Hydraulic TO Bearing and clutch pedal travel Help...

[Tom.A]

Looking for some feedback from those whom shimmed a hydraulic TO bearing.

I had to get a tow home yesterday after I lost my hydraulic clutch. I had hope that the fluid leaking under the car was because bleeder had vibrated loose but it was not. It is coming from the lower housing. I plan to try and yank the trans tomorrow and inspect. I have listed a little details of the application:
LS3 with a TKO 600, Using the Hurst Drivline supplied kit which inlude a tilton master with a aluminum bracket. Throw out bearing is a Ram with a max travel 0f .700". I am also using a LSX Hurst bell housing which is a new casting (LSX style) of the old 621 style bell. Here are my measurements when I installed prior. Bell depth was 3.08" to the bell housing face from the pressure plate fingers, for the gear box it was 2.47" from trans face to the face of the TO bearing (compressed/relaxed) so that left me with a delta of .61". As per the instructions each conical shim is .100". Looking at my notes I used 4 shims which brought it to 2.87". The bearing to pressure plate gap needs to be a min. .125" to a maximum of .225", so 3.08" minus 2.87" = .210" . Fast forward about ~ 600 miles and I got a leaker. Sorry for the details but I just want to be sure I am not missing something simple.
Now with the above shimming in mind here is my next question: My clucth pedal would have to be all the way to the floor and the littlest (release)travel it would move the car. I always thought it should have more travel before it disengaged. Would this be an indication of more or less shims needed?
I am considering trying an external slave cylinder but it I may just give another try with a RAM bearing. Thanks in advance for i=any feedback.

[67ragtp]

Tom,

Had the same situation on my ls7/tko 600 with regards to the release point. Just barely disengaging when depressed to the floor and releasing immediatly off the floor. My numbers came up with a difference of .210 to .215 this puts you on the high side leaving to much gap between the bearing and fingers of the clutch. Another words your not depressing the pressure plate deep enough. You need to close up the gap, problem is another .100 conical shim wil close it off to much. What I did, to put me in the center of the range was machine off .050 from one of the shims and tig tack(around the perimeter) the shim on to one of the .1 shims to give me a shim that yielded
.150". This moved my difference number to .160 and now it grabs in the center of the clutch pedal travel.

I dont think that your adjusment parameters are what caused your bearing failure, the first thing that comes to mind is weather or not your slamming the back of the master. I would expect the leak to be up top if that was the case. The pedal stop is very important, you should hold the pedal firmly to the floor and adjust the clevis until the master bottoms out. Then back off two full turns.

maybe its a line failure where the lines enter the release bearing, when you get the trans out please let us know what you found, Jim over at hurst drive line will support you as well, he's very good.

Rich

[Fluid Power]

I feel your pain. I went thru the same drama. Let me drag my notes out as well and see what I can do. My RB came with 2 different thickness shims. I believe .100 and .050. I may have extra if needed. But for starters, the tech guys at RAM are awesome. I would start with them. (no offense to the Hurst guys) but it is RAM's product.

It took lots of math and measuring but I got it right and it works perfect. Much better than the 2 McLeod POS's I bought. Yes, I am very good at pulling transmissions!

Darren

[Tom.A]

Originally Posted by 67ragtp

Tom,

Had the same situation on my ls7/tko 600 with regards to the release point. Just barely disengaging when depressed to the floor and releasing immediatly off the floor. My numbers came up with a difference of .210 to .215 this puts you on the high side leaving to much gap between the bearing and fingers of the clutch. Another words your not depressing the pressure plate deep enough. You need to close up the gap, problem is another .100 conical shim wil close it off to much. What I did, to put me in the center of the range was machine off .050 from one of the shims and tig tack(around the perimeter) the shim on to one of the .1 shims to give me a shim that yielded
.150". This moved my difference number to .160 and now it grabs in the center of the clutch pedal travel.

I dont think that your adjusment parameters are what caused your bearing failure, the first thing that comes to mind is weather or not your slamming the back of the master. I would expect the leak to be up top if that was the case. The pedal stop is very important, you should hold the pedal firmly to the floor and adjust the clevis until the master bottoms out. Then back off two full turns.

maybe its a line failure where the lines enter the release bearing, when you get the trans out please let us know what you found, Jim over at hurst drive line will support you as well, he's very good.

Rich

Rich, Thanks for reply. I did not think of smaller shim as I just assumed .100 was the smallest. I did not get the trans out today but I did get it up and off the ground. Looking in the side and feeling lines with my finger tips it had no sign of media leaking. So I am pretty sure it is likely an o-ring failure. I will post back when I get it out. I must admit I never really fussed with a pedal stop. I will give that some thought.

Originally Posted by Fluid Power

I feel your pain. I went thru the same drama. Let me drag my notes out as well and see what I can do. My RB came with 2 different thickness shims. I believe .100 and .050. I may have extra if needed. But for starters, the tech guys at RAM are awesome. I would start with them. (no offense to the Hurst guys) but it is RAM's product.

It took lots of math and measuring but I got it right and it works perfect. Much better than the 2 McLeod POS's I bought. Yes, I am very good at pulling transmissions!

Darren

Darren, thanks for sharing. I suspect newer RB must come with two shims sizes. I read that the Ram 78125HD is a better offering now than a few years ago. I will call them this week and ask them. I also saw this in the Chevy Hi Performance mag: http://www.ramclutches.com/zen-cart/...roducts_id=677 it seems the HD bearing has a longer travel of 1" and somehow this will help adjust? I will report back.

Thanks again for the feedback guy's

[andrewb70]

Tom,

Personally I think a gap of .210" is a little much. I use a Quarter Master bearing which doesn't have nearly as much maximum travel as the Ram or Howe, so for me, every bit of travel is important. I set my LS7 clutch with about .100" air gap. The LS7 clutch is nice in that the springs don't have to move very far to achieve full release. I am using a .700" MC and have about 2" of pedal travel before the clutch starts to bite.

Since you will have to remove the trans, I would suggest rebuilding the Ram bearing, if a rebuild kit is available, and reducing your gap to about .100-.125"

Andrew

[Tom.A]

Thanks Andrew. I think agree about closing the gap more. I may still spend the money to get the heavy duty Ram TBO in hopes that it may last longer because flat backing a trans sucks!