Front Brakes and Bleeding Help

[Eddie]

So anyway, my front brakes had been feeling as tough they were putting sufficient pressure and they seemed to be a little stuck as the front wheel did not spin freely in released position. So I decided to clean my caliper pistons and bleed my brakes.

Turns out I was correct and a couple of the pistons were stuck. Problems started to arise when while spinning the pistons to clean one of them came off and I lost some brake fluid. So I went to autozone, got some dot 3 brake fluid and one of those Mityvac brake bleeding kit.

One of the calipers seem to have no air, but the one whose piston came off seems to have some air in. I spent about an hour pumping the hell out of that brake line and refilling the fluid and while I can tell that I got some pressure (which I imagine if to the caliber whose piston did come off) I can tell that I still have air in that line.

I understand that if too much air is coming out of the bleeding tube than I might have air coming in from the outside (which is a big no no). However, since I lost a lot of fluid when the piston came off I thought I makes sense that I have to spend a lot of time bleeding the line.

Nonetheless, my neighbor happens to have one of those air compressor brake bleeders, which I think is the best thing to try next. I'm hoping that bleeding the line with the air compressor tool will solve my bubbly problems.

Nonetheless, I was wondering the following:

1. When I was cleaning the caliper pistons I inadvertently pressed a couple of pistons from the outside and left a small mark of those pistons. Can you take a look at the attached pictures and let me know if they could be the cause of air coming in? I have not noticed that I'm loosing fluid through the pistons (or anywhere in the line for that matter) so I suppose that that is a good sign.

In short, I believe I have pressure on the caliper whose pistons/lines remained intact however I believe that the caliper whose piston came off is the one that still has a lot or air in. I am hoping that neither one of the calipers have leaks but I'm unsure how to diagnose that other than looking for fluid leaks.

Thanks a lot,

Eddie


Also, there is a small nick on the outer plastic of the steel brake line so I'm not sure if that could be relates in some way. There is no leaking observed at this point.

[wesvailco]

-dust covers on pistons? sometimes they'll pinch if not seated properly.

[Eddie]

-dust covers on pistons? sometimes they'll pinch if not seated properly.

Will check. Thank you. I thought I did a pretty good job cleaning those pistons.

[Falko]

why were the pistons stuck?

[Eddie]

why were the pistons stuck?

Not sure. I think they were dirty. After cleaning they were fine.

One of the auditors here at work just pointed out that when you loose fluid like I did, you should pump fluid in through the lower valve while the valve above is open. And that will push the air out through the upper valve. I'm going to try that. I'm praying that that will work

[CBR929RE]

try pushing the pistons all the way in and put a piece of wood or some cardboard in between there. take up as much space in between the pads are you can so that you have less air trapped in the caliper to try to get out.

and the covering on the line won't allow air in. SS lines are actually 3 lines inside each other. the outer cover, SS braided then another hose inside that actually carries the fluid.

[Paul_E_D]

Yes, definitely reverse bleed with a syringe. Did you actually mar the chrome pucks? That's some hard metal. Did you grab it with channel locks or something? If those bite marks can be felt with your fingernail, they will potentially damage the seal causing fluid to leak out. If you're lucky, they are too far out to damage the seal. Time will tell.

[Eddie]

Yes, definitely reverse bleed with a syringe. Did you actually mar the chrome pucks? That's some hard metal. Did you grab it with channel locks or something? If those bite marks can be felt with your fingernail, they will potentially damage the seal causing fluid to leak out. If you're lucky, they are too far out to damage the seal. Time will tell.

I just marked the chrome on the very edge - I'm hoping that the part that I marked does not go into the seal as the piston does not retract all the way. I can actually barely feel it with my nail. Thanks.

[Paul_E_D]

take a scotchbrite pad or steel wool to the pucks to polish those out.

[Falko]

Block the pistons, reverse bleed, then pressurize with the handle and see if you get leaks around the pistons.

[Eddie]

try pushing the pistons all the way in and put a piece of wood or some cardboard in between there. take up as much space in between the pads are you can so that you have less air trapped in the caliper to try to get out.

and the covering on the line won't allow air in. SS lines are actually 3 lines inside each other. the outer cover, SS braided then another hose inside that actually carries the fluid.

Thanks a lot Brett. I will do that. Remember how you were saying that my bike felt heavier than your bike? I noticed that the front wheel would not travel freely so it made sense to check the calipers. And sure enough a couple of those pistons were stuck.

I'm going to try to do the following:

1. Push some wood or cardboard in between the pistons as to drive them inside (as per your suggestion;
2. Make sure that the pistons are not damaged;
3. Push the fluid up via the bottom valve with an oil pump;

I already have a call to Degsy, so if all else fail I'm sure Degsy would be happy to take at look at them.

