very mushy front brake

[greg maz]

it won't stop the beast, and I mean even at stand still

when pressed, the lever gradually sinks

I just changed liquid which was black (rear is still clear but just as old), did the 24h pressed lever trick to get rid of bubbles, no change.

Could it be the rubber seal travelled on the piston (by the brake lever)?

I don't remember the front solo brake of the xj being so lame, shortly after fully pressing on the lever, the wheel is free

don't torch me, I know, I'll have to dismantle it, just what should I be looking for?

[dpotter58]

Did you have the problem before changing the fluid?
Did you bleed the whole system?
Is there fluid leaking out of the caliper?
Is your master cylinder working?

[TopCatGr58]

Hey Greg,

You say you changed the fluid. Did you just remove it from the Master Cylinder, and put in fresh? As DPotter asked, did you BLEED the brake lines. The 24hr pressed lever trick is when putting a new MC on, and trying to get the bubbles out of the very end of the descending brake line and end of MC.

Air compresses quite a bit, and so IF you have air in the lines, yes, you could easily have the lever continue to compress as the air is squeezed in the lines. Also, if you have the OEM lines, they are also very pliable, and stretch under pressure. I had what I assume was an XJ MC on my bike with the OEM lines and driving 2 calipers, and with proper bleeding and such, I had to pump the lever a time or two to get a good response on the front brake, and still had to squeeze the lever almost to the grip!

Then I put on SS lines, and now it's rock hard with only 1 squeeze, and have room between lever and grip/fingers!

T.C.

[greg maz]

no leaks, mc working, it has been like that for a good 4 months - xj have linked brakes as you well know so it is ridable, I noticed the decreased perf & the dark color so decided to take care of it by replacing fluid and bleeding.

Sounds like it's not the rubber plonger but a combination of a mean bubble plus original line (ss line are about a buck, ain't they?)

is there a better way to bleed, and what would explain the difference in color between the fluids of the 2 mcs?

thx for replies - long time no hearing from you guys, the bike has been that good

[dpotter58]

I have 81 midnight special and i think the brakes are set up the same way as yours. The hand lever only works the right front, correct? Have you looked at the tech tips or searched for bleeding advice? There's better info on here already than I could write for you.

[TopCatGr58]

Hey Greg,

You can't necessarily rule out the MC plunger. If there was enough crud and such in there, then it could have damaged the edges of the plunger while trying to use it.

Back when I did work on old cars, a classic sign that the MC was damaged/leaking around the piston rubber was when you would push the pedal, get pressure, but then it would slow depress down, as the fluid would leak past the plunger seal back into the MC.

Hopefully it's the need for a good bleeding instead!

But if the MC was all cruddy, the same stuff is down in the caliper, and you may need to remove, disassemble, clean it as well??
T.C.

Yeah, buck plus $30 or so for a single line with 2 fittings!

[greg maz]

I think you hit it TC, you described it better than I could.
I cleaned the whole system last winter when reviving the bike, followed every tech tip I found or got - not that I wanted to at first, but still used old to rebuild old.
xj front brake lever commands single right front brake
should I get the plunger on ebay?

[Ivan]

The part about it being black is what caught my ear. I know this may be too elementary, but there wasn't any ATF or other type mineral oil in it was there? mineral based oil is not good on the brake system. Usually Black fluid meant ATF in the system when I was wrenching cars. It would make the rubber spongy and the supposition was that some of it dissolved into the fluid turning it black.

[greg maz]

could you explain ATF?
thx

[petejw]

could try bleeding the mc

ATF, auto transmission fluid,

You can also try bleeding the master cylinder,
if its on the bike, wrap a rag around the bango bolt
so u dnt spill any fluid, while depressing the brake handle
slowly crack the banjo bolt, if theres air in the line
you'll notice it,b4 the lever touches the grip tighten the
bolt, do this til no air in the system.

how did u go about bleeding ur system?

[greg maz]

that's what I thought atf meant, but wasn't sure, how could I mix up some of it with the dot3. I am crafty but... well u never know, at least I've learned something new.
Regarding the bleeding procedure, didn't do nothing fancy but squeezed lever opened drain and locked before end travel until no sign of air. Read about the banjo bolt trick, you described it a tad better and I will try tomorrow. Helpful.

[greg maz]

cracked banjo bolts, helped a lot

would make a remark as far as filling the reservoir, do observe that fill line and get a little under as the overflow seeps out and in the screw holes (cover mount)

[Dan Hodges]

Front Brakes

Hey Greg,

You can't necessarily rule out the MC plunger. If there was enough crud and such in there, then it could have damaged the edges of the plunger while trying to use it.

Back when I did work on old cars, a classic sign that the MC was damaged/leaking around the piston rubber was when you would push the pedal, get pressure, but then it would slow depress down, as the fluid would leak past the plunger seal back into the MC.

Hopefully it's the need for a good bleeding instead!

But if the MC was all cruddy, the same stuff is down in the caliper, and you may need to remove, disassemble, clean it as well??
T.C.

Yeah, buck plus $30 or so for a single line with 2 fittings!

Two years ago when I started messing with my Eleven again the front brakes started dragging and I rebuilt the front calipers with Yamaha OEM rebuild kits. The calipers were totally funked out. I cleaned them up and put all back together and bled the system and I was good to go. This fall they started dragging again. I took it from the MC down this time and rebuilt the MC using OEM Yamaha parts including a new MC diaphragm. The MC was pretty cruddy particulary at the front of the piston. I used Goodrich Stainless steel lines and fittings and rebuilt the calipers again with new OEM Yamaha kits which were again full of crud causing the