What rear drums for 4.5" axle swap

-
Muswagon

Muswagon

Well-Known Member
Joined
Jan 20, 2020
Messages
372
Reaction score
280
Location
Winnipeg
I ordered new 28" axles and bearings in 4.5 inch.

I did not even think about drums.

Which drums do I need or is it more complicated than that with changing the whole brake setup?

71 340 car 8.75 rear

Help would be much appreciated
 
Depends on the axles you ordered talk to the manufacture.
 
You need the entire brake setup; drums, backing plates, hardware; 10" or 11". Source from any B, C, F/M/J or light duty truck/van with 5 x4.5 drums. Late ('73+ w/4.5) A bodies, some Jeep XJs (Cherokee) and ZJs (Grand Cherokee) with 8.25 rears, and first gen 5 lug Dakotas are also possible donors.
The offset of the backing plates match the drums, so get them as a matched set and order your parts as if they're for the donor vehicle. Don't mix and match.
 
Last edited:
what axle hang out did you order . a bodies 8 3/4's were different than the others . if you ordered them , how much from the housing to the axle hub are you getting .
 
sireland67 said:
Depends on the axles you ordered talk to the manufacture.
Click to expand...

pomonamissel said:
what axle hang out did you order . a bodies 8 3/4's were different than the others . if you ordered them , how much from the housing to the axle hub are you getting .
Click to expand...
True, 90% of the aftermarket axles use the full size flange offset, but there are a few that still offer the 5 x 4.5 in the A body offset, and want you to redrill your A body drums... So, OP, we need to know which axles you ordered.
 
I canceled my order at Summit... I clearly should have not ordered without checking first lol

The Dr Diff axle set is cheaper anyway. I will get more details from him on what I need but sounds like you guys have listed basically an entire 10" or 11" setup

I don't know what offset they are, but Dr Diff website says cannot use redrilled drums so must be a different offset and the summit setup does not say that, but in the questions section everyone says same thing will not work with A body offset stuff.

Thanks again
 
I used Dr. Diff axles and the complete drum set up off a 7.25 rear, fit nice.
 
Order 8 3/4" A-body axles (If housing is OEM.) set up for B/E body bolt pattern (4.5") & brake assemblies (10"x2").

FYI - the drum register on the axles is different between A (Smaller on '72 & earlier.) and E/B body brake assemblies as well.
 
I ordered from Doctor Diff. His A body axle setup, which requires the 10" or 11" setups as you guys have detailed.

There is a local guy here that has complete setups, both 10" and 11", what do you guys suggest?

I think they are both 2.5" wide

Now please help me understand the offset thing. if the length of the axle is the same as stock, 28", how does it end up wider? Sorry I am having trouble phrasing that question properly lol

if the wheels sit out more with the 2.5" setup vs the factory 1.75 that is perfect. My centerlines touch the leafs without a spacer stock, and I like the wheel arch over the wheel look with the back end high. This car is my inspiration on what I want my stance to be, if this is one you guy's car, well done

0
 
Muswagon said:
Now please help me understand the offset thing. if the length of the axle is the same as stock, 28", how does it end up wider?
Click to expand...
When the catalog states "stock width", they are referring to the housing dimensions, which in turn relates to the axle length from the tip of the splined end to the bearing shoulder.
Overall length is from tip of splined end to the outer face of the axle flange. Stock A body is 27 11/16". 28" aftermarket axles therefore give you 5/16" extra width per side (this extra width shows up as the distance the axle flange protrudes from the housing-i.e. "flange offset") which allows you to use the standard B, C, etc. 5 x 4.5 BC drums.
As far as which drums (10" or 11") to use, either will work fine. Some people don't like the extra weight of the 11s, some feel that the extra braking power offsets the extra weight in their particular setup. Your call. I run both- I have 10" drums on one car paired with 10.95 front discs, and run 11" drums on another paired with the 11.75 discs. Are they necessary? In my case, probably not; but I had them, so I used them- and they perform flawlessly. I have also considered swapping to the Jeep Grand Cherokee/Liberty rear discs, but I have a hard time justifying the replacement of something that already works well.
 
Thank you for the explanation, kinda figured it had to be the flange itself. I am so used to 8.8 Mustang stuff.

Appreciate the in depth explanation.

Going with 10", it is what he has off cars right now so easy decision. Plus new stuff seems to be alot cheaper for 10" system, I have no idea what condition the stuff is in, priced out replacing all of it and its pretty cheap relatively speaking
 
You must log in or register to reply here.
-

Back
Top