[Eddie]

Block the pistons, reverse bleed, then pressurize with the handle and see if you get leaks around the pistons.

Sounds like a plan. Thanks Falko!!

[Eddie]

take a scotchbrite pad or steel wool to the pucks to polish those out.

All right...all right!! Thx...



Thanks a lot to everyone who pitched in and provided advice. You guys are awesome. I'll provide an update tomorrow after I perform the work tonight.

[Eddie]

Okay guys, I tried all that a couple of nights in a roll and I'm still not have much success. The lever still feels a little mushy however at least I have some compression.

I suppose that the next thing we will try is a compressor bleeder which my neighbors are willing to assist with.

[keeena]

I know its too late, but in the future I wouldn't spin the pistons in an attempt to clean them. The areas which are tougher to access are cleanable by flossing using a strip of rag/paper towel/etc...soaked in brake fluid (assuming you're not planning on popping the pistons out).

I personally only use vacuum bleeding or forced injection for initially priming the system. If you have compression w/ the lever, those things shouldn't really be necessary. Trying can't hurt though.

Do you have a bleeder on the M/C? If so, give that a crack to make sure no air worked its way up there.

If you can, get the bleeders at the very highest point (lower M/C and/or raise calipers). Tapping the calipers w/ a rubber mallet might help free up air pockets and get them to move.

[Paul_E_D]

Before you go to more trouble, just zip tie the lever overnight and see if it's better in the morning...

[The Snowman]

Also, if you have a very soft rubber mallet, tap everything in the system (calipers, MC, even brake lines) and try to drive all trapped air out of its crevices.

Degsy helped me with my SV's caliper rebuild a couple of months back and after you seem to get all of the big bubbles out, crack each bleeder and continue to pump the brake handle, slowly, never hitting either full in or full out stop and watch the bleeder for tiny bubbles or trails for really tiny bubbles.

While doing that, don't forget to watch the fluid level in the reservoir.

Also, crack the banjo bolts and let fluid run out of them to possible allow trapped air to escape from there as well.

[Eddie]

Before you go to more trouble, just zip tie the lever overnight and see if it's better in the morning...

Thanks again Paul. One last thing...do I have the leave the master cilinder valve open when I do this? Cheers!!

[Eddie]

I know its too late, but in the future I wouldn't spin the pistons in an attempt to clean them. The areas which are tougher to access are cleanable by flossing using a strip of rag/paper towel/etc...soaked in brake fluid (assuming you're not planning on popping the pistons out).

I personally only use vacuum bleeding or forced injection for initially priming the system. If you have compression w/ the lever, those things shouldn't really be necessary. Trying can't hurt though.

Do you have a bleeder on the M/C? If so, give that a crack to make sure no air worked its way up there.

If you can, get the bleeders at the very highest point (lower M/C and/or raise calipers). Tapping the calipers w/ a rubber mallet might help free up air pockets and get them to move.

Thanks brother. Actually the whole thing started with me noticing that the brake felt somewhat muchy and I also noticed that the front wheel wasn't spining freely. So I cleaned the pistons just as you explained. Sure enough they were stuck. While cleaning the pistons one of the pistons came off and I lost fluid and allowed more air into the system. I will try your suggestion if all else fails.

Also, if you have a very soft rubber mallet, tap everything in the system (calipers, MC, even brake lines) and try to drive all trapped air out of its crevices.

Degsy helped me with my SV's caliper rebuild a couple of months back and after you seem to get all of the big bubbles out, crack each bleeder and continue to pump the brake handle, slowly, never hitting either full in or full out stop and watch the bleeder for tiny bubbles or trails for really tiny bubbles.

While doing that, don't forget to watch the fluid level in the reservoir.

Also, crack the banjo bolts and let fluid run out of them to possible allow trapped air to escape from there as well.

Thanks a lot Chuck. While bleeding with a manual pump I did allow for the fluid to ran out...just my luck. Had to restart from square one. I suppose that bleeding is a very meticulous process.

[Ray-Ray]

Let me know if you need help Eddie, Im right up the street

[Eddie]

Let me know if you need help Eddie, Im right up the street

Sounds good Ray. Thank you!! What's your availability like this week? Btw, when are we going to see your gixxer trackbike?

[Ray-Ray]

Sounds good Ray. Thank you!! What's your availability like this week? Btw, when are we going to see your gixxer trackbike?

Well this weekend im booked. Im helping another member of the forum with his bike all day Sunday. But I'm free Friday! The bike should be painted and decals installed the week before the classic

[Paul_E_D]

Thanks again Paul. One last thing...do I have the leave the master cilinder valve open when I do this? Cheers!!

No, there's a pinhole breather in the cap that allows the bladder to move as air comes out of the fluid.