8 inch brake backing plates on a 9 inch

ive got a 68 mustang 289 auto with an 8 inch out back. im converting it to a 9 inch to accommodate the new engine mods. Ive got the chunk and everything but i dont know if i can use the brake backing plates from the 8 inch and for my new 9 inch.

This is supposed to be a direct bolt on unless you have a large bearing 9 inch...If the rear end is out of a mustang or cougar you should be fine.

If it is a small bearing 9" then they will bolt right on. Depending on the original application for the 9" the only problem you may have is the axle flanges may stick out further if the original brakes were wider but most likely not. I'd say bolt them on and see how they compare. I'll bet they work fine and if not you'll only have spent a little effort.

Thanx for the info. does anyone know off hand know the deminsions or measurements of the bore/bolt pattern on the big bearing 9 inch?

Are all 31 spline axles big bearings?

I think as long as the axle tubes on the housing narrow down at the ends you have a small bearing housing...A 31 spline axle does still fit in these housings so they can be small bearing...

Whats the stock width of a 68 mustang 9 inch housing w/o backing plates?

Ford rear ends


PM me with email and I'll send you a diagram of the flange dimensions