10" rear backing plates??

[northeastmopar]

Are the 10: rear backing plates the same for the 1 3/4" drums/shoes as the 2 1/2" drums/shoes? I am assuming that since the Abody 8 3/4 only came with the small bolt pattern and the 1 3/4" brakes, that the backing plates I will need to use to install the larger axles and the 2 1/2" brakes will need to come from another model car?? I just bought a pair from a member here, and the first thing I noticed was that they only have 1 adjuster spoon hole rather than 2 and they seem to have no raised areas for the shoes to rest against? Does anybody have a picture of the what the correct backing plate would look like to change over from the small 1 3/4 brakes to the 2 1/2" brakes and the larger axle pattern? Thanks.....

 

[Oklacarcollecto]

Are the 10: rear backing plates the same for the 1 3/4" drums/shoes as the 2 1/2" drums/shoes? I am assuming that since the Abody 8 3/4 only came with the small bolt pattern and the 1 3/4" brakes, that the backing plates I will need to use to install the larger axles and the 2 1/2" brakes will need to come from another model car?? I just bought a pair from a member here, and the first thing I noticed was that they only have 1 adjuster spoon hole rather than 2 and they seem to have no raised areas for the shoes to rest against? Does anybody have a picture of the what the correct backing plate would look like to change over from the small 1 3/4 brakes to the 2 1/2" brakes and the larger axle pattern? Thanks.....

The backing plates are different on the 1 3/4" drums that were originally used. There are many threads on doing the swap if you use the search engine on this site. There are axle length differences in the after market axles are slightly longer if I recall correctly because they are designed to use the 2 1/2" wide brakes.

http://www.forabodiesonly.com/mopar/search.php?

 

[72bluNblu]

The 10x1.75" backing plates are different than the 10x2.5" backing plates.

The backing plates I sent you are 10x2.5", I know this because they had 10x2.5" drums and shoes on them before I stripped them down to the plates. Those plates will work just fine with BBP axles, as long as they aren't re-drilled SBP axles.

Some of the later backing plates are slightly different from the earlier ones, the later ones only had one slot and only one of the parking brake cable holes was drilled, so there's a left and a right. That particular pair of backing plates came off of a late '80's Diplomat, so there may be some slight manufacturing differences from the '70's versions. They work just fine.

 

[northeastmopar]

The 10x1.75" backing plates are different than the 10x2.5" backing plates.

The backing plates I sent you are 10x2.5", I know this because they had 10x2.5" drums and shoes on them before I stripped them down to the plates. Those plates will work just fine with BBP axles, as long as they aren't re-drilled SBP axles.

Some of the later backing plates are slightly different from the earlier ones, the later ones only had one slot and only one of the parking brake cable holes was drilled, so there's a left and a right. That particular pair of backing plates came off of a late '80's Diplomat, so there may be some slight manufacturing differences from the '70's versions. They work just fine.

OK, I was just curious as to what prevents the 1 3/4" backing plates from not working on the 2 1/2" brakes when they are both 10"?? I guess I am always intrigued by this stuff. Just curious? Do you know what exactly prevents them from working?

 

[Oklacarcollecto]

OK, I was just curious as to what prevents the 1 3/4" backing plates from not working on the 2 1/2" brakes when they are both 10"?? I guess I am always intrigued by this stuff. Just curious? Do you know what exactly prevents them from working?

Lay one each of them side by side on a flat surface and take a tape measure to measure the offset.

 

[SGBARRACUDA]

They are different because the spacing from housing flange to axle flange when the axles are installed is a diiferent measurement. A body 10 x 1 3/4 only work with the 5 on 4" 8 3/4 A body axles.

 

[northeastmopar]

They are different because the spacing from housing flange to axle flange when the axles are installed is a diiferent measurement. A body 10 x 1 3/4 only work with the 5 on 4" 8 3/4 A body axles.

I think my dumb mind gets it now. I am still waiting for the Dr Diff axels to arrive. I was not doubting what 72bluNblu shipped me. I was just trying to find out what prevents one from not working. I find I better understand things that way. Actually 72bluNblu was a good guy to break up the whole brake set to just sell me the backing plates and he shipped them quick for a very reasonable price, so I hope he does not take offense to my stupid questions. Thanks Brother....

 

[SGBARRACUDA]

That is how we learn.

