Front brakes issue for 83 1100ESD

[Oakley]

Asking for comments (help) on front brake issue. Rebuilt master cylinder and both calibers (pistons/seals kit - Suzuki parts). Typical problem (I believe) with master cylinder piston removal, but finally managed to get it out. Cylinder walls looked good, same with calibers (excellent). This model has the anti-drive system connected to the brake lines. Did not disturb the this except for removing and re-installing brake fluid lines. The problem is with bleeding. It appears like there is an air leak (?). I am using a hand vac pump bleeder that has always worked before for me. Following the book on bleeding sequence (left anti dive, left caliber, first...etc.). Have done it over and over...... Now have front brakes, but lever pull for brakes is just short of hitting grip and you cannot pump it up. The brakes appear to hold okay (good for rolling bike around) but would not go out on road with this situation. This first time I every experienced this type of situation in bleeding brakes (bike). Anyone that can give advice is appreciated. I suspect it is the master cylinder, but don't know if it could be in the anti-drive system. Brakes appeared to work before rebuilding system, but I always rebuild on old bike before riding it. Everything really needed servicing. Bike is new to me (have not ridden it yet). Have been looking for replacement master cylinder (good used - hard to find) or newer version. There are no NOS master cylinders available anymore from Suzuki. Any suggestions on this issue would also be appreciated. thank you

[Nessism]

First of all, good work with the full system tear down. We get way too many people around here that think the only thing you have to do to refresh old brakes is flush the fluid. I hope you have replaced the tired old rubber lines while you are doing the job otherwise scale inside the lines will contaminate your clean system. Also, the caliper pins need fresh high temp. caliper grease otherwise the caliper won't slide the way it should. The anti-dive mechanisms will create a somewhat spongy hand lever feel but I don't think the problem you describe is related.

The soft lever feel is one of three things: air in the system, the piston calipers have not come out of the caliper bore all the way and adjusted themselves yet, and lastly, the caliper is binding on the sliding pins. Vacuum bleeding is good but it's some times hard to tell if there are any bubbles remaining in the lines. You might want to double check to see if there is air in the system by using the old fashion method of pumping the master while bleeding with a piece of clear tubing so you can watch for bubbles. Wrapping the bleed nipples with teflon tape makes the bleeding job easier since the tape seals the threads nicely thus any bubbles in the line are coming from inside the system, and tapping on the lines to dislodge any bubbles is a good idea too. After you are satisfied there is no air in the system, another thing to do is pump the lever repeatedly to build some pressure followed by strapping the hand lever against the grip. The pressure in the system will press on the caliper pistons and force them out of their bore and against the pads/disc. Leave the lever strapped over night, or at least several hours as the pistons will creep out slowly. It may be necessary to do this a couple of times to get the pistons out all the way.

Hope this helps and good luck

[Oakley]

Thank you. The lines are replacement SS braided. I did grease the pins with the proper grease, that came with the piston kit. I will do the hand pump and taping the lever, letting it set overnight. If nothing happens, I guess I will look into the caliber and recheck everything (blow pistons out and put all back together again). thanks again.

[salty_monk]

When you've finished all that... you can take them off & upgrade to the Kawasaki Twinpots for some real braking power...

[7981GS]

This, looks familiar to your set up:



Daniel

[Joe Nardy]

Thank you. The lines are replacement SS braided. I did grease the pins with the proper grease, that came with the piston kit. I will do the hand pump and taping the lever, letting it set overnight. If nothing happens, I guess I will look into the caliber and recheck everything (blow pistons out and put all back together again). thanks again.

Before doing all that, try this:

Remove one brake caliper. Put something in between the pads to keep them from jamming together. I use a piece from a thick plastic protein drink powder container folded in half. Squeeze the brake lever slowly to push the pads together. Don't jam them too tight. Wedge something in between the plastic and slowly push the pads back out. Push them just far enough so they will slide back over the rotor. I wedge the bottoms of the pads further out than the tops so the rotor is actually pushing the pads back as the caliper slides on. Bolt the caliper back on. Repeat on the other side.

I had the same issue after rebuilding my calipers and master and this tip (from someone else - I can't take the credit) worked great for me. I have seen it work on at least two other GS's since then. I think the issue is that the caliper pistons slide so easily that they pull away from the rotor until they get to a 'resting' position. You may have all the air bubbles out and a solid system but the first part of the lever travel is used up pushing the pads back into contact with the rotors. Doing the above procedure seems to reset the 'resting' position closer to the rotors.

Good luck,
Joe

[Oakley]

Thank you....will do this today!

[Im Faster]

Did you figure out the problem?