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8.8 rebuild help

Discussion in 'The Hokey Ass Message Board' started by A.Rykowski, Apr 20, 2015.

  1. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    Hi everybody, just looking for some advice on an 8.8 rebuild. I am rebuilding my rear and installing 3.08 gears. The gears I have are used but look absolutely mint. I bought a rebuild kit with all new bearings, races, shims etc. I've installed all the new bearings and races and everything seemed to go together just fine. The install of the pinion went pretty well too. We set the preload on the pinion to about 16 inch lbs and it feels nice and smooth as it spins. Now, when I set the carrier in I can get my backlash to about .014" I believe .008-.012 is the acceptable range. I've found that I can spin the pinion with the carrier in place and it will spin nice and free for about a turn and a half and then it feels like it binds a little. I've checked the run out on the ring gear and found a variance of .002 +\- which I think would be acceptable. Has anyone ever run into this before? Is it possible I am feeling a bit of the previous wear pattern in the gears? I'm at a loss and frustrated to say the least. I certainly appreciate any insight anyone can offer.
     
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    Were these gears in this housing before or did you buy them separately?

    What does the contact pattern look like on both the drive and coast sides?

    If you have bind when you turn the pinion, it is not gear wear, it is a bearing issue.

    With a runout of 0.002"+/-, these gears were likely operated on worn bearings.

    Your backlash should be closer to 0.010". Your gears wont last long, and will be noisy at 0.014"

    I do not like used gears. A new Ford 3.08:1 gearset is $155.
     
  3. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    With that backlash and runout it shouldn't be binding... at a minimum it would be at .012. Did you turn the pinion all the way thru without the carrier installed?
     
  4. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,910

    dirty old man
    Member Emeritus

    I'm piggybacking to bump you and to eavesdrop on the discussion of the black art of R&P setup.
     

  5. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    They were separate of the housing when I bought them. The contact pattern appears the same as i've seen in past experiences but that's not saying much. Do you think it could be possible I have the carrier shimmed too tight and its binding the bearings?
     
  6. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    @ grey beard I did turn the pinion all the way through without the carrier and it feels perfect
     
  7. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    You need to re-shim the carrier to tighten up the backlash, and then paint marking compound to check the loaded contact pattern.

    Post pictures.
     
  8. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    If you had the carrier tight enough to be binding you wouldn't have .014 backlash. I would pull the carrier back out, verify the pinion has the same amount of drag thru a few turns. Then measure your shims before setting the carrier in place. If the one on the ring gear side is thicker than the other one..... swap them, even if it creates a lot of backlash. Turn it thru and see what it does. These are pretty easy to build ( I have done a bunch of them when I worked at the dealers) and if you are having a problem.... start over! See what the backlash is by putting the thin shim in the ring gear side. If it spins freely, measure the backlash in at least 4 places around the ring gear.

    One more thing to look at while the carrier is out....... make sure the ring gear is seated on the carrier all the way around !!! Easy mistake to make !
     
  9. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    Another question..... how did you select the shims for the pinion? This is more critical than the backlash when setting one up (that is why there is a "window" for backlash.... not so much on the pinion depth).
     
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    Yup. This is what separates a 300,000-mile rear end from a 300-mile rear end.
     
  11. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    Ok, I just pulled the carrier out (again) and verified the pinion spins smooth throughout about a million rotations. I re- shimmed the carrier and got my backlash to .009 in 4 places. Still have the bind tho. I see your bringing me back to pinion shims, this is almost definitely where I'm screwed up. What do you suggest for selection or a measurement for the pinion depth?
     
  12. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    I'll grab a few pics in the AM.
     
  13. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,910

    dirty old man
    Member Emeritus

    Is this where those special measuring fixtures come into play?
     
  14. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    You either have to use a specific tool, or use the marking-compound method.

    One requires a special tool, the other, finger paint.

    This will show you the contact pattern. The contact pattern will indicate the pinion depth.

