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Please advise about possible solutions for poorly functioning disc brake.

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Please advise about possible solutions for poorly functioning disc brake.

Old 06-09-05, 12:30 AM
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Quad
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Please advise about possible solutions for poorly functioning disc brake.

Hello. I'm new here, and basically only signed on in the hope that someone has a solution for my problem. I'm not a complete neophyte when it comes to bikes, but I don't know much. I have spent hours working on this, to no avail.

I have a RhoadesCar one-seater quadracycle with a Tol-o-matic MB1 Series disc caliper brake. The problem is, I cannot make the brake firm enough without locking up the adjusting barrel in diagram 2 (below). The brake handle does very little, and I can't seem to adjust it so that the handle is firm and supplies sufficient pressure. For instance, the adjusting barrel at the handle (diagram 1) has broken twice now, and it is virtually immobile (cannot be turned, adjusted) because of the slit that runs down its length, i.e., when I try to screw the barrel in or out, the cable snags on the slit, and I end up forcing it to the point that the barrel simply comes apart. Can one buy these without the slit?
I can't imagine that would be the source of the brake's problem though. The handle is not pulling enough on the lever (diagram 2). Ideally, the lever would move from the bottom of its opening in the caliper to the top through the actuation of the brake handle. Instead it only moves a little. I have tried using pliers to pull the cable as tight as possible at the point where it meets the lever, but I don't want to break something. On the other hand, tightening of the cable should be achievable by adjusting both ends of the cable, no? (as seen in both diagrams)
Any advice would be appreciated
Diagram 1

Diagram 2

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Old 06-09-05, 12:38 AM
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Raiyn
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Try this as it sounds like a simple matter of new cable stretch.
Tighten both ends of the cable back into the lever and caliper. Loosen the bolt holding the cable. Using your hand pull the slack out of the cable. Then tighten the fixing bolt agian. This should give you more options. And for crying out loud you've got WAY too much loose cable on that disc brake. Clip it down to where it can't get sucked into the caliper
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Old 06-09-05, 04:11 AM
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I've got a couple of ideas about things that you could try.

The first is that I suspect that your barrel adjuster is bent. You should be able to get a new unbent one from an LBS. Be sure to take your old one in with you because there are a couple of different diameters.

If you still can['t get your brake lever to pull enough cable, I'd try a linear pull brake lever. They pull twice as much cable. Actually, if it were mine, I think that I might skip looking for a barrel adjuster and go right for the new brake lever. If you do that, however, you will have to figure out how to mount it on your flat steering wheel spokes.

Good luck.
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Old 06-09-05, 05:05 AM
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Other than not stopping, how is that thing working for you? Can you get it going pretty fast?
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Old 06-09-05, 05:14 PM
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Thanks very much Raiyn and Retro Grouch. I will give your ideas a try. I don't think it is related to the tautness of the cable, however, as I have pulled it as tight as I can. Grouch, when you say barrel adjuster, you mean the one up by the handle, right? It is broken. One of my main problems is that I can't make adjustments with it because of the damned slit that gets caught on the cable.

Expatriate: Actually, because of the weak brakes, which have been a problem since I got the thing in '97, I have been too discouraged to use it much. It's very comfortable (with the marine seat) and easy to ride (with 36 gears) on any terrain, but it's difficult to ride at high speeds because of the instability.
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Old 06-10-05, 01:45 AM
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Interesting. Time to think outside of the box. Make sure there's not some funky business going on with the cable housing where it's compressing. Check the mount of the brake caliper to make sure it's rock steady. Check the pads, and maybe even scuff up that brake disc with some fine sandpaper (circular motions). It's a pretty simple mechanism, so there's only a few things that can go wrong.
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Old 06-11-05, 08:27 PM
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Will do. Thanks.
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