greg bender

http://www.thisoldtractor.com/gtbender

Brake adjustment

I extracted this information from Greg Field, Bruce Giller, and Paul Linn on the Yahoo! Loopframe_Guzzi news group.

Drum brake adjustment with wheel still on bike

by Paul Linn

  1. Disconnect cable and tie rod.
  2. Move one lever so that shoe just barely comes into contact with drum surface. (Check this by spinning wheel and listening for the tell tale scrape of the shoes on the drum surface)
  3. Mark this position with an upright mark on splined part only.
  4. Repeat step 3 for other lever.
  5. Place levers on splined parts so that the tops of the levers are now lined up with the marks made in step 3.
  6. Rotate front lever to its upright position and connect tie rod.
  7. Rotate rear lever to its upright position and check length of tie rod. If it,s to short or to long, adjust tie rod now so it can connect to the rear lever.
  8. You will have to fine tune the tie rod so that both shoes contact the drum at the same time.
  9. Connect cable, adjust freeplay and test brake action.

This same procedure can be used for the rear drum also. Your drum brakes will now be just a good as a disc setup. After following this simple adjustment procedure you will no longer have that mushy feeling most people find with the front brake switch style cable and you will be able to STOP on a dime.

Synchronizing four leading shoe brakes

by Greg Field

  1. Center the hub by spinning the wheel and locking the brake and retightening the axle bolts.
  2. Get all linkages to "optimum" position. This means that when the shoes contact the drum, the actuating arm and pull rod are as near a right angle as possible, for best mechanical transfer of force. Rotate the actuating arms on the shaft until this is so.
  3. Pull off the right cable
  4. Remove the pin for the back shoe on the left side.
  5. Adjust slack out of the left brake cable until there is significant brake drag (light scraping is not enough).
  6. Manually actuate the rear shoe until the brake drag doubles. Then, adjust the link rod until the pin can be re-inserted. Fine-tune adjustment if necessary to keep drag equal between the two shoes. Hopefully, the andgle between rod and arm wil still be near90 degrees.
  7. Slacken left cable till all brake drag goes away.
  8. Repeat steps 3 through 6 for right side.
  9. Then adjust slack out of left cable till brake drag from the left side doubles what was already there from the right.
  10. Adjust out slack at the hand lever, which preserves left-right synchronization.
  11. Then, for gnat's-ass perfection, re-center the hub, and fine-tune the left-right adjustment.

When done thusly, most folks I've done this for want them de-adjusted so they're not so grabby and sudden, but this is the place to start because if your shoes aren't 100 percent perfect, this will make them the best they can be.

Here are the Steps to a Great Front Brake

by Bruce Giller

  1. get new shoes with modern material. If your shoes are original, recycle them at a brake recliner or put them on the wall as Guzzi Art. Mark E. sells them
  2. arc the shoes to the drum. (see instructions below)
  3. adjust the front brakes so that both leading shoes contact the drum at the same time (see instructions below)
  4. as the shoes wear, re-position the front drum's brake levers to compensate. Adjusting the brake cable is useful over a short range - plus the cable itself tends to lengthen. (I'm still writing this one up...it is Paul Linn's tip)

For those who want to do arc the brake shoes to the drum:

  1. Obtain some 80 grit sandpaper with a sticky back (you can find strips of sandpaper at your local auto paint store)
  2. Line the inside of the brake drum with one layer of the sandpaper (you will have to cut the paper to the width of the drum)
  3. Pencil on hatch marks over the entire width and length of each shoe
  4. Assemble wheel back on the bike.
  5. To center the wheel, use the front brake lever several times while spinning the front tire, then hold the brake lever down while tightening the front wheel nut
  6. Spin wheel and apply brakes a few times to sand down shoes
  7. Remove wheel and inspect pencil marks. If some of the marks are still there, repeat Steps 3-6 until the pencil marks have completely disappeared
  8. Remove paper from the drum and clean out the drum. This procedure will leave a pile of shoe particles inside the drum, especially if the shoes are new

You want to make sure that the two leading shoes are contacting the drum at the same time when braking. The procedure works better if you have 3 arms but can be done by one person.

  1. make sure that your front wheel is centered on the axle. To center the wheel, use the front brake lever several times while spinning the front tire, then hold the brake lever down while tightening the front axle nut
  2. Disconnect the metal rod connecting the two splined levers for each shoe from the front lever. It has "forked" end pieces which are held in place by a small pin with a cotter pin. The rod is welded to one end and screwed into the other.
  3. Squeeze the brake lever to where the point where the front shoe is contacting the drum
  4. At the same time, manually make the rear shoe contacts the drum by pulling back on the rear brake shoe splined lever
  5. Adjust the length of the connecting rod for a tight fit between the two shoes. You probably won't get a perfect fit due to the large adjustment distance. You have to turn the forked end 180 for each adjustment. I made mine a bit tight to compensate for future shoe wear
  6. Test the action of the front shoes. Put the cotter pin back in the front lever's pin. Now when you pull on the front brake lever, the two shoes will contact at the same time.