Mopar 8 3/4 axle shaft
- Thread starter bbmopars
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doug 371
Well-Known Member
Guy above said they would? Have you done it before?
Professor Fate
Push the button, Max...
No.
The entire axle needs to be upgraded, not just the studs.
Big bolt circle axles have a larger flange offset than small bolt pattern axles, and require different backspacing on the backing plates. BBP and SBP brake setups have no major interchangeable parts.
doug 371
Well-Known Member
If you are redrilling small bolt axles, you must use the small bolt brake parts including backing plates shoes and drums
Professor Fate
Push the button, Max...
Did you have the axles redrilled to the big bolt pattern, or just drill the axle holes to accept the larger studs?
If you changed the pattern, then you still need to use the small bolt pattern drums; and you need to have the original drums redrilled to match.
The different flange offset in addition to the different size center register precludes swapping drums and backing plates.
If you changed the pattern, then you still need to use the small bolt pattern drums; and you need to have the original drums redrilled to match.
The different flange offset in addition to the different size center register precludes swapping drums and backing plates.
Just the drill axle holes to accept larger studs
So If I understand...
You changed your lug studs on your SBP factory axles from 7/16" lug studs 1/2" lug studs. And you want to know if the stock drums will fit. The answer is no, you will have to enlarge the lug stud holes in the drums to accept the 1/2" studs. The drums holes are 0.488" which is too small for .500" studs
Oh ok,l already have a set of factory big bolt pattern drums.will they fit after the 1/2 stud conversion?
Professor Fate
Push the button, Max...
No, the bolt patterns are different. All you did was change the stud size- you did NOT change the bolt pattern.
You still have a 4" bolt circle. There is no way to make a 4.5" bolt circle drum fit that.
Additionally, as I said previously, the center registers are different sizes between the two. And the flange offset is less on the smaller pattern axles.
Big bolt pattern brakes will NOT FIT unless you use aftermarket axles.
Oh ok l see,ld have to use the small bolt pattern drums and drill them to the 1/2 stud size.l may just get wheel adapters go from the 4.0 to 4.5 inch bolt pattern.which will change the bolt pattern and stud size.Then l can use the big battern drums?
Daves69
Well-Known Member
More info might help.
What exactly are you working on and which differential??
If you are drilling axle flanges you need to be dead on with the bolt circle.
1/2" SCREW IN studs get pretty close to the flange edge of my 8-3/4. The 7/16" holes were filled.
Drilling drums is not as critical as the register will keep the drum centered.
Professor Fate
Push the button, Max...
No, no, NO!
Wheel adapters fit outside of the drums.
YOU CANNOT USE BIG BOLT PATTERN DRUMS ON SMALL BOLT PATTERN AXLES!!
8 3/4 with small bolt pattern axle shafts
cudamark
Well-Known Member
My understanding is that you replaced the original small bolt pattern axle with big bolt pattern ones. If you're just redrilling the small bolt pattern axles for the larger pattern and 1/2" studs, ignore my response.
If you have SBP backing plates you MUST use SBP drums (10 x 1.75)
If you want BBP you would be best to replace your Axles AND backing plates to BBP backing plates, 10x2, 10x 2.5, 11x ##
You can get new BBP axles set up for SBP backing plates, then drill out your SBP drums.
The ONLY way to use BBP drums on your housing is to replace the backing plates to BBP backing plates AND getting BBP new Axles.
As others have stated several times the spacing is different SBP to BBP axel flange to housing flange.
You also have to use backing plates that are designed for the shoe diameter and thickness the drums need
If you want BBP you would be best to replace your Axles AND backing plates to BBP backing plates, 10x2, 10x 2.5, 11x ##
You can get new BBP axles set up for SBP backing plates, then drill out your SBP drums.
The ONLY way to use BBP drums on your housing is to replace the backing plates to BBP backing plates AND getting BBP new Axles.
As others have stated several times the spacing is different SBP to BBP axel flange to housing flange.
You also have to use backing plates that are designed for the shoe diameter and thickness the drums need
Oh ok l see,you can use 8 1/4 backing plates and drums on a 8 3/4? If you use big bolt pattern 8 3/4 axle shafts.
Ok l see
I believe that is correct, I'm not well versed on 8 1/4 parts.
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