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Paging bicyclerepairman : coasterbrake discussion ...(4 posts)

Paging bicyclerepairman : coasterbrake discussion ...Humma Hah
Sep 4, 2003 2:21 PM
Hey, bicyclerepairman, I just noticed you asked a question about my Bendix coasterbrake failure, but I missed it because it scrolled off General.

I had mentioned that the hub failed by way of the flanges slipping on the hub, and you had a question about brake pad wear on the hub. I was a little confused by the question, but would love to chat about it.

The inside of the hub, where the shoes act, is in pretty good shape, only lightly scored. The hub is presently running a 4-shoe set (the Bendix 98 innards), although it was originally a Mexico-built Bendix 70, with two shoes. It has had 3 shoe sets in its life, and has been overheated by long downhill breaking maybe a dozen times it its life (I know exactly how the Repack downhill on Mt. Tam got its name). The original clutch parts had started to crumble, too, and I originally thought they were responsible for the occasional slippage that finally turned out to be the flanges. Despite the abuse, the hub is in good shape.

I re-spoked the rear wheel with 4 mm spokes back in the 70's, when the abuse of mountainbikeing and BMXing it proved too much for the originals. I bought a similarly-spoked ruggedized wheel from Schwinn for the front: either the Crested Butte MTBers or the cruiser-class BMXers created enough demand for ruggedized parts that Schwinn actually built them. Anyway, the flanges were slightly drilled out to accomodate these spokes, and experienced some mighty loads in their time.

The flanges appear to be pressed on to the hub, probably against serrations. I believe the serrations have simply worn out. I'm hoping I can re-couple the flanges to the hubs by drilling small holes along the interface and inserting stainless steel rivets or screws to provide the needed mechanical interface.
I was curious about 'drum' wear, since I've never openedbicyclerepairman
Sep 4, 2003 10:56 PM
one up with that many miles on one. Too bad about the flanges...I wouldn't risk re-attaching them. Consider retiring that hub from road use, and...oh, I don't know, maybe making a pepper grinder out of it. Something to give it new life, out of respect for its having hung in there all these years. BTW, the last coaster brake hub I worked on was a SunTour...well made, but it weighed a ton...
I wonder how many of 'em have EVER ...Humma Hah
Sep 5, 2003 9:35 AM
... had that mileage on them. I'm totally amazed at how hard and tough the drum metal is. They must have machined the thing with diamonds. One of the bearing cups is a little chipped on the edges where I dropped it once, but otherwise you could look at the thing and conclude it was barely used. I've worn out a couple of sets of bearing cups on it.

Trying to control speed on a descent of 500 ft or more causes the grease to liquify, and the result is a banshee screech that makes you sure the guts will be galled to heck, but subsequent disassembly has never revealed anything worse than some wear on the steel shoes. I finally found a rear V-brake adapter that made use of the coasterbrake unnecessary, to avoid this problem in the California hills.

I'm not planning on heavy use of it once gotten running again, but do consider the wheel a bit "historical". It has an S-7 rim, matches the front S-7, and I have a set of original-type Westwind tires for it. That's how I rode it while developing it into a mountainbike before the term existed. The bike is very likely the only prototype MTB still in daily use, and I want to preserve as much of the early running gear as possible.

For daily use, though, a set of wheels that are round and which I can easily get tires for are MUCH more practical.
Just think....that pepper grinder would last ...forever....bicyclerepairman
Sep 5, 2003 12:12 PM
You could leave it to someone in your will!