Hello everyone,

I have a 1971 CS with power drums front and rear.

The brakes are all new, wheel cylinders, shoes, small hardware parts, drums, all lines and the distribution block.

Wheel bearings are new too.

Since the car was pulling to the left while braking, i tried to adjust the front drum brakes and made sure that the self adjusters do their job.

BUT... after a few adjustments (which havent made a big difference) my left front brake makes a odd grinding noise when braking a bit harder. So i took the drum off and figured out, that the metal on the lower side of the shoe was grinding on the inside of the drum. How can this be with new bearings, cause this tells me that my left hub is too close to the brake.

My front drums are finest chinesium from RockAuto.

Im not sure if the drums are the problem, because this problem started AFTER some shoe-adjustments. Before, it wasnt grinding.

Thanks for any ideas, i hope i was able to explain the problem good enough!

Greetings from Austria!

 

Could you have the wrong width of brake shoes?

 

Look to see how you put it together, if you had the wrong part it should be doing it on both sides. Compare the right to the left and see if there are any differences. Post some pictures.

 

When ever I have issues with a vehicle pulling to one side when braking the issue was with a loose wheel bearing.

 

Check whether you have the correct placement of Primary and Secondary shoes, and the correct color spring holding them down.

 

Ok, ill take dome pictures next time i work on the car!

Wheel bearings are all new and snug.

Thank you for the input!

 

For diagnostic purposes, swap drums side to side and see if it follows the drum or stays on the same side.

Good luck!!!

 

Here are a few pictures of the grinding left front brake, the spots i marked yellow are the spots where its grinding when braking a bit firmer:








Maybe just grinding the metal off the brake shoe?

On Passenger side, everything is ok.

Drums, brake shoes, wheel bearings and hardware are all new.

maybe you guys have some ideas?

Greetings from Austria

 

Is it possible that there is something on the backing plate where that shoe rubs that is pushing it outward? Or could the backing plate be bent outwards a bit there to cause an interference between the shoe and drum?

I second the idea of swapping drums from side-to-side to exonerate either the drum or the brake assembly.

 

thanks a lot for the ideas! Im going to check that.
its true, i painted the backing plates with a good layer of rust protection paint. Maybe this pushes the shoes a bit too far to the drums.

 

Inspect the depth of the groove in the drum that interacts with the backing plate. Chances are it's not cut to spec (shocker) and rubbing on the backing plate? Ask how I know this one.
Root Cause...Chineasium JUNK cast from rusted scrap cut by a 5-year-old with a missing arm on a worn-out lathe from WWII out in a field belt-driven by a 3600 rpm yard tractor up on blocks with one wheel turned into a sheave!

 

You can take a file to the metal on the side of the shoe/s or take the drum to an auto parts store with a lathe and have that area on the drum clearance.

 

haha nice story of how chinesium drums are made

but its definitely not rubbing on the backing plate. Its the metal of the shoes (shoes are Federal Mogul).

I think im gonna file/grind the metal of the shoes a bit off, it stands a bit over the pad itself and try it out.

Thank you all!

 

Could spindle be worn, allowing hub / bearings to slide on a bit to far.

 

Are the shoes 2 inches wide or 2 1/2. Rear shoes on the front?

 

Those shoes do look a bit wide.

 

The front shoes are 2 1/2, got it from Rockauto and they list all front shoes 2 1/2 for this car, but i gonna measure them.

 

Never saw that before... I think it maybe that backing plates are bent or missaligned?? Let us know what you find!

 

My backing plates are fine. Ive just measured the the shoes. The pad itself is 63mm wide, which is 2 1/2 inches. BUT, the Metal of the shoes is 65mm wide, and the metal is the part which is grinding in the drum. So i think Federal Mogul is chinesium too .

I will grind the overstanding metal off to make it clear to the pads itself and give it a try.

 

Now i disassembled both front brakes, scrapes the paint off the "sliding points" of the backing plate (the was a lot of Paint on those points, i hope this helps to get a better clearence too) and grinded the overstanding metal off the shoes. Next few days im gonna take the car for a test ride.

 

Old thread I know - I assume you resolved this issue long ago by grinding the shoe backing plate down or tossing the drum out and getting another drum or brand?

 

Issue solved long ago by converting the car to front disc brakes from a 71 chevelle.

But back then, what i did with some clearancing on the brake shoes and scraping off the paint on the points of the plate where the shoes lie, solved the issue with the drum brakes too.

 

Converting to disc seems to be the solution, thanks..

 

The conversion is really easy to do and a huge improvement over front drums. I used all used GM original parts to make sure i can re-use my 14 inch rally wheels. cleaned them up + painted them.

If i remember corretly, you basically need:

- disc brake spindles from any GM A Body car - 72
- the calipers + mounting brackets + maybe a caliper rebuilt kit
- the "dust plates"
- new stock style brake discs
- new brake pads
- new front rubber brake lines
- correct disc/drum brake distributor valve
- correct disc/drum master brake cylinder

- and for sure, some brake lines + flared nuts to do the plumbing with the new master cylinder/distributor valve.

 

Thanks.

 

Sorry, but this is BS. The brakes did not rub or grind when the car left the factory. Spending $1000 to fix something that should not be a problem in the first place is just kidding yourself. No, I'm not suggesting that the disks aren't a better braking system, but frankly, if one can't find the cause of a simple problem like this, one's ability to correctly do a disc brake swap comes into question. And once again, nearly EVERY aftermarket disc brake kit is poorly designed. Go read the other thread where a simple thing like the bracket to hold the combo valve doesn't fit on a conversion that is being done.