pilot bearing


erubin
12-17-2004, 06:23 AM
I just bought a clutch set and refaced the flywheel. The clutch set came with two pilot bearings. They are the same ID but different OD.

The truck is apart at my friends house. this is the firsat clutch job I'ver evr done so I need help.

Both pilot bearings are smaller OD than the hole in the center of the flywheel. I assume that's OK and that the pilot bearing doesn't actually touch the flywheel.

When i inspected the back of the engine once the trans was out i recal that there was a sort of stepped shaped piece in the crankshaft. i thought that was the pilot bearing. But one side of it was broken. the pilot bearings i have in the kit don't look like the broken piece. I need to get over there with the parts to see what's wrong.

can anyone shed some light on this?

I borrowed a pilot bearing puller from Autozone but it is too large to fit in the ID of the pilot bearings in the kit. I guess i'll have trouble extracting the old one.

busa_4
12-17-2004, 07:59 AM
the pilot bearing is a pressed or tight fit into the flywheel. if it is too small then it defeats the purpose of it. it needs to support the input shaft. if it is too loose the the input shaft will be moving around causing damage to the clutch system and the tranny.

erubin
12-17-2004, 12:29 PM
Oh! that is a problem. I was hoping it only got press fitted into the rear of the crankshaft and not the flywheel. The truck is an hour away so i'd hate to get there with the wrong parts.

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12-17-2004, 12:31 PM
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erubin
12-17-2004, 12:47 PM
Busa,

before I go back to the parts store and raise a fuss looking for another pilot bearing...Is it not possible that the pilot bearing is pressed into the crank and not the flywheel?

busa_4
12-17-2004, 01:30 PM
oh, damn! sorry, i ment to say crankshaft not flywheel. you need a really small puller to get in there. the best way to remove them is to use a small slide hammer.

busa_4
12-17-2004, 01:30 PM
sorry, didnt mean to confuse you!

BlazerLT
12-17-2004, 04:00 PM
Bro, buy a repair manual for your truck, it will help you with things like this.

tom3
12-17-2004, 06:37 PM
I usually take a hacksaw blade by itself, cut a groove through the old bushing (tedious work) and it can be pulled out of the back of the crank. Very important to replace this too as those T5 trannys will start getting real noisy in first and reverse due to bearing wear, if the input shaft is allowed to wobble around. This bushing does go in the back of the crankshaft, pretty deep in there.

gaggrouper
12-18-2004, 09:25 PM
Hey, I feel your pain.

I put a clutch in my S-10 4X4 (4.3 TBI, new venture 5 speed)a few months ago and had a similar problem. The kit I purchased had one pilot bearing (aka: bushing, some actually have small bearings) it was made of a very soft metal that looked like it was pressed together from powder during manufacturing (like an aspirin), more on that later. The bearing was the wrong size (ID) the trans shaft would not fit in it. Only, I did not test fit it on the shaft first. After removing the old bearing, I gently hammered the new one into the back of the crank, bolted the clutch assembly in place, put a new throw-out bearing on and tried to put the trans back in place. No dice. After 4 hours of trying, I dropped the trans out again to see what was wrong. Thats when I relized the bearing was the wrong size. My point of telling you all this, is because I had to get the wrong size-new bearing out. Not easy. I also borrowed a puller from autozone and it was to big for the ID of the bearing. So I modified it. I took off a little material from the ends of the tool so it would fit in the bearing. I used the slide hammer a couple of times, and the tool pulled out of the bearing, cutting two shallow grooves in the bearing. I did this several times, and each time removing some material. It was working but it was a slow process. So I used a chisel to cut the bearing away. As I said earlier, the material is very soft and the chisel went through it with little effort. I do think the saw blade idea that I read about in an earlier posting is better because you dont have to hammer on the crank (must be careful not to damage the crank). I went back to the auto store to get the correct bearing (take old bearing to compare). Once I had the correct bearing things were fairly straight forward.
The bearing should be a tight fit. It should have to be lightly hammered into the back of the crank. Be gentle, the crank has runout tolerances that can be affected if hit to hard. Also, the factory service manual that I have says to lube the inside of the bearing and to use graphite on the shaft were the throw-out bearing slides. I highly recommend you getting a manual of some type. There are numerous things to consider when doing this job, there not difficult if you know about them. One other thing that was not in the manual but makes the job easier: the manual says to remove the gear shift handle but this leaves a short lenght of shifter sticking out of the top of the trans. This made removing an reinstalling the trans very difficult. If you have not already done so, you can remove the entire shifter by unbolting the shifter base from the top of the trans giving much needed clearance.

I know this was wordy but thought it was needed to be as clear as possible. Hopefully you can get this in time to be useful.

erubin
12-19-2004, 01:26 AM
Thanks for the info. I will definetely check the pilot dia compared to the trans before installing the pilot in the crank. If the pilot is that soft i bet they break all the time on install and you don't even know it. In fact the old one is broken and maybe i did that when i removed the trans.

