piston turns inside the cylinder, it scores up the cylinder walls, and then the piston seal is no longer able to seal against them and hydraulic fluid leaks through:


Unfortunately, this is a fundamental design flaw. If the pressure plate fingers are touching the outer ring, the HRB will fail, regardless of preload or adjustment. It's just a matter of time.

I was never able to adjust mine to bite in the middle of the clutch stroke, and I tried for quite a while. It was always closer to the top of the pedal stroke. The factory setup would bite around mid-stroke, and I think ClutchMasters decided to regurgitate that into their instructions, even though it may not be possible.

I had this issue too. Seeing how the outer ring is contacting the fingers, I think the reason it squeaked was the extra friction of needing to turn the piston in the cylinder would cause the fingers to rub along the outer ring, the bearing and piston remaining still. A quick jab of the pedal would seat the bearing to the fingers, overcome the static friction of the piston in the cylinder, and get the piston/bearing turning, and the squeak would go away. Once it was spinning, the dynamic friction was low enough that the piston could keep turning with the pressure plate. I called ClutchMasters about this problem, and they actually recommended adjusting the master cylinder rod to put more preload into the HRB; this not only made the engagement point even higher in the clutch pedal stroke, this would actually get the piston turning more and damage things faster.

I wonder if the piston seal spins with the piston, rather than the piston just turning on the seal. If the seal is turning too, it could be wearing down, leading to the dark fluid. After my HRB started leaking, I still drove the truck and topping off the fluid as needed. Because the HRB was always being fed fresh fluid, I never got a sense of the color after the CM HRB was removed.