[nepatfn]

Does anyone know how to tell the rear drum size on a 73 318 challenger? Is there any marking todetermine the size?
Thanks
Mike

[nepatfn]

Is 10” x 2-1/2" the only size available, or can you put larger drums on a 8 3/4 rear?

[moparmaniac (owner4)]

You could get 11" x 3" for the rear. You would have to change backing plates and all brake hardware to accomplish this.

[moparmaniac (owner4)]

e-mail me or send a PM, I think I have 11" backing plates on an 8 3/4 out back I would be interested in selling. I just need to make sure they are spares and not collected for my 71 cuda.

[dave-r]

If you just take the wheel off and then take the drum off you can measure the inside diameter of the drum. That is your drum size.

10 X 2.5 inches front and rear drum brakes were standard most years.

11 X 3 front and 11 X 2.5 rear (not 11x3!) came with heavy duty brake options like on the big block R/T.

Where front disc brakes were fitted the rear drum size was always 10 X 2.5.

If you upgrade to a 11 inch rear drum without upgrading the front brakes you will upset the brake proportioning front/rear - making the rear wheels lock more easily. You could make up for it with an adjustable brake proportioning valve but that would take away any benifit of fitting the larger rear brake.

[moparmaniac (owner4)]

Sorry Dave. I was using guess mode.

[dave-r]

I think you will find that I fall foul of guess mode more than anyone around here!

I should add that I use the 11x2.5" rear brakes (standard on my car) . Even with bigger 11.75" disc brakes on the front it still locked up the rears easily until I dialed a large amount of proportioning in.

[dave-r]

I checked and the AAR and T/A e-bodies had 11-inch rear drums. But I don't know if they used a different proportioning valve or not.