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My truck eats throw-out bearings...Figured out why...Pictures and reasons on PG 2

broncoman6524

broncoman6524

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When I first put the 465 in my blazer I had a mechanical clutch set-up. I could not keep the linkage together, so I swapped to a hydro set-up. Thinking I was good.

Wrong, I have put two throw-out bearing in in three months. First an autozone brand, which went bad because of a plastic collar:eek1:. This time It is a Napa brand. It's been in maybe 2 weeks.

I can tell its the bearing because it rattles and whines, but if i rest my foot onthe pedal it goes away.

Anybody got any ideas why? I seem to recall both bearings not being tight onthe bearing cap on the trans, is that normal?

I re-ordered a second HAYS bearing, because I tore the first one apart from the linkage coming off because of the mechanical set-up.

Chris
 
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Make sure the bearing slides freely on the tranny collar. If it sticks, the hydro pressure can push the thing apart.

Emery cloth on the collar and a LIGHT coating of lubriplate is what I do when installing a new bearing.
 
Ok, but how close should the clearances be?

For some reason I want to say that with some of the bearings I could move them around on it easily. Not back and forth, but up and down/side to side.
 
Just curious, 3 finger or diaphram type pressure plate?
 
Diaphram style plate, I'm thinking that the stock bearings are not strong enough to press the fingers in? Maybe it's stressing the bearings and wearing them out faster?
 
broncoman6524 said:
Ok, but how close should the clearances be?

For some reason I want to say that with some of the bearings I could move them around on it easily. Not back and forth, but up and down/side to side.
Click to expand...

Clearance should be only a couple thousanths, if you can slide the bearing on the collar and move it around you have the wrong bearing or the wrong collar. Are you getting a TO bearing for a hydro clutch? You may need to change the collar if you are ordering the hydro bearing and it isn't fitting correctly. I don't know much about the standard trans stuff but maybe the collar is different between manual and hydro clutch.
 
I never thought of that...the trans was originally a mech set-up.

According to advance adapters Fact page it just says one size for the bearing retainer.
 
If you can move the bearing up and down and side to side, it's not right.

The clearance front to back should be a minimum of ~0.060" (going from memory) between the pressure plate and the bearing face. If they touch during use, the bearing will burn out very quickly. You might check the return spring and make sure it's pulling the bearing all the way back.
 
There should be a return spring on hydraulic set-ups?

The fork I have does not have a hole for the spring to seat in.
 
You probably need a spring. There MUST be a gap between the bearing and plate when the clutch is not engaged.

There are two conventional ways to do create the gap/clearance:

1. When you release the clutch pedal, the pressure plate will force the bearing back only until there's no movement left in the pressure plate, but that will still leave the bearing in contact with the plate. Even if it's only touching a little bit, that will cause the bearing to spin and burn out.

2. Some master cylinders (1996 and later do, but not sure about earlier) capture the pedal pushrod so that when you lift your foot off the clutch pedal, the clutch pedal springs will try to draw more fluid back into the master cylinder and pull the bearing back away to create the necessary gap. But to do that, the clutch fork needs to be tied directly to the slave cylinder pushrod with a clip or other device so that when the master cylinder pulls back, the slave cylinder will pull the bearing away from the pressure plate. If they are not tied together, that can't happen.

I suspect you are using something like mine where the clutch fork is the old style where the slave cylinder pushrod is held against the fork without a clip. If that is the case, you need a spring (like I did)
 
That makes sense. I am going to assume that my slave cylinder does not have the clips you're talking about. Its just a rod that fits in a sunk area on the fork.

I guess when I have it all apart I'll compare the hydro and mechanical forks, and see if they are the same geometry wise. If so, ill use the mechanical one since it has holes for springs. Maybe get a set of the double throttle return springs, and put one on the top and bottom of the fork?
 
If I remember correctly the last hydro conversion I saw done on a older truck/blazer did Have a spring to return the fork back to the neutral position.. Made the pedal a little stiffer but keeps from going through bearings...
 
I think my clutch fork was a really old style and didn't have an obvious spring hole, but I used another hole and it seems to work fine.

You can test whether your current setup is ok or not by pushing the fok back to the rear of the truck and seeing if there is any movement before the bearing hits the plate. If there is movement, make sure it moves back after you let go. If there isn't any movement, that's a problem.
 
Check the input bearing retainer that the TOB rides on. I had to replace mine when my TOB failed. The TOB wore groves into it and the new TOB wouldnt seat right on it.
 
Talked to two of the mechanics at work today, both said hte same thing. Check the pilot bushing...never thought of that. If it's bad, cracked, wrong, it will let the input shaft wobble...and it will eventually tear up the bearings.
 
Discovered my problem...

This is how a normal 465 input shaft should look.
002.jpg

With a throw-out bearing on
003.jpg

This is how mine looked...
004.jpg

With a bearing...
005.jpg

Guess whats missing???
007.jpg

006.jpg

If you cant tell/ don't know...the tube is missing off of the bearing cover...Which is where the bearing rides and what keeps it in one place...

I guess the previous owner of this trans though it was not important...I found no remenents of it in any of my bearings...

No wonder I went through them like crazy...Frickin things must have been bouncing around like a 2 year old with a coke!

Needless to say I swapped out the bearing covers and no more noise...weird. It actually goes into gear easily now, and I can downshift!

haha
 
Hell yeah!! haha, does not make any noise. A little bit of a squeak at 4500+, But I have yet to install springs, so maybe that will go away.
 
that trans might have been behind a ranger overdrive then, when you intsall on eof them you have to cut that part off
 
Chevy305 said:
Check the input bearing retainer that the TOB rides on. I had to replace mine when my TOB failed. The TOB wore groves into it and the new TOB wouldnt seat right on it.
Click to expand...

And guess who said that was your problem... You can thank me later :haha:
 
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