8.2 or 8.5?

Discussion in 'Got gears?' started by buickman7076, Jun 27, 2017.

  1. buickman7076

    buickman7076 Member

    Hello all

    I've recently been wanting to change my 70 Buick skylark from a peg leg to a posi unit. I have done a lot of research so I'm trying to narrow down the right fit for me. The engine is stock. Might do some mild upgrades in the future but nothing to wild. Has a TH350, but will probably change it to a 4 speed in the future. I want the car to act like a everyday driver and climb nice size hills when going on a road trip, but can still get off the line at a stop sign. So my question is do I stay with the BOP 8.2 rear that it has? Or go with a GM 8.5? I say the 8.5 because I was hoping to find a complete rear end in the junk yard with disc brakes already on it. Any ideas if I could find that as well? Hope to hear from all of you. Thanks for all the help in advance.
     
  2. techg8

    techg8 The BS GS

    There is not a stock junkyard 8.5 rear with disc brakes as an assembly that would be a direct fit. Its a needle in a haystack to find one that has been modified in that way, but its possible.

    For your intended use, the 8.2 sounds like it would be fine, although that year of Buick rear is an oddball setup. Contact Jim at JD Race and Restoration (jdrace.com) - Monzaz here on the board. See what he has available for your rear - I would recommend about a 3.08 ratio but I'm not sure whats available. I do know Jim can modify a new posi unit to work for your rear. AND he does sell Disc brake conversion kits.
     
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  3. buickman7076

    buickman7076 Member

    Thanks techg8. I was thinking of the 8.5 because everywhere I was reading it was easier to get parts for that rear end.
     
  4. BrianTrick

    BrianTrick Brian Trick

    Depending on if you can find an 8.5" core,and what you pay for it,you could possibly build that whole thing for less than what you have in the parts for the 68-70 Buick 8.2". The gears alone,for the 8.2" are about $575.00,and your choices are 3:42 & 3:64. You would still need the posi unit and all of the bearings/seals to rebuild it. You will have over $1100.00 just in the parts for the 8.2". Then you still have to build it,or pay to have it built.
    If you can find an 8.5" out of a 71-72 Cutlass/442 or a 71-72 Skylark/GS,that is the more practical way to go,especially if you are not concerned with originality or matching numbers. The only thing you will need to do when swapping from the 8.2 to the 8.5 is shorten your driveshaft. That is an expense you would want to research locally,to see what that costs in our area.
    As for the rear disc brake kits,the kit that The Right Stuff Detailing sells is pretty good. Basicly,it is a late-70's Cadillac caliper,and a late-70's Camaro/Firebird rotor. They supply a properly Machined bracket to make it all work on an A-body,and also include e-brake cables and hoses. The nice thing about this kit is that the wearable parts can be bought at a local parts store. Their kits are about $425.00,and go up from there,if you want other options,like drilled/slotted rotors,or powder-coated calipers.
    If you want a rebuilt 8.5" rear,done,ready to install,from me,it would be $1300.00 plus the freight. I can add a disc kit for additional cost,or you can do that.This would be a rust-free housing that gets hot-tanked,blasted,primed,painted,new Motive gears(any ratio),new Eaton posi or Detroit Tru-Trac,Timken bearings & seals,and everything is assembled,filled with fluid & additive,and ready to run. Gear choices are 3:08,3:23,3:42,3:73,etc.,
     
  5. buickman7076

    buickman7076 Member

    Thanks for the help Brian. What does freight usually cost on a monster like that?
     
  6. 12lives

    12lives Control the controllable, let the rest go

    Buickman - if you have a friend with a business (or maybe where you work) you will find shipping to a business cheaper than residential delivery - just a thought!
     
  7. techg8

    techg8 The BS GS

    That is true.

    I was thinking for the 8.2, monzaz could hook you up with a posi and gearset that you could just throw in.

    If you were looking at a complete rebuild, it might be worth upgrading to the 8.5, although not necessary for your stated use.
     
  8. techg8

    techg8 The BS GS

    I know when I use FedEx LTLfreight, terminal to terminal it costs about $200 across half the country. Coast to coast can be twice that or more.
     
  9. BrianTrick

    BrianTrick Brian Trick

    Where are you located? I have used ABF Freight for the majority of these,for the past 18 years,but in the last two years,I have been using Fastenal. They ship store to store,and are always cheaper than any conventional freight company. Even when I use ABF,it is terminal to terminal. A residential delivery will almost triple the price.
     
  10. buickman7076

    buickman7076 Member

    Live in Southern California. If I had to ship it I think I have a friend that would let me use his work as a delivery point possibly.
     
  11. BrianTrick

    BrianTrick Brian Trick

    For whatever reason,Fastenal will ship out of CA,but they will not ship into CA. I can recheck with them again,to confirm. Do you border another state that you could cross over to get one,if needed? ABF isn't a problem,but it will cost more. Leave me a zip code and I can get some quotes.
     
  12. bigtorque5

    bigtorque5 Well-Known Member

    the rear u joint takes straps in stead of ubolts
     
    Last edited: Jun 28, 2017
  13. BrianTrick

    BrianTrick Brian Trick

    Yes,but same 3R u-joint. The straps and bolts are included.
     
  14. BrianTrick

    BrianTrick Brian Trick

    I did confirm today that Fastenal will NOT ship into California,only ship out. No idea why. I can ship ABF,but it will be in the $300.00 range.
     
  15. knucklebusted

    knucklebusted Well-Known Member

    Also, be aware that the Right Stuff rear disc brakes work great but will not fit with factory Buick 15" chrome wheels. It will take modification or a spacer to get them to work properly. The hat on the rotor is too shallow and the caliper rubs the wheel.
     
  16. hugger

    hugger Well-Known Member

    Just done a right stuff kit, you need 5/8 longer studs and 1/2in Billet spacers
     
  17. BrianTrick

    BrianTrick Brian Trick

    You will need longer studs with any of the rear disc kits because the rotor hat is thicker than a drum. I haven't had to use any wheel spacers,but I have heard that about some of the OEM wheels. If you use a spacer,you will need even longer studs,and at that point,I would suggest 1/2" studs.
     
  18. BrianTrick

    BrianTrick Brian Trick

    The studs I use for the rear disc applications,that are NOT using spacers,are Dorman 610-259,or Moser 8259,also called Corvette studs.
    Another thing,if you are installing rear discs,you will need to machine the outer diameter of the wheel flange down,from 6.25" to 6.00",for the rotor hat to clear. I order all of my aftermarket axles with a 6.00" flange,so they can be used with whatever.
     
  19. hugger

    hugger Well-Known Member

    The right stuff rotors clear the 12 bolt axles, I did have to take a carbide bit to the inner hub of the the Hat to clear the axle, needed to be opened up about 1/16in, and yea I needed the 1/2in spacers for the stock wheels
     

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