Best way to break in brakes?

[kxnomore]

Just re-did the rear wheel brakes, bearings, and turned the hubs/ drums on my 71k20 rear brakes. It has the Eaton 14 bolt deal with the 12 X 2 shoes.

Long story but the bearings were very dry and when I tried to press them out to grease them they powdered apart on my bench. After 3 tries at various parts stores, we finally got the correct parts and things are looking much better.

the problem is the brakes now feel weak and the parking brake no longer holds even though it's adjusted very tightly. I put in all new shoes and wheel cylinders and Napa turned the drums. The shoes were adjusted to just barely scrape the drum, but now that the axles are in it's hard to tell exactly what's going on.

could it be that the shoes need to be broken in somehow? maybe they are not meeting with the drum correctly?

Any help would be greatly appreciated. Thanks!

[estig70]

Originally Posted by kxnomore

Just re-did the rear wheel brakes, bearings, and turned the hubs/ drums on my 71k20 rear brakes. It has the Eaton 14 bolt deal with the 12 X 2 shoes.

Long story but the bearings were very dry and when I tried to press them out to grease them they powdered apart on my bench. After 3 tries at various parts stores, we finally got the correct parts and things are looking much better.

the problem is the brakes now feel weak and the parking brake no longer holds even though it's adjusted very tightly. I put in all new shoes and wheel cylinders and Napa turned the drums. The shoes were adjusted to just barely scrape the drum, but now that the axles are in it's hard to tell exactly what's going on.

could it be that the shoes need to be broken in somehow? maybe they are not meeting with the drum correctly?

Any help would be greatly appreciated. Thanks!

what does the pedal feel like (soft)??? you mentioned replacing wheel cylinders, may have air in the system still.

Eric

[woodridge]

Did you measure the drums for being oversize? Every time a drum is turned the radius changes but the shoes are ground for the original nominal size. If the drums are close to, at or above max diameter then the shoes are not going to have proper contact to the drum and will not hold. Driving and using the brakes is one way to "wear" them in. If your drums are still in tolerance,another and better option would be to find a brake shop that has a shoe grinder and have your shoe re-arched to fit your drums, doing this you have almost perfect brakes the first time you use them.

[kxnomore]

Originally Posted by woodridge

Did you measure the drums for being oversize? Every time a drum is turned the radius changes but the shoes are ground for the original nominal size. If the drums are close to, at or above max diameter then the shoes are not going to have proper contact to the drum and will not hold. Driving and using the brakes is one way to "wear" them in. If your drums are still in tolerance,another and better option would be to find a brake shop that has a shoe grinder and have your shoe re-arched to fit your drums, doing this you have almost perfect brakes the first time you use them.

Thanks Woodridge,
That sounds like what it could be, because the machine shop said the drums were close to being maxed out. Plus the pedal feels pretty firm, or at least as good as it used to be.
I'll drag the brakes around for a while (couple of weeks if need be) while being careful not to overheat them, and see if that works. I bet that's it, because even if there was air in the line, the parking brake would still work I would think?
Thanks again!!

[Robert1970C20rstbukt]

I had the same problem, brakes felt weak and was hard to get the truck stopped. Turned out the shoes needed to be adjusted out farther for more drag, then they wore in at the end of the day and adjusted themselves.

[estig70]

because even if there was air in the line, the parking brake would still work I would think?


very true, just a thought. good luck!!!

Eric

[cooters]

Robert is right, if the e brake doesnt hold then you need to adjust star wheel on back brakes. The shoes will wear to match the contour of the drum within moments