Brakes are fucked up.
 

Ever since I put new shoes and drums on the rear of my truck, I have the awful Vibration when braking, especially from higher speeds.

I brought the drums back and got new ones, and the problem is still there.

The shoes are not on backwards or anything. One shoe has the pivot pin for the adjuster while the other does not.

The only thing I can think of is that somehow the shoes are fucked up.


Anyone have any ideas?

Re: Brakes are fucked up.
 

If a drum is warped it will cause the rate of braking to surge, for a given pedal effort. You'd feel pulsing through the pedal, and the surge, no vibration though. It's not uncommon with some el cheapo drums, they are meant to be turned before you use them for some stupid reason that makes no sense.

I don't think a shoe issue would cause a rotational vibration, at least not without visibly wearing them up in a pretty short time. None of that stuff rotates, you see.

I'd guess you lost a weight off of one of your wheels during the brake job. Try rotating the tires, see if the vibration moves around.

Re: Brakes are fucked up.
 

Maybe although I didn't find anything on the floor afterward.

The drums are Car Quest drums. The label on them says no finishing required. This is the 2nd set of drums and there is still a vibration. What are the odds that 2 different sets are fucked up?

I'll check the wheels out and see what's up with the weights.

Re: Brakes are fucked up.
 

On both sides the shoes have strange marks:

Attachment 16369
Attachment 16370


Could it be possible that something is fucked with the brake cylinder?

Re: Brakes are fucked up.
 

your brakepad was bonded, then cut with a hollow grind, in degrees, vs cutting one solid radius. stick some sandpaper inside your drum glue it down somehow, tension the shoes on the drum, then spin.

either that or the bond was walked on with a multi sided press roller, to promote faster wear-in to the drum face and just creased the lining.

i dunno. whats your measurements on the drum size?

Re: Brakes are fucked up.
 

IIRC, 297mm is the max diameter for turning on the drum.

Could I just carefully scuff them with some 80 grit by hand?

Re: Brakes are fucked up.
 

you need the radius of the drum to take the high spots off

Re: Brakes are fucked up.
 

in my experiance high speed shakes are normally front rotors, I dont find warped drums to really be bad at high speeds, usally slower stops. Those shoes are fine, they will brake in, no sand paper or glue needed. Can you feel the shake in your ass or steering wheel or brake pedal? You need to turn cheap drums because they pack 1000,000 of them in a container from chine and the wieght on them make them go out of round.

Re: Brakes are fucked up.
 

It is definitely the rear, because the front rotors and pads were the first thing I changed, and there were no issues at all for like a month or two until I got off my ass and did the did the drums. I can feel the truck shaking through the seat more. Nothing really in the steering. Not too much through the pedal. I've felt warped rotors through the pedal before, not really like that at all.

Re: Brakes are fucked up.
 

your drums are not centered to the hub, as in rotors are drilled wrong.

try rear drums for a 1500gmc shortbed, like a '90. iirc theyre 12" and not offset from the hub face like the longbed/tow package dealys