rear end swap

Discussion in 'Got gears?' started by GMMADMAN, Feb 26, 2018.

  1. GMMADMAN

    GMMADMAN Well-Known Member

    In my 66 Skylark i have the original 8.2" open 10 bolt with highway gears. I will be running a '73 455 that I was told from TA that it'll be a 500+ HP build when i'm done. I found a 69 Olds type O 12 bolt open rear end for sale somewhat locally and I was wondering if it will be a good upgrade from the 8.2? The guy wants $650 for the rear end, although I haven't bartered with him yet because it's a 4 hr round trip to get it. I'm waiting for more info on it like ratio, condition, etc. I plan on running a posi unit. Should i save up for a different rear or would this be a good one to build for street and occasional strip? Thanks guys
     
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  2. Bigpig455

    Bigpig455 Fastest of the slow....

    I wouldnt build the olds rear, and 650 is WAY to much for it no matter what gears it has. The olds rear will still be an 8.2 when youre done, and kind of an oddball for parts too. Contact JD Race, Brian Trick or Everyday Performance to see if someone can build you a 71-72 Buick/Olds 8.5 rear for what youre about to spend on that Olds 8.2....
     
  3. Bens99gtp

    Bens99gtp Well-Known Member

    Your 66 rear if orginal, is narrower than than the later cars but a little over an inch if I recall. Just something to keep in mind
     
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  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Unless you plan on racing with slicks, I would just build your current rear. Gears and Posi are readily available out of the Jegs/Sumitt catalog. The Olds is an oddball rear, 12 bolt with 10 bolt internals, not a bad rear though.
     
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  5. BrianTrick

    BrianTrick Brian Trick

    A 12-bolt O-axle can handle the power. However,I would NOT pay $650.00 for one that wasn’t a posi. A typical 2:56/2:78 non-posi is a $150.00 core. If it has 3:23’s,it’s worth a little more because it has a desirable gear,but still nowhere near $650.00.
    I would either build your existing rear,or build a 71-72 8.5” 10-bolt.
     
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  6. 12lives

    12lives Control the controllable, let the rest go

    Your 66 has bolt in springs? To go to a 8.5 you will need different wheels (offset), different springs at a minimum. I'd build up your existing rear, it can take the BBB you are building. Send it to one of the folks Rhett mentioned.
     
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  7. GMMADMAN

    GMMADMAN Well-Known Member

    Thanks for the input. I've been looking at BOP style 12 bolt posi rears on Feebay, but they are $1500-$4000 and most are local pick up only. I would like atleast an 8.5 posi with 3.42 or 3.55 gears. I'm in Utah so maybe I will wait to see what pops up locally. I'm in no rush.
     
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  8. FJM568

    FJM568 Well-Known Member

    I've got a 71 Buick 8.5 10 bolt 3.08posi in my 66 Skylark w/455. I'm running the standard 15x7 Buick rally wheel 235/60-15 BFG Rad TA on it, no problems. You will need a different length driveshaft if you put the 8.5 in. Bought the 8.5 open rearend for $100, then bought full rebuild kit, used 3.08 gears, and rebuilt posi unit from Monzaz(JDRace) of the board here. Put it together myself and probably have as much in it as that used Olds rear you were looking at.
     
  9. BrianTrick

    BrianTrick Brian Trick

    You will not need different springs. Yes,your current axle may have the style that bolt to the flat plate,but the ends of those springs are shaped the same as the later ones,and fit over the perch. Your 66 rear should be the same width as the 71-72. BOP only used the narrower rear in 64-65. There might be some early 66’s with them. Chevy kept the narrow one for 64-67. When swapping from the BOP 8.2” to the 71-72 8.5”,you will need to shorten your driveshaft about 3/4”. The driveshaft is your only modification. It still uses the same 3R U-joint.
     
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  10. Bens99gtp

    Bens99gtp Well-Known Member

    Thanks for clearing this up I though buick kept the narroworld housing till 68 as well, love this place learn something new every day
     
  11. BrianTrick

    BrianTrick Brian Trick

    I’ll be here all week,and then some.
     
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  12. PGSS

    PGSS Gold Level Contributor

    What were the biggest changes to the GS rear ends over the standard Skylark? Axle shaft size and bearings?
     
  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I don't think there were any changes other than the Posi carrier and gears. Axles and bearings were the same. I could be wrong. I'm sure BrianTrick or Monzaz can answer definitively. All the Buick rears were bolt in axle and used the big u joint unlike the 12 bolt Chevys.
     
  14. monzaz

    monzaz Jim

    Yes That is all - and in 1970 there was NO Difference at all - They all used the oiled Set 9 bearing type.
     
  15. wkillgs

    wkillgs Gold Level Contributor

    Axles and bearings were not the same as regular Skylark.
    The 65 GS and Sportwagon used a wheel bearing with a larger OD. The axle tubes were larger near the brakes to accommodate the larger bearing. Bearing was a RW507A
    Starting in 1966, The GS and Sportwagon also went to a larger diameter axle, requiring a change in the bearing to a RW507G. this was used thru 1968.
    I lost track of the changes after that..... I don't have any of those 'new' GS's.
     
  16. 12lives

    12lives Control the controllable, let the rest go

    Thanks for clearing that up - This board is great for that.

    Jim F - How close to the fender is the tire? Could you go with a larger tire?
     
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  17. Swagon

    Swagon Well-Known Member

    If I were to do it again I would spend the money on a 9" because of more gear selection. But I had a chevelle 8.2 upgraded with 9" ends, narrowed an inch, and moser axles, 3.73 gears. theres a guy with a 496 nova that did this and his car runs 8.90's and its holding.
     
  18. monzaz

    monzaz Jim

    Hummmm a CHEVY 8.2 running 8.90....I would really like to see that...The car must be a engine only no body frame etc. 8.2 CHEVY is weaker than the 7.5 10 bolt in the pinion area...
    Take some pictures of the rear under that car the next time you see it run 8.90. :D lol. Jim

    There is not even a spool for that rear??? They only came in 28 spline ... soooo. MAny it is a 8.5 and looks like a Chevy rear because they take the same rear cover and are interchangeable... Could have put a Chevy cover with the eyebrow on the 8.5 rear...lol.
     
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  19. BuickV8Mike

    BuickV8Mike SD Buick Fan

    If your not cheating or lying your not trying.......many believe it unfortunately.
     
  20. BrianTrick

    BrianTrick Brian Trick

    8’s with an 8.5”? Yes.
    8’s with a Chevy 8.2”? I really doubt it.
     

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