I already took the whole shifter off since i don't have much cleareance working under jack stands. i did not disconnect the exhaust though and wiggled the trans out w/ no help and no trans jack. Maybe you recommend that i take the exhaust off now since i may break the pilot wiggling the trans back in.

The rear main seal looks good and dry. Should they be changed everytime on principal anyway?

As for manuals i have Alldata instructions (see attached image). Very limited info but with your help I hope it will go fine.

http://files.automotiveforums.com/gallery/watermark.php?file=/500/2026261992_S10_4cyl_clutch_replace_copy1-med.jpg

gaggrouper
12-19-2004, 08:01 PM
The bearing can take a little abuse but be easy. I would still recommend a service manual for the additional info it provides, there not that much and you may need it for something else.
If you have adequate room, leave the exhaust alone. I removed mine and broke two flange bolts, but I needed the room. You do what's needed to get the clearance.
I used a trans jack adapter attached to a floor jack and still had a time getting the trans back into position. I can't image doing it without something to firmly support the weight of the trans. You mentioned jack stands. I also used jack stands to lift the entire truck up. A few weeks later a mechanic friend of mine did a clutch on an Explorer in his driveway. All he did was lift the back of the vehicle with a floor jack on the differential. I thought it was pretty slick.
With respect to the rear main, I'm not sure. I did not replace mine, it was not leaking. And to tell you the truth, I didn't think about it, besides I had enough work to do.

erubin
12-20-2004, 01:07 AM
Well everything was going great. I ground down the pilot removing tool tabs and it fit perfectly into the old pilot. With a slide hammer the old one popped out. Installed a new one. Then I assembled the flywheel and clutch parts with the alignment tool and that went great. i then mounted the new fork and throwout bearing to the trans and it all looked great. then i spent an hour wrestling with the trans getting it back in and that worked.

Here is the bad news:
The fork and the throwout bushing still don't make contact with the pressure plate. This is the same problem as we had before dissasembling. I looked in the inspection hole and can see that the throwout bushing only starts to make contact when the fork is pushed completely foreward to the end of its travel. It doesn't even start to depress the pressure plate. Very depressing.

My friend had the clutch replaced last by a mechenic that obviously had the same problem and the truck didn't work then either. I thought by buying all new parts and assembling it correctly i would solve the problem.

one theory: for some crazy reason the throwout bushing that i got in my kit from Autozone is too short (it's under 1 1/4" in length). It looks a lot shorter than the one in the diagram (attached photo in my last post). But why would the old throwout bushing I replaced be too short as well? It's as though some spacer or something is missing. A spacer or longer throwout bushing, at least an inch, maybe two inches is needed to bridge the gap. What's going on? I'm desperate. A shop manual is not going to solve this problem. Could this be a clue: the 1992 4cyl S10 pickup came with two different manual 5 spds, a Muncie or a Borg Warner T5. This truck has a Borg Warner. When you buy a clutch the trans model never comes up though. It's as though both trans' take the same clutch.

erubin
12-20-2004, 01:37 AM
I checked a second source for the throwout bearing. Here is the one offered on Napa's website:
http://files.automotiveforums.com/gallery/watermark.php?file=/503/202626217506_1_.jpg

It looks identical to the one from autozone. I think it's safe to assume that I have the correct one from Autozone.

The bearing's wider diameter (bottom in the photo) should press against the spring diaphram of the pressure plate. the smaller dia side is held by the clutch fork's retainer clip.

I either need a longer bearing or some spacer placed somewhere to bridge the 1-2" gap that exists between the bearing and the pressure plate. Any suggestions?

BTW, there is no way the flywheel was ground down the 1-2" that I'm missing. i doubt the flywheel is even more that an inch thick to start with. I'm starting to suspect that the trans is not original but it bolts to the engine OK. maybe the clutch housing is too deep and needs a longer throwout bearing. How do i go about finding a longer throwout bearing? Should the bearing make contact with the pressure plate in the completely engaged position (clutch pedal released) or should there be a small gap (how small?) before stepping on the clutch?

OverBoardProject
12-20-2004, 02:28 AM
I'd be more inclined to balame the fork. It's possible that it was broken, then replaced with the wrong one.
I've only heard good things about AutoZone, which we don't have where I live. If you ask them to bring in a new fork to compair they probably would.

The other possibility is the bell housing might have been changed before.

erubin
12-20-2004, 04:54 AM
I already bought a new fork (ordered by application not by matching to the old one) and it is identical to the old one. Assuming the bell housing is deeper, what is the easiest solution at this point? Can a thicker bearing take up the gap? Should I bring the fork to a welder to heat up and bend? Can a spacer be put somewhere in the assembly to take up the space? Bending the fork seems the trickiest because things might not line up right after.

I believe/hope i can do one of the above "fixes" without yanking the trans completly out (ouch). By parting it from the engine a few inches i should be able to reach in and R&R the fork and bearing.

