8 3/4 10" brake drum problem!!!help!

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69 Valiant Kid

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hey guys, in my restoration of my valiant i put some pictures up and have had a few replys there....but im looking for some more input. ill put the pictures up here as well. but i put my gears and axles in yesterday and find that my drum is 1/2" too deep so my drum hits the backing plate before it hits the axle flange....these parts guys are retarted in napa and such...im really getting po'd here...somebody has to have 10 " rear brake drums for the small 1" and 3/4 brake shoe!!!!!! my blood is boiling!

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the shoes are 1 and 3/4 inch wide....and i dont even think that matters here because the problem is the drum is too flipn wide!
 
well, i guess im replying to myself on this one...im finding that they didnt make a drum for big bolt pattern 10 inch, with 1 and 3/4" shoe width. i guess ill have my 10 inch drums i have now machined down a half inch...
 
Are you using the stock backing plates that were on your a-body rear? Big or small bolt pattern axles? The 10" backing plates on the small bolt pattern cars were different than the 10" big bolt pattern ones. You will need some backing plates from another car like a b-body or similar. What drums do you have? I had this same issue, tried to use the sbp backing plates with a bbp drum, hit the same as yours. I had a set of 11" cop car brakes sitting around so I used them instead.
 
i have the backing plates that came with my 8 3/4 rear housing that i bought from a guy on here...and yes i have big bolt pattern moser axles. the drums are 10 inch by 3 inch (machineable brake surface on the 3 inch measurement) the backing plates fit perfect in the drum groove....just 1/2" left from the axle flange to the drum...
 
so 340sedan...the b body backing plates would provide that extra room for the 10 inch drums to fit?!...does the backing plate go that much farther back to the middle of the rear end housing?
 
If it was me I'd take the 2 1/2" drums back to the parts store and trade them for 2, 4" bolt pattern 10" drums. My next stop would be a machine shop to have them redrilled for the 4 1/2" bolt pattern. The bolt pattern changed in 1973 to 4 1/2". This was also when the rear brakes became 2 1/2" wide. Can't really blame the parts guys since every 10" drum with the 5 on 4 1/2" bolt pattern used 2 1/2" shoes whether it was for a '66 or a '76. Prior to 1973 they were used on B bodies. Hope this helps.
 
Yep, the B body backing plates have a deeper dish in the center. That's what I am running on my '66 Valiant, no problems.
 
I'd have to o with Grump on this one. If you go with the BBP drums the register will be too big like it is now. You'll need the SBP drums drilled to BBP so you can use your current backing plates.
 
69 Valiant Kid said:
so 340sedan...the b body backing plates would provide that extra room for the 10 inch drums to fit?!...does the backing plate go that much farther back to the middle of the rear end housing?
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Not too much farther back but they will fit with the proper backing plates. You could also do what grumpuscreature suggests, have the sbp drums drilled for the biggern pattern. If it were me, I would locate the corrrect backing plates, larger rear shoes means a little better stopping power! Keith.


grumpuscreature said:
If it was me I'd take the 2 1/2" drums back to the parts store and trade them for 2, 4" bolt pattern 10" drums. My next stop would be a machine shop to have them redrilled for the 4 1/2" bolt pattern. The bolt pattern changed in 1973 to 4 1/2". This was also when the rear brakes became 2 1/2" wide. Can't really blame the parts guys since every 10" drum with the 5 on 4 1/2" bolt pattern used 2 1/2" shoes whether it was for a '66 or a '76. Prior to 1973 they were used on B bodies. Hope this helps.
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oh believe me,in dealing with parts guys every day, ive heard enough of the "like i said"s and, well "it says in the book"...and the "thats what it calls for"s....but i understand what you're saying....
 
well i just called 2 machine shops...and they said they wouldnt be able to do something like that...whata joke...what do you mean by register?
 
69 Valiant Kid said:
well i just called 2 machine shops...and they said they wouldnt be able to do something like that...whata joke...what do you mean by register?
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The register is the hole in the middle of the drum that locates it on the axle. It looks like your axles have the small one for the SBP axles and the drums are larger. Those need to match to keep your drums centered with the brake parts.
 
I had the same problem with my eleven inch rear brakes. I bought the backing plates off o Ebay and was told they were 11x2 inch off of a truck.I must of went through 10 sets of drums until i found the right ones. I finally found an auto parts store that had all the old specs with dimensions. They ended up being 74 Plymouth Grand Fury drums. Keep atient you will find the right ones.
 
I raced home after work and whent streight to my shop to check.

I grabed my axle and put it in my diff, then grabed my brand new drum and put it on, and........

It fit perfectly. :supz:

If you want my measurments just let me know.

Phil
 
Grump and 71Dartguy have the correct answer for your problem.

You need to get SBP rear drums and have them drilled for large bolt pattern. I have done it my self its really not that hard.

Too bad I have some new SBP drums that have been drilled for LBP but the register is for the larger axles.
 
I have the exact same brakes on my car

The Drumbs are 10 inch wide and 3 inches deep

My brake shoes are 1 and 3/4 inches

The backing plates are off of a A body. ( I am 99% sure of that)

The drumbs are for 10 inch big bolt 1966-1979 Cornet, Or 77-80 Diplomat NON WAGON.

My drumbs are brand new and fit perfectly, However, I am using a stock Axcle with the larger opening for the drum to sit on. 2 3/4 inches opening

My drumbs would work perfectly for you if......

A. You could get an adapter to make your performance axcels work with a larger hole on the drumbs ( don't know if there is a part for that)

B. Looked for a different pair of big bolt axles

C. Changed your backing plates to a larger 11 inch. and changed the rest of your set up too.

Hope this helps.

let me know

Phil
 
we just took the small bolt axles out of my brothers dart.the axles and drums have been drilled to the larger bolt pattern.We installed b body brakes and drums along with yukon axles.so i have extra axles and drums with both patterns. I can ask him if he would like to sell you the drums.they would be drilled for both patterns. But worked fine..
 
folks....i bought 400 dollar axles from moser.....taking those out is not an option....my small bolt pattern drums are being drilled out by a machinist....so ill be money in the bank. sorry all this came about today at lunch, but thanks for everyones 2 centskies..
 
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