Front Brake Bleeding, Once Again
Posted: Sun Jan 09, 2011 2:58 pm
First of all, let me admit that I'm not the sharpest tool in the toolbox. I'm great at normal maintenance, as long as its not too technical. I've replaced clutches, adjusted valve clearances (though not on the CBX), changed brake pads, sprockets, chains, gaskets, bled brakes the old fashioned way with a small jar and a clear plastic hose -- that kind of stuff. But I have never rebuilt a caliper or replaced fork seals. And I didn't want the CBX to be my first try at it, since I know my limitations and didn't want to take a chance on doing any unnessary damage. So recently when the CBX had at least one front caliper and the rear caliper stuck, as well as a leaking fork seal, I decided to take it to a very reputable shop that does work on CBX's. They replaced all the fork seals, and rebuilt all three calipers. No biggie.
When it was time to pick the bike up, I towed the trailer two hours to the shop, but it had been raining and the shop has a fairly long dirt / gravel driveway. Normally I would go for a quick test ride, but I didn't want to take a chance dropping the old girl on the slick mud, so I loaded it on the trailer and headed home. When I got home, I took it for a test spin to make sure everything was working properly. Uh-oh, I've got a spongy front brake lever. The rear brake is fine. I called the shop and was told that they had spent an hour on the brakes with a vacuum bleeder and though they did not test ride the bike either, everything was fine when they were done. I'm wondering if there may have been some air hiding in the system somewhere and the jostling on the trailer on the trip home made it show up.
Since the shop is two hours away, I decided I would try to bleed the front brakes myself. I didn't want to go through the hassle of bench bleeding, and I don't have a vacuum bleeding system. I did some research on this site and others, and decided to try bleeding the front brakes with a syringe set-up very similar to the one below:
I was able to get fluid to flow out of the system into the syringe and then force fluid back through the left front caliper to the master cylinder no problem. No air bubbles were evident in either direction. I then tried the right caliper. The fluid would flow out of the caliper into the syringe (squeezing the lever of course), again with no air bubbles evident, but for some reason I could not force the brake fluid back in the caliper, either with the brake lever depressed partially or fully out. Not really sure why, so I just buttoned everything up. I've still got what I consider to be a spongy lever -- the brakes will stop the bike fine, but the lever goes back to within maybe a half inch of the grip when you squeeze it hard. You can pump the lever a couple of times and it will get firmer, so I'm assuming there still may be some air in the system somewhere.
Currently I've got the bike on the sidestand with the wheel all the way to the left, and the front lever depressed maybe halfway with a cable tie. Over the course of the next day or so, I'll go tap all the lines (braided stainless ones) and the splitter several times with a screwdriver handle in the hopes that any remaining air will find it's way up to the master cylinder. Short of taking the bike back to the shop, any suggestions on what else I should try? Thanks in advance, and sorry for the long post.
When it was time to pick the bike up, I towed the trailer two hours to the shop, but it had been raining and the shop has a fairly long dirt / gravel driveway. Normally I would go for a quick test ride, but I didn't want to take a chance dropping the old girl on the slick mud, so I loaded it on the trailer and headed home. When I got home, I took it for a test spin to make sure everything was working properly. Uh-oh, I've got a spongy front brake lever. The rear brake is fine. I called the shop and was told that they had spent an hour on the brakes with a vacuum bleeder and though they did not test ride the bike either, everything was fine when they were done. I'm wondering if there may have been some air hiding in the system somewhere and the jostling on the trailer on the trip home made it show up.
Since the shop is two hours away, I decided I would try to bleed the front brakes myself. I didn't want to go through the hassle of bench bleeding, and I don't have a vacuum bleeding system. I did some research on this site and others, and decided to try bleeding the front brakes with a syringe set-up very similar to the one below:
I was able to get fluid to flow out of the system into the syringe and then force fluid back through the left front caliper to the master cylinder no problem. No air bubbles were evident in either direction. I then tried the right caliper. The fluid would flow out of the caliper into the syringe (squeezing the lever of course), again with no air bubbles evident, but for some reason I could not force the brake fluid back in the caliper, either with the brake lever depressed partially or fully out. Not really sure why, so I just buttoned everything up. I've still got what I consider to be a spongy lever -- the brakes will stop the bike fine, but the lever goes back to within maybe a half inch of the grip when you squeeze it hard. You can pump the lever a couple of times and it will get firmer, so I'm assuming there still may be some air in the system somewhere.
Currently I've got the bike on the sidestand with the wheel all the way to the left, and the front lever depressed maybe halfway with a cable tie. Over the course of the next day or so, I'll go tap all the lines (braided stainless ones) and the splitter several times with a screwdriver handle in the hopes that any remaining air will find it's way up to the master cylinder. Short of taking the bike back to the shop, any suggestions on what else I should try? Thanks in advance, and sorry for the long post.
