New drums...hrrrmmmmmmm when applying

[69moredoor]

9” front drums. New brakes. Used old drums. Drums were def out of round/vibes and appeared VERY old if not original.
Replaced drums. Stops great. No vibes. Just makes a hrmmmmmm sound when stopping. Guessing it’s the shoes seating in the new drums?

 

[flingdingo]

Its a vibration causing the noise, its just not bad enough for you to feel.

Have the drums turned. I always turn new drums, its amazing how out-of-round many of them are.

 

[mobileparts]

"New" brakes -- that is certainly most of the problem.
This new garbage of today grind and grabs and rips and shreds brake drums to stop, and you can hear that....
I have ++ N.O.S. ++ Asbestos ++ brake shoes -- Fronts and Rears -- for your car -- the nicest smoooooothest
Braking system known to mankind....
You would be smart to put them in there, especially if you care about your car!!!

 

[1994redram]

I've seen a bunch of original drums that have a spring wrapped around the outside of the drum. I've always guessed that the spring was to stop some vibration or resonating noise.

 

[pishta]

Its called the anti howl spring.....?

 

[AJ/FormS]

Furthermore
new shoes on old drums are only gonna contact over a very small patch usually near the center portion of the friction surface, away from the ends. It will take thousands and thousands of stops before the entire lining is again contacting the drum. In the meantime the edges of the linings will be ground up by the rusty ridges found there on the inner and outter edges of the drum. And the shoes ability to self-energize will be seriously compromised.
Between all that going on, it will take waaaay more pedal pressure to make effective stops. The shoes will glaze and the drums will ring, until they seat, probably late next summer.
You can possibly machine your drums, but now they will have an even smaller contact patch.
The shoes can be ground down on a special machine, so their arc matches your newly machined drums, but the machine grinds off thousands of miles of braking material, to do it.
In the end, new standard drums will be far cheaper. Everything fits, and bonus, they are quiet.

 

[Jimacuda]

Deffinately re-arch your shoes if you want to get the best out of your drum brakes.
any shop that relines shoes should have the equipment.
some will use a thicker lining to compensate for the process.

 

[George Jets]

Yes there is a process call Re-Arching the Shoes. When the used drums get cut to larger than stock, then the new shoes do not fit the enlarged radius. So then they Re-Arch the new shoes to fit. Have seen this done many times. Used to be standard procedure back in the 4 wheel drum days.

 

[RustyRatRod]

Did you burnish the new brakes? If not, that's the first thing you should do. Run it up to about 50 and stop really hard down to about 20. Do this three or four times.

 

[RustyRatRod]

Furthermore
new shoes on old drums are only gonna contact over a very small patch usually near the center portion of the friction surface, away from the ends. It will take thousands and thousands of stops before the entire lining is again contacting the drum. In the meantime the edges of the linings will be ground up by the rusty ridges found there on the inner and outter edges of the drum. And the shoes ability to self-energize will be seriously compromised.
Between all that going on, it will take waaaay more pedal pressure to make effective stops. The shoes will glaze and the drums will ring, until they seat, probably late next summer.
You can possibly machine your drums, but now they will have an even smaller contact patch.
The shoes can be ground down on a special machine, so their arc matches your newly machined drums, but the machine grinds off thousands of miles of braking material, to do it.
In the end, new standard drums will be far cheaper. Everything fits, and bonus, they are quiet.

He's not using the old drums. he replaced them.

 

[pishta]

We had that brake shoe archer in our old auto shop in high school. Chuck the brake shoe in the machine, set the drum ID size plus over size in thou and then swing the shoe across the router looking bit. BRRRrrrrrrr! ..and the asbestos went flying......circa 1984.

 

[George Jets]

You are right RustyRatRod, he did swap out the out of round used ones for new in the end of his post.

Carry On . . .

You know he ran the brand new shoes on the old out of round brake drums for a bit then changed to new drums, that probably put an odd cut on the shoes.

For sure now he should get them re-ached to straighten them up again.