Tech Tips

Mechanical Brake Maintenance and Repair

If you want to pick up that lovely, you gotta be able to stop. You know very well that if you can’t stop that sled, it’s a bitch to pick up a chick, or there went that tavern we were going to stop at. So a few brake basics will help the ol’ scoot outta the oak tree at the end of the block.

     First, before we get to repair, here are a few rushes on how to make your brakes work better and longer. If you run any kind of quick throttle or custom throttle’ the positing of the hand lever and throttle body can make quite a difference. The proper front lever clearance is a must. If the rear brake ever goes to lunch, the whole world depends on the front stopper. So loosen and swivel the throttle around so it is as much out of the way of the brake lever as possible. Then adjust the brake so that the lever is fully released, there is at least some slack between lever arm and the body (1), and when it is pulled in, the full force of the brake can be applied before the lever bottoms out on the chrome throttle body.
     It’s not too likely, but the smaller cables can corrode or wear out, so if a broken wire is spotted the cable should be replaced. When cables are first installed, they should be greased, but it’s almost more important to hit them with oil or grease every so often after there in use - makes then last longer. Last but not least in the cable department is the position. If the cable is run in other than gradual curves, the rider squeezing the lever for his life is fighting more than friction and springs in the drum

     The linkage for rear mechanicals (2) should be checked once in a while for similar problems. The brake pedal itself should be greased on the shaft where it rides, and the axle should be checked for looseness now and then. If that pedal axle stud is loose, it can bind the pedal or simply break off—bummer. So have the stud rewelded from the back before it gives you any trouble. The front brake rod takes little or no maintence, but the clevises and rod should be checked for stripping. If it looks as though either is losing a few threads, either brace them up or get a new one before they snap. And last, but almost more important every six months replace the cotter keys that hold on the clevis pins and be sure the washers are there. The brake cross over shaft should be checked once in a while for play. If it starts wobbling around in the frame, it’s going to bind and make the brake hard to engage. The shaft levers on the right and left ends of the crossover shaft should fit snugly in place and the nuts should be kept tight.
     The rear brake rod should be inspected for the same problems as the front and the cotter key and washer replaced every six months or so-or they may wear, break, and fall out- it happens all the time!
     A good brake anchoring system means quick and sure stops. No hesitation should be allowed when you need brakes. So, for any mechanical (or cable) braking, the anchoring must be strong and tight.
     Now we will get into the drum assembly and rap some maintenance and repair procedures. The moving and moved-upon parts in the drum should be greased, but only lightly, so that crap stays off the brake linings. The brake cam, shoe ends, and shafts should be clean, free of rust, and slightly lubricated with graphite grease or heavy grease applied lightly.
     The woven asbestos brake linings should be checked for grooves or excessive wear. Don’t let the fiber wear beyond the rivets.
     Like brake drums, linings should be kept oil free. Mishaps some time occur, though, and if you catch a lining while oil is fresh and has not had the chance to impregnate the material, there are a couple of things you can try to do to make them last a few more miles. If it just some grime or glazing, there is a chance that hitting them with a file will cure the lost braking. (Most brake linings are made with materials containing asbestos which is super dangerous to breath. When filing the fibers or cleaning drums, ect. , Don’t get your face in it.)
     Lightweight oil soaking may be remedied by giving the linings a good soak in gasoline and putting a match to them. That method is a taste shaky’ cause it might waste the linings or make then brittle. One last effort can be to scrub the shoes with trichloroethene, sold in stores as spot removers. (Carbona, energine), or detergent. As long as the oil isn’t deep in the linings, so heat and friction won’t draw it out again, the cleaning will do them good. But if there’s any doubt about those fiber shoes, get them off its too easy to rivet a new set in place.

Okay, so the linings are wasted. With a new set of fiber shoes and rivets, the brakes will be primo again. Lock the metal shoes in a vise, fiber side down, and pop off the rivet heads with a chisel (3). Then use a punch that is smaller in diameter than the rivet hole in the shoe and punch out the old rivets.
Clean the shoes in white gas or some solvent to get the them free of oil and grime. Then attach the new linings with rivets, starting at the center of the shoe, working your way out to each end, one by one.

Peen each new rivet over with a hammer as you go, using a punch or small diameter rod as a bed for the rivet on the other side of the shoe (4)
If solid rivets are used, a rivet set must be made to finish the job. Take a short length of 1/4 inch diameter mild steel rod; heat one end cherry red and tap it Down over a ball bearing a taste larger diameter (5). The concave surface this creates on the end is great for peening solid rivets into place. A flat punch is better for tubular or semi tubular rivets if a rim punch is not available.
Once the linings are mounted on the shoes, chamfer the ends at about a 45-degree angle (6).
Use a rasp or rough-cut file to do the job, and the new shoes are ready to go or stop-whatever.but be sure the drum is all right before the scoot hits the streets if it's grooved or badly worn, it may need to be replaced. After a few miles (100) check the linings for high spots and file them off so there is as much surface contact as possible .to centralize the shoes when everything is back on the putt. Loosen the brake shoe nut, then have someone step on the pedal a couple of times. The third time, hold the pressure on and tighten the pivot stud nut. The brake shoes should be smacking the drum when there supposed to, and the scoot is ready for the road