New Drum Brakes Are Howling

[Sinister]

Didn't have time to do it myself, so took my '69 C-20 in to have the front drums done. New shoes, drums, wheel cylinders and hoses. Mechanic told me I'd probably have to adjust the shoes in a few days. Drove it home, stopped O.K. Next day the front drums are screeching, howling. Adjusted the shoes until there was a slight drag on the drums then backed them off a little bit. Still screeching. Do I need to adjust the shoes out some more?

[Sinister]

Pulled the drums again and readjusted. Still making noise. On the side that's making noise, it looks like the primary shoe is only making contact on the ends of the shoe. Possibly a bad shoe?

[BluTrukker]

Possibly the wrong size shoe, or the wrong size drum? It should make fairly even contact over the whole drum.

[Sinister]

I think it may be a bad primary shoe. Passenger side shoes look fine, don't make noise. Truck doesn't make any noise braking in reverse.

[68gmsee]

Yeah, sounds like bad shoes. Normally the only reason shoes squeel is contamination like oil, brake fluid, etc. or cheap shoes. I've had some that were just cheap materials, some that made a grinding sound (metalic) and others that squeel.

The materials used these days are non asbestos type and vary in quality depending on manufacturer. Your best bet is to buy the best you can afford and replace them. No amoung of adjusting is going to keep them from squeeling whether they became contaminated or not.

[Sinister]

Well, sounds like it's time for some new shoes. Kind of sucks after paying to get em done, now I have to do it anyway.

[Sinister]

Well, just got off the phone with Classic Parts. (Brake parts were a Christmas gift), and they're going to send out a new set of shoes. So that's cool, hopefully I'll just have to swap out the bad shoe and be done with it.

[Sinister]

Update. It occurred to me the drum might be bad on the driver side. Swapped drums from side to side and the noise is gone. Gonna check contact area on the shoe in a couple of days.

[Smallz72project]

Its quite possible that the drum is slightly out of round. What most people dont realize is that even though its a "new" drum or rotor, that alot of the time you have resurface them on a light pass or however many it takes to straighten out. I have seen this happen multiple times as I am a brake technician for a living. Also make sure when you reinstall them that you preload the bearings correctly and evenly side to side. If it still doesnt work, one other thing you can try is to chamfer the top and bottom edges of the shoes.

[Sinister]

Thanks, it seems to be O.K. now. Will keep an eye on it though.

[hayhauler71]

Make sure the primary and secondary shoes are installed on the right side.

[Sinister]

Originally Posted by hayhauler71

Make sure the primary and secondary shoes are installed on the right side.

All good there.