Originally Posted by
AlanHK
I got a mountain bike from a neighbour, who obviously hadn't maintained it.
I've never used disc brakes, which this has. They're Promax, can't tell more than that, The only thing that might be a model number is "4C" or 4G" near a mounting bolt.
The rotor has "LZ" and "160" on it.
Looked on their website, they only have info about current models, no mention or info of older models.
So just winging it on generic info.
I cleaned them up and the cables are good. They pads made good contact when stationary, but when I gave it a ride, they were very weak, would be unsafe on the road or any hill.
I wiggled the pads out and had a look. They were pretty rusty, but the pads are 2mm thick.
When I did that though, there was also a small magnetic button I found loose, just one, no idea if it's a loose part of the brake, if so, where it should go (which I why I'd really like to find the manual).
(See photo with two pads and the button.)
The button fits very loosely in the hole in the back. But again, only one-- on the wheel side.
So, can anyone advise: do I need new pads? How do I adjust them? And what about the magnet?
Honestly, I don't know that they
ever had a manual. Some OEM company may have had manuals for them but I doubt the manual was ever in wide circulation.
I can't offer any advice on the pads as I've never changed one. But I have adjusted them and are kind of a pain to adjust compared to other discs. In your first picture, that large silver disc is an Allen bolt that is used to adjust the inboard fixed pad. You screw it in until it just clears the rotor. Like most mechanical discs, the inner pad is stationary and the mobile pad (the outer one) pushes the rotor into the stationary pad.
To adjust the outer pad, you'll probably have to pull up the cable tighter. I would screw out the adjustment barrel on the brake and/or the lever (I would probably do both), then pull up the cable so that the brake is locked but not too tight. Then back out the cable adjusters until the outer (mobile) pad just clears the rotor. That should improve the braking.
I also agree bout replacing the bolts on the rotor.
For the magnet on the pad, I'd put a touch of silicon caulk on the back of the magnet against the caliper. That should keep it in place. It might be tricky getting it in there but it would be worth it to not lose the magnet during a pad change.