? Replacing electric brakes

[jimcol]

I have 46k miles on the original brakes. I purchased new self adjusting brake assemblies from Dexter. Several people who know brakes suggest when I install the new brakes I should change the drums as the facing the magnet rides on is no longer true. Their thought is I could eat up a fourth of the new magnet as it seats into the non true facing. New drums appear about as cheap as having old drums turned for both shoe and magnet facings. Your thoughts appreciated. Jim

[Ozz]

Jim, my 2 Cents on this would be to get new drums if the cost is close, the person doing the machining could leave turning grooves if they don't do it right: (as a machinist in the Navy repairing boats at the New London Sub base)
The new drums would be pristine as far as that goes.

[jimcol]

Thanks Oz. That is exactly what the people at Croft were telling me. I know you are very familiar with them and hold them them in pretty high regard. Jim

[dieselguy]

I'm going to respectfully disagree in part here. If the surface the shoes ride on is deeply grooved or you believe it to be out of round ... I'd have them turned. If you are worried about where the magnets rub only, I've never seen this surface to be an issue. Magnets are a metal on metal operation ... they're going to look scuffed ... that's the design new or old. You have 46K on them now ... are the magnets worn down to nothing? Probably not. Admittedly not on my TV, but I've done several trailer brake replacements including my own by just scuffing the inner surface with a dotco and 180 pad to assist in the burnishing of the new shoes and reassembling. I've had the drums off since with no unusual wear to the magnets shown and the brakes have performed fine. One thing I would recommend even on new brake assys ... place a SMALL dab of antiseize or wheel bearing grease on each of the 3 mounting pads on the backing plates where the shoes rest aaginst. At about $85 each plus shipping, I'd really look your situation over. A reputable brake shop might be worth a try as turning drums around here is nowhere near $85+ each.

[Tom S.]

Ah, the stories I could tell about brake drums, including have to remove them with a cutting torch!

Turning them is ok provided the person doing the turning is qualified. I've had drums ruined by people who shouldn't have been allowed near the machine. There are things to watch for. Drums have a maximum inside dimension they can be turned to. Going beyond this dimension puts you at risk of premature brake failure due to the drums getting hot and warping or cracking. Additionally, turned drums will wear the leading edges of the shoes faster than a new drum because the larger diameter affects the surface bearing geometry. How much this can affect the life of your new shoes depends on how much the drums had removed and the surface of the drum after turning.

The good news is new drums are very cheap. The bad news is they are made in China. Most of the replacement drums and rotors I've seen have been OK, but there have been a few clunkers in there that were crap and didn't last long. My personal preference is to replace the drums/rotors when doing brakes if the old ones are worn badly or grooved. If the surfaces are clean and smooth, and the old shoes/pads show no uneven wear, I've even left them alone and just replaced the pads/shoes.

[jimcol]

Thanks for all the input. It will be awhile before I need to make a decision as the tech packing the bearings said 60% of original shoes still there. I had no idea brakes shoes would last this long as many of our miles have been mountain driving. Jim

[Phil P]

Hi

I changed my brake shoes at about 40,000 miles. Didn’t do anything to the drums. They were round and evenly worn and by a drum gage had less than 5 thousands wear.

The event that caused me to do a brake job was one of the arms the magnet is on rusted at the pivot and caused the brake to drag. So I did all the brakes. Make sure and lubricate that pivot with something like AntiSeize to keep them from rusting. NAPA sells this in a tube like tooth paste and it makes it easy to use and store.

By the way you can purchase the units you are going to install for very little more than the shoes cost.

I prefer to adjust my brakes myself so I didn’t purchase the self adjusters.

Phil P