Brake pedal pulsing after changing rear brakes

Hey, it seems like this is an issue for many people across all generations but I can't really find my exact scenario or a good answer. I just replaced rear shoes, drums, hardware, proportional valve, and bled all brakes. After finishing up the job and driving the truck on the highway to work I now get an aggressive pulse in the brake pedal and at times makes the truck feel like it's hopping. I would think it's bad front rotors but why would they now be acting up after servicing the rear? Could a bad bleed job be the culprit? Any input or ideas would be appreciated. Thanks

 

So it started after the the Rear Brake job?

 

Correct, which is why it seems like too much of a coincidence for it to just be the front rotors.

 

What kind of parts did you use?

 

Got a powerstop kit with everything for rears

 

Sounds like the rear drums are out of round...

 

How does one go about rounding them?

 

Any shop that has a Lathe can fix you up...
https://youtu.be/JbP1BNTdYbE?si=6BobwIZ719sVdH7U

 

Thank you the input, didn't know warped drums were a thing. I may try to warranty them first as I only ordered the kit 2 weeks ago. If all else fails I'll go the lathe route.

 

Might not be that serious -- maybe a blob of grease made its way to the drum and its doing a slip-grab-slip-grab-slip-grab.

 

Many, many years ago I was an apprentice mechanic and did a lot of brake jobs.
Anytime I replaced drums or rotors I would machine them first taking off just enough material to ensure they were straight and round.
I was fortunate enough to work with a mechanic that taught me the most thorough method of doing any repairs then would show me some shortcuts without compromising quality.

 

Thanks for the suggestions. Powerstop is sending me a new drum, hopefully a round one. When I pull the current one off I'll check for grease. Worst case I'll bring it to a shop to be lathed if a new one doesn't help.

 

Yeah
There’s a thread somewhere

member had same issue with rear drum brake job

Multiple members said that drums sitting so long on auto part store’s shelves….stored upright, would warp the drum

honestly, i thought BS

the OP returned the drums and got new ones……issue went away

I was amazed
TG I didn’t post what I thought and just listened/followed thread till the end!

 

Forgot to update this last week. Powerstop sent new drums and I swapped them but still have the pulsing brake pedal. I'm assuming it must be the front rotors at this point, which makes sense as I've been driving with exclusively front brakes for awhile just odd that the problem surfaced when doing rear brake work. Maybe the brake bleed made it noticeable. I'll report back after changing the rotors this weekend.

 

Good luck. It’s easy to check the fronts if you can get your hands on a dial indicator

 

Swapped front pads and rotors for new ones and still get the pulsation in the brake pedal. It's unnoticeable when first pulling out of the driveway and driving around the neighborhood, but gets bad when picking up speed on main roads/highways. If I have to drastically slow down on the highway it feels like the truck is hopping. I've messed with the load sensing valve and deducted that it's not the rear brakes and changed the fronts so it's not that either. Could air in the lines cause this? Bleeding the brakes is the only thing I can think of.

 

Next time driving and there is no one behind you twist the parking brake lever and slowly pull it out, dont let the ratchet lock it in place, this actuates the rear shoes only, if you feel the pulsations it is in the back. Auto parts are in a very bad state ATM, most of the stuff, even new, is bad out of the box. Take the drums and see if your local o reillys can chuck them up in their brake lathe just to see IF they are out of round. The next thing is to see just how they sit on the axle flange, If you can slide it up and down that isnt good. There is a lip on the drum that self centers on the axle flange, if this does not self center thats a problem.

 

I think the rears are not actually the issue. I figured the drums weren't round so I changed them out, still have the issue. I also have the load sensing valve set so that almost all braking is to the front and still have the pulse. I'm thinking maybe there's air in the lines, just curious if this could be a symptom of that.

 

Air shows as a soft pedal