    Here's a good video:
     
  15. JeffB2
    Joined: Dec 18, 2006
    Posts: 9,484

    JeffB2
    Member
    from Phoenix,AZ

  16. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    I just looked in my factory manual.... there is no spec for pinion depth listed. You use the special tools to select the shim by sliding shims between gauge block and tube and find one that has a slight amount of drag. What I have done before is remove the shim from the original pinion and install it on the new pinion, set the backlash (which is .008-.015) and then check the pattern and adjust from there.
     
  17. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    If I'm reading this right, according to your link Greybeard and my vid, I need more pinion shim? ImageUploadedByH.A.M.B.1429628379.634587.jpg
     
  18. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    That's exactly what I'm going to do, use the old shim as a starting point. I should have done that to start. My own worst enemy sometimes. Thank you for all the help. Very knowledgeable. You guys really make this forum head and shoulders above any other.
     
  19. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    You need a LOT more pinion shim.
     
  20. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    Thanks Gimpy, I'll give that a shot and see what happens.
     
  21. oj
    Joined: Jul 27, 2008
    Posts: 6,454

    oj
    Member

    Did you 'block sand' the back of the ring gear? Block sanding removes residue from oxide used to treat the gears, if you have used gears block sanding will remove the raised ridge around the bolthole.
    Shouldn't the pinion be about 25inch pounds for new bearings? 15inch pounds for used? The pinion bearing tolerance won't affect what you are dealing with.
     
  22. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    Let us know how thick the shim is you have in it and what shim was on the old pinion. Another thought on the binding... if the pinion is too deep, it can actually come in contact with the carrier and drag (seen this happen with worn pinion or carrier bearings also). I need to see the pattern on the coast and pull side.... can't tell from that photo.
     
  23. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    Well I had a .020 shim on the pinion. I went to .032 and this is the pattern I have: ImageUploadedByH.A.M.B.1429679002.302343.jpg ImageUploadedByH.A.M.B.1429679054.874547.jpg I am at .009,.009,010,and .009 on the back lash. It seems to doi with less bind but I Still have a spot where I feel more resistance when I turn the carrier over with the pinion.
     
  24. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    See if you can isolate the spot where it is binding. Mark the pinion and ring gear and roll it thru again and see if it duplicates in the same spot every time. There may be a burr or a nick on a ring gear tooth (not thinking pinion because you mentioned turning it 1 1/2 turns before you felt it).
     
  25. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    Well after wasting several days with this bs I decided to buy another set of carrier bearings and installed a carrier out of another 8.8 I had. Used my ring gear from the first one and bingo. It's absolutely perfect now. I have still not found what exactly was wrong with the original carrier but two sets of carrier bearings and God knows how many hrs wasted I don't care enough to find out anymore. I appreciate all the help from everyone.
     
  26. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    I have never tried it, and was always told not to do it..... don't use a pinion out of one gear set with a ring gear out of another set. It will work, but you don't know how much noise it will make. Gears are sold in a set because the 2 gears have been honed together as a set to keep noise at a minimum.
     
    gimpyshotrods likes this.
  27. 302aod
    Joined: Dec 19, 2011
    Posts: 275

    302aod
    Member
    from Pelham,Tn.

    I set up many R&P over the years when I worked at the local Ford Place. But now don't have access to the set-up tools. Had a 3.08 rearend and needed a 3.55 and just bought a whole rear end with a 3.55. It was $100 off Craigs List, Cheaper than a new R&P and quiet.
     
  28. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    I'm not saying I mix matched the gear set. I set simply put my ring gear on another carrier. ImageUploadedByH.A.M.B.1429797837.098856.jpg ImageUploadedByH.A.M.B.1429797856.203492.jpg
     
  29. A.Rykowski
    Joined: Aug 13, 2014
    Posts: 48

    A.Rykowski

    @302 smart man haha.
     
  30. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    OK.. mis-understood :)
     

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