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Lost my braking power in the front .. Need help w troubleshooting

5K views 17 replies 8 participants last post by  redfish 
#1 ·
All. After storing the bike for a good 4 months in garage, I changed the sparkplugs, clean it up, lubed the chain and took it out. I found that I have no braking power in the front. Rear brake works, but I need my front brakes too :)

The brake lever on the handle comes to a stop as I squeeze it, so the pressure in the brake system is adequate.
I cleaned the rotors twice with brake cleaner and the wiped.
I took out the brake pads. They have 3 and 4 mm on them, so still above spec of 1mm. I cleaned them with brake cleaner as well.
I opened the brake fluid reservoir at master cylinder and topped it off. I then opened the brake bleed screw and pushed in the brake handle.. the brake fluid came out of the bleed screw with no bubbles. I tightened it back closed before letting go of the brake handle. Repeating that a few times I saw no bubbles.
I topped off the reservoir again and closed it.
As I tested the bike again in the parking lot, the brake still has no power. Basically I go to 5-10mph, push in the brake, the brake lever feels firm - I can't push anymore in and it doesn't reach the handle grip. The bike brakes very poorly and slowly. As it comes to a halt it lets out a low pitched squeal. Same symptoms as before. I'm confused as to what the heck is going on. I've never heard the low pitched loud squeal in the past as I was braking on the bike.

I'm guessing either the brake pads are not pushing the rotor disk enough or the brake pads or rotor have become slippery for some reason. Very confusing. I feel that there's enough pressure in the brake handle and thus I don't think it's lack of pressure .. but who knows. And I feel that I cleaned the rotor and pads with acetone well enough.. I don't know how they could have gotten contaminated all of a sudden. I had this bike for 2 years and the brakes were always excellent. Rear brakes still works great and stops the bike very easily.

Also perhaps the caliper isn't working, but I'm not sure how it works and what could be wrong.

Any advice would be appreciated!
 
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#2 ·
Two things come to mind:
1) Put a hose on the bleed valve into a container of fluid suspended above the caliper. Open the valve and squeeze the lever, verifying that you get a steady steam of fluid. If so, you've confirmed that the master is pushing fluid all the way to the caliper. Bleed as needed if you got any air in the system during this test.
2) Assuming test 1 passes, you can get a rebuild kit for the caliper for about $20. I believe the part number is 32-1319. I'd do that next to ensure that the caliper is cleaned up and fully operational. You can bottom the piston in the bore with a clamp when you're done and squeeze the lever to ensure that it's being pushed out properly.
 
#3 ·
fp,, brakes. mos 'portant item on any sled.
calipers. take em off . tear them down. rebild them.
master cyl. take it off. tear it down. rebild it.
hoses. old rubber ones. pitch em. get new s/s braided lines.
fluid. drain old fluid. push new fluid in, ALL old fluid out. once a year. maintenance. it cost a few bux and hours. worth it. you will ride better. poncho
 
#5 ·
Be SURE and use only brake specific cleaners and lubes on any braking system. Some brake cleaners are not safe on rubber components as would be acetone.
If the caliper boot covers have been exposed to ANY petroleum products, they will swell and seize the caliper piston. That includes any types of solvents, bearing grease, etc.
 
#7 ·
I used the brake cleaner .. just assumed it's same as acetone.
I didn't know the boots can affect caliper piston movement. If that was the case, what would be the fix? Would changing the boots be a straightforward procedure that would repair the break in that case?

Thanks for the idea.
 
#8 ·
Find out if they don't slide. If so, pull the caliper and grease the slide pins with high temp caliper grease. Make sure everything else looks good while you have it apart.
Poncho isn't wrong - if you have the time and money it's a good opportunity for a stainless line, caliper rebuild, etc. If you just want to get things going though, confirm the source of the issue and repair accordingly.
 
#9 ·
The problem was a stuck caliper! Someone called it here.

I took off the caliper and removed the brake pads. While pressing the brake handle, the piston goes out as it should, but then goes back in after I depress the handle. I know that a healthy setup should push the piston out and leave it there. That's how you keep the brake action strong when the brake pads thin out - the piston will move out to compensate for thinner pads and stay there.

Here the piston gaskets got stuck to the piston and it pulls the piston back in. I looked it up and apparently this happens when the motorcycle is stored for a long time without riding. The solution is to depress the piston back in with a vice - to unstick it from gasket, and then pump the brakes to have it come back out.

Of course at that point I pushed out the piston completely and took the caliper apart. I'm going to rebuild it after the rebuild kit come in the mail. The seal/gasket closer to outside of the piston cavity is a bit warped. So it's a good call to rebuild caliper to prevent further issues.

Quick question: the piston has some rust marks (see photo I took - attached here); it seems that part of the piston stays outside of the caliper cavity, so shouldn't affect anything. In fact that's how it got rusty over the years. But does anyone think it's an issue and piston needs to be replaced? I will attempt to take it off with steel brush.
 

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#11 · (Edited)
I ordered a US made stainless steal braided brake line and banjo fittings to replace the OEM hose. The caliper rebuild kit and master cylinder rebuild kit should also arrive soon. I'm thinking the piston has rust on the part that stays outside the piston cavity (i.e. exposed), thus I don't need to replace it.

This should help get the brakes to peak condition on this bike.
 
