"Spongy" lever on front brake....?

[Jammerkiller]

Hi guys,

I've been lurking around this forum for right at a year now. Thought I would finally say "Hi" and ask for some advice.

I've been working on these EX250's for several years. I currently have 3 in the garage. ('98,'04,'05) I just recently picked up the '98 for a project for my 18yr old son. His brother (21 yr old) has had his '05 Ninja for over 4 years now. Something that I have not been able to completely "master" is the front brake bleeding in order to get that "firm" feel. Both my '04 Ninja and the older son's '05 have rebuilt calipers with new seals, rebuilt master cylinders with new parts, S.S. lines, new washers and new EBC pads. (FA 129HH) We have bled new DOT 4 fluid from the cylinder through the line and into the caliper using multiple methods (pump/squeeze/open/close method, Mity-vac method, overnight compressed lever method, tapping the line to get air towards the cylinder method, etc., etc.) and I still get a slightly spongy feel from the two, newer bikes. I noticed that the '98 must have all original parts on the front brake, because its lever is very firm compared to the other bikes. The funny thing is, I have rebuilt the front brakes on my VFR750 a few years ago with all new parts and S.S. lines, and when I bled those brakes, I got a very firm lever from that bike, no problem.

So, besides the obvious methods that I've tried, is there something else that I may be missing? I did read how it may take multiple tries with the "compressed lever overnight" method, before it actually firms up. I have searched the net (and this forum) for brake bleeding info, and pretty much come up with the same methods, over and over. Just curious to see if anyone else has had this problem and what their fix was.

Thanks to everyone for their time in reading this. It would be great if someone had a different approach to this problem.

BTW, I'll post a pic of my '04 racer, if I figured out how to upload....

[ForceofWill]

My guess is that the re-manned master cyls suck. I went through 3 on my supra and never got back a good feel like stock.

[GeorgeRYoung]

Make sure the two little holes at the bottom of the master cylinder are clear, a toothpick works well. Considering you have been bleeding the system, they're probably clear already.

Turn the bars so the master cylinder is at its highest point.

With the caliper bleed valve CLOSED, gently squeeze the brake lever until you see some bubbles rise up through the holes in the master cylinder. Let the brake lever snap back. Shoogle the bars back and forth a bit. Repeat until you see no more bubbles.

In my opinion, the caliper bleed valve is only to release air trapped in the caliper that can't rise to the top. Gravity makes bubbles in the line rise. It has always seemed counter productive to try to chase line bubbles out the bottom. And, yes, I've done this multiple times, starting with new empty lines, and it works for me.

[dcj13]

Welcome!

After performing the above procedure, follow it up by placing the bike on the side stand, squeezing the brake lever fully, and strapping the brake lever in that state and leaving it for a day or two.

Then remove the strap (can also use huge rubber bands) and see how it works.

[ForceofWill]

The reason I say crappy re-manned master cyl's is because he said he's already tried all that stuff and it seems like he knows wtf he's doing with brake bleeding. My front took a lot of pumping to get firm but no more than 20 mins. After all of the stuff you've tried I can't think of anything else.

If you feel like breaking it all down again you could try and swap the good OEM master onto one of the other bikes and re-bleed and see if it works.

[Racer x]

If all else fails remove the caliper and raise it above the master. It is hard to push air down hill. Also don't pump the break lever fast. It will foam up the fluid.

[baz666]

There's a new gadget that attached to bottom end of the brake hose and drawn air downward rather than trying to push it down from above. I've read good things about it. Sorry I don't have the official name but I saw it on the Dennis Kirk site and I'm thinking of buying one myself since this brake bleeding business can often be a pain in the butt. And it's not pricey.
I'll let you know the name when I find it again.

[dcj13]

Originally Posted by baz666

There's a new gadget that attached to bottom end of the brake hose and drawn air downward rather than trying to push it down from above. I've read good things about it.

Mighty Vac ("A handy little sucker") does a good job (not all that new...). The only problem is the tiny air bubbles from the bleed-nipple-to-caliper interface. Speed Bleeder sells a thread compound (it's included on the threads when you buy Speed Bleeders) that takes care of that annoyance.

One can also make their own pressure bleed system out of a garden sprayer (I haven't done this yet) to pressure bleed the system from the master cylinder.

[dcj13]

Originally Posted by ForceofWill

The reason I say crappy re-manned master cyl's is because he said he's already tried all that stuff and it seems like he knows wtf he's doing with brake bleeding. My front took a lot of pumping to get firm but no more than 20 mins. After all of the stuff you've tried I can't think of anything else.

If you feel like breaking it all down again you could try and swap the good OEM master onto one of the other bikes and re-bleed and see if it works.

Bad master cylinder is a possibility. My experience (albeit limited, as a shadetree mechanic) is that a bad master cylinder either doesn't pump up pressure at all, or pressure can be pumped up to seemingly normal with a few strokes of the lever (or pedal, as the case may be) before going limp again after sitting for a while. I've never seen one "partially fail" as described. But I'm sure it's possible.

Another thing to consider is a bad hose from the MC to the caliper. Could it be soft and expanding slightly in diameter as one squeezes the brake?

[ForceofWill]

Originally Posted by dcj13

Bad master cylinder is a possibility. My experience (albeit limited, as a shadetree mechanic) is that a bad master cylinder either doesn't pump up pressure at all, or pressure can be pumped up to seemingly normal with a few strokes of the lever (or pedal, as the case may be) before going limp again after sitting for a while. I've never seen one "partially fail" as described. But I'm sure it's possible.

Another thing to consider is a bad hose from the MC to the caliper. Could it be soft and expanding slightly in diameter as one squeezes the brake?

