I have a 73 Valiant with a 7.25 axle and 9 inch rear brakes. I am considering the possibility of upgrading to the larger bolt pattern with 10 inch brakes.

My plan is to install wheel studs for BBP in the voids between the current wheel stud holes and install 10 inch backing plates and drums.

I have several questions. Will the spacing between the backing plate and axle flange be correct, or will the brake drum hit the backing plate before seating against the axle flange? Will the backing plates from a larger car even bolt to my rearend tube, or is the bolt pattern a different size? Has anybody ever tried this method?

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My other car is also a mopar.

Simplest thing is to get a big bolt rear for your car. They came in all 73 and later darts,valiants, and dusters with disk front brakes. You can get either an 8 1/4" one, or a 7 1/4" one. They will both fit. The 8 1/4" rear will require a shorter drive shaft. The 8 1/4 rear is considerably stronger,and will even take the power of a moderately built v-8. Put the disk brakes from the front of the same donner car. There are after market kits out there that will upgrade your small bolt front brakes to BB disks without changing any of your front end parts. They just mount a special adapter for the calipers.

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69 Dart Swinger, 230 ci slant, t-5 five speed, intercooled turbo, 4 wheel disk brakes, tubular upper control arms.

The donor car for the front disk brakes will be either a 72 satellite or 84 diplomat. Changing the rear axle would obviously be easier, but I do not have an A-body rear axle available at this time. Shortening an axle or building custom rear wheels would be too expensive.

The other possibility is if someone in my area has a BBP rear axle that they wouldn't mind parting with.

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My other car is also a mopar.

Go to Moparts.com and see what is for sale. Look for a disk brake 73-76 Dart Duster or or Valiant. Check your local junk yards. There has to be a couple of these still out there. I would opt for the 8 1/4 rear over the 7 1/4" one. I have a 7 1/4" one in my back yard, but it is promised to someone else, and it would cost a furtune to get it to Oregon.

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69 Dart Swinger, 230 ci slant, t-5 five speed, intercooled turbo, 4 wheel disk brakes, tubular upper control arms.