10” Drum Brakes Options for A-Body 8-3/4 with Moser Engineering BBP Axles

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Duster256

Duster256

Honolulu, Hawaii
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My ‘71 Duster H-code has a factory-spec 8-3/4 rear housing measuring 52-5/8” flange to flange. The previous owner replaced the original SBP axles with Moser Engineering axles with RP400 O-ring type green bearings and 5 x 4.5” BBP. The brake (axle) offset is 2.36”.

Previous owner also replaced the original 10” drum brakes with a Wilwood 140-0260 forged Dynalite drag race rear disc brake kit, which has NO parking brake. I NEED a working parking brake in order to pass the local annual vehicle safety inspection, which a requirement for the annual vehicle registration. Wilwood doesn’t have a retrofit emergency brake caliper or an internal parking drum brake kit to fit this particular drag race brake due to clearance issues. So this Wilwood drag race brake kit needs to go and be replaced with either a disc brake with parking brake, or a drum brake kit.

Cass at Dr. Diff (he’s the best!) said that his 10.7” rear disc brake kit has a parking brake and will fit my 2.36” axle offset. He also said that his 10 x 2.5” drum brake kit will fit but that kit is out of stock.

I’m tryna keep down the cost of this parking brake swap-in. Before I sink $700 into Cass’ rear disc brake kit, does anyone here have experience with or advice for me on which Mopar 10” rear drum brakes assemblies might fit my BBP axles with 2.36” offset? Ernie at Moser Engineering speculated that B-body drum brakes might fit. And what about ‘73+ Duster rear drum brakes (BBP, unsure of offest?) Thanks FABO Nation.
 
Have you looked into the Jeep Liberty or Jeep Cherokee disc conversion? I don't know enough to give you sound advice, but I know they can be fitted on an 8 3/4 and have an e brake which there is a thread on which cable to use. Maybe someone who has done this conversion can chime in? Very low cost conversion too.
 
If a 10x2.5” drum brake kit will work you have a standard BBP offset axle. All Mopar BBP axles have the same offset, so you can literally use drum brakes from any RWD Mopar up to about 1991 with axles that have the 5x4.5” pattern. A/B/C/F/M/J/R bodies and even some of the lighter duty vans and trucks. The majority of them will be 10x2.5”, but there are also 11x2”, 11x2.5” and 11x3” drums out there.
 
Yup, any B/C/E/F/M/J (and late A, as you mentioned) drum setup will fit. Also five bolt Dakota, Jeep Cherokee (with the Chrysler 8.25 rear), and earlier pickups and vans that still had the 5x4.5 bolt circle. Just double check the drum size before you pull them, as the Dak and Jeep also had 9" drums on some models, as well as the 11s being available on the cars. All will hook up with the stock cables.
The Grand Cherokee/Liberty rear discs are worth checking out too, since they work fine on an 8.75 with green bearings. Again, double check the bolt circle on the GC as they eventually went to a 5x5 bolt circle in '98 or thereabouts.
Some of the backing plates/caliper mounts may need the fifth hole drilled, depending on original application.
 
Professor Fate said:
Yup, any B/C/E/F/M/J (and late A, as you mentioned) drum setup will fit. Also five bolt Dakota, Jeep Cherokee (with the Chrysler 8.25 rear), and earlier pickups and vans that still had the 5x4.5 bolt circle. Just double check the drum size before you pull them, as the Dak and Jeep also had 9" drums on some models, as well as the 11s being available on the cars. All will hook up with the stock cables.
The Grand Cherokee/Liberty rear discs are worth checking out too, since they work fine on an 8.75 with green bearings. Again, double check the bolt circle on the GC as they eventually went to a 5x5 bolt circle in '98 or thereabouts.
Some of the backing plates/caliper mounts may need the fifth hole drilled, depending on original application.
Click to expand...
Thanks, great info! I was wondering what to do about the lack of a 5th hole in some drum backing plates!
 
72bluNblu said:
If a 10x2.5” drum brake kit will work you have a standard BBP offset axle. All Mopar BBP axles have the same offset, so you can literally use drum brakes from any RWD Mopar up to about 1991 with axles that have the 5x4.5” pattern. A/B/C/F/M/J/R bodies and even some of the lighter duty vans and trucks. The majority of them will be 10x2.5”, but there are also 11x2”, 11x2.5” and 11x3” drums out there.
Click to expand...
Thanks for the info, super helpful. When I’m at the junkyard pulling drum assemblies, I’ll be sure to measure the brake offset to verify that the donor axle offset matches my 2.36” offset.
 
Everything needs to match too. The backing plate, shoes and drum. The backing plate offset is what sets the width and diameter for the drum size.
 
Duster256 said:
Cass at Dr. Diff (he’s the best!) said that his 10.7” rear disc brake kit has a parking brake and will fit my 2.36” axle offset. He also said that his 10 x 2.5” drum brake kit will fit but that kit is out of stock
Click to expand...
bet its not out of stock in a wanted ad here on FABO! very common rear brake size. might also check on FBBO and FEBO
 
OK. Now that's all cleared up, I'm in the market for a pair of used, reasonably priced 10" x 2.5" rear drum brake assemblies with backing plate (with or without drums) to fit my 8-3/4. A current ebay poster wants $500 for a rebuilt pair without drums - too rich for me, for what is supposed to be a very common rear brake size. I will be posting in the FABO and FBBO parts wanted forum. Thanks.
 
In your original post you stated that your flange to housing offset is 2.36. That is the original A Body offset. B,C,E body offset ( C are most not all) are 2.5. Be certain of your offset. If it is indeed 2.36 you must use A body drum
 
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