Is there a wear indicator on 68 drum brake shoes? If not, how do you tell when the shoes need to be replaced?

 

No, shoes don't come with indicators. You tell they are ready to replace simply by looking at them. You can run them down to paper thin if you want but, I would change them when they get down to about 2/32 usable lining left. "Usable" means before they get to the shoes if they are bonded linings, or before they get down to the rivits if they are riveted. Once you get into the metal, they tear the drums up real quick.

I like to "monitor" mine and check them every time I change oil. That way you get to know how much longer you can go on what is left.

 

Thanks. I have one drum that has some deep grooves in it, so I'm assuming that someone let the shoes wear down too far. Probably not good to just replace the shoes without replacing the drum. Is it better to replace the drum or can it be smoothed out and re-used?

 

You can take them down & have them turned but if theres deep grooves there may not be enough material left to cut. All you can do is try . I'm not sure how available those drums are new but I know newr models aren't that expensive. Good Luck

Rik

 

Thanks. I priced drums on NPD and they're about $52 each.

 

Check locally first. I think I paid about that much from local auto parts supplier. You'll save on shipping and the wait time.

 

Yeah, Napa can get drums for most of these cars without much problem.

 

what's the difference between riveted and bonded shoes?

 

Yes, back in the day, brake inspection included removing one front and one rear drum in order to monitor lining thickness. It's a pain, but it beats letting them get to the point that ruins a drum or two, which is what you are dealing with now.

Turn the drums if they can be cleaned up and still be within specifications. If not, don't take a chance. The loss of mass due to turning them too thin drastically reduces the effectiveness of your drum brakes. When they get too thin their capacity to hold heat is reduced to a dangerous level.

Bonded shoes have the linings basically glued onto the shoes. Riveted linings are attached with brass rivets. Over the years I have seen a few bonded linings come loose. When this happens it can wrap around and wedge itself in place LOCKING that wheel. A VERY dangerous situation. This is a RARE occurrence, but I've seen it with my own eyes and it's not pretty.

Riveted shoes are typically of higher quality in general, plus the chance of bonding failure is eliminated.

In the old days, the best drum brakes you could have were custom made by the local reliner. Have them rivet in place three small sections of lining material with about 3/8 or 1/2 inch distance between the sections. This makes a shoe that dissipates its heat much better. Brake feel as well as capacity is improved. Today, I don't know where you could find anyone who still has lining and riveting equipment to do this, but they might be out there.

The other improvement for drum brakes is Tru Arcing the shoes to fit the drums. We used a Tru Arc machine to grind the correct arch in the shoe so that it fit the drum exactly which gave you brakes instantly without the need for the shoes to wear into the drum. This also eliminated the negative effects to the lining material that are incurred during such break in.

When you put them back together, make sure you get the self adjusters back in correctly and in good order. You can then back it up, brake hard and let it roll forward to adjust the brakes instead of getting out and getting under.

 

Bonded shoes were factory equipment as far back as the 50's. I have never seen or heard directly of a bonded shoe failure, even as a kid I remember my Dad would use nothing else. I have seen many, many drums destroyed by the rivets on riveted shoes. They will do this without any squeaks or other symptoms. Back around 1970 a shop I frequented for repair had a brake drum lathe had a shoe grinder to match the new shoes to the precise curvature of the newly cut drum. This machine was old at the time. I remember there was no dust protection on this shoe grinder. Did a good job, though, there was virtually no break-in time at all on brakes done on this machine.