Hey everyone. It's been awhile since I've been on here, not that anyone probably noticed lol. Anyways, I've got an issue I think with my rear drum brakes. Whenever i slow down from highway speeds applying my brakes, it feels like my rear end starts to shudder. Like the pads are grabbing, then not grabbing really quick. It also feels like maybe the drum is out of round, but I got new drums, had them turned, new shoe hardware, cylinders, the whole nine yards. I can't for the life of me figure out why it does this. When I get below 35ish mph it goes away, it's just braking from faster speeds really. It's even had a suspension check and everything is tight. Can there be something I'm missing?

 

Any issue with the anti lock brakes?

 

No issue I'm aware of. No ABS light on in the cab. I think it's only 2 wheel abs. Don't know if the two wheels that do it are in the front or rear. Either way, the ABS on these old trucks have a lot to be desired.

 

If you have 2 wheel ABS it works off a sensor on your rear differential. Have someone follow you and watch the rear wheels. I spent a week working on a customers car once and couldn't find the problem. I had one of the guys drive it while I followed. Then I noticed one wheel wobbling. It had a bent axle but you didn't notice it unless you were watching it.

 

Have you check the rear brakes, to see what kind of condition they are in? When mine was doing that, it's because the shoes were worn down to the rivets......

 

Is that regardless how hard you brake ? Or how much weight is in the bed ? Does it feel the same when you slightly apply the parking brake ?

 

Mine did that too. It was a warped brake drum. I am an experienced mechanic. I took the drums off , and went through it with a fine tooth micrometers. They looked fine. I bought one drum, and it got a little better ... I bought 2 , and it disappeared. The problems seemed to have started when I let someone else drive it . They said it was a really sluggish truck. Then it dawned on me !!?? The idiot somehow left the E- brake on !!! Might as well change the axle seals while you're down there if its old

 

Sorry guys, been without a computer for a couple days.

I had my wife drive it while I followed and to my naked eye it looked just fine. I even put all 4 wheels in the air on jack stands and inspected them while it was set on cruise at 45. That's pretty nerve racking I'll tell you what. Note, the brakes work real well and quick when there's no weight on them....

Yeah, like I said, everything was new and everything looks new still.

When I brake hard, like from 60 I'll hit the brakes hard to stop vs progressively harder it actually seems to be better, but still slightly feels like it's shuddering.

Oh boy I'd hate to open up a can of worms if it's not broken with the axles seals.

Could there be air in the wheel cylinders causing this? They were bled, but maybe some air got in there?

 

Air in the lines would give you a spongy pedal. If the pedal feels good, I wouldn't worry about that. They *may* just be breaking in. Might try a couple hard stops from 45 mph, and see if they don't improve. (after letting them cool)

 

I wonder if we're over thinking this. If you have, or can get, a dial indicator gauge, put the truck on stands and remove the rear wheels and drums. Clean the drums really well with brake cleaner. You could have a spot of gooky stuff (<---fancy technical term) like a small spot of brake fluid. Bolt the drum on inside out so the brake surface is out. Set a dial indicator up and rotate the drum by hand. Look to see how much run out shows. Something simple like cleaning or a VERY light dressing will stop the shudder.

You aren't letting the truck watch horror movies in the garage are you? It might be shuddering from fear.