1982 GS1100 Front Brakes arent making pressure

[FlordiaMan]

During a caliper rebuild the piston is pushed deep into the caliper housing.

The first few times you pump the lever the piston walks out of the caliper and moves closer and closer to the disc. When in the proper position the piston (as spaced by the pads) are just a few thousands of an inch from the disc. Then when you pump the master pressure builds and the piston moves closer still, only it doesn't actually slide in the seal, the seal sort of flexes towards the disc when pressure is present. When you have binding in the caliper the piston doesn't move close enough to the disc so you get a firm lever. You grab a handful of lever and the piston moves towards the disc but doesn't make full contact before the lever travel is gone. You need the move the piston closer to the disc, then when you pump fluid from the master the pads will make strong contact and you will get a firm lever.

Sir, can i just say, god bless you and your family and your soul and ur whole being, this has been bugging me for half a month, and i was almost ready to just say screw it and buy a whole new calibers. I pressed my M/C with the calipers off the rotor, then forced them back on and bam, good brake pressure and i havent even bled them yet. Thank you so much.

[Rich82GS750TZ]

I love a happy ending

[Nessism]

The trick of pumping the lever to build pressure and tying it back against the grip over night is to get the piston to move into the proper position near the disc. Be sure to do that when you are done installing the calipers and bleeding the system. Another thing is to make sure the sliding pins in your calipers are properly greased. You need to use heavy black caliper grease. Not regular grease. And on some bikes there are plastic collars on the sliding pins which swell up from grease contamination and cause the caliper to bind and not slide properly. If that happens you won't get proper grip feel either.

Good luck