I have a 98 Fatboy that has had Performance Machine 4 piston calipers front and rear since new. The past few years the rear has been giving me trouble overheating so I rebuilt it only to have the same problem. I gave up on it and bought a new one, it ran much cooler so I thought I corrected the problem. For the past three weeks I have been sick so have not ridden. Today I took it out for a short ride and when I got home it was very hot again, at this point I am clueless. I have a two year old OEM rear brake master cylinder a one year old brake rotor and used new fluid, any ideas? One more thing, I have the caliper shimmed about as good as you can get it.

 

I would have recommended a caliper rebuild but you've done that. I have no useful ideas to pass on. I would however investigate the following:

1. Remove the pads and check that they are wearing evenly on both sides.
2. Insure that the caliper is moving freely when the suspension articulates.
3. Measure the thickness of the rotor.
4. Insure that there are no contaminates in the system preventing fluid pressure from releasing.

Good luck and post a followup if you determine the cause.

 

Sound like the rear pads are dragging. Have you rebuilt the rear master cylinder?

 

For some reason one or more of you pistons aren't retracting properly. Perhaps;

You need to clean out the caliper, pistons and the brake line with denatured alcohol then put in new fluid.
Or,
You need to clean out and/or rebuild the mc.
Or,
You need to check the stop adjustment on your brake pedal. I had one work loose and back out enough so as to keep the pedal from returning all the way thus keeping pressure in the line.

Let us know what you find.

 

You didn't say. Is it both calipers, or just one? I have never had this issue with a bike, bit on cars it is always the caliper sticking. Time for a rebuild. Since you have had this issue before, are you using the correct type of brake fluid? The wrong type will cause the rubber fittings to swell and this can be the result.

 

Thank you all for your comments, every thing suggested was done with out helping and as I said I put on a brand new PM caliper, new fluid and my rear MC is a year old OEM HD. The outside pistons are not retracting enough compared to the inner ones, don't know why. I will probably put the OEM caliper back on and eat the cost of the new PM one I bought.

 

Clean caliper very good, remove pads and push brake to move the pistons out. Clean very good the pistons and aply silicon grease/oil in the pistons and rubber gaskets of pistons.
After, retract the pistons and move the pistons out various time for lube the gaskets and pistons.