I had it happen a couple times with re-manned in a car. He said he's using SS lines.

[Jammerkiller]

Originally Posted by ForceofWill

My guess is that the re-manned master cyls suck. I went through 3 on my supra and never got back a good feel like stock.

Thanks for all of the replies.

Just to clarify, (ForceofWill) I rebuilt the original caliper and master cylinder with OEM Kawasaki parts. (from Cheapcycleparts.com, I think...) It's not a reman unit from a store, sorry for any confusion. When I removed the old parts from the cylinder and compared with new, they were identical, and didn't lead me to believe they wouldn't do the job. Yet another reason why this whole ordeal is irritating as hell... and I'm sure it's annoying to you guys, too.

dcj13, I do have a Mighty-vac and did use it. What you mention about air bubbles coming in through the bleeder valves threads is exactly true. I didn't think to use any type of thread filler or tape when I put the caliper back together. (I should have done that ) Also, you mentioned possible bad lines from cylinder to caliper. My S.S. line was manufactured new at a local brake shop, with all new parts. (sleeves, line, banjo ends, etc.) This is why I'm going nuts trying to figure out why the brake is not working properly, especially compared to a 16 y.o. bike with stock components that has more "feel" than my completely and newly built system on my '04.

Plus, to top it all off, I also did a complete rebuild on the rear brake. It works just fine. ...Once again...

I will try you guys' bleed ideas and overnight lever method again, today. I'll let you all know how it goes.

Thanks again for the replies...

[dcj13]

Any chance the new front SS brake line is just a tiny bit squishy? (In the BMW bike world, that's been known to occur). It's longer than the rear line, so there's a greater opportunity for volume growth under pressure.

[Jammerkiller]

If by squishy, you mean I can pinch the line and it will give a bit? Then no, it's firm. I did try raising the caliper above the cylinder and bleeding afterward. Also tried squeezing in the pistons on the caliper to force any trapped air towards the cylinder and then re-pump to fill the caliper with fluid. Still no change.

[fast1075]

When I installed the SS line on mine, the old pump/squeeze did not work well. What got it done was the gravity bleed. With the cover off the MC, crack the bleeder (use a piece of vinyl tubing on the nipple to keep from having a mess) and just let it drip all on it's own. Do not pull or compress the lever. Just keep an eye on the fluid level. Be generous with the fluid, it takes a while.

[csmith12]

Welcome Mike! Nice machine you got there. Good luck getting your brake sorted.

[Jammerkiller]

Thanks guys! Currently I've had a clamp on the lever since yesterday. I'm going to leave it on until Wednesday and see if that helps. I'll tap the lines and parts with a screwdriver, every now and then, to try and dislodge any bubbles.

[r6boater]

We ran into a similar issue on Draik's race bike. We did a complete front brake disassembly, clean, reassemble, new pads, & bleed. Everything was good...so we thought... he went out for the first session of practice and noticed the brakes felt squishy. Checked everything out... the glue that held on the friction material to the pad back plates was bubbling out from behind the friction material. Luckily we had the old pads and switched them out. Problem solved... the suspect pads were EBC and the old but good ones were Vesrah.

[ktp1598]

I have the same problem with my sportster AND my 250 so I'll be watching this one. The sportster has a new SS line and the 250 is all stock. I'd say I have 75-80 percent of what I should have. Mighty vac't it and all.

[triumphtriple]

I am having the same problem. I can't figure it out. I think its coming from the master cylinder. I can't get any air at all out of the caliper.

[Jammerkiller]

Okay, here's what I did.....

Like I may have mentioned in an earlier post, I "clamped" the brake lever against the grip to hold the brake for 2 days. On the 2nd day, I released the lever and retried the lever action. I would be lying if I said that I felt a difference after the 2 day treatment, but I did get an improvement after this next step....

With the lever released, I removed the caliper from the fork/rotor. (some 'twisting' may be needed in the case that you may have a slightly edged rotor.) After doing so, I followed what someone else did and pressed in the pistons by hand (use a glove to keep pads clean) forcing fluid, and maybe some trapped air, back into the line and MC. (watch your reservoir level!). Then, hold caliper in different positions while "smacking" it with a plastic handle or rubber mallet, etc. to dislodge any stuck air bubbles into the line, or into the bleed valve area. Then, re-attach caliper to fork, being careful to hold caliper in it's upright position as you re-attach it so you can re-bleed at the valve. From here, work the brake lever until the pads contact the rotor, and "pump/squeeze/bleed" at the caliper's bleed valve.

If there were any air bubbles in the line, they would have been sucked back into the MC reservoir while I was pumping the pads against the rotor. Also, with the caliper in the upright position while pumping, any trapped air at the valve had no chance to go anywhere else except stay there until bled out.

This is a bleeding method that actually used several different techniques. I did NOT use my Mighty-Vac on this second try, as you can introduce air bubbles back into the caliper through the threads of the bleed valve. After doing this, I can honestly say that it feels better, and more "firm" when pressing the brake lever. However, my '98 Ninja with old fluid and original brake line still feels firmer and engages a bit quicker.

Many thanks to everyone who contributed their ideas and methods to this repair. Very much appreciated! If any of you are in my area anytime soon, I'll buy you a beer at Barrio Brewery for the assistance.

Thanks again and good luck to all,

Mike in Tucson.

[dcj13]

Good news!

I'll put that strategy in the memory bank. Thanks for the update.

[agentbad]

I guess I am too late but I just bled my brakes getting ready for the spring and the tube into a bottle method works well. They were a little bit weaker after so I did the zip tie trick and pinned the lever to the throttle and left it over night. Brakes feel so much better with the fresh fluid now. In the future I might just get a speed bleeder since they aren't that expensive.