Maintenance

Here are the virtually free things you can do to improve ATE's braking performance and or discover problems. From the handlebar down:
 

• Clean and lube (axle or lithium grease) barrel end of cable at handle bar lever and master cylinder lever. This is where most cables break from binding, then flexing the cable until it fails from metal fatigue. It should rotate smoothly under load w/o any creaking, groaning or stutter.

• Check the lever's pivot pin on the handle bar. There is a white plastic bushing and wave washer. If the bushing is worn, replace it.

• Inspect the brake cable that goes from the handlebar to under the tank. Excessive friction, frays or kinks are reason for immediate replacement. You DON'T want failure to occur right when a car pull out in front of you. Replace cable boot if cracked, damaged or missing.

• Lube cable IF APPLICABLE. Cables from roughtly '78 on are teflon-lined and should NOT be lubed. Replacement cables bought from a BMW dealer nowadays are likely teflon-lined. Check first.

• Adjust cable end at master cylinder using the U-shaped BMW feeler guage in the bike's toolkit (it's 1.2mm thick). Freeplay of 4mm between the handlebar lever and its stop is recommended. Make sure the rubber "sock" covering the lever mechanism is in good shape and properly seated. The BMW part also has feelers for valve tappets, spark plug gapping and ignition points. Lube pivot and check boot as above.

• Clean and lube thrust pin between the master cylinder's cable lever and piston.

• Test brake fluid light by connecting contacts on the resevoir cap. Fully bleed/flush the brake fluid with DOT 4 (do NOT use DOT 5!!). Brake fluid absorbs water and should be replaced/flushed annually regardless of how often it is ridden and whenever a hydraulic component is serviced/replaced (hose, caliper seal, etc). This helps prevent the master cylinder's and caliper's bore/piston from developing rust spots and pitting which is often a problem on an unmaintained bike.

• Inspect/replace brake hose. There should be NO bulging, cracks or soft spots under pressure. Kinks and the internal swelling of the hose over time (especially if 20-years-old) can restict brake fluid flow.

• In addition to the brake hose, the inside of the steel brake line (tube) might also need to be checked for rust if you suspect brake fluid restriction dirty brake fluid that's sat in the system for years w/o flushing.

• Inspect the brake pads. If they look like "|||\ \|||" from the top, that does NOT mean they are wearing unevenly. New pads contact surface is NOT PARALLEL to the pad backing, but rather it has a trapezoidal cross-section. If you do not know how old the pads are, baseline it by replacing them with new ones since pads harden with age and lose there effective "grip."

• Choose ones with the highest rating you can find. BB is higher than AA. One letter refers to performance when the brakes are cold, the other hot. GG or so should be easy to find. Break in new pads gently to avoid glazing them and allow for a maximum surface area interface. Gradual braking and scanning least twelve (12) seconds ahead so you can begin braking or down-shifting to engine-brake earlier can aid in break-in process for the first 500 miles or couple tanks of gas. Actual break-in durations may vary.

• Clean and lube eccentric pin (E-pin) and its housing in the caliper and fork leg. You'll have to remove the large nut cap below the caliper and screw in a bolt like the ones used for the fork brace and axle pinch bolts and pull/lever it out. The E-pin also has an o-ring. Replace it if needed.

• Adjusting the E-pin (one method): Spin front wheel and turn E-pin until slight rotor drag is felt (turn the E-pin with a large screwdriver, not a bolt which would turn the E-pin out of place when removed). Mark this point as 0-degrees (in relation to the E-pin, not the wheel), turn pin back through free rotation zone until rotor drag is felt again, note the number of degrees the pin was turned, turn the E-pin BACK halfway. We'll call this the Parallel Zone (p-zone).

• ATEs have TWO p-zones. One with the caliper pulled in nearer to the fork/axle and one with it farther away. You want the FAR p-zone setting for maximum caliper leverage. If you were previously using the near p-zone, you will have to gradually break in the pads to their new orientation to the rotor's sweep.

• The disc should be replaced if it is less than the minimum thickness or if a "pulsing" is evident when braking (most noticable at slower speeds). Sometimes a pulsing disc can be turned and trued, but only if it can be kept within spec and it's integrity has not be compromised.

• Radial GROOVES in a disc do not necessarily indicate a bad disc. In fact, they provide greater contact area with the pads. However, the deepest groove must be within the minimum thickness spec and brake pads may take longer than normal to break in.

• Disc carrier bolts should be replaced if corroded. Make sure to use ny-lock nuts to prevent them from vibrating loose.

• Additionally, it may be necessary on many bikes, especially barn queens, to rebuild the master cylinder and or caliper. If the bore or piston of either is pitted (likely from lack of maintence as mentioned above), it will likely need to be replaced. Pits can eat seals and hamper movement leading to the poor application and or release of hydralic force. I know of no way to inspect the bore short of disassembly and measurement.

As you can imagine, much of the above is often "let go" by previous owners. Sometimes small things can have a significant effect on braking performance. And just about any bike left to sit with the same brake fluid for a dozen or more years can have the system effective freeze up from internal corrosion. Even with newly installed heavy duty springs on my naked R80/7, I still can really compress the forks under aggressive braking, and this is on a single disc! Maintenence pays sweet divedends.

Modifications

Many riders have augmented their ATE setup in one of several ways. Before doing this, the stock system should be totally serviced first for two important reasons: mods are much more expensive than the basic maintenence, and the mod may not address what is really hampering performance meaning the same or better results could have been achieved via simple maintence. That said, here are some of the more common mods I've heard of with a few +'s and -'s, though many still ride well-maintained, bone-stock set-ups:

• Dual Discs
  + improved braking
  + can be done with OEM parts
  - pretty pricey: requires buying a new fork leg, caliper, master cylinder, hose, line, bracket, disc, etc.
  - more to maintain and adjust, but not much

• Stainless Steel Braided Brake Hose
  + less hose swell for firmer lever feel and brake response
  + some prefer braid aesthetic
  - less likely to show signs of age and potential failure
  - steel braid can rub off paint on frame leading to rust

• Smaller Master Cylinder Bore
  + smaller bore provides better leverage at handlebar
  - more lever travel means greater risk of it bottoming out against grip (In a similar vein, the '74-'75 used 38mm calipers and '76-'80 40mm.)

• Different Disc (solid cast iron common to /6 and drilled stainless steel to /7)
  + cast iron discs "grab" better
  + stainless steel doesn't rust
  + drilled discs have better wet stopping
  + undrilled discs present a greater area for the pads to sweep
  - cast iron rusts easily (you can cad-plate it so only the pad-swept area rusts)
  - stainless steel not quite as "grabby" iron

• Different Pads
  + as a rule, fresher (not old) pads, of a higher rating (GG > FF) and correctly broken in brake best
  +/- with the variety of materials available and potential pad/rotor combinations, some will work better, some will give off less black brake dust, some will last longer, some will wear less on the disc(s)

• Different Braking Set-Up
  + potentially "modern" brake system
  +/- countless possible variations and results - can be very costly

Joe #3335
'78 R80/7