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Technical 10 bolt 8.5” width chart

Discussion in 'The Hokey Ass Message Board' started by WilieE, Sep 4, 2018.

  1. WilieE
    Joined: Mar 28, 2018
    Posts: 22

    WilieE

    [​IMG]

    I’ve got this 10 bolt 8.5” rear differential in a 54 Chevy 210. While bleeding the brakes yesterday I discovered several problems ranging from noisy gears to missing parts behind the drum. This unit is 61” flange to flange and if I fix it I will need to replace my wheels with more backspace. Therefore it may make more sense to find a 58-59” wide diff than spend all that money on gears and wheels. Found some charts on widths but not much on these 10 bolt 8.5’s. Hoping the geniuses here might know. Thanks


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  2. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Check out an S-10 4 x 4 rear axle assembly.....should be what, or very close to what, you need. 5 x 4.75 bolt pattern, decent ratios available.

    Ray
     
    gimpyshotrods likes this.
  3. The S-10 is a good rear but it is a smaller ring gear.

    Look for a Nova 12 bolt or a *Chevelle 10 or 12 bolt.

    *'65 will be pretty narrow and should be a 10 bolt not a drop out rear, The '66 or '67 will be about the same maybe a little narrower.
     
  4. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Not sure I can agree with that., especially a 4x4 model and/or a V6. I am pretty sure the 4x4 used 8.5 diffs.
    But, that said, I have been wrong before...and recently....and will be again......:(

    Ray
     
    Nailhead Jason likes this.

  5. KevKo
    Joined: Jun 25, 2009
    Posts: 926

    KevKo
    Member
    from Motown

    S10 with V6 and stick will have the 8.5. 2wd will be 54" wheel mounting face to wheel mounting face. 4x4 will be 56, ZR2 will be 58, IIRC.
     
  6. They are a metric rear even the 4x4. They used the same rear for the Banger pickup and the 350 Trans AM. You didn't get a different rear (in a 10 bolt) until you got into the corporate rear in a bigger truck or Limo. I don't remember what the ring measures in inches but it is quite a big smaller then 8.5.

    There isn't much wrong with one until you try to mount earlier aluminum wheels then you have to message the holes a little bit. WE had one behind a big torque 355 for a while, then we put the rear behind a 554 in an OT Cutless where it still resides. That gear and carrier swap happened in '99.
     
  7. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    I know/agree with 54" for 4x2 but also believe there is more than two inches width increase on the 4x4 models. The 4x4 track is wider than a 4x2 and the 4x4 uses deep backspace wheels whereas the 4x2 are closer to 0 offset. Several other threads report having used 4x4 S-10 in '50s era Chevy passenger and in all cases claimed they were correct width for that purpose.

    Ray
     
  8. The 4x4 is 58 if I recall. It may be as narrow as 56 but the 54" rear is a 2WD rear and is actually 54.25" if you want to get picky about it.

    I played with S-10s for a while in the '90s. Slammers, Street Strip trucks, and Mini truck roundy rounds. Not HAMB friendly but they were a versatile truck and didn't weigh much. ;)
     
  9. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    I too had Chey S-10 and GMC S-15 in early 2000's and that experience informs my opinions, though I am not claiming 'expertise', only a general familiarity with them.

    Ray
     
  10. the rear from a 83 to 88 Monte Carlo Super Sport is an 8.5 inch rear and if your lucky has a posi. It comes in at 58 1/4 inches wide WMS to WMS. Yes you need to weld on the leaf spring pads and cut the control arm brackets off, but it works great. that is what I put in my 51 Chevy. I can fit an 8 inch wide wheel with 255/60 15 tires on it with 3 and 3/8 back spacing and the tires do not rub.
     
  11. The first gen S trucks were all the rage around here in the '90s. We used to rob the posi units from a TA or Camaro in the U pull it because they were easier to come by than an S truck rear that was a posi. Same housing they were a bolt in. You could also snag the disc brakes from a TA at the U pull it cheap.