 

[Torch]

Hey guys,,, I don't get it? I have a small bolt pattern 8 3/4 rear end. 10" drums fit the backing plate that came with it. drums are from the 7 1/4 rear end I took out of it. Problem is not sure what the backing plate is off? Have purchased 2" and 1 3\4" shoes, neither fit? Backing plates have 1 hole for emergency brake cable,,, so left and right. Inside of my 10" drum is a total width of 2 1/4",,, so 2 1/2" shoes are a No go. what is not correct with this installment?
Thanks for your time!

 

[SGBARRACUDA]

If they are A-body 8 3/4" original backing plates, you need to use the OEM drums with them. They have a unique axle offset.

 

[Torch]

If they are A-body 8 3/4" original backing plates, you need to use the OEM drums with them. They have a unique axle offset.

Thanks Roy,,,, that's the problem,, not sure of backing plates? A lot of time has gone into trying to find out.

 

[Jimacuda]

Measure the offset of what you have...
That should narrow it down.
Stock axles or aftermarket?
Does the drum fit on the center register and into the edge of the backing plate?
Something is amiss...

 

[Torch]

Measure the offset of what you have...
That should narrow it down.
Stock axles or aftermarket?
Does the drum fit on the center register and into the edge of the backing plate?
Something is amiss...

Measure the offset of what you have...
That should narrow it down.
Stock axles or aftermarket?
Does the drum fit on the center register and into the edge of the backing plate?
Something is amiss...

Thanks for helping Jim,,,,
I measured offset,, 2" I do believe.
yes 10" drum fits the center and edge of backing plate.
The rear 8 3/4 housing I believe has been shortened to A body spec;s,,, it is 43" in width.
and is SBP. Drum is off 7 1/4 rear end that was removed from Cuda.
8 3/4 rear end is installed,,,, but as you know can't match any shoes? 2'' do not fit or 1'' and 3/4?
axles where in the rear end with No taper when purchased.

 

[SGBARRACUDA]

I'm thinking you have 10" backing plates off a B body or something that is non A body 8 3/4"

 

[dogbreath]

i believe the only a-body 7-1/4 rears that had 10¨brakes were the 73 up big bolt units necessary when paired with front dics brakes.

 

[Torch]

I'm thinking you have 10" backing plates off a B body or something that is non A body 8 3/4"

Thanks again,,,,, I don't know what to look for to fix this problem?
everything was a bit crazy with changing U bolts, mtn plates,, conversion U joint etc. Any ideas?

 

[SGBARRACUDA]

Well at this point if you have small bolt original axles, I would look for original A-body 8 3/4 backing plates and drums.

 

[Torch]

Well at this point if you have small bolt original axles, I would look for original A-body 8 3/4 backing plates and drums.

Thanks Guys,,, sounds like this car is off the road for a long time. From what I hear not many backing plates made for what I need. I just wanted to keep small bolt pattern so I could keep my tires and rims. I thought backing plates that came with rear end were ready to go,,,, guess I have purchased someone elses mistake!

 

[Jimacuda]

with what you seem to have it sounds like 1.75 shoes are what should fit.

Recap...
Your drums, backing plates, axles, etc. all fit together as an assembly, correct?
Nothing grinding, no gaps btwn drum and backing plate...

Let's see a better picture of the pieces.

 

[Torch]

with what you seem to have it sounds like 1.75 shoes are what should fit.

Recap...
Your drums, backing plates, axles, etc. all fit together as an assembly, correct?
Sure is nice of you to take time to help! I have some Chevy friends... They are having a good Laugh.
Yup,,, everything seems to bolt up nicely,,,, till I put shoes on?
I will get out to garage takes some pic;s and get back.
Nothing grinding, no gaps btwn drum and backing plate...

Let's see a better picture of the pieces.

 

[Torch]

Think I;m responding in the wrong reply at times?
Thanks for the help. I will update more pic's soon.

 

[Torch]

These are Pic;s of backing plates and 10'' drums on newly installed 8 3/4 rear end. Drum is from 7 1/4 that was taken out.
Can't figure out what shoes will fit, or if backing plate, drums are wrong?
I was hoping to get this done before cold weather, but garage is damp and cold now. Ohhh well it'll warm up in 6 months.
Thanks for having a look!

 

[Jimacuda]

Nothing looks off to me....
What's the issue...what doesn't fit right on assembly?

If someone could post pics of an 8.75 A body 10x1.75" brake assembled...mine are all 10x2.5's.

 

[Torch]

Hello Jim,,, Maybe I jumped the gun?
Hope so? I was told by a Mechanic looks
like I have wrong backing plates?
I will have to Look into this a little further.
Nice that you see nothing wrong in pictures,,,
Thanks again for your time,,,,
Hope to get 1 last warm day in garage? Snow last night.