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Technical Throwout bearing - what the heck?

Discussion in 'The Hokey Ass Message Board' started by midnightrider78, Oct 12, 2017.

  1. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    Got my car back apart after only 40 or 50 miles. '56 chevy, 383, super T10. When I got it apart I just happened to notice that the throwout bearing(which was new when I assembled everything this summer) has an insane amount of slop. The thing moves about 1/16 of an inch(inner part of the bearing in relation to the outer).
    I'm told some bearings are designed this way, but the extra bearing that I have does not move like this.
    The bearing seemed to be in the fork properly.
    Did I goof up?

    The only thing I could think of was that maybe I had the fork/linkage adjusted improperly. I had it set up so that there was very little movement of the fork before the clutch began to disengage. Could this have been the cause of the bearing wear? How much travel should the fork have before it begins to press on the pressure plate?

    Thanks for the help.
     
    Last edited: Oct 12, 2017
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  2. DDDenny
    Joined: Feb 6, 2015
    Posts: 6,429

    DDDenny
    Member
    from oregon

    One possibility.
    The spring tabs on the fork are easy to get wrong, the t.o. bearing flange does not sandwich between the spring and the fork.
     
  3. 302GMC
    Joined: Dec 15, 2005
    Posts: 4,442

    302GMC
    Member
    from Idaho

    Most manuals would give 3/4'' - 1'' free play. I like a lot more, so release is closer to the floor. Any time the release bearing is in constant contact w/ pressure plate, certain failure awaits.
     
  4. Mr48chev
    Joined: Dec 28, 2007
    Posts: 21,336

    Mr48chev
    ALLIANCE MEMBER

    That is free play at the pedal. When everything is right with the world you should be able to push the pedal down about 1 inch before you feel the throwout bearing engage the fingers or diaphragm on the clutch.
    Also if you don't have a return spring on the pedal the weight of the pedal might push the throw out bearing against the clutch and cause it to spin all the time.
     
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  5. southcross2631
    Joined: Jan 20, 2013
    Posts: 1,369

    southcross2631
    Member
    from Florida

    Beware, Chevrolet has 3 different lengths of throw out bearing. Do you have the right one ?
     
  6. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    That was the first thing I double checked and I had the bearing in the fork correctly
     
  7. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    I was wondering if that may have been the problem. When I adjusted it, I hadn't considered that having it so close may allow it to be in contact when I didn't intend it to be.
     
  8. blowby
    Joined: Dec 27, 2012
    Posts: 4,307

    blowby
    Member
    from Nicasio Ca

    In my opinion, even if the bearing was spinning all the time, in only 40-50 miles it would not wear 1/16" unless there was no grease in it, and if it did you'd either have metal dust on the outside or feel it when spinning it. Are clutch issues the reason you took it apart?
     
  9. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    Did not know that. I assume I do as the worn bearing matches the extra bearing that came with the transmission setup(which came out of someone else's tri-5). But, you know what they say about assuming things. Guess I should look into this a bit more.
     
  10. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    Nope. Clutch seemed to work great. Catastrophic engine failure was the reason it ended up apart.
     
  11. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    The pedal has the return spring on it. However, I don't have the small spring that goes between the clutch fork and pushrod.
     
  12. 302GMC
    Joined: Dec 15, 2005
    Posts: 4,442

    302GMC
    Member
    from Idaho

    Lots of the '55 - '57 Chevs that got rodded were Powerglide equipped when new. Damn few of the "back yard" stick changeovers had the entire factory pedal ass'y parts installed at the same time. There's an "overcenter" spring, lots of bushings, & some alignment of parts that got overlooked on most of them, making for a crunchy, grating feel when operated. Make sure all the moving parts under the dash are as they should be.
     
  13. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    This car has been a manual it's whole life. I replaced every spring(except the aforementioned one on the clutch fork), bushing, etc when I was building the car. The clutch worked smooth as can be for the brief time that I drove it. That's why I was totally blown away when I realized the throw out bearing had so much slop in it.
     
