stock elimator rear axle?

[rod]

why is it that nhra ruled that a car [any car] can update to a different year rear axle, but it has to be by that mfgr.?
i have nothing against a 12 bolt, but i do not see a drop out center '56 chevy rear being any where near a 12 bolt chevy. whereas a 9" is almost exactly the same axle.
what if you had a '50 olds, your choice would be to a clunky, heavy, out dated and weak '57 axle or a B.O.P. rear from the 60's. no choice.

thoughts

thanks rod in AZ

[Ed Fernandez]

Youse picks the combination youse follow the rules.If the 50 Olds was put back in the guide you could probably get away with the early Olds,if you can get the gears you want.Otherwise you put a 12 bolt in.But since the only early cars reinstated are the 55 Chevies you have the same choice.I think the strength of the 12 bolt speaks for itself.How many are under GM stockers?

[Tom keedle]

would it be the same as "corporate" rear?
i can run a 8 3/4" mopar rear (and am) in my amc,wouldn't the same apply to the olds?
i'd think a 12 bolt would be legal but i'm not the guy making up the rules..

[Tom Turner]

Tom is right. The key word in the rules is "corporate". If you had a 56 Chevey stocker, any GM passenger car rear would be OK. Most would use a 12 bolt or an 8.5, strength and gear selection being the criteria for judgement. Your 57 Olds analogy is a little off base. Those rears are very strong but the gear selection nowdays is poor and they are heavy. I agree that in these days of purpose built stockers, the rear end rule is one of our "stupid" rules but the present rule beats the original rule hands down. Back in the day, the Ford guys got to use the 9in, the Mopars got Dana's and 8 3/4's and the Chevy guys got.....you guessed it, the Chevy dropout. As sticks were the transmission of choice, you can imagine the result. TT

[Run to Rund]

In the second half of the 60s, Olds and Pontiac bought Ford top loader "Dearborn" three speeds. Hmmm, that makes Ford a drivetrain vendor to GM. Now can Olds use the 9" Ford rear?

[brett3533]

I think that it has been worded like this to allow the new and old cars both to be able to use a rear end housing manufactued by its corporate company, the corvettes have independent rear axles as do the new challengers and camaros maybe even the production mustangs. It allows the racer to put in the strongest its manufacturer has to offer and the safest for the racer, competitors and spectators.

[Run to Rund]

Today, a rear is built with aftermarket "everything" sometimes even the housing like on 12 bolts and Danas. The cost is very similar for whatever you choose to build. If safety is the issue, why does NHRA care what diff you use? If a Vette can convert to a solid axle, the horse is out of the barn.

[Jeff Lee]

A lot of formerly fast D/S cars sure let their voices heard when I had them all covered and in the process had a Dana 60 under my D/S '70 AMX! Apparently the fact that AMC was bought by Chrysler in 1987 meant nothing and it was a corporate merger. Corporate rear ends have always been allowed.
That means corporate, not anything else so no 9" Fords under an old Pontiac.
As mentioned earlier, that's just part of the game and if your choice of ride is limited in this department, look at something else! Or another alternative is to make what your offered work. Anything can be made to work with cubic dollars!

[Tom Turner]

Run to Rund;
The Corvette (and any other swing axle car) is allowed by NHRA to use a solid rear as a safety item. If you had ever seen what a broken halfshaft can do you would most likely understand. The rules for replacement of the swing axle (especially for Corvette) are hardly a carte blanche suspension bonus. The adaptation for the solid housing must utilize all of the OE attachment points and trailing arm configuration; shock mounts included and then there is that pesky transverse leaf spring (another bonus). I have two of these cars; a 71 (C3) and a 96 (C4) with solid rears. They are not even similar as the rear suspension is very different in O.E. design. Both were a challenge to sort out but thanks to Alf Wiebe and a fairly serious testing program they turned out to be pretty good little race cars. Are they better than a Camaro? Maybe in theory but in the real world?.......I doubt it. By the way, these cars work great with a swing axle. TT

[Jeff Lee]

Originally Posted by Tom Turner

Run to Rund;
The Corvette (and any other swing axle car) is allowed by NHRA to use a solid rear as a safety item. If you had ever seen what a broken halfshaft can do you would most likely understand. The rules for replacement of the swing axle (especially for Corvette) are hardly a carte blanche suspension bonus. The adaptation for the solid housing must utilize all of the OE attachment points and trailing arm configuration; shock mounts included and then there is that pesky transverse leaf spring (another bonus). I have two of these cars; a 71 (C3) and a 96 (C4) with solid rears. They are not even similar as the rear suspension is very different in O.E. design. Both were a challenge to sort out but thanks to Alf Wiebe and a fairly serious testing program they turned out to be pretty good little race cars. Are they better than a Camaro? Maybe in theory but in the real world?.......I doubt it. By the way, these cars work great with a swing axle. TT

Besides being a whole lotta work and R & D, I'm sure it wasn't cheap either.
And in the end, it's still corporate.