Ford F-150 - 1997-2003 :: Violent Chattering From Rear Axle With Either Light Or Normal Braking

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.