Moser 12 bolt or 9" Ford?

Discussion in 'Got gears?' started by jmos4, Mar 9, 2021.

  1. jmos4

    jmos4 Well-Known Member

    Hi all,

    Got a 65 A-body and wonder which rear axle is a better choice.

    Running 450hp 510 torque, 200r4

    Which is a better design vs cost?

    Thanks for any info

    Regards,
    Jim
     
  2. knucklebusted

    knucklebusted Well-Known Member

    From what I understand, a Ford-based 9" will soak up a little more power but you can have a couple of different center sections for quick change.

    If you go with the Moser 12-bolt, I assume you will have bolt-in axles?

    Either one should be more than sufficient for 500HP. A decently built 8.5 10-bolt will hold up as well.
     
  3. LARRY70GS

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

    8.5 10 bolt is all you need. The 2004R will be the weak link anyway.
     
  4. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    I agree with Larry. Heck if you don't plan on putting slicks on it I'd run what you have. I believe parts for the earlier 10 bolts are available..
     
  5. nekkidhillbilly

    nekkidhillbilly jeffreyrigged youtube channel owner

    i was thinking the 8.2 would be fine for that if no slicks
     
  6. sean Buick 76

    sean Buick 76 Buick Nut

    Just build a 8.5
     
  7. jmos4

    jmos4 Well-Known Member

    Hi,

    My car is a 65 so 8.5 is a little wide, and potentially requires custom offset rims.

    I believe either 9" or Moser I could get in the same width as my current 8.2 BOP

    Regarfs,
    Jim
     
  8. stump puller455

    stump puller455 1970 GS 455

    I could not get past a FORD REAR IN MY GS just did not like the sound of it went 12 bolt instead
     
    MRP likes this.
  9. bignastyGS

    bignastyGS Maggot pilot

    I have no issue putting a 9 inch rear in my car...I like the fact I can swap gear ratio somewhat easier that the 8.5
     
  10. Bens99gtp

    Bens99gtp Well-Known Member

    Once the initial setup is complete, 8.5 gear set swap pretty quick....just keep the shims in order......alot cheaper than a whole other 3rd member.



    8.5 can be narrowed down and new housing ends installed. You can choose an end that fits more common brakes if you plan to upgrade ever

    I think 12 bolts are crazy expensive for the little to no strength gain over an 8.5. 9" can be strong once everything is replaced.....seen sbc in the 12s eat stk ford axles.
     
    Last edited: Mar 9, 2021
  11. bignastyGS

    bignastyGS Maggot pilot

     
  12. BrianTrick

    BrianTrick Brian Trick

    If you have to go aftermarket,I would go with the Moser 12.
    This is Stump Pullers 12-bolt. This is a GM 12-bolt that I narrowed 1/2” on each side,Moser #7900 ends welded on,33-spline Moser axles,Tru Trac posi unit,Motive Perfromance 3:73’s,Strange 1350 steel yoke,TA aluminum girdle cover.
    Whether I do a 12-bolt Chevy housing,or an 8.5” 10-bolt,I can narrow them however needed. I recently did one for a 65 that I narrowed 1.25” on each side,so the customer could run old school SS Cragars with a deep dish and little backspace. That is about as much as you can narrow one without getting into the control arm perches.
     

    Attached Files:

    stump puller455, Bygblok and tdacton like this.
  13. Bens99gtp

    Bens99gtp Well-Known Member

    The new aftermarket 12 bolt housing are quite a bit stronger the factory units......seen several break the webbing where the bolts for the caps go into.
     
  14. monzaz

    monzaz Jim

    So what are you doing with this car?
    Why do you think your stock 8.2 will not work?
    You can get parts for it...3.36 3.55 3.73 4.10 etc.
    Everyone wants to spend all this money on a HD rear that costs 3000.00 + When most never need half the power output that would strain the rear.
    We get Many people say they are going to the track and end out doing 2-3 times and then realize that the car will not go any faster and do not ever go again.
    Money wasted.
    Please be sure you need all that rear before blowing a huge wod ...
    also are you going disc brake or drum?
     
    knucklebusted likes this.
  15. LARRY70GS

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

    1st post Jim, Running 450hp 510 torque, 200r4.

    I told him the 2004R will go before his 8.2.:)
     
  16. jmos4

    jmos4 Well-Known Member

    Hi,

    Mostly spirted driving, and the zero to a buck on the empty side road, haven't taken any of my fun cars to the strip, but can't say I won't.

    If I build the 8.2 which is the weaker case Buick design vs the Pontiac (Pontiac has a extra gusset in the casting), I will have just under 1500 bucks with new axle shafts, posi, gears and new bearings.

    Do I need it, you all tell me?

    I'm in favor of saving a few bucks, but if I do all that and blow up the 8.2, then I get to spend the money again along with additional funds, think that is more of what I am worried about.

    Regatds,
    Jim
     
  17. jmos4

    jmos4 Well-Known Member

    Hi,

    The 200r4 is supposed to be built for 600hp, hopefully it holds out if not 3 pedals might be in the future as not a big fan of automatics, but the car is fairly original and resisting the urge to cut a hole in the floor.

    Regards,
    Jim
     
  18. LARRY70GS

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

    The only time you need to worry about blowing a rear is if you hook it up solid at the track with big torque. Then the weak link lets go. I'm thinking in a situation like that, the 2004R is the weak link, not the 8.2 rear. All the BOP rears are bolt in axle, and stronger than a lot of guys realize. Back then they overbuilt things, today, not so much.
     
  19. LARRY70GS

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

    Who built the transmission? The shock loads from a manual transmission are even higher I would think.
     
  20. jmos4

    jmos4 Well-Known Member

    Hi,

    I would have to look through my paperwork as my engine builder had his expert build it, he's down in Florida think near Jacksonville, bunch of CK parts used.

    Regards,
    Jim
     

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