Hydraulic Throw Out Bearing Problem

Superbeemike

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I recently 4 speed swapped my Super Bee and while doing the conversion, I went with an American Powertrain Hydraulic throwout bearing kit. I went step by step, and dialed everything in according to the instruction. My throw out bearing was set with 0.163" and within the specified range. Pedal and pedal travel all within spec. I have a new Mcleod clutch and flywheel (10.5"), and used a 69' A833 18 spline trans. Bellhousing is an aluminum Lakewood. Note I did not check the runout of the bellhousing when I installed it. It is on stock dowel pins.

Everything installed and running, I drove the car about a mile before the throw out bearing starts making a scraping noise and won't disengage from the pressure plate. I put it up on jack stands. I looked underneath and the throw out is indeed not returning after the pedal is released. I cracked the bleeder and there is no hydraulic pressure present. I cracked open the supply line from the master and again, no unusual pressure present. After the car cools off over night, the throwout bearing is back to normal, at least until I drive it again and it warms up (maybe a couple miles of driving).

I called American Powertrain and they said I need to check the runout on my bellhousing and get that dialed in first. I'm not sure how that can effect the throw out but I will check it regardless. They also said to reverse flush it in case there is debris in the system. I will also be doing that as well.

Problem I have is I'm not sure those suggestions are going to have an effect. Hoping someone here has a suggestion or possibly experience regarding this. I'm kinda stumped.

Thanks,
Mike
 

RemCharger

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I would have someone in the car working the clutch while you watch. At least you'll have a few more clues to if it's releasing properly.
I have seen them not returning due to obstruction.
Not that exact brand-setup , but similar
 

69Bee

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How tight was the throw-out bearing sleeve on the front bearing retainer? The only thing I could envision is that binding when hot, then releasing after a cool down.
 

Superbeemike

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I would have someone in the car working the clutch while you watch. At least you'll have a few more clues to if it's releasing properly.
I have seen them not returning due to obstruction.
Not that exact brand-setup , but similar

I will look at it more tonight for sure. I think my kid will be home to help.

How tight was the throw-out bearing sleeve on the front bearing retainer? The only thing I could envision is that binding when hot, then releasing after a cool down.

It was snug on the bearing retainer. There's an o-ring in the bore to keep it snug. The bearing/hydraulic portion of the assembly moves independently and does not slide on the bearing retainer. (sorry, hopefully that makes sense)
 

Superbeemike

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I pulled the transmission tonight and inspected the bearing assembly. The fluid inside the unit was dirty and had debris in it. I’ll take responsibility on not flushing the lines while assembling everything. I’m not sure what I could have done to get dirt in the system but It will be clean going back together. The scraping noise was from the face of the bearing slipping on pressure plate. The bearing spins smoothly so I’m not sure what the issue is with that. Maybe the Throwout was pitching sideways when it was hanging up.

561B5979-E2D4-4A5A-AFC0-7E9FF4B192B9.jpeg 10A62EE9-DE31-4C47-9516-7922F8702ABA.jpeg
 

BB BELLA

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I would think clutch is going to break in almost immediately so I'd redo math on clearance since you have trans out!
check the runout and eliminate the possibility it's the reason! I'd try opening up the clearance to larger end of spec. and make sure pushrod is allowing the master to to return to home position!
 

Superbeemike

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I would think clutch is going to break in almost immediately so I'd redo math on clearance since you have trans out!
check the runout and eliminate the possibility it's the reason! I'd try opening up the clearance to larger end of spec. and make sure pushrod is allowing the master to to return to home position!

Yes, great suggestions. The American Powertrain kit came with an extra set of O Rings. I’ll change those out too.
 

Superbeemike

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Spent some time sorting out my issues here. I cleaned and flushed everything up for reassembly. Going back together I noticed the TB guide pin was too short for the bearings travel which allowed the bearing to slide off the pin and get stuck. I removed the guide pin and made a new one that is longer. Hopefully the pictures explain my problem better. Trans is back in and I’ll finish it up tomorrow.

CC26F2A5-17FF-4038-8DCC-1EF27FF39BC8.jpeg 3B0A84A2-B006-443A-AEA6-D041906173C0.jpeg C404054A-338F-4321-AABF-209719E70AAF.jpeg C8091EE9-7FCD-4A49-9FB7-8790C30672E9.jpeg 15459E97-4374-4D26-870D-A46B4F1B99EB.jpeg
 

BB BELLA

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that's quite the shim stack! when the bearing is shimmed so far out the retaining pin is too short suggests to me the parts combo isn't ideal! flywheel and/or pressure plate is designed for another application. I would contact mcleod and tell them what your trying to do! It may work okay with the extra shims and long pin, but it makes me think of a lot more possiblity for misalignment, hoping it works fine!
 

RemCharger

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I put a fancy McLeod TOB in a tremec behind a sbf, and it didn't have that locating part at all. It just floated in there. The hoses were about all that located it.
 

