Rear end swap ideas.. (Purists need not enter)

Transmission and Drivetrain Tech

  1. cross_thread72

    cross_thread72 Tattooed white trash

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    Ok, I'm new to this mopar thing, I was a hardcore chevy guy for years, so I have some parts left over. In a recent lapse in judgement I sold my 8 3/4 because I was never going to build it, and I had an 8 1/4 with gears and a posi ready to roll, the 8.25 disappeared from a friends shop so it's back to the drawing board. I have a 10 bolt chevy II rear end that has a spool and 4.56 gear, it's roughly 57 3/4" wide roughly 1" wider (on each side) than my 7 1/4. I also have an S10 rear end that's roughly 54 1/4" which is roughly 1" narrower on each side. I've got a Mancini spring relo kit that will be used on whatever goes in. My question is would it be better to use the wider one or the narrower one? Please keep the flaming to a minimum, I don't care about bolt patterns or brand loyalty, I just want to go very fast in a very short amount of time, the rate of acceleration is the only concern. All my measurements are from wheel mounting surface to wheel mounting surface.
     
  2. memike

    memike Super Moderator Staff Member FABO Gold Member

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    I would think the more Narrow if it will fit between your springs, any wider then stock will give you tire clearance issues..
    10 bolt rear ends are prone to throw an axle if I remember right and the 12 bolt is stronger. I wonder witch rear end uses up more hp ?
    subscribed and ready to learn
     
  3. cross_thread72

    cross_thread72 Tattooed white trash

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    The 12 bolt is stronger, but creates far more parasitic drag. The 12 bolt uses an 8.875" ring gear and the pinion diameter is 1.625". The S10 rear end is of the 8.5" and variety, built like a brick out house. It carries the 8.5" ring gear and shares the 1.625" pinion with its 12 bolt brother, mine has a lightweight spool, 4.88 gears, C clip eliminators to prevent the dreaded 10 bolt shuffle, 30 spline axles, and a girdled cover to help with the carrier cap distortion issues. This rear end was under my 49 ford sedan behind a dart headed 406" sbc and a jerico 4 speed, it was repeatedly kicked in the face by 4500 rpm clutch drops and two stages of spray, so I don't think the wheezy 318 is going to break it. I'm looking at cost effectiveness, it's free and I don't have to find, build, cut, weld then drive. I can simply weld and drive since its already stripped of its perches and my chop saw can handle any driveshaft issues.
     
  4. memike

    memike Super Moderator Staff Member FABO Gold Member

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    sounds like you just answered my question, S10 it is I would think.
    JMO...
     
  5. 67Dart273

    67Dart273 Well-Known Member

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    I wouldn't put a 10 bolt in a Cushman scooter

    [​IMG]
     
  6. Abodybomber

    Abodybomber Breaking street machines , since 1983.....:) Legendary Member

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    Check out,a 8 inch Maverick rear.Bolt in,supposedly.......
     
  7. 74DartSwinger360

    74DartSwinger360 The Brat Pack

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    How about the disc brake rear out of an 85-89 IROC it would have 3.42s and a posi.
    Thinkin of gettin an 89 IROC this week too.
     
  8. Supershafts

    Supershafts Well-Known Member

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    The camaro rear is the JUNK 10 bolt, it will break under the camaro stock with slicks (unless it's the 9 blt which is better than the 7.5 10 blt).

    There are several versions of the 10 blt and you can use 2 of the wrong versions that aren't the strong 10 blt.
     
  9. 74DartSwinger360

    74DartSwinger360 The Brat Pack

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    Yes I was talking about the 9 bolt camaro rear end. Cant remember the ring size though.
     
  10. fishy68

    fishy68 Tyr Fryr's Inc. FABO Gold Member

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    I don't know if the 10 bolt in the Chevy 2 is the same as the 10 bolt rears used in 70 Chevelles but they were junk. Back when I was a kid I had a 70 Chevelle with a bone stock 350 4 barrell (250 hp version) and tore up 2 10 bolt rears. Didn't even have sticky tires on it.
     
  11. cross_thread72

    cross_thread72 Tattooed white trash

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    I saw that, but finding one around here would be like finding hens teeth. Most of the dirt track guys have snatched them up, and they seem to think they're gold plated.

    "I don't know if the 10 bolt in the Chevy 2 is the same as the 10 bolt rears used in 70 Chevelles but they were junk. Back when I was a kid I had a 70 Chevelle with a bone stock 350 4 barrell (250 hp version) and tore up 2 10 bolt rears. Didn't even have sticky tires on it."

    Both of mine are well built, most of the Chevelles had the 8.2 they're not as tough, but I've broke 12 bolts with a 305 too.

    "How about the disc brake rear out of an 85-89 IROC it would have 3.42s and a posi.
    Thinkin of gettin an 89 IROC this week too."

    Most irocs had the 7.6 10 bolt, the 9 bolt version was most common in the trans am gta's it had a 7.75" ring gear and a weird ass worm gear locker, better known as the Borg Warner 78 series, they're still produced in Australia and quite popular over there.
     
  12. Supershafts

    Supershafts Well-Known Member

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    I have customers 1.3 60's on 10 bolts in single digits at 3600 lbs...

