Rear Brake Fade - MC rebuild?

[STAg93]

Greetings,

Occasionally, even when starting out (cold), the rear brake pedal goes "to the floor". Fluid has been replaced, system bled, new pads. Still happens from time to time. I haven't found much info about servicing/rebuilding the rear master cylinder and it doesn't seem Honda makes a kit. It also seems that accessing the rear MC means removing right side exhaust, foot peg bracket, etc. I guess not much compared to an alternator upgrade but a lot to get to a MC.

Anyone dealt with this before?

PS: Bike is a 93 ABSI; non-linked system. Modulators were rebuilt by Norm K around 15 yrs ago but quit working a few years after that. Tape over the ABS dash light has been effective since.

 

[Uncle Phil]

Tape over the ABS dash light has been effective since.

If the ABSI is like the ABSII, there are a couple of connectors on top of the speedo/tach unit that can be disconnected and 'solve' the light problem.
The bulbs are 'internal' so you can't remove them (at least on the ABSII).
Yeah, sounds like your rear master cylinder could be leaking internally and letting fluid bypass.

 

[GreenZR]

Rear master cylinder rebuild kit from Ron Ayers Honda is part number
43520-MJ6-315
Gary.

 

[STAg93]

Thanks for the info. Much appreciated!

 

[STAg93]

Late update: the All Balls 18-1007 rebuild kit is a match for my '93 ABSI rear master cylinder. Working fine again.

 

[jfheath]

Greetings

Welcome !

Occasionally, even when starting out (cold), the rear brake pedal goes "to the floor".

Check the runout on your rear disk (runout = wobble).

If it isn't running true, depending on how far out of true it is, the disk nudges the piston back into the caliper so that the next time you apply the brakes, they have to be pumped back out before they bite.

You might think that you would feel a pulsing under your foot in this case - but in fact you don't feel anything unless you have fitted brand new OEM pads with the heat insulation plate.
Otherwise, the caliper oscillates with the disk surface and you cannot feel it under your foot. New EBC pads tend to be thinner than New OEM, so you wouldn't feel it even with brand new pads.