T18 throw out bearing or clutch fork is the problem

...at least I think that's the problem. I need some advice and maybe even part numbers for this. I had a problem with the hydraulic clutch system releasing the clutch. I dropped the trans today to inspect everything. Good news! I am still alive! Second good news...the clutch plate was installed correctly.

The bad news that I need help with is that I think I have either an incorrect release bearing or clutch fork or both. Here are some pics, and even a video. These are all brand new parts, never even been on the road yet.

Fork without the release bearing attached...it was the same fork that was used on my T150:


Fork / bell housing pivot point on the ball bearing...note the fork notch has been done to clear the bell housing bolt


Old bearing on left (was on J truck); New bearing on right, everything else is identical.


My Borg and Beck style clutch housing


Click on the pic to see the video...


Found some information on the World Wide Web (whatever that is)...seems Timken #614034 is the proper bearing for a T150 3 prong clutch...is this interchangeable with the T18 then?

 

Aha...not so fast...after some additional reading I decided to take a pic of the pilot bushing. As you can see it is flush with the crank surface, should this be driven deeper into the recess and if so, how much? The shop manual only says to make sure it's "fully seated".

I'm thinking this might be binding the trans input shaft which would exhibit the same behavior as the clutch plate not releasing.

NEVER MIND about this pilot bushing question. After a series of measurements I determined that I have about a 1/4" of the input shaft going into the bushing, leaving about 3/4" before it hits the splines.

 

Norm,
I dont see any red flags...what was the angle of the clutch fork when the to bearing was at light rest against the fingers?

 

I can't answer that question...when it was installed I didn't look into the opening to see what it did against the clutch fingers. It all seems pretty square though.

 

Norm,
I guess what im getting at is this...I dont see from your pics anything that would cause your problem. I followed your previous thread. What I can tell you is if you are using a push type slave you must make sure your fork angle is correct and that you have the correct length throwout bearing. I would mock everything up and see what it looks like. Please remember I am no mechanic or expert just a guy that finished a hydraulic clutch that works recently

 

If you have the same setup do you have any part numbers that you can share...at least as far as the TO bearing? I really don't want to do this again if I can help it.

The two TO bearings in the pics above are slightly different as the old one is taller. I'm thinking that the longer length keeps the bearing square to the shaft better.

 

Norm,
Thing is I am running a buick v6 and sm420 so we dont have the same setups

I used a 85ish slave that came out of a cj5/7 with a gm 2.5, homemade bracket to mount it and a universal 7/8 master cylinder.

 

You should have a little forward angle on the outer end of the release arm. If it is square to the centerline it probably won't release fully. Two ways that you can acheive this is either with a longer TO bearing or with an adjustable pivot stud. (Available from Novak Conversions). However it is better to do it without the adjustable pivot if you can. As I recall you should have at least 5 deg forward angle. The other thing, did you check the pilot bearing on the trans shaft to make sure it fits right before you installed it? A tight pilot bearing will cause a feeling like the clutch isn't releasing. Also, a little bit of difference on the length of the TO bearing makes a much bigger difference on the outer end, depending on the ratio of your release arm.

 

Continuing saga of my hydraulic clutch woes...

After some research I decided to replace the 1st "new" throwout bearing that I bought because it was for the multi-finger clutch and not the 3 finger clutch variety. This picture shows the bearings side by side.

left is for multi-finger clutch (1st. "new" bearing), middle is original, right is 2nd. "new" (Timken 614034) for 3 finger


Put it all back together and voila...it still doesn't work! Dang! After making sure the bleeding was done and everything was bolted down correctly I put the come-along onto the clutch fork and pulled...and pulled, and got the clutch to release a little. At least I know it could work, but the length of the push rod is definitely going to be too short...and...

Another search turned up that the pedal swap to the 76+ style pedals resulted in the clutch pedal hitting the floor before having enough travel to engage the clutch. I think my next step is to bend the clutch pedal arm so that I have enough travel before bottoming out on the floor. I'll keep posting until this is resolved.

 

it's hard to tell from this picture, ( for me anyway) but the press plate levers appear to be collapsed already; they don't look like they have enough room to work properly.
optical illusion ?

http://i986.photobucket.com/albums/a...h/IMG_0584.jpg

 

The "press plate levers"...I assume you mean the "s" shaped springs? They seem to work well. I test fit and moved the throwout fork through full motion and it all seemed to do what they are supposed to.

 

It's kinda hard to tell, but it looks like all three of those bearings are the same length. The collar that presses into the bearings is available in different lengths, or I should say the TO bearings are available in different lengths as a set. The bearings are all the same, but the collars are different. As I stated earlier, if you don't have forward angle on the clutch fork you won't get the clutch to release. If you can't find a longer bearing set get an adjustable pivot stud from Novak Conversions and that should work for you. I've been in exactly the position you are in when I put my T18 in with a hydraulic clutch.

