Backplate any difference between 10"x2" & 10"x2-1/2"?

[Josh Brink]

Hello All,
I have a quick question. Is there any difference in the rear drum backplate for a 10"x2" and a 10"x2-1/2"? In other words can I upgrade/change from a 10"x2" rear drum to a 10"x2-1/2" and keep the same backplate?
Thanks for the help.

 

[69Bee]

Not sure, but they might have moved the backing plate inward (deeper backspacing) the half inch so as not to grow anything outward.

 

[moparmarks]

Yes they have different backing plates.

 

[69Bee]

For '70 & '71, They only list 2 1/2" PN# 2880602, 2880603. For 11" brakes, they do list a 2 vs. 2 1/2", and they do carry different part numbers, so I agree with moparmarks comment

 

[Josh Brink]

Thanks for the quick response,
So here's my next question. 1966 Belvedere 4 door small block 318 all stock. Car came with 10"x2-1/2" rear drum, I removed those and sold, to upgrade to rear disc. Changed my mind and got some 10"x2" complete assembly from a friend. Front is 11.75" disc. Will this application work?
Thanks again

 

[moparmarks]

Sure.

 

[4mulas]

So the answer to your first question is NO. 2” backing plates must be used with 2” drums. If you want 2 1/2” brakes you must change the backing plates which match that drum width.

The answer to your second question lies within the answer to the first here.

2” needs 2”backing plate, 2.5” requires 2.5” backing plate

 

[R413]

Anytime the shoe width changes the backing plate changes.

that large pin at the top is a different length sticking out. The shoes have the spine in the middle of the shoe and the pin and spine have to match up or the shoes won’t mount.