which rear to use for autox?

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1qwikScamp

1qwikScamp

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I am currently building a road/autocross car out of my 71 duster and I have several rear axle choices. I was wondering which rear end would do well in my application due to the hard cornering and such. I have at my disposal a stack of 8.75s a ford 9" and a ford 8.8. The 8.8 worrys me a little being a C clip type, and i have heard that the green brgs in the 8.75s dont like alot of hard cornering and i would assume the 9" would be very simmalar to the 8.75. but im looking for your oppionion on this thanks
 
I'd use the 8-3/4 but keep the stock axle bearings. The 8.8 rear is an ok rear if your not making big power but unless you install a C-clip eliminator I wouldn't even think of it. The 9" can have either style of bearings, tapered like a 8-3/4 or roller bearings like Green bearings. I've torn apart a few 9" and it seems hit or miss as to what you find.
 
Of that stack, I'd go with the 9inch or 8 3/4

IMO the 8.8 is a great axle while on a budget, but why settle for less when you already have two better choices?
 
Can you convert one of those to a floater? If you are serious, that would be the best route to go to prevent axle knock-back.
 
Lots and LOTS of US vehicles used a setup similar to "green" bearings for years and years, that is, a great big ball bearing. I certainly would not be afraid of 'em as opposed to tapered.

I agree that "C" clip are "Crap." First time I tore down a buddy's Chevelle with a 10" C clip rear I just about crapped.
 
I thought about using a standard tapered bearing with an 8.75 but I am a little leary of the strength of the adjusters on each axle. Wonder if it could handle the side load? I have green bearings in my scamp and not had any trouble for years but its mostly a street and strip car. In the duster i am running a 6.1 hemi with a inetrtia srt max cam and some port work on the intake with a good tune, so i estimate around 425-450hp to the tires. a t56 six speed with 335/35/17s in a 3200 lb car im just worried about walking out from under an axle under power coming out of a tight corner. i really want something that is going to last a good while.
 
67Dart273 said:
Lots and LOTS of US vehicles used a setup similar to "green" bearings for years and years, that is, a great big ball bearing. I certainly would not be afraid of 'em as opposed to tapered.

I agree that "C" clip are "Crap." First time I tore down a buddy's Chevelle with a 10" C clip rear I just about crapped.
Click to expand...

i have seen many chevys spit out axles at the drag strip would hate to see it taking a hard turn
 
I would like to suggest two axles you never see in a A body.
1. Jag IRS
2. Ford IRS

The jag IRS you could get from Pull apart in Atlanta for a low cost. Very easy to narrow. Easy to install. Inboard disk brakes, Set up for quad coil over shocks. The center section is very close to a gm 12 bolt rear axle. MADE IN AMERICA.
The bad part about the jag is the bolt pattern is 5 x 4 3/4".

The ford will cost more but its lighter and has the correct bolt pattern.
The came in some Mustangs, some Thunderbirds. and some Lincolns.
The Ford is made from a 8.8" axle.

http://home.bresnan.net/~dazed/JaguarIRS2.html
 
contact member "autoxcuda" he road races the crap out of his 68 cuda notch, i think hes running a standard 8 3/4.....
 
BigWhip said:
I would like to suggest two axles you never see in a A body.
1. Jag IRS
2. Ford IRS

The jag IRS you could get from Pull apart in Atlanta for a low cost. Very easy to narrow. Easy to install. Inboard disk brakes, Set up for quad coil over shocks. The center section is very close to a gm 12 bolt rear axle. MADE IN AMERICA.
The bad part about the jag is the bolt pattern is 5 x 4 3/4".

The ford will cost more but its lighter and has the correct bolt pattern.
The came in some Mustangs, some Thunderbirds. and some Lincolns.
The Ford is made from a 8.8" axle.

http://home.bresnan.net/~dazed/JaguarIRS2.html
Click to expand...

i dont know much about the jag irs, but my buddy has a terminator cobra and has snapped a few axles with it and is basicly stock other than a pulley, long tubes and a tune. we swapped it over to a solid axle like that would come in a GT car. He had a few super coupe thunder birds a few years ago with basically the same rear end. i dont like the dinky control arms and besides that they are still c clip rears. i will look into the jag stuff though thanks for the advice
 
Run the 8 3/4 or the 9". Performance will be the same.

To me it's about the finacials and what you exactly have in your stack of rearends. I mean if you have to shorten one and get new axles vs. another one that doesn't need that, that a big $$$ difference. And factor in what rear rims backspace you have on your current rims. Or if you are going to other rims.

I think it's cheaper to find rear disks that bolt to a 9" ford rear. If you are going to buy a brand new limited slip unit (~$500) look into the Tru Track/Quaif/Torsen all geared limited slip. Those are the best for autox and street and road race. And those might be cheaper in 9" form.

Also stick in some axle baffles to keep rear end fluid from coming out the axle seal during high G turns. Those will fit either 8 3/4 or 9" tubes. That mostly would happen on a road course. Autox doesn't have the long sustained high G corners. http://www.summitracing.com/search/brand/Seals-it/Product-Line/Seals-it-Axle-Seals/?autoview=SKU Measure you axle tube I.D. to check fitment.

I wish I had some of those baffles. It will leak out the vent tube when I'm at a track day and I seem to be leaking out the axle ends more frequently. I haven't had my center section out in 13 years to put some baffles in.
 
BigWhip said:
I would like to suggest two axles you never see in a A body.
1. Jag IRS
2. Ford IRS

The jag IRS you could get from Pull apart in Atlanta for a low cost. Very easy to narrow. Easy to install. Inboard disk brakes, Set up for quad coil over shocks. The center section is very close to a gm 12 bolt rear axle. MADE IN AMERICA.
The bad part about the jag is the bolt pattern is 5 x 4 3/4".

The ford will cost more but its lighter and has the correct bolt pattern.
The came in some Mustangs, some Thunderbirds. and some Lincolns.
The Ford is made from a 8.8" axle.

http://home.bresnan.net/~dazed/JaguarIRS2.html
Click to expand...

The ford dif out of a Tbird is pretty strong , had a 1990 T-bird S/C with a boosted supercharger , 450 hp + and the dif lasted over 450,000 km without trouble . And I beat the crap out of that car , mega burnouts , ran it on a road course about 20 times , 6 winters all kinds of torture . Think it had 3:91 gear set . I was always expecting trouble with that dif , never had any .
 
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