    The mini trucks at least around here required a stock rear end housing. The were mostly V8 trucks, but no Bow Tie NASCAR stuff allowed. Off topic but I did sneak a pair of Trick Flow twisted wedge heads past the techs. They came with a C.A.R.B. number which made them stock replacement heads. LOL

    I like the little 10 bolt that could. They are tough. I seldom suggest them because they are a late model rear. Under a custom where no one is gonna look I think they are fine as frog hair, I probably wouldn't put one out where everyone could see it though.

    OK just checked. the ring gear size for the S-10 through '92 is a 7.5" (actually 7.625) The GM G body in that era used the same rear.
     
    Last edited: Sep 4, 2018
  12. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    So, maybe I am confusing '10 Bolt' with 8.5" rear end. That seems likely (old age is a bitch) as after reading your mention of 'G body' I immediately recalled that they are the 7.5" in most applications and that is what my local good buddy has in his '37 Chevy 350/350. In any case, they seem dependable in reasonable use. I think I'm going to have to 'fact check' myself more before posting...I've had a bad run in recent weeks :confused:

    Ray
     
  13. WilieE
    Joined: Mar 28, 2018
    Posts: 22

    WilieE

    Is the pinion offset being a 4x4?



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  14. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    I don't understand your question. 4x4 is an abbreviation of 4 wheel drive ( 4 wheels driven by 4...aka 4WD)
    As for pinion offset, that is an entirely different matter, quite common, but I don't know if the '4x4 S-10 rear ends have an offset pinion or not. It may be centered, but it seldom matters in most vehicles unless they have avery narrow driveshaft tunnel in the floor boards. Hope that clarifies the matter.

    Ray
     
  15. WilieE
    Joined: Mar 28, 2018
    Posts: 22

    WilieE

    I understand 4x4. But I used an explorer 8.8 in my 51 GMC and due to the driveshaft coming out of the transfer case, the pinion (input shaft) is offset like 2+”. This requires a CV joint in the driveshaft which is expensive.


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  16. WilieE
    Joined: Mar 28, 2018
    Posts: 22

    WilieE

    Not all 10 bolts are 8.5. I spent hours researching this yesterday since I didn’t know what I had.


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  17. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    How long is your driveshaft? A 2" offset of the pinion does not automatically require a CV (Carden) joint. It depends on the angle of the driveshaft to pinion. The sideways offset, for all practical purposes, is no different than the the downward angle of the driveshaft to the pinion. It is referred to as a 'compound angle', but it seems that is a distinction without any consequence in this sort of situation provided the driveshaft is long enough to not form an extreme angle (5+ degrees) at the u-joint.

    Consider that vehicles produced with offset pinions have the transmission usually centered in the chassis. (a few may have eng/trans offset too, but even when that is the case, not as much as the pinion. So, for those with centered trans and offset pinions, they usually do not have CV/Carden rear joints. If you look at a clock face the shaft is typically centered. '6' would represent the direction the driveshaft would take ('downward') if both trans and pinion are centered. Now look to the '5'. That is where the driveshaft would point with pinion offset. The driveshaft could be angled toward any of the numbers, up down or sideways, and it would not matter so long as the u-joint angle does not exceed it's recommended range.

    This has been discussed on the HAMB several times before so there are threads you can search if you wish.

    Ray
     
    Last edited: Sep 13, 2018
  18. paintman27
    Joined: Apr 23, 2011
    Posts: 287

    paintman27
    Member
    from new jersey

  19. 54 Chevrolet
    Joined: Aug 29, 2018
    Posts: 102

    54 Chevrolet
    Member
    from Wv

    I used A 72 nova 8.5 in my 54 bel air, it was the same width as the original rear.
    Bought A kit at Butch's speed shop in Ohio. The kit came with new spring perches, centering plates,new shocks ,shock mounting kit,very nice kit for the money .
    ALL 72 and up nova's will have A 10 bolt 8.5.
    71?
    70 and older will be A 10 bolt 8.2 or A 12 bolt .
     
  20. Slow down
    Joined: Jan 7, 2014
    Posts: 125

    Slow down
    Member

    This might help. [​IMG]


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