Throwout bearing issues.

Old 09-06-2013, 07:16 PM
  #1  
Incognegro
Senior Member
DYNO TECH
Thread Starter
 
Join Date: Jan 2009
Posts: 414
Default Throwout bearing issues.

I need some assistance here, Im having clutch slippage issues


I have a Howe Hydraulic throwout bearing #82870 and am utilizing a Centerforce Chevy pressure plate, mated to my Chevy 350 and Jerico 4 speed.

When I do all the clearance measurements of the bellhousing to the pressure plate fingers it seems that my throwout bearing is roughly .20 of an inch to thick....When I install it it Im assuming it is pressing the fingers on the pressure plate which Im assuming is not what you want..

My clutch will not engage properly as a result, the .20 or around 3/16ths which is apparently enough to release the clutch engagement ever so slightly. I have Compared the Howe racing thowout bearing to the stock GM and it is the same size. I need to move the transmission away from the bellhousing or bellhousing away from the motor since I am assuming I can not get a smaller throwout bearing.

Is there some sort of motor plate or spacer Im supposed to be using? Help...I want to get some drive time before the weather gets crappy..
Incognegro is offline  
Old 09-07-2013, 07:57 AM
  #2  
gearhead1011
Senior Member
EXPERT BUILDER
 
gearhead1011's Avatar
 
Join Date: Jan 2004
Location: Shepherdsville, KY
Posts: 313
Default

You will need some clearance between the PP levers and the TO bearing because the levers will move some at RPM due to the counter weight effect. I think somewhere around .250". The thickness of your disc will affect the lever height so you need to make sure all that is set up right. Do you have a block saver plate on it now? Some guys will double up on the plate to increase clearance. You might also be able to make a spacer plate to use between the transmission and the bellhousing. Make sure you have enough input shaft, to reach the pilot bearing and enough dowell pin and bearing retainer register to keep the transmission centered when doing any spacing. You might just need a different TO bearing. You might try the UMTR forum here www.umtrnorth.com/forums to see if someone else has a similar set up. You have to be a logged in member to view/post but you will find more stick car info there than anywhere else on the web. Good luck.
gearhead1011 is offline  
Old 09-07-2013, 09:00 AM
  #3  
Incognegro
Senior Member
DYNO TECH
Thread Starter
 
Join Date: Jan 2009
Posts: 414
Default

Thank you. I did just order a Lakewood industries transmission spacer which measures .250 this should help my issues. Also the statement you made about the counterweights now makes sense cause initially it just slipped at higher rpms. I guess now that the disc has worn a bit, it has gotten undrivable.
Incognegro is offline  
Old 09-07-2013, 05:18 PM
  #4  
Incognegro
Senior Member
DYNO TECH
Thread Starter
 
Join Date: Jan 2009
Posts: 414
Default

On a hydraulic throwout bearing once you depress the clutch pedal and it extends does it automatically retract or does it need the pressure of the clutch fingers to push it back into position? Im playing around with the throwout bearing and it might be bad or I might have an issue with my master cylinder. It seems once it extends, it needs to have the bleeder valve cracked to retract back to the starting point if you push it by hand.
Incognegro is offline  
Old 09-07-2013, 06:35 PM
  #5  
Incognegro
Senior Member
DYNO TECH
Thread Starter
 
Join Date: Jan 2009
Posts: 414
Default

Also Is it common to have to utilize a spacer in between the bellhousing and tranny to get the proper clearance for the TO bearing?
Incognegro is offline  
Old 09-08-2013, 05:35 PM
  #6  
gearhead1011
Senior Member
EXPERT BUILDER
 
gearhead1011's Avatar
 
Join Date: Jan 2004
Location: Shepherdsville, KY
Posts: 313
Default

Originally Posted by Incognegro
On a hydraulic throwout bearing once you depress the clutch pedal and it extends does it automatically retract or does it need the pressure of the clutch fingers to push it back into position? ...
...It seems once it extends, it needs to have the bleeder valve cracked to retract back to the starting point if you push it by hand.
I believe the bearing should retract on it's own. If you have to open the bleeder to get it back it sounds like a restriction or a problem with the master cylinder. The master cylinder must be fully released for the throw out to release. If the pedal holds just a slight amount of pressure on the master cylinder it won't allow the slave cylinder to retract.

Originally Posted by Incognegro
Also Is it common to have to utilize a spacer in between the bellhousing and tranny to get the proper clearance for the TO bearing?
The fact that there is a spacer available will tell you it is fairly common. When you start swapping stuff around you just have to do what you have to do.
gearhead1011 is offline  
Old 09-08-2013, 05:59 PM
  #7  
Incognegro
Senior Member
DYNO TECH
Thread Starter
 
Join Date: Jan 2009
Posts: 414
Default

Originally Posted by gearhead1011
Originally Posted by Incognegro
On a hydraulic throwout bearing once you depress the clutch pedal and it extends does it automatically retract or does it need the pressure of the clutch fingers to push it back into position? ...
...It seems once it extends, it needs to have the bleeder valve cracked to retract back to the starting point if you push it by hand.
I believe the bearing should retract on it's own. If you have to open the bleeder to get it back it sounds like a restriction or a problem with the master cylinder. The master cylinder must be fully released for the throw out to release. If the pedal holds just a slight amount of pressure on the master cylinder it won't allow the slave cylinder to retract.

Originally Posted by Incognegro
Also Is it common to have to utilize a spacer in between the bellhousing and tranny to get the proper clearance for the TO bearing?
The fact that there is a spacer available will tell you it is fairly common. When you start swapping stuff around you just have to do what you have to do.

What would I look at or test on the master cylinder? Or could it be a air bleeding issue?
Incognegro is offline  
Old 09-08-2013, 08:20 PM
  #8  
gearhead1011
Senior Member
EXPERT BUILDER
 
gearhead1011's Avatar
 
Join Date: Jan 2004
Location: Shepherdsville, KY
Posts: 313
Default

Originally Posted by Incognegro
What would I look at or test on the master cylinder? Or could it be a air bleeding issue?
Make sure there is nothing preventing the piston in the master from fully retracting. Just a small amount of pressure on the pushrod can cause problems. If the pedal stop or push rod is adjustable make sure there is some slack in it. If all that is good I would suspect a master cylinder problem. Air would just prevent the clutch from releasing, it wouldn't maake it slip.
gearhead1011 is offline  
Old 09-15-2013, 04:27 PM
  #9  
Incognegro
Senior Member
DYNO TECH
Thread Starter
 
Join Date: Jan 2009
Posts: 414
Default

I registered for that forum you suggested and am still awaiting an administrators approval.. Im curious to see what the issue might be with my set up.

I have since ordered the .250 spacer from lakewood and measured with the spacer. I get 2.637 from the spacer to the fingers of the pressure plate. My TO bearing to tranny is 2.600, so now I have a gap of .037 and the car will not go into gear, it is grinding like the clutch is not releasing. My TO bearing has a throw of between .43 and .688 depending on the stroke. My Master cylinder has a 1.1" stroke. so I should have around .50 of stroke.
Incognegro is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service