DMF 

Suntour XC roller cam rear brakes. In each mounting post there is a captive spring that retracts the arm against the cam. The spring tension is set by a post cap that looks like a hub cone and is adjusted with a cone wrench. How much tension should be on the spring? 1/8 turn? 1/4 turn? Best guess?


Know of a set of instructions for setting these up?

One problem I have is spreading the arms to remove the rear wheel. There's no release per se. At the top of the cam there are detents for the rollers to drop into, opening the arms wider than the normal ramp. But if I set the shoes to clear the tire when the rollers are in the detents, there's not enough travel from the brake levers to close the shoes to the rim. Tires are 26x1.95. Are they that much wider than original tires on 1985 mountain bikes?

carpediemracing 

tension - probably as much as possible. Make one pretty tight (so it clacks into place when you pull it off the rim and let go) and then use the other arm's adjuster to center the two arms.

QR - what you need to do is squeeze the pads together so the rollers separate. Then pull the cam thing out from between them. Not really clean but that's how it was meant to work. So adjust so the pads are pretty close but leave enough room that you can squeeze the pads enough to get some room at the rollers.

hope this helps
cdr

DMF 

Yes, it does. Thanks.

Ironically, I've done that for adjusting. Didn't make the connection. So I guess the detents fulfill two roles. Semi-clever design.