After a lot of work and money...it's official--no front brake at all

[Guest]

I've been fighting this front brake since March.

I installed a stainless steel line, rebuilt the MC, rebuilt the caliper (with all OEM Suzuki parts) and had brakes--sort of--all summer. The lever pull was pretty long and I sure didn't want to have to pull an emergency stop.

The bike spent more time with the lever tied back then it did with it not tied back this summer.

Decided I'd invest the time and money to get them right this fall. Purchased a GS500 MC off a 2006 bike on the recommendation of another GR650 owner that used the same MC, ordered new seals for the front caliper AGAIN and reinstalled them on Sunday.

Bench bled the MC and hooked up banjo bolts with new crush washers.

Been bleeding them for close to an hour. Absolutely no pressure building at the lever and I can see no movement at all from the caliper.

There are no visible leaks of fluid anywhere in the system.

I just don't get it. I've done all the things are supposed to work. The system just isn't that complicated and I have cleaned and reworked every part of this system and I have LESS braking power now than when I started in March. No shops around here will work on a 29-year old bike, but I'd take it in at this point.

[haztoys]

Do you have "pull back handle bars"...?

Air bubbles go up (as in a beer) ... So if the banjo bolt is higher then the lever then you need to unbolt the master and get the lever higher then the banjo bolt...you get what I'm saying..?

Get the master at a point all the air will go up hill...

[barnbiketom]

buy beg or borrow a mightyVac or similar..

you hook it onto the bleeder and SUCK the fluid and air out.

[jwhelan65]

Try filling the calipers with fluid first, the more fluid in the system to start with equals less air that will need to be forced out. Fresh lines can take awhile...

[Steve]

After rebuilding the master cylinder, did you purge it?

.

[oldrookie]

No pull back bars--I use dirtbike bars on my bike.

I have a MityVac and have become rather adept with it.

I did bench bleed the master prior to beginning to bleed the system. I ran a hose from the banjo belt insertion point back up into the MC and used a screwdriver handle to pump fluid back into the reservoir.

[oldrookie]

Haven't tried filling the caliper first. May have to try that next.

[chuck hahn]

Level the bars and take some pics...guessing blind isnt worth squat. You rebuilt the master...get the right kit? Is the circlip that holds the piston in inserted in the inner most groove? Did you use new crush washers and the right size ID on them? Have you wrapped the bleeder nipple threads with teflon tape so your sucking air ONLY from the system and not from the threads? Single or dual brakes? If dual, is the splitter valve clogged? New lines or the old ones reused? Are the pistons in the calipers stuck? New seals in the calipers and lubed with brake fluid before you put the pistons back in? Are the seals seated fully and smoothly in the caliper grooves ( stuck piston symptom here )? Did you scrape all the scale out of the piston seal grooves in the calipers? Scale decreases the inside diameter of the seals when you put them in and pinch against the pistons and can seize them up that way. Gotta recheck each and every detail in the entire system is my opinion.

[chuck hahn]

Pics of the forks and caliper would be usefull as well.

[chuck hahn]

To clean the groove in the caliper i prefer one of these 2 ways.

1)..I borrow my buddies dremel and use the little wire brush to clean them.

2) Chemically. Close off the bleeder valve, put a regular bolt in the banjo bolt hole and set the caliper with the cavity facing up. Fill cavity with Berrymans just enough that it flows into the groove. Set overnight and quickly dump it back into the can and wash the caliper with hot soapy water. Then run a green dish scrubbie around the groove to clean it. Inspect and use a small pick to remove any left behind scaly stuff.

[oldrookie]

Level the bars and take some pics...guessing blind isnt worth squat. You rebuilt the master...get the right kit? Is the circlip that holds the piston in inserted in the inner most groove? Did you use new crush washers and the right size ID on them? Have you wrapped the bleeder nipple threads with teflon tape so your sucking air ONLY from the system and not from the threads? Single or dual brakes? If dual, is the splitter valve clogged? New lines or the old ones reused? Are the pistons in the calipers stuck? New seals in the calipers and lubed with brake fluid before you put the pistons back in? Are the seals seated fully and smoothly in the caliper grooves ( stuck piston symptom here )? Did you scrape all the scale out of the piston seal grooves in the calipers? Scale decreases the inside diameter of the seals when you put them in and pinch against the pistons and can seize them up that way. Gotta recheck each and every detail in the entire system is my opinion.

Some great questions.

I rebuilt the original MC early this summer. Twice. OEM parts using Boulevard Suzuki's online parts fiche. I became convinced that it was still leaking air and purchased the GS500 MC late in September. It is that one that is on there now. It was not rebuilt, but there are no visible fluid leaks, nor is that any indication that it is leaking air into the system. I don't see much fluid moving internally when the lever it used with the lid off. The old one would squirt fluid into the air.

Had been using teflon tape on the bleeder. Purchased a new one this week along with new caliper seals and did not put teflon in again. It looked kind of mushy on the old one when I took it off to clean it this time.

Lubed everything with brake fluid before installing the piston. Inner seal was still tight; had to put a block of wood over the end of the piston and lightly tap on the wood to get the piston back in. Possible it is stuck? I think I can feel it moving when using the lever.

Doesn't look like the caliper is moving the inner brake pad up against the disc. Can see the inner "hooks" moving like they are trying to pull the pads against the disc, but there isn't a lot of movement.

There was next to no scale in the caliper either time I pulled it apart. Cleaned all parts well while I had it apart.

[oldrookie]

Pics of the forks and caliper would be usefull as well.

I can get pics up tomorrow. Any particular parts you want see? I'll get a collection up tomorrow night after work.

The inner part of the caliper was nearly pristine. Inspected it with a magnifying glass. I just don't see any problem from scale being possible.

Single disc and line on the GR.

[chuck hahn]

Ok that answers a lot of questions. Take a flat tip and force the pad that on the piston side well back off the disc. Stick itm in there and litterally use the disc as a fulcrum and move the psiton back...keep an eye at the master that fluid doesnt over flow the edge. Youll want to take the cover off the master also so theres a place for the fluid to displace back upstream. Once you have moved the pistons back, put the cover back on and work the lever and watch the pads to see if they are actually moving back toward the disc. If not, reinspect the caliper and seal..could be the seal is pinched a bit and hanging up the piston..and they should be pretty snug going in, but your comment about smacking them in with a board sounded the alarm bells in my head. Its a bit of a wiggle and push till they first start into the caliper but then i can normally push the pistons all the way into the cavity with thumb pressure easily enough.

[chuck hahn]

Look at the bleeder on the caliper too..is it at the top when mounted on the bike....that was my thought when asking for a picture of the forks.. I have actually seen people put them on the wrong sides ( on dual cliper bikes) and wonder whats up when the bleeers are at the bottom and they cant get the air out....

[BigD_83]

I had what I thought to be a sticky piston, and went through a similar headache. I finally narrowed my problem down to the caliper pins on which the pads slide. There was just enough scale/dirt/grime on them that the pad was binding. I would not have thought it possible, but I had much improved feel and power after cleaning them up.