rear brake vibrations

I've been troubleshooting an ongoing issue with my 2002 Toyota Tacoma Limited Double Cab 3.4L 4x4 automatic. The problem seems to be a persistent vibration that feels similar to ABS activation.

Initially, I replaced both rear axle seals due to a leak on one side. I then installed new brake drums (from NAPA), but the vibration persisted. Next, I replaced the brake shoes—still no improvement. I decided to go further and installed brand-new PowerStop drums, pads, and hardware. The original hardware appeared to be in good condition, but I replaced it anyway. I also applied high-temperature brake grease to all six contact points per side and lubricated the slack adjuster.

Despite all of this, the vibration is still present. It feels like a pulsing or ABS-like feedback, and it occurs while driving. I have relatively new Continental tires, so I’ve ruled them out as the source. I’ve narrowed the issue down to the rear brakes by pulling the emergency brake while coasting at various speeds—the vibration remains exactly the same. This leads me to believe the issue isn’t hydraulic, though I’ve ordered a new proportioning valve as a precaution (not yet installed).

I'm fairly confident the rear wheel bearings aren't the problem, but I'm running out of ideas. Any insight or suggestions would be greatly appreciated.

 

If those napa drums have the warrantee on them, swap 'em out for new ones. I would also consider leaving the rear shoes under adjusted at first, and slowly work the rear brakes into adjustment over time. IMO it's possible to over adjust them which would result the drums warping quickly.

The other thing to consider, is that vibrations easily travel, and you should be looking at the entire rear drive line.

 

https://www.tacomaworld.com/threads/am-brake-drums…-every-manufacturer.859335/

 

Meh
I wouldn’t believe it if
#1- read it here
#2- dealt with it on my neighbors Silverado


If u search, the going theory is
Drums stored vertically at warehouse/store shelves. After a period of time….warps the drum

as Andy stated, take them back to NAPA

Neighbor and I tested the ‘theory’ by putting the old worn drums back on
Vibration/Shudder disappeared….like a fart in the wind

 

BTW
neighbor had to spend $30 a side to have the new drums turned
He had parts too long, and couldn’t return them
Freakin BS

 

Make sure your driveshaft is well lubed--do it twice. I had persistent vibes (very severe while braking) that would not go away even after several "warped" drum changes. It finally stopped after I got serious with a grease gun and pumped all the dry crud out of the slip joint in the driveshaft.

 

While you might have gotten a result this way, it's actually worse to pump the slip joint "full". You should actually clean all that grease out of there and just apply a decent amount of grease to splines. Having the whole cavity full has been proven to hydro-lock (of sorts) the slip joint in place and make vibrations worse. It's a known flaw in the design.

 

Agreed. It wasn't left totally full of grease, I had to disconnect it from the axle and work it back and forth. The point is that a few pumps of grease won't cut it and they can almost freeze up over time.

 

“It’s crazy that the drums could warp just from sitting, but I guess that makes sense. I already backed off the slack adjusters so the drums were completely free-spinning, and the vibration was still there. So I guess the next step is to have them turned. What a headache. While that’s happening, I’ll go ahead and grease all my zerk fittings. Thanks for all the responses!”

 

I'm not sure having the drum turned will solve your problem, as it's more of an issue with the entire drum being out of round / out of balance.

 

What about the wheel cylinders? I also have a vibration during braking, mostly when going downhill that I believe is from a defective wheel cylinder on the drivers side. It has a slight leak and only pushes out one of the shoes. I’ll check back in this weekend after I do the repair.