New Rear 11" Drums - Don't Fit - Need Advice

[doubleyellow]

So far bought from Autozone and O'Reillys. Both sets will not fit over the backing plate of the axle. I do not want to grind down the backing plate. I assume the drum diameter may be undersize for some reason. Anybody have this problem? Do I have to get the drums cut down a bit until they fit? or someone have better luck with another source to procure the drums?

 

[ramenth]

Anyway you can post pics?

What part of the drum is hitting the backing plates?

 

[doubleyellow]

Anyway you can post pics?

What part of the drum is hitting the backing plates?

The inner machine diameter where the pads would ride. Seems the inner diameter needed to be about 1/16" larger to clear the backing plate. Would be tough to take a pic of it from the back. Hope this helps.

 

[ramenth]

Are these factory backing plates?

At that point you'd be getting damned close to maximum turn diameter to have the drums turned to fit. Take 'em back to where you bought 'em from and have them get you another set. If they don't match then it's a bad run of parts and need to be defected out.

 

[challenger6pak]

Could have something to do with the axles being out of adjustment making the drums sit in the wrong location.

 

[ramenth]

Could be.

But 1/16" of an inch all the way around on both sides?

 

[68bigblock]

I don't remember for sure but doesn't the back plate go into the groove between the machined surface and outside dia. of the drum. what I'm asking are you sure you need 11" and not 10" drum

 

[challenger6pak]

We are all in a guessing game until we see pics.

 

[ramenth]

We are all in a guessing game until we see pics.

Pretty much.

 

[ramenth]

I don't remember for sure but doesn't the back plate go into the groove between the machined surface and outside dia. of the drum. what I'm asking are you sure you need 11" and not 10" drum

That's what I was thinking. There's a groove for the backing plate. It shouldn't be anywhere near the machine surface for the shoes.

 

[Mr Gangrene Genes]

There are also at least two widths of 4-1/2" bolt pattern 11" drums.
E-body is probably 2-1/2", C-body and pickups are usually 3" wide.
The backing plates have different spacing to match.

 

[AUSTA]

So far bought from Autozone and O'Reillys. Both sets will not fit over the backing plate of the axle. I do not want to grind down the backing plate. I assume the drum diameter may be undersize for some reason. Anybody have this problem? Do I have to get the drums cut down a bit until they fit? or someone have better luck with another source to procure the drums?

Here is some measurements if it helps 11" Finned

 

[moparleo]

Are you trying to build an 11" rear brake assembly from scratch ? It seems that if you had one of the old drums that fit, it would be pretty simple to diagnose your problem. Otherwise you just might not have all of the proper components to work with.

 

[doubleyellow]

Are you trying to build an 11" rear brake assembly from scratch ? It seems that if you had one of the old drums that fit, it would be pretty simple to diagnose your problem. Otherwise you just might not have all of the proper components to work with.

Guys,

Thanks for all the advice so far. I haven't had the brakes on for 20 years. Old drums long gone. Rear is a Dana 60. Have front disks. I bet I actually have 10". I just assumed 11". I have Track Pack, but do you only get 11" with Super Track Pack?

 

[doubleyellow]

Are you trying to build an 11" rear brake assembly from scratch ? It seems that if you had one of the old drums that fit, it would be pretty simple to diagnose your problem. Otherwise you just might not have all of the proper components to work with.

OK. I feel like an idiot. I just read that if you have front disk, rear drums automatically are 10". My bad. Thanks for all the responses.

 

[challenger6pak]

You're not an idiot. It is hard to know or remember all these things. That's what this board is for. Glad it is figured out.

 

[moparleo]

Onward.