Having some issues with my drum brakes was hoping I could get some help with.

I blew a wheel cylinder and opted to replace the shoes, drums, bearing, axle seal and hardware a while back. Once I got a few thousand miles on the new brakes it developed a loud squeek when the wheel rotated to a certain postion (as if there was a high spot). I cleaned, greased, and readjusted and the problem went away and has now returned again. This time there is some visual uneven wear on the shoes that doesn't look right.

Initially, I thought maybe a warped drum but I mic'd the drum and found no anomalies. I brought the truck into a shop to get a second opinion and was told my backing plate was bent and someone had likely left the Ebrake on and driven the truck. I opted to go with a Ford replacement backing plate rather than screw around with trying to straighten and weld / grind the old pads on the old backing plate. The old backing plate has some serious wear on the bottom right pad where the shoe rests.

I got the new backing plate installed and have noticed that there is still a slight alignment issue between the outer lip of the backing plate and the outer lip of the drum. The top measurement shows an extra thou' clearance compared to the bottom. I rotated the wheel to several positions, and the measurement remains the same at each, so that rules out a warped drum or bent axle. I cleaned the snot out of the axle hub and applied anti-seize before installing the new backing plate so there is no rust affecting how the backing plate is installed- Not that there was much rust to begin with.

So now my question is, is 0.1000 " difference in runout between the top and bottom of the drum to backing plate clearance enough to be concerned about? Is shimming the backing plate to square it up with the drum the correct method to correct this? Anyone seen or dealt with anything similar?


Top drum ext. lip- plate clearance: 0.6000"
Bot drum ext. lip - plate clearance: 0.5000"

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0.1000" is not a thou .... it's one tenth which is 100 thousandths.

0.6000 - 0.5000 is 0.1000, that is fact.

A thousandth is 0.001"

You have a new backing plate, there have been no impacts to bend the axle housing or flange where backing plate fastens. Back in the old days shops often ground brake shoes to fit better to the drum .... now you wear them in. 1/10th of an inch top to bottom difference in brake drum flange to backing plate would not cause me any great concern. I'ld double check my assembly of shoes and springs, apply a dab of brake grease where the shoes ride against the backing plate as designed, install new hold down hardware maybe .... adjust up and drive.

 

Have you thought about using spacers on the bolts that attach the backing plates to get the alignment correct?