 

On the bearings...they are all nearly identical, the biggest difference is in the height of the collar. The 3 finger variety is taller so it can extend further down the shaft without coming off. The face of the TO bearing is slightly different as well, but again the 3 finger variety match very closely if not identical.

The distance from where the fork sits and the face of the bearing that makes contact with the clutch springs is the same among all 3.

I agree that an adjustable fork pivot point would effect how well the TO bearing engages the clutch. The AMC bellhousing that I am using does not use the threaded pivot, it's just a ball on a pedestal. Did you have to drill and tap the bellhousing to install your adjustable pivot?

 

On mine the pivot screws into the bellhousing. Sounds like that won't work on your bellhousing. Check this link:
http://www.novak-adapt.com/knowledge/clutches_etc.htm A little over half way down on the page is a chart of throwout bearings with their lengths and PN's. Also the article on the page explains pretty well clutch setup. Your best bet might be to call Novak and talk to one of their tech people. They are very helpful and very knowledgeable about Jeep conversions. I know what a PITA it is to keep putting in and taking out one of these pigs trying to get the clutch to work. In one day I had mine in 5 times. Even with a real tranny jack it wasn't all that much fun.

 

This is very frustrating. What I thought was going to be a relatively easy swap/upgrade is turning into a nightmare.

I trimmed out a wedge from the clutch pedal arm so that the arm and pedal angle would allow it to go all the way to the floor. It worked a little. I could press the pedal all the way to the floor and the Jeep would move, but the clutch would not release completely yet.

I'll give Novak a call and see what solutions they can offer.

 

Is it a match set? Did buy all from the same dealer, you stated the first throw bearing was for a difference plate. The friction dish can be too thick to release. I had one that would touch just enough to grind, after few day it broke in fine.

 

All the parts are new...and matched.

I'm starting to think that my 11" clutch set is not the right one for this kind of setup, even though it's for a 360. I think I'll have to go to the 10 3/8" clutch set. Any opinions on that?

The very last paragraph of Novak's very good write up (link above) on how to install a clutch says..."the hydraulic slave system on 1980 to 1986 4 cylinder CJ's will usually not completely release a 11" clutch on a conversion engine. It does not have the necessary travel".

 

From everything you quoted and what I've gathered from your posts this is a hydraulic slave travel issue, NOT a clutch issue. I think I mentioned that in your previous thread. I think you need to be looking at the travel of your hydraulics, not your clutch...

 

Nick, I don't disagree, but the hydraulics will only go so far and other components have to take over. I see the issue being "fixed" a number of ways, and my input to those solutions...

1. Keep the current M/S matched pair setup and install a longer push rod.
This is done already and will only go so far as the amount of fluid lost in the slave is simply displaced further upstream and pushes back to the slave up to the point the pedal hits the floor. This worked up to a point for me, but it won't disengage the clutch 100%.
2. Change the fulcrum height for the clutch fork in the bellhousing so the slave can push the throwout bearing further against the clutch.
This might actually work, if I didn't have the pedestal style ball bearing mount and could just screw a new one in there. This one comes off the list
3. Change the throwout bearing to one what has more meat between the bearing face and where the fork attaches so it contacts the clutch sooner and throughout the full motion of the slave cylinder.
This does almost the same as the fulcrum height, except I have to be careful of how much space I have between the clutch and the TO bearing so the TO doesn't just ride against the clutch all the time.Thinking about this solution.
4. Change the clutch and plate to one that is a smaller diameter and/or different type.
This might work too...the 3 finger Borg and Beck style requires more "throw" on the throwout bearing and so the travel of the slave just isn't enough to push it through to the point it releases. A multi-finger Rockford style...and/or a smaller diameter clutch will need less "throw" to disengage. This is based on reading the Novak article. Thinking about this solution
5. Get a new fork.
The ratio on the fork (slave to fulcrum > fulcrum to TO) might not be good enough for the slave to push the TO through to where it needs to be so I might need a new fork (which might also lead to a new TO bearing).Thinking about this solution
6. Scrap the 4 cylinder GM M/S setup for something different.
No guarantee that this will work either. I know the one I have can work, based on my changing out the push rod length and getting partial release from the clutch.
I think my solution is buried in one or a combination of the other options.

Or I just totally misinterpreted what I've been reading and I'm way off base.

 

I think this says it. A longer push rod doesn't change the amount of travel you have in a slave cylinder. Only allows full travel if you are not getting it to begin with.