Rear Drum Brakes vehicle shake/shudder/vibration?

Been trying to diagnose this vibe/shrudder for a few months and want to address it when I rotate my tires next month.

Tires are new, so wheel balance is ruled out. Bearings are quiet while coasting (no cabin hum). Propeller shaft vibe is ruled out because I super-greased all 5 zerks them in Dec, and the vibe doesn't occur during any acceleration at any speeds. I've somewhat ruled out the Drivers side Front Needle bearing - my front right drive axel is loose by like 1/8" like everyone else's, but putting the truck into 4WD then braking still causes the same problem below.

The shudder, which is more like a total-vehicle-pulse in sync with each wheel turn, only occurs during braking. My seat feels like someone gently kicking the back of your seat in a theater, over and over, while braking. I replaced the front brakes (TRD and Brembo) and caliper pins just 7 months ago, broke them in - and I think doing that hard break-in process may have caused a warp in the rear drums. I didn't service or do anything for the rear brakes due to time (lots of time wasted on those fused-in front caliper pins!).

Has anyone experienced the shudder symptoms above while braking? If I take the rear drums off, what should I be looking for on the braking surface? A run-out or uneven surfaces on the drum, unevenness on the shoes? Help is always appreciated and thanks in advance !

 

Sounds like a brake drum out of round, take the drums to a parts store or machine shop and have the run out measured, let them cut the drums if they are still below maximum diameter, slap a set of shoes on (I find the cheapest organic shoes are best) and lubricate all the shoe rub points on the backing plate, install drums, adjust the shoes and be DUN with it.

 

Thanks! So you think its the drums that are out of round. And get them re-machined, replace the shoes, do a clean up and lube up, and done.

 

Hey Matt, did replacing your drums fix your vibration issue?

 

What about warped front rotors? Mine had a shake while braking around 100k and replacing the rotors solved it.