Dipstick

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I looked underneath and the throw out is indeed not returning after the pedal is released. I cracked the bleeder and there is no hydraulic pressure present. I cracked open the supply line from the master and again, no unusual pressure present. After the car cools off over night, the throwout bearing is back to normal, at least until I drive it again and it warms up (maybe a couple miles of driving).

This is something I've wondered about for some time. I see no mechanism to pull the TO bearing away from the pressure plate when the pedal is all the way up. This seems true on both aftermarket and factory hydraulic clutch setups.

What am I missing?
 

RemCharger

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The pressure plate springs are very strong. They push it back.
 

Superbeemike

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This is something I've wondered about for some time. I see no mechanism to pull the TO bearing away from the pressure plate when the pedal is all the way up. This seems true on both aftermarket and factory hydraulic clutch setups.

What am I missing?

The throwout bearing is always in contact with the pressure plate, just not loaded until your foot pushes the pedal. Not sure how long the bearing will live this way. Guess I’ll find out eventually.
 

BB BELLA

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This is something I've wondered about for some time. I see no mechanism to pull the TO bearing away from the pressure plate when the pedal is all the way up. This seems true on both aftermarket and factory hydraulic clutch setups.

What am I missing?
works the same as disc brakes, there's no springs to return the pads away from the rotor! they just stay close to the rotor and even rub lightly!one trick for super speedway qualifying a race car is to push the pistons in all the way in before hitting the track and not touching the brakes until slowing down to leave the track, less drag on the wheels.
I believe that is part of the reason you want the belhousing true and runout dialed so the bearing hits the fingers evenly and properly centered so there's no orbital action on the bearing and fingers causing premature wear!
I know there suppose to be self adjusting but don't understand how .150 is enough to maintain clearance as the clutch wears! I think some of the premium hyd. throws have an adjustable spacer so you don't have to remove trans. to maintain maximun pressureplate pressure throughout the clutchs life!
it's been a long time since I ran an 833 with factory clutch setup in a B but I think I've adjusted the pedal 3-4 times through a clutch disc. lifespan to maintain freeplay!
I have a video of Bella with the newly built stroker/bellhousing/ZFs6-40 installed for a road test to pick a rear gear before everything was dialed in and inside the car it sounds like the motor has a blower or geardrive timing setup, the throwbearing and trans input shaft bearing were singing "take me home now"
 

Darrah

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The throwout bearing is always in contact with the pressure plate, just not loaded until your foot pushes the pedal. Not sure how long the bearing will live this way. Guess I’ll find out eventually.

That's normal for the hydraulic bearings in Tremecs. I noticed the same thing putting a T56 in my son's RX7, and turns out that's the way it's designed. Lots of F-bodys out there with lots of miles, so that's good enough for me
 

Dipstick

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When I was a kid, we were told that a mis-adjusted clutch could cause a TO bearing to fail because it was in constant contact with the PP. Now, it would seem that the TO bearing has been redesigned to allow it to spin constantly but a check of some parts books shows the same TO bearing used with mechanical linkage in the 60's and 70's is used with hydraulic setups in the 80's and 90's. :realcrazy:
 

biomedtechguy

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I had the same non-problem problem...It was especially troublesome for me, as I had worn out the last mechanical TO bearing from not having enough clearance. I was going to the Hydramax hydraulic TO bearing in order to use the HitMaster launch control, and I see no clearance between the PP and the TO bearing. American Powertrain assured me, several times (lol), that it is supposed to ride on the tips of the PP diaphragm springs. Top it off with a new to me dual disc clutch, AND it was creeping forward in 1st gear w/the clutch pedal fully depressed!
I put it up on a lift, but I couldn't see why I was having trouble, but I did see the TO bearing never had a gap between it and the PP diaphragm spring tips.
It worked itself out, and works fine, but I had a hard time understanding that if there was a gap between the TO bearing and the PP, that would make the clutch hard to disengage, because the TO bearing pushes forward on the springs, and any gap would have to close before any disengagement could occur.
So I have to believe the bearing is high quality enough to spin, all the time, and one advantage is zero clutch "slop". Push the pedal and disengagement begins immediately.
 

Carcinogen

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Been thinking about getting this kit and ran across these videos of installation. Might help.



They also had to shim out and replaced locating pin with longer one.
 

biomedtechguy

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Been thinking about getting this kit and ran across these videos of installation. Might help.



They also had to shim out and replaced locating pin with longer one.

Yes, I spoke with Jed (in the videos) a few times and he's a good guy.
My mechanic who did the myriad of work, parts and systems installation, welding in the subframe connectors and torque boxes, and the hydraulic throwout bearing and McLeod RXT dual disc clutch installation had the aluminum spacer of the American Powertrain Hydramax kit machined to make it work.
I'm sure I'll have a better understanding of "all that" when I get involved in the installation of the 572 stroker.
 

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