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02 R1150RS removed ABS now front brake is mushy

sterob

New member
I recently removed the ABS module on my bike and fitted new Spiegler brake lines all round at the same time.
I have bled the brakes until my eyes hurt, but the front brake still feels mushy....I bought the Non ABS splitter to fit on the front and have a bleed nipple located there as well.
If I pump the lever it seems to improve somewhat, but I am concerned that if I grab the brake in an emergency, there will be a probelm.
Bike has only done about 40k/km but its 16 years old.
Rear brake is fine...just what I expected.

Should I start looking at the master cylinder and look at replacing the seal in that and trying again? maybe it has deteriated with age and the Servos cloaked the problem?
No visible leaks anywhere, I can see.
Steve
 
Before you assume that the MC is bad, I would say that you still have air in the line.

Get a syringe from an animal feed store and a small length of clean tubing that fits onto the bleeder. Connect the tube to the ABS bleed nipple and open the MC cover and bleeder. Push brake fluid into the line at the bleeder up to the master. Air bubbles always go up easier than down. This is an iABS system, right?
 
I've done many sets of Spiegler lines.
Unless IABS (which you say you removed) I always push the fluid up from each caliper to the master first with a syringe.
To finish I conventionally vacuum bleed.


MIqxTqa.jpg
 
Could actually be normal; the ratio on those systems is such that it tends to feel soft when you are stopped even with no air in the system. You may find that when you are riding it, the brakes feel fine.
 
Might be control cylinder

I thought I would chime in with a possible alternative solution... My 2004 RT has Evo brakes, and developed a mushy feel last year. It developed slowly, so it was pretty mushy by the time I decided that something other than bleeding was the culprit. What I found was that the seal on the brake control-circuit piston was not holding full pressure. That is, by replacing the brake-lever system, I returned to crisp brake feel. I researched and found that one can still buy a rebuild kit, although it is hard to find in stock. What I did instead of installing new parts was to buy a used unit off eBay, and cross my fingers that it would be an improvement. I got lucky.

Replacing the brake lever is a PITA, but having an exploded-view diagram helps a lot. And now I have a spare unit that I can rebuild with a new seal if the problem returns -- and keep the bike in service until I have the spare unit repaired.

As an aside, during the research I found some suggestion that the piston seal can be damaged during brake bleeding, by squeezing the brake lever too far, and forcing the seal to bottom out in the cylinder, which causes it to deform. Of course, I would never do such a thing... Well, I can't recall ever doing that. :scratch In any case, the seal on the unit removed from my bike didn't look any different than the one that I installed, so perhaps the damage is subtle.

Cap
 
Yes! I missed the fact that the OP says he removed the ABS system. So, GSAddict is correct. The fluid should be pushed up from the caliper bleed nipple to the Master Cylinder. Air bubbles find it so much easier to go up instead of down.
 
Could actually be normal; the ratio on those systems is such that it tends to feel soft when you are stopped even with no air in the system. You may find that when you are riding it, the brakes feel fine.

Thank you gentlemen. Some good thoughts there.
Anton: It feels just a bit too mushy for my liking....It just doesn't feel right. I will have to look further.


I'll try the syringe trick first. ( I'd not thought of that, but makes perfect sense. )

If that doesn't work, I'll dig further into replacing the MC seal and see how it goes.

GSAddict:
Not sure what the fitting is. Is is a small ball valve?
MIqxTqa.jpg
Steve
 
Thank you gentlemen. Some good thoughts there.
Anton: It feels just a bit too mushy for my liking....It just doesn't feel right. I will have to look further.


I'll try the syringe trick first. ( I'd not thought of that, but makes perfect sense. )

If that doesn't work, I'll dig further into replacing the MC seal and see how it goes.

GSAddict:
Not sure what the fitting is. Is is a small ball valve?
View attachment 72134
Steve

Yes, keeps things clean.
 
I did the 'push brake fluid up from the calipers' trick yesterday and there was no change.
I gently forced the fluid up , from both calipers, and watched the MC the whole time and not one air bubble was seen. I must have push 1/2 of a 100 ml syringe up from both sides.
I assume that would have been plenty.

Brake lever still moves over 1/2 way before any resistance is felt. Maybe I need to change the seals now.
If I sqeeze the lever quickly I get a spurt of fluid coming out of the little hole in teh MC.
Steve
 
If I squeeze the lever quickly I get a spurt of fluid coming out of the little hole in the MC.
Steve

That's normal. Even trying to be careful, I still get the periodic squirt. I drape the entire instrument panel with a large towel to catch the fluid.
 
I drop a quarter over the hole in the master cylinder.

Thanks....I'll have to use a 20 cent piece. :)

I will have another go this weekend.I fitted a splitter onto the steering head and bled nipple and maybe I need to bled from there as well.

I won't know unless it fixes it...lol

If that doesn't work then its new MC seal(s) , I guess.
steve
 
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