Brake information

[ken5124]

Finally obtained an 8 3/4 narrow perch rear end housing with small bolt pattern axles.. It has backing plates but no brake hardware or drums.. Will those peices off my 7 1/4 fit??

 

[chasduster]

I doubt it....7 1/4 had 9 inch and 8 3/4 has 10 or 11 inch brakes...I believe...what year and what did they come out of.....

 

[ken5124]

KInda figured that... 7 1/4 is the stock one from my 65 valiant signet..
8 3/4 is the narrow perch one not sure which year it is should be 65- 72 I think.

Anyone else??

 

[Steve Reynolds]

My 8 3/4 has 9in brakes & they are on a 71 Demon.
Isn't it true that all Mopar backing plates interchange?
I hope they do, as I am looking to put 11in on the Demon.
Any info would be great,
Steve

 

[ken5124]

hmmmm then my 7 1/4 ones might work... I ll find out more next weekend when I pick up the rear end

Thanks Steve

 

[Demon 408]

Drum and backing plates need to be from the same size brake. So yes, your 7 1/4 drums and backing plates will fit the 8 3/4 as long as the axle bolt pattern size is the same. For example, I swapped 7 1/4 drums and backing plates (10 1/2) from a 1974 Dart onto my 8 3/4. Both had the large (4 1/2) bolt pattern.

 

[grumpuscreature]

My 8 3/4 has 9in brakes & they are on a 71 Demon.
Isn't it true that all Mopar backing plates interchange?
I hope they do, as I am looking to put 11in on the Demon.
Any info would be great,
Steve

The determining factor is the diameter of the housing ends. 7 1/4" rears through '72 used 2 1/2" axle tubes so those backing plates and brakes will not swap onto a rear with 3" axle tube ends (8 1/4", 8 3/4", 9", '73 up 7 1/4") and vice versa. 2 1/2" axle tube brakes were either 9"X2" or 10"X1 7/8" (SBP). 3" axle tube brakes were either 10"X1 7/8" (SBP), 10"X2 1/2", or 11"X3". In short, if the axle ends are the same size, swap away. Hope this helps.

Drum and backing plates need to be from the same size brake. So yes, your 7 1/4 drums and backing plates will fit the 8 3/4 as long as the axle bolt pattern size is the same. For example, I swapped 7 1/4 drums and backing plates (10 1/2) from a 1974 Dart onto my 8 3/4. Both had the large (4 1/2) bolt pattern.

 

[pettybludart]

hmmmm then my 7 1/4 ones might work... I ll find out more next weekend when I pick up the rear end

Thanks Steve

Sorry,I didn,t want to give you the wrong answer.I,ve just always done 8 1/4 or 8 3/4,never really looked over the 7 1/4 cause of V8,s with some HP!Someone will chime in with proper answers!

 

[Steve Reynolds]

My car has lbp so the only thing I need to worry about is drum bolt pattern
when putting 11x3 brakes on my 8 & 3/4, is this true?
thanks, Steve

 

[ken5124]

I am a dumas, I actually have LBP...

See my thread in suspensions for more questions about the type of axles I have
Thanks