4in vs 4.5in bolt circle rear axle

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The small bolt 8 3/4 rears had the small pinion carrier so they wouldn't be the strongest. 741 carrier
 
toolmanmike said:
The small bolt 8 3/4 rears had the small pinion carrier so they wouldn't be the strongest. 741 carrier
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But the pinion can be swapped out.

Personally I do not see the size of the bolt circle making a difference, that is assuming you are comparing like for like ie 8-3/4 to 8-3/4


Alan
 
I refering soley to the bolt pattern
Am I less likely to break the 4.5 wheel studs or the 4 in . Does the bolt circle matter ?
 
4.5 bolt pattern is definitely stronger,and it has the 1/2 studs too.also I've had a lot of small bolt 8.75s with the 489 case in them.
 
Cuda Al said:
But the pinion can be swapped out.

Personally I do not see the size of the bolt circle making a difference, that is assuming you are comparing like for like ie 8-3/4 to 8-3/4


Alan
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tooslow said:
I refering soley to the bolt pattern
Am I less likely to break the 4.5 wheel studs or the 4 in . Does the bolt circle matter ?
Click to expand...
Difference in flange sizes? I have never seen dimensions posted. The small bolt studs are smaller.
 
I have only ever dealt with SBP on a A-Body, so I'm out.


Alan
 
The 5 on 4 is weaker than the 5 on 4.5, aside from the stud size difference. Enough weaker to be dangerous? Short of LOTS of power, I would say no. Just use the best studs you can find.
 
I am building a 360 turbo non drag race car , no drag strip but occasional road course . 500hp max
Is the A Body 8 3/4 Differential just over all a weak rear end , if not I can buy after market axles
 
Well if it means anything '69 M code 440 cuda's and Darts came with a 4'' bolt circle with an auto trans. and E70 14s.
 
I would say the stud size is the main issue to be concerned about. Not just the shear strength but the swage surface. It is true that (given the same wheel/tire diameter) the smaller bolt circle experiences higher shear stress on each stud at launch, but the difference is small. Combined with the smaller studs, though, it would definitely be weaker. As far as the rear end, I don't hear a lot about 8-3/4s breaking in street use. It is overall one of the stronger rears out there.
 
tooslow said:
Is a 4in BC as strong as a 4.5in BC
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Not IMO.
On a road car only though, 7/16" should be fine.

A56 said:
Well if it means anything '69 M code 440 cuda's and Darts came with a 4'' bolt circle with an auto trans. and E70 14s.
Click to expand...

Try it with a 4 spd and slicks. Keep the hook and body panel repair shop numbers handy.
 
O.P. have you done or are you going to do a disc swap? If doing a rear disc swap, you will almost have to go to the big pattern, but then you won't have to worry about drum brake compatibility with big pattern axles.
For what you are planning, the 8 3/4, even with a 741 center, is plenty good enough.
 
The stress in the flange would be spread out more evenly with BBP but I wouldn't say significantly so
 
Most big HP race cars are using 5/8 studs. Must be a reason? I was always told bigger is better. LOL, At least that is what my wife says.
 
Daves69 said:
Not IMO.
On a road car only though, 7/16" should be fine.



Try it with a 4 spd and slicks. Keep the hook and body panel repair shop numbers handy.
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Just sticking to the question. Not the what ifs.
 
This guy races this original cuda M code in Pure stock. That's a "whole lotta hammering" on 4'' bolt circle.
The blabber mouth on this video is annoying though.
 
Some time back there was discussion about some pretty fast cars running FOUR stud such as Mustang/ Falcon/ etc stock bolt circles. I guess you have to ask yourself, "just how much is enough."

What did the AA/F cars use back in the day?
 
67Dart273 said:
Some time back there was discussion about some pretty fast cars running FOUR stud such as Mustang/ Falcon/ etc stock bolt circles. I guess you have to ask yourself, "just how much is enough."

What did the AA/F cars use back in the day?
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5 on 5, left over from olds/Pontiac swaps into chevies, going back to the late fifties.
Got 5 on 5 in my nine inch that was built in the seventies (summers bros axles).
I also ran a nitroused 327 in a Vega with an 8 3/4 swap...... and a FOUR lug conversion.
 
tooslow said:
I refering soley to the bolt pattern
Am I less likely to break the 4.5 wheel studs or the 4 in . Does the bolt circle matter ?
Click to expand...
Yes. Is it needed for Your app? If You've got the tires to really stick it to the track, the 4.5" is preferred, what is the projected weight? The problem with most replacement axles to convert is they ditch the tapered axle brgs, the "green brgs." weren't designed for huge side loading, I'd avoid that route for what You're doing. The 8.75" rear is more than strong enough, power-wise. Your avatar pic is an E-body, I assume that's not what We're discussing here tho'.
 
I am a Mopar nut , by junk and build it . The avatar is my 500 stroker kicking A### at Road america , yep a BB
My present project is a 68 Cuda notchback
Thanks for all of the replies
I am going to change axles to a 4.5 bolt circle .
what is the easiest most inexpensive way to do this ?
 
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