  14. gene-koning
    Joined: Oct 28, 2016
    Posts: 387

    gene-koning
    Member

    In the last few years, I'm on the 3rd clutch in my coupe, the first two were replaced because of a throw out bearing failure. The chassis in my coupe logged over 150,000 miles on the original factory clutch.
    The 1st throw out bearing locked up in around 500 miles. There was still grease in it and the clutch was properly adjusted! One day it just quit spinning, and every time I stepped on the clutch, I heard a squealing sound. It was part of a clutch "kit" and I replaced everything, fortunately it was covered under warranty.
    The 2nd throw out bearing broke an ear off the bearing housing. Yep, it was the replacement kit. That one had about 1000 miles on it. It was a defective casting, and I had to replace everything in the kit.
    The current clutch is working great, there is almost 10,000 miles on it.

    The current crop of replacement auto parts is no where near the quality of the parts from years past. Unfortunately, I don't see that changing in the future. I suspect we will be changing a lot of parts simply because they have failed without a good reason, other then because of crap quality. Gene
     
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  15. henryj1951
    Joined: Sep 23, 2012
    Posts: 2,100

    henryj1951
    Member
    from USA

  16. henryj1951
    Joined: Sep 23, 2012
    Posts: 2,100

    henryj1951
    Member
    from USA

    Different styles of pressure plates (1000 finger / 3 prong )can require different bearings, we used to run the ford LONG style in few of our chevys.
    Different forks, bearings and ADJUSTMENT....
    I have no answer on your dilemma, just pointing out some variations.
     
    Last edited: Oct 14, 2017 at 12:02 AM
  17. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 4,326

    56sedandelivery
    Member

    Improper clutch adjustment allowing the bearing to continue riding against clutch fingers? OR, typical cheap, offshore junk? Virtually EVERYTHING is made in China now; I always check labels, and it's getting to the point I don't want to do that any longer; it's depressing. At least with some automotive parts, we can still find NOS parts made right here in the U.S. of A. I am Butch/56sedandelivery.
     
  18. henryj1951
    Joined: Sep 23, 2012
    Posts: 2,100

    henryj1951
    Member
    from USA

  19. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    I hear ya. I pretty much gave up on looking at where things are made when I had some MAC tools warranted and the replacements where made in China.
     
  20. 302GMC
    Joined: Dec 15, 2005
    Posts: 4,442

    302GMC
    Member
    from Idaho

    The release bearing that comes in our locally sold Chev clutch "kits" looks like some weird plastic. I can't tell what the pilot bushing is made of, but won't use either. I stocked up on USA made parts years ago just by cleaning & preserving used parts discarded by people who had to have new.
     
  21. The TO bearing that came with my Zoom clutch set was noisy for a short while. I didn't hear it until I was above 3200 RPMs and it quieted down after that. Something to think about. I have a few name-brand used TO bearings around. If it takes a dump, I'll use one of those.
     
  22. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

  23. I've never seen a worn bearing retainer before. They should be very smooth all along the length. The Hays one looks good. Double check the I.D. though, 1.375" seems big to me, just to make sure you get the right one.
     
  24. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    The reason that I questioned the bearing retainer being worn is that there seems to be a bit of a ridge around the retainer about 1/2" or 3/4" out from the trans.
    How close should the bearing fit to the retainer? Should there be any measurable gap between the bearing and the retainer?
    The bearing I used originally, as well as the bearing that I got with the trans(which was on it for 30k or more), both have 1/32 to 1/16 of potential movement side to side when the bearing is on the retainer.
     
  25. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    bearing retainer arrow.jpg It's not great, but here's a pic of the retainer. The arrow shows the ridge I was talking about. There is about .005 to .008" difference between the two areas.
     
  26. I don't think that would hang up the TO bearing. Got access to a lathe? It would polish out most likely. Have you got a new TO bearing yet? I've seen them loose before, but how loose is the question. I would go with a made in USA one and see what happens.
     
  27. midnightrider78
    Joined: Oct 24, 2006
    Posts: 671

    midnightrider78
    Member

    My Uncle has a lathe... but he's 100 miles from me. I have ordered the TO bearing I mentioned is post #22.
     

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