How much of a gap should exist between the thrust bearing and the pressure plate springs when the clutch is moved completely back? and does the slave cylinder allow the fork to move completly back? I really don't know how much travel the slave cylinder provides and if all of its travel is used to compress the pressure plate or some to take up free play like you have with an ordinary clutch.

busa_4
12-20-2004, 10:02 AM
i am thinking 3 possibilities: 1: the fork is for the wrong vehicle. 2: the throwout bearing is for the wrong vehicle (unlikely but could happen). 3: the input shaft is missing the guide sleeve. the throwout bearing rides on this sleeve mounted to the input shaft. if it is not there or the wrong length you will experience the problem you are facing.

erubin
12-20-2004, 02:11 PM
Thanks for trying to help:

1. the fork is correct for the vehicle on two accounts. a) it was already there. b) i ordered anew one based on the year, make model of the truck and it's identical to the old one. this is not to say that the trans is not original to the truck though.
2. the throwout bearing is correct for the above reason as well. the Napa diagram i showerd in a previous post also looks identical.
3. The bearing rides on the trans input shaft sleeve perfectly. the sleeve is not missing.

I think Overboardproject who posted a few back was onto something when he wrote: "The other possibility is the bell housing might have been changed before."

Back to my question. how do i take up the gap now?

busa_4
12-20-2004, 02:50 PM
if overboard is correct, i think it would be better and safer for you to find the correct bellhousing.

busa_4
12-20-2004, 02:51 PM
do u have a digital camera? i want to see what this looks like.

OverBoardProject
12-20-2004, 07:14 PM
I agree with Busa 4, It might be tough or imposible to find the correct fork for the bell housing.

If you try bending the fork it'll probably break, however welding on a plate to shim it might just get you bye until you feel like pulling the bell housing

Good luck, and if you can send Busa 4 a photo of the bell housing he might be the best advice to make things stock again.

gaggrouper
12-20-2004, 10:12 PM
An interesting problem. I'm not aware of a spacer. As you likely already know, the back half of the bearing is designed to accept the fork and the front, as you mentioned, engages the spring assembly. The trans on my truck has a one piece casting, that is, the bell housing is part of the case not bolted to it. Not sure where your problem is. Not sure what kid of money you have in this project, but with the number of these trucks out there you might consider getting a used trans from a salvage yard. Of course, only after all else fails.... Just a thought. I think at the very least you need to find out if you have the correct bell housing and fork. Just can't see why anyone would switch them. How did you acquire the truck and is it possible to contact someone with info on it?

erubin
12-21-2004, 04:46 AM
I found another throwout bearing at a parts store. It's the bearing for an older (80s?) GM setup. This bearing has an extention ring (about 1") behind the front half of the bearing. This takes away an inch of slop between the fork and pressure plate. It's gruelling work doing the trans R&R alone with just a floor jack. It should have been easier then the first time since i only had to slide the trans back about 5" and slip in the new throwout bearing. Getting the trans and engine to mesh up again was hell. It finally slipped right in when i lowered the tail of the trans a little more than seemed correct.

Now the slave cylinder is completly compressed and the throw out bearing is in contact with the pressure plate in the rest (clutch engaged) position. I hope that is what it's supposed to look like. The clutch pedal feels firm and the pressure plate gets compressed about 3/4" of an inch when the pedal is depressed. Eureka!? I hope so but won't know till I get everything back to gether and test drive later this week.

busa_4
12-21-2004, 07:55 AM
so what your saying is you have an older 80's tranny in your vehicle. if the spacer works that should confirm it.

OverBoardProject
12-21-2004, 10:50 PM
I sure hope that it all worked out for you.

If it does make sure that you write a little referance note in your owners manual, and shop manual if you have one, including year, and part number of the bearing.

erubin
12-21-2004, 11:50 PM
I haven't had time yet to go further. when i do I'll update this post. I can't believe that the trans is from a early 80s vehicle. Afterall the other clutch parts (spec'ed for a 1992 S10 4ctyl) seem to match up fine. I don't want to say too much more until i try it out.

OverBoardProject
12-21-2004, 11:57 PM
If that new bearing works out well you might want to buy the guy from the parts store.. that found the right bearing a christmas beer for the help.

Congrats on your first clutch job, and the rest are all easier

erubin
01-05-2005, 05:28 AM
Finally got back to the truck. The nightmare continues.

everything is installed and the truck will not allow shifting 9can't get into forward gears and grinds going into reverse. I suspect the clutch pressure plate is not being pushed in enough. Please advise:

1. how far should the pressure plate get compressed when clutch pedal is fully depressed.
2. My slave cylinder only pushes in the fork about 3/4" (measured where the slave push rod contacts the fork). Is 3/4" enough?
3. I have bleed both cylinders countless times by using the old brake bleed method of pumping and then keeping pressure as the bleeder is opened. i installed a new master. the slave is only 1 month old. neither is leaking.
4. I will replace the slave cylinder unless someone can give me some other advise.
5. If 3/4" fork throw is enough could a bad trans cause this problem?

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