Brake Grinding


#1

1950 cadillac - standard drums on all 4 corners.

I put new wheel cylinders on each drum, and replaced the drivers front hose, as it was clogged. The passenger side I left because it works and doesnt leak.

Ive cleaned all the brake surfaces, shoes and drums, and bled everything.

When I brake, and only when I brake, the front right makes a grinding noise and the car pulls to the right.

I tried tightening the star wheel today to bring the shoes inward in hopes that would equalize brake pressure up front, but when trying again today, I got that grinding sound still.

Theres no scoring or gouges on the shoes, drum, and the inner and outer ball bearings seem fine - round chrome balls with no discoloration, no gouges on the spindles. Granted I dont drive this far at all, especially now that I have this grinding.

Any ideas? How can I really tell if its the ball bearings? It only makes the grind when Im on the brakes.
Thanks


#2

You’re sure the primary and secondary shoes are in their proper position on that drum?

Tester


#3

I never removed them so they should be right


#4

You can’t assume that they are correct! A buddy had a Mustang he bought new on which the rear drum brakes were installed in reverse!


#5

I didnt realize you could do that. I’ll take pics today. I think these were used on the car for a while, although they still have life left.


#6

it s easy to mix up. on my jeep, the primary shoe is smaller than the secondary shoe, I had to triple check it because it seemed counter intuitive to me.


#7

@wesw‌ If the shoes are of a different size, the smaller one is always the leading, or forward shoe, and the larger is the trailing, or rearward shoe.

Or as an old-timer taught me way back when, “the fat chick rides in back.”


#8

Shoes are correct.

Naturally the picture uploading for this forum from a mobile device is unresponsive


#9

Do the best you can to make sure the shoes fit the drum properly and are adjusted properly. If the arc on the shoe isn’t correct it will hit on a small portion of the friction lining. That may be a problem with the left brake (the one opposite the pull). The right pull indicates the right brake is working better than the left. The right brake grinding may indicate one or the other shoe is not mating quite right with the drum. You may be able to bed-in both sets of shoes (carefully because of that pull!) and then adjust them if things get a little better to even things out. Drive around the block at 25 mph braking for each corner until the brakes get hot. Let is col and do it a couple more times to bed in the linings. May help even things out after another adjustment.

Drum brakes, by design, help magnify the force applied by the slave cylinder. That means when you have one brake working better or worse than the other, it is a LOT better or worse. Disk brakes don’t have so much gain so small errors stay small.


#10

Saw car show where they put car on roller device to measure %difference between left/right wheel. You need to verify performance to legally register car in that locale. Interesting


#11

Im having the drums resurfaced now. Re-greasing the inner and outer bearings didnt solve the problem. A pic i posted on a hot rod website gave me a comment that it looked to have hot spots.

Took me two tries and having to go
Back and get my shop manual for specs for a shop to take them on and resurface them. The first mechanic had never worked with drums like this. Understandable with it being 64 year old technology.


#12

Did you grease the backing plates? Ball bearings?


#13

Unless you are talking about a bicycle that should be roller bearings.


#14

I thought “roller bearings” too until I saw this:


#15

Insightful you got it. Thats the outer and theres also an inner bearing set.

The resurface fixed the problem! And guess what else, the guy didnt charge me! He said it was too much hassle, the system only allows them to charge 199 for a brake job and he wasnt going to charge me that. He insisted a handshake and a smile was all he needed. How about that!?


#16

Incredible. Put that guy on the mechanics file.


#17

At least drop off a couple dozen Krispy Kremes the next time you pass by.


#18

nice…

looks like you found a good shop for future work


#19

Yeah, I’ll have to do something tomorrow for the guys


#20

I have drums all around on my early 70’s Ford truck, with the similar type of removable bearings (on the front). But I think on the truck they are rolling cylinders, not spherical bearings.

Anyway, when I do this type of job on the truck – very infrequently as the truck isn’t driven very many miles per year these days – I always re-pack the removable front bearings as part of the process. I also put witness marks so I can be sure to install the drum in the same orientation w/respect to the hub as it was.

After removing the drum (often a challenge) I remove the shoes and springs, I clean everything off to the point of being close to spotless with brake cleaner. Then I lube the metal to metal points with brake grease, and re-install the shoes, etc. I do one side at a time, so if I’m confused which part goes where, I always have the other side for reference. That has saved my bacon several times. Plus it prevents accidentally switching parts from the right to the left etc. I often find while doing all this I need to replace some part or the other due to wear, usually it is something to do with the automatic adjustment mechanism.

Before I re-install the drums, I take the opportunity to rough the drum’s contact surface with some 100 grit Al O2 sandpaper, in a cross hatch pattern. Then I thoroughly clean the drum surfaces with brake fluid. After that, it’s simply replace the drums and minimize and equalize all the shoe-to-drum distances with the star wheel adjusters.