    The only 10 bolt to stay away from are the 7.5's

    The BW or Aussie 9 bolt is much much better than the GM or AAM 7.5 10 bolt.
    Add the T/A cover the studs and the right person doing the set up and they'll handle a fair amount of hp.

    .
     
  13. VDART

    VDART Well-Known Member

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    come to Wichita Kansas I have an 8.75 from a 68 satellite complete drum to drum. Lawrence
     
  14. fishy68

    fishy68 Tyr Fryr's Inc. FABO Gold Member

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    I don't doubt you can build just about anything to handle a decent ammount of power. I'm not sure what was in my 70 Chevelle. Maybe it used the 7.5? That was nearly 30 yrs. ago and I wasn't into Chevy's long enough to learn much about them. I do recall that just about every guy I knew that built his car up to even run in the 13's and used the 10 bolt scattered it pretty quickly.
     
  15. OldmanRick

    OldmanRick Well-Known Member

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    Fishy, the early Chevy 10 bolt, late 71'ish and earlier, was a 8 1/8" ring gear and a small pinion and yes they were weak. The 8.5 came out around 71' and the 7.5 came out about 75'. I've been around dozens of builds back in the day with these rears. Most of my own i used 12 bolts, but a 8.5 10 bolt with good axles, a good carrier (auburn) and the tubes 360* welded to the center section will take almost anything you can throw at it, especially on the street. Surprisingly the 7.5 built the same way will live behind a auto. trans for quite a while. As far as the OP's question, throw the 4.88 S10 8.5 in and forget about it.
     
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    • dustoff440

      dustoff440 Well-Known Member

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      explorer 8.8 or mustang same, probably can find one posi. cheap, lots of the stangs had 3.73
       
    • fishy68

      fishy68 Tyr Fryr's Inc. FABO Gold Member

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      Thanks Rick. I remember back then the 12 bolt (car version) was the one to have but the Chevy guys thought they were made of gold so I never had one. Didn't have the Chevelle long enough to go that far anyway.
       
    • fishy68

      fishy68 Tyr Fryr's Inc. FABO Gold Member

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      Actually the Ranger rear's are the ones to use IMO. Explorer rears are a bunch wider than an A-body so you have to cut them down. Ranger rear's are within 1" of the same width of an A-body. Plus they have the 5 on 4.5" wheel pattern.
       
    • cross_thread72

      cross_thread72 Tattooed white trash

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      Do the rangers have an offset pinion like the exploders?
       
    • fishy68

      fishy68 Tyr Fryr's Inc. FABO Gold Member

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      Yeah but not nearly as much offset. It's been about 4 yrs. since I measured one (it was a 95 if that makes any difference) so the memory is a little fuzzy but if I remember right the offset was within 1/4" of an A-body and so was the width. Except for cutting the Ford mounting brackets off and welding on Mopar spring perches and getting the special yoke it takes to connect it to a 7260 U-joint it looked like a real easy swap. You might have some diff. in driveshaft length to deal with also but you'd probably have that with just about any swap.
       
    • cross_thread72

      cross_thread72 Tattooed white trash

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      That sounds like a good prospect, when I finally get some downtime I'm going to half ass mock up the 10 bolts and do some measuring to see if I'll even be able to get wheels for either one.
       
    • kt340sport

      kt340sport Well-Known Member

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      Find a good mopar rear end and be done with it , sell all the chebby stuff and find a good 81/4 on here from somebody , it will be cheap and put a set of gears in it.
       
    • dustinmoran91

      dustinmoran91 Well-Known Member

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      most ranger 8.8's had drum brakes and 28 spline shafts, the explorer 8.8 although needs 3'' off the driver side tube has 31 spline shafts, disk brakes, and most times 3.73 limited slips. i put one in my duster and it was simple. if he is going to be cutting brackets and things off already its no more work to take 3'' from the tube, weld it back and put a passenger side axle in it. also it has the 5x4.5'' bolt pattern to. i would much rather have to take 3'' out of a tube but have 31 spline shafts and disk brakes over having a rear that still needs brackets and has 28 spline shafts and drum brakes. that's just my opinion though.
       
    • Demon416

      Demon416 A-Body

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      Don't know how much power you plan on putting to the ground, but that 10 bolt won't hold much before it goes "bang." VDART offered a complete 8 3/4, you might want to save the headaches and go get it.
       
    • fishy68

      fishy68 Tyr Fryr's Inc. FABO Gold Member

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      Do you suppose he has a jig to properly narrow the explorer rearend? If not it's not as easy as just wacking off 3" and welding it back together. If not done in a jig it's not done right, i.e. the wheel bearings won't be aligned properly. Just a few thousandths off and your giving up hp and causing more wear. If he doesn't have the jig (which very few average mechanics have) he's looking at the expense of having a shop do it which can run $125-250 depending on location. I agree that the 31 splines are stronger and disc brakes are nice but it sounded to me like he's looking at a simplistic swap which I believe the Ranger rearend to be. I don't think he mentioned the HP level he's at but as long as it's not real high the 28 splines are plenty strong. JMHO

      BTW: what did you do for a axle for the side you shortened?
       
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