Truck is a '99 2WD with drum rear brakes. 81K miles.

I rebuilt the rear brakes due to a leaking wheel cylinder. The old shoes were not completely gone, but were worn evenly - everything looked normal.

Not a professional wrench, but I've been re-doing my own drum brakes since the '60's, so it is not rocket science to me. Still, as a precaution, I did them one side at a time so as to have reference point, and also snapped a few cellphone pics just to be safe.

Replaced both wheel cylinders, all hardware, and of course the shoes. Gravity bled the cylinders first, followed by the old tried-and-true, wife in the driver's seat, "down-and-hold, now up" routine. Adjusted shoes to just contact drums lightly, and buttoned it up.

The problem is that I'm getting a violent chattering from the rear axle with either light or normal braking. The chattering is worse as the brakes warm up - shakes the whole truck. At first I thought I had a bad rear ABS sensor, but then I did a couple of stops just using the parking brake, and got the same chattering.

Now I've pulled the drums off to re-check. There is nothing loose, nothing out of place, nothing leaking, but there was a heck of a lot of brake dust in there and the lead shoes on both sides were noticeably more worn than the trailing shoes - and I've driven maybe 100 miles since the rebuild.

You can't reverse these shoes, since the trailing shoe has a peg to hold the automatic adjuster, so that is not the issue. The drums were turned less than 1000 miles ago, so I did not have them re-done at this point.

I had my "assistant" partly depress the brake pedal while I had the drums off to confirm that the cylinders were expanding both shoes, and they are.

I'm stumped! Any ideas??

 

Stare at it long and hard.
You put something together wrong.
Good luck.

 

Mine had that bad shake after a brake job also. Drove me crazy rechecking everything. Finally replaced the axle bearings and that solved it. Made no sense to me because it was fine before I did brakes. I even took the new drums back and all the shoes and did it over....nothing helped. My seals did not even leak. I did replace one axle at the same time because it was flaking under the bearing. Hope you figure it out.

 

Spotty, that's very interesting. The thing is, ever since I've owned this truck (13 years or so) it has had a slight pulsation in the brakes at lower speeds, from the rear (replaced the front rotors and it made no difference), and I've always wondered if there was a problem with the rear axles - or maybe the bearings?

I'll look into this - thanks!

 

You sure are having more than your share of problems with drum brakes!

81k miles wouldn't be very many miles to have rear wheel bearing problems.

Some/most brake shoes these days come with their leading and trailing edges chamfered. I have always taken a sanding block with some rough sandpaper on it and chamfered them myself if they didn't. Otherwise you could get chattering problems as the shoes rotate with the drum against the anchor pin, the leading edge can tend to dig in to the drum's surface.

Beyond that, I'd be looking at parts and assembly as bluegrass suggests.

To each his own, but I won't mess with turning brake drums anymore. If there was an out-of-round chattering problem with them, and they were turned-down to cure it, they are thinner and more likely to deform under braking. I went the same way with brake rotors, too. Thinner after turn-down means less heat transfer and heat resistance, and they seem to warp or cause problems again.

I turned the front rotors on my F-150 @22k miles due to chattering, the pulsing came back pretty quick after towing. Replaced them, no problems since.

 

Maybe that was a leaking axle seal rather than a wheel cylinder? Ive seen MANY leaking axle seals on these and cant recall a leaking wheel cylinder in years. Just a thought

 

Torky2, you're right, these have been something of a headache for a long time. Since I bought the truck from the original owner when it was 1 year old, I got all repair documents, and the dealer had even re-done the rear brakes under warranty, but I don't know what the complaint was. I also had your experience with the fronts and finally put on new cross-drilled rotors - no warpage since then.

Chamfer, or lack thereof, was one of my first ideas as well, before I pulled the drums again, but all ends on these shoes are chamfered as they should be. And, triple-checked the assembly, made sure the assembly wasn't binding on the backing plate, and even watched a professionally-produced YouTube video of rebuilding a similar year's drum brakes, just to be certain I didn't miss some odd detail.

Yesterday, I ordered a new pair of drums from RockAuto, so I will see if that is the cure. Don't like to throw parts at a problem, but it seems that this is the next logical step. If this doesn't do it, I plan to replace the shoes with a different brand.

Axle bearing problem is doubtful as well. I've since checked the axles for movement - nothing unusual found. I also put a dial indicator on both axle flanges to see if one or both was off-center, and they were both within 0.005" run-out.

The strange thing is that both sides are having the same problem - it isn't just something occurring on one assembly. So, it is possible that it is the material in the new shoes, or they could be out of spec (what?? Chinese brake shoes, out of spec?? how could that be? )

Thanks to all for the great suggestions! I'll report back.

 

No, definitely the wheel cylinder. Left a puddle of brake fluid on my driveway, and it was leaking out of the backing plate above the axle.

 

New drums installed, driven +/- 200 mi. since, and the problem seems to have disappeared. Apparently the rear drums were messed up in some way and have been fora long time. Turning them did no good - as I originally stated, I'd had the old ones turned about 1K miles before the brake job. Interestingly, the new drums are AC Delco (!!!) so apparently GM can make better drums than Ford??

Thanks again for all the suggestions!