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Hi all from an Ohio hick (ie. Kerry: "can I get me uh huntin' license here?"),
Just replaced pads two weeks ago, then rebuilt calipers and master cylinder last night on 1981 GS750E for reasons of preventative maintenance. (Brakes worked good before I started, and after I replaced pads. Since there was evidence of seeping under the caliper boots, I decided to rebuild calipers and master cylinder after a few weeks. Meanwhile, brakes worked perfectly.)
The job seemed very straight forward as I have rebuilt probably 100 calipers over the years as a professional mechanic. Cleaned and verified bore dia, then replaced pistons, seals, boots with genuine Suzuki parts. Cleaned and lubed caliper pins and bore, then reassembled. Bled brakes at bleeders and banjo bolts -- no more air. After doing this, the brake lever would go fairly low the first pull, then normal if pulled immediately again. Action nice and firm, not spongy. I then rebuilt the master cylinder (nothing wrong inside though). After prebleeding, installing, and bleeding again, the lever is still low first pull, then normal if pulling immediately again. The only unusual thing that I feel might be related is that the lower caliper "axle No.2" (SGP # 59306-45200) has an undercut, with a rubber tubular insert that has hardened with age so as not to provide fricton (especially after lubing with grease). It is my feeling that the rubber inserts provide friction to hold the caliper/pad in position so as to provide slight contact with rotor, therefore preventing excessive movement which would create low brake lever until tension taken up (by "pumping"). I ordered new pins, but alas, they do not have rubber insert (even though pictured). Has anyone else ran into this? (Any suggestions as to source of rubber tubing of correct ID/OD/durometer?) There is no air in the lines -- have bled them very well. Lever is not soft, just low on the first pull. Brake pad backing plate flat and in place (along with spring clip and pad rail shim). Rotors true with no runout. Slight clicking noise from lower caliper axles (the loose greased ones) when actuating lever indicating slight movement.
This reminds me of a car that has the rear drum brakes way out of adjustment (but no air in line): initial brake action low until pedal "pumped up". Adjusting brakes always takes care of low pedal in this circumstance.
Thanks for any help!
Brian
Just replaced pads two weeks ago, then rebuilt calipers and master cylinder last night on 1981 GS750E for reasons of preventative maintenance. (Brakes worked good before I started, and after I replaced pads. Since there was evidence of seeping under the caliper boots, I decided to rebuild calipers and master cylinder after a few weeks. Meanwhile, brakes worked perfectly.)
The job seemed very straight forward as I have rebuilt probably 100 calipers over the years as a professional mechanic. Cleaned and verified bore dia, then replaced pistons, seals, boots with genuine Suzuki parts. Cleaned and lubed caliper pins and bore, then reassembled. Bled brakes at bleeders and banjo bolts -- no more air. After doing this, the brake lever would go fairly low the first pull, then normal if pulled immediately again. Action nice and firm, not spongy. I then rebuilt the master cylinder (nothing wrong inside though). After prebleeding, installing, and bleeding again, the lever is still low first pull, then normal if pulling immediately again. The only unusual thing that I feel might be related is that the lower caliper "axle No.2" (SGP # 59306-45200) has an undercut, with a rubber tubular insert that has hardened with age so as not to provide fricton (especially after lubing with grease). It is my feeling that the rubber inserts provide friction to hold the caliper/pad in position so as to provide slight contact with rotor, therefore preventing excessive movement which would create low brake lever until tension taken up (by "pumping"). I ordered new pins, but alas, they do not have rubber insert (even though pictured). Has anyone else ran into this? (Any suggestions as to source of rubber tubing of correct ID/OD/durometer?) There is no air in the lines -- have bled them very well. Lever is not soft, just low on the first pull. Brake pad backing plate flat and in place (along with spring clip and pad rail shim). Rotors true with no runout. Slight clicking noise from lower caliper axles (the loose greased ones) when actuating lever indicating slight movement.
This reminds me of a car that has the rear drum brakes way out of adjustment (but no air in line): initial brake action low until pedal "pumped up". Adjusting brakes always takes care of low pedal in this circumstance.
Thanks for any help!
Brian
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