8 3/4 brake support question

[68satt]

I recently picked up a complete 8 3/4 (741 case) to replace the 7 1/4 in my 68 Satellite currently. The 8 3/4 I picked up is out of a 68 Coronet and measures correctly however the backing plates that are on the housing measure 12" so I am assuming it will be 11" drums and hardware. With having 10" front drum brakes will the 11" in the rear cause too much braking in the back and possibly be dangerous or should it be ok?

I believe the backing plates and brake components on my current 7 1/4 will not work on the 8 3/4 from what I have been reading.

 

[pnora]

Take the drum off and measure. Most likely 10 inch. If 11 I doubt you will notice anything.

 

[68satt]

I have 10" on the rear now on the old diff, the new diff did not come with brake drums, only backing plates that are 12" diameter.

 

[Rockland71GTX]

I think it will be fine, but I would definitely test for rear wheel lock up before serious driving. If there is an issue it can be corrected with either a smaller wheel cylinder or an adjustable proportioning valve.

 

[Rishi]

Can you not move the 10 drums assemblies (backplates and all) over to the 8-3/4? That might be the simplest way to go, but I'm not sure if any 8-3/4 had 10-inch drums or if they even fit.

 

[68satt]

Can you not move the 10 drums assemblies (backplates and all) over to the 8-3/4? That might be the simplest way to go, but I'm not sure if any 8-3/4 had 10-inch drums or if they even fit.

I would like to do this but from what I have read so far the backing plates are different for the 7 1/4 compared to 8 3/4 but I don't know for sure, maybe someone has done this with success.

 

[R413]

Thousands of b-bodes came with 10" brakes on a 4 corners. And every factory disc brake b-body came with 10" rear drums, 1966-1972.

The bolt pattern isn't the same on the backing plates to swap them over from a 7.25.

 

[68satt]

Good to know, now its to try and find backing plates for the 10" brakes.

 

[gkent]

now its to try and find backing plates for the 10" brakes.

Not that big of a deal - just make sure they're for 2-1/2" shoes as they do differ depending on shoe width. Try to find a set that has ALL the hardware - including the two parts the arrows are pointing to. Complete assemblies run around $100. (US) but if missing those pieces you'll be spending that much more !!