Motorcycle Repair: front axel, honda cbr 1000, dot 4 brake fluid

Question
Just put a new set of tyres on 96 honda cbr 1000.
Left front brake disk rubs on left hand cornering only.
Any suggestions?
 
         Thanks,Paddy.

Answer
Hi Paddy,

I've dragged knee, boot, and elbow roadracing. What you've described is serious lean angles. : )

I think you mean the brake disc rubs the caliper during left cornering.

If wheel and front end is assembled properly, I "suspect" the caliper(s) needs cleaned and seals replaced. Brake fluid in calipers changes chemically forming a gel like substance, which eventually crystalizes. This substance forms in the grooves behind the seals and causes caliper pistons to stick or not retract fully. When turning left, forces exerted may cause brake pads to contact/rub disc.

I would would need to inspect the MC to accurately diagnose the problem. I hope this is helpful. If you need repair information, send me an email address. I'll return a few related info. files.

Respectfully,
Mark Shively



Sample file:

Brake/Clutch Bleeding 101
By Mark Shively  

Use high quality DOT 4 brake fluid (or preferred type) from a sealed container. Remove the old fluid from the master cylinder reservoir. Use a cooking type squeeze bulb baster to remove the bulk of the fluid. Use a paper towel to remove any remaining fluid. Top off the empty reservoir. Top them off periodically during this procedure. Do not spill any fluid on your bike because it may damage the paint. The front brake reservoir tends to spit fluid out the top during this process so make sure you place a bunch of rags, old blankets, or towels over the fuel tank.  

You can make a bleeder drain container fairly easily by taking a plastic container with a screw on lid. Put a hole in the container lid just large enough to get the hose through. Put a short section of hose on the bleed valve on the brake caliper. Put the drain container on the other end to catch the runoff. You'll need to move the hose and container around to each caliper as you work, or use more than one container.

Use a wrench to open the bleed valve while simultaneously squeezing the lever (or pedal). About 2/3 of a turn on the wrench will do it. Fluid should run out of the hose at this time. When you squeeze to within 3/4 of your full lever pull, use the wrench to close the bleeder valve. It is important that you close the valve before hitting full travel on the lever. Release the lever and repeat the process (squeeze lever, open valve, close valve, release lever) until the fluid runs with no bubbles and the lever is firm. You'll be amazed how firm you can get your system.
While this way will work and there is absolutely nothing wrong with it, it is a big misconception that you have to shut the bleeder valve between every pump/squeeze of the lever. People do this on their cars, too. Pump, Open/Close; Pump, Open/Close…. You really don't need to do this. As long as you've got fluid flowing through the bleeder tube, you can just keep pumping/squeezing the lever until fresh brake fluids runs through the system. The end result is a flushed and bled system. Just make sure the reservoir stays topped off. If you bleed it dry, you'll have to start all over again. This how pro motorcycle mechanics flush a hydraulic brake system.