Drum Brake Advice

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71DartGuy

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I am picking up an A-Body 8.75 axle this weekend. The only drawback is that it only has the backing plates as far as the brake parts go. What is the easiest way to put some drum brakes on this thing? A couple things that might help:

1) I have already changed the front to Big Bolt Pattern so the rear would need to be 4.5" also.
2) Car currently has the original 7.25 rear under it.

I know I will have to re-drill or buy new axles. I have read a few other posts on this subject and have seen that the register is smaller for the smaller bolt pattern so the axles may still not work after being re-drilled. I hope I gave yall enough information. Thanks for the help- again

Mike
 
If you redrill the axles just have the new drums redrilled also. If you go to an aftermarket axle (Yukons are the cheapest) then you will just use any 8 1/4, 9 1/4, 7 1/4 or 8 3/4" 4.5" brake hardware. Yukon A-body replacement axles have the flange offset the same as the "regular" rears.

Yes, the 4.5" 7 1/4 stuff works. I have just took brake hardware off a 7 1/4 and put it on an 8 3/4 that I changed over to 4.5" and it bolted right on.


Chuck
 
Ok, so just to clarify, as long as its a brake setup from a car with a 4.5 inch bolt pattern, I just need to swipe everything from the backing plates to the drums (if I dont re-drill mine)?. My 7.25 has the 4 inch so I dont think anything in there will be any good to me. Another question, does the size of the drums matter if I match all the hardware to the size?
 
Yes, you need the 4.5" stuff. The 4" stuff has a different axle flange offset.

all of the 4.5" 10" brake stuff is the same width.

You could put 11" stuff on your car but I think it is overkill even though really there is no such thing as to much braking.

Chuck
 
71DartGuy said:
I am picking up an A-Body 8.75 axle this weekend. The only drawback is that it only has the backing plates as far as the brake parts go. What is the easiest way to put some drum brakes on this thing? A couple things that might help:
Click to expand...

I did the same thing. Only a 8-1/4 rear was selected. I found a suregrip equiped 8-1/4 for $200. Only backing plates. This suited me fine since I have Cordoba 11 inch everything from a parts car. The rear was otherwise complete with the larger bolt pattern axles and 3.21 suregrip.

I just popped the axles out and swapped out the backing plates. Ordering brake parts to the young guns at the counter is as easy as..." '78 Cordoba, 11 inch drum brake shoes please."

Everything swapped over without issue and is now a working system on the 8-1/4.

1) I have already changed the front to Big Bolt Pattern so the rear would need to be 4.5" also.
Click to expand...

No, it wouldn't need to, but 2 spare tries would suck, he he he.

2) Car currently has the original 7.25 rear under it.
Click to expand...

Excellent paper wieght. Sell it if you can. Roll over the dough to the new rear or wallet.

I know I will have to re-drill or buy new axles. I have read a few other posts on this subject and have seen that the register is smaller for the smaller bolt pattern so the axles may still not work after being re-drilled. I hope I gave yall enough information. Thanks for the help- again
Click to expand...


I like the ide of new axles, even more so if your going to make some real good power. Everything can be custom ordered to fit. Or as simple as stock axle diamentions for any car equiped with a 8-3/4 rear and big bolt pattern.

Let me ask you, to just so I'm clear, the "Register" is the area of the axle where the studs go through?

If so, I don't have any experiance in re-drilling them and how much is left or avialable to re-drill for a larger bolt pattern. I guess the math of it all would be easy enuff to figure out and measure up.

I hope this helps some.
 
That does help. Thanks a lot. I'm not at all against using 11 inch brakes, I just recall some calling them overkill, but if its as easy as walking in and sayin 78 cordoba etc, I could do that. Thanks again Rob, I appreciate it.
 
He did say over kill in a sense I believe the factory wouldn't have done it, but he did also say theres no such thing as enuff good brakeing. More the merry.
 
Don't know how much travel is in the sliding yoke of the driveshaft. Due to the differences in the ring gear and pinion of the axles, the 7¼ rear uses a driveshaft that is more than 2 inches shorter. Rear u-joint angle increases to 2.5 degrees.
 
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