#13 ·
As I recall, the brake kit that I got when I rebuilt mine included a new piston, which was a good thing because the original one was heavily corroded. Yeah, for peace of mind, you want everything down there to be as close to as-new condition as possible.

I also wanted to go with a new braided stainless steel covered brake line and fittings but was unable to locate one for an EN500. Anybody got a source/part number for one of those?
 
#14 ·
Stainless lines are a little murky on the 500. The A model used one line, then 96-02 C's used another, and that part number was superceded by the 03-05 number so 96-05 C's are definitely interchangeable. 06-09 C's use a third part number. I have no idea what the physical differences are between each of these. To confuse the issue further, ABB makes a stainless line that they advertise as fitting all A models and 96-97 C models.

Does that make things muddy enough for you?
 
#15 ·
Right! I did order the piston for the peace of mind. $30 for K&L supply aftermarket.

With stainless steel lines I went with universal. I ordered a Goodridge brand SS line - 44" length (I have mini ape bars on my bike; 43" is enough for OEM bars). Also I got the 10mm banjo fittings for each side of the line. And 2 pairs of crush washers (10mm also). The banjo fittings come in angled as well, but I saw someone comment that even the 35degree angled is too much for this bike and straight ones fit better. Goodridge parts are US made and have lifetime warranty. Great reviews too.

I got my parts from JPcycles. Will post results in 2 weeks when all is done.
 
#16 · (Edited)
[Edit:] See the very next reply - fixed the issue described here.

Ok, stuck again!! I have rebuild the brakes per Poncho's advice. As I mentioned above I have rebuild both the caliper and the master cylinder including a new piston in both cases. I also got the Goodridge stainless steel line and banjos. Got the new banjo bolts and washers as well. After cleaning everything and putting everything back together exactly the same way I proceeded to bleeding the brakes. This is where I hit the next wall.

I filled the master cylinder with brake fluid, opened the bleed valve at the caliper and hooked up a plastic tube to the nipple. The several initial pumps burped out bubbles and brake fluid level went down. Any further pumping resulted in nothing - no bubbles and the brake fluid level didn't change. To continue I had to pull in the brake lever and then close the bleed valve, then let go of the brake lever. Then open it and repeat. This purged air and bubbles until eventually no more air came out. Around that time I have accidentally didn't refill the master cylinder with fluid and heard air sucked into the master cylinder.
I figured I will redo the whole procedure, but shortly after I wasn't able to get anywhere. The brake lever has no pressure at all. When I pump it whether with bleed valve closed I see the caliper piston move forward by a millimeter and then move back. I don't understand why it would be stuck like that. When the bleed valve is opened the brake fluid does not flow out anymore. So I can't purge the air.

Is there a specific technique for restarting the process? Also what's the deal with the caliper piston moving in and out as I push the brake lever. It should be moving forward only. Also when I used a channel lock to squeeze the piston back into the caliper, even though the bleed valve was closed, there was no resistance except friction. I'm assuming there's air in the line. But I can't seem to be able to purge it. I don't see any leaks anywhere. They should be obvious. And once again the brake fluid level is not changing at all anymore.

Any similar experiences or words of wisdom? Appreciate your advice.
 
#17 · (Edited)
Solved .. finally!!

I gave it a second shot the next morning. Basically I have physically raised the caliper to the level of the master cylinder with hoses and everything else still attached. I tightened everything up again and began the bleeding process again.

Maybe letting it sit since my first failed attempt yesterday helped or maybe it was the fact that caliper was elevated this time, but after burping out several big air pockets from both master cylinder and caliper, and then pushing through the remaining bubbles, I only saw clear liquid coming out and everything was working as normal. At some point the piston was pushing out because my bleeder valve wasn't opened enough. I pushed the piston back in and continued until I was sure there are no more bubbles. I tapped on both banjos, the brake line, cylinder and caliper with a wrench here and there. What helped also was that I was alternating from pushing in the lever in slowly and pushing it in very quickly. The stronger quick movements seemed to get bubbles out better.

After I reattached the caliper where it belongs and routed the brake line without disconnecting it. Test drive in the garage showed brakes responding fantastic!! I can't tell yet if the stainless steel makes the brakes more responsive, but that's what I've read from other reviewers.

One last note: the stock banjo bolts seem to be made of soft material. The 12mm head on them was damaged as I was taking them off. So I replaced them with aftermarket parts. I couldn't find the spec for those guys, so I had to figure it out by trial and error. Correct spec for banjo bolts is: thread 10mm x 1.25mm pitch, length ~1.2in (although slightly longer or shorter works just the same). Although 10mm x 1.5 and 10mm x 1.0 are popular in auto parts stores, I had to special order the correct 10mm x 1.25 size because they don't carry it in stock.

Photos of the brake line are attached. I cut off a piece outer cover from the old OEM brake line and wrapped it around the new one in the place where it's routed through the bike's clamps so it reduced wear by friction. Great experience!!!

Thanks for all the advice fellas! Next task - flush and replace coolant with Engine Ice to see if I can cool the engine down, otherwise it just feels too uncomfortably hot on the warm summer days.
 

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#18 ·
Good thread and good job, granstan. Great to see you got your front brakes whipped, and thanks for the good information you provided - might come in handy someday. That front brake on the 500 does just about all the work, and I think that's good in fact. You're less likely to lock up the rear drum brake during a panic stop, unlike the rear disk brakes on other bikes, which I dislike.
 
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