8 3/4 bolt pattern question

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eric1987gt

eric1987gt

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Hey guys, I’m sure this question has been answered elsewhere, and I apologize if this is the wrong board— but I’ve got a stupid question.

I have a 71 Demon with an 8 3/4 that still has the small bolt pattern and drum brakes. I’d like to convert it to the larger bolt pattern - what’s the best way to accomplish this task? Or the least expensive way? Or the easiest way?

If it makes any difference, my plan is to get this car set up a little better for drag racing (nothing too extreme, but might eventually mini-tub it).
 
Aftermarket rear axels, bbp backing plates and drums.

Front later model front disks with bbp.

Everything but the axels are OEM parts.
 
You'll get as many opinions on this as there are members on this site...
Decide what you want: best, cheapest, or easiest.
You'll cover the most bases by just giving Doctor Diff a call, he'll get you covered.
DoctorDiff Drivetrain Components
 
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You can do a lot without cutting the car. Spend some money on good springs and shocks. Don’t try to use old slicks, they seldom hook very good.

and BFG radial TA’s forget about any traction for racing,
 
Don't hear people talk about it, but how about replacing your Small Bolt Pattern 7/16" studs with the stronger 1/2" replacement studs on your existing axles and continue using the 8 3/4" stock drum brakes that go with your SBP axles?

An easy simple way to increase strength where the wheels mount up.

Can always do the more major conversion to Big Bolt Pattern setup when you feel the need.
 
eric1987gt said:
View attachment 1715915587 Hey guys, I’m sure this question had been answered elsewhere, and I apologize if this is the wrong board— but I’ve got a stupid question.

I have a 71 Demon with an 8 3/4 that still has the small bolt pattern and drum brakes. I’d like to convert it to the larger bolt pattern - what’s the best way to accomplish this task? Or the least expensive way? Or the easiest way?

If it makes any difference, my plan is to get this car set up a little better for drag racing (nothing too extreme, but might eventually mini-tub it).
Click to expand...
I already gas 5x 4.5" but wanted to ditch my 8 1/4 321-1 Sure Grip since I wanted a stronger rear end and had plenty of 3rd members.
I got an A body 8 3/4
Converted to 4.5 " bolt pattern with Moser axles , green bearings. And screw in studs.
I hit up the U Pull It grabbed Truck / Van 11" drum from an 8 3/4 As it was the cheapest route.
 
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If you plan to race the car, IMO, there's no other way to do it but post #2.
 
82-89 Chrysler M body rear brakes 10"x2.50" from backing plates out will bolt up to the 8.75 axle, and parking brake will hook up. Go to Doctor Diff for A body width BBP 8.75 axles. All this is direct bolt up and will give you the larger bolt pattern, 1/2" studs, and all the brake parts are readily available including heavy duty finned drums.
 
Cheapest? Sell the 8 3/4 for $$$ and buy an $ BBP 8.25 SG or Ford 9.
 
413 said:
You can do a lot without cutting the car. Spend some money on good springs and shocks. Don’t try to use old slicks, they seldom hook very good.

and BFG radial TA’s forget about any traction for racing,
Click to expand...
I agree, but want to add also that you can roll the lip, and with the right offset, easily fit a 275-60R15 in there. Same inner and outer wheel houses as a 67-69 barracuda. I bet you can even fit wider without modifying the wheel houses on it. Once you cut n move the wheel houses, and spring relocate, it's a lot harder to put it back to stock if you decide on that later. Ask me how I know.
 
413 said:
You can do a lot without cutting the car. Spend some money on good springs and shocks. Don’t try to use old slicks, they seldom hook very good.

and BFG radial TA’s forget about any traction for racing,
Click to expand...


Do you have a recommendation for springs and shocks?
 
eric1987gt said:
I have a 71 Demon with an 8 3/4 that still has the small bolt pattern and drum brakes. I’d like to convert it to the larger bolt pattern - what’s the best way to accomplish this task? Or the least expensive way? Or the easiest way?

If it makes any difference, my plan is to get this car set up a little better for drag racing
Click to expand...

call Doctor Diff, tell him what you are doing and he will sell you the proper axles..

"DoctorDiff's business is conducted entirely online. Please use the website to place orders. Questions can be asked via email, or sent via text to the number below.

doctordiff@gmail.com

(406) 646-6727

Hours of Operation

10 a.m - 6 p.m. M-F
Mountain Time"




as for the brakes doctor diff can sell ya rear disc brakes or just get any 10 or 11 inch drum set up from a b,c or ebody car...



.
 
abodyjoe said:
call Doctor Diff, tell him what you are doing and he will sell you the proper axles..

"DoctorDiff's business is conducted entirely online. Please use the website to place orders. Questions can be asked via email, or sent via text to the number below.

doctordiff@gmail.com

(406) 646-6727

Hours of Operation

10 a.m - 6 p.m. M-F
Mountain Time"




as for the brakes doctor diff can sell ya rear disc brakes or just get any 10 or 11 inch drum set up from a b,c or ebody car...



.
Click to expand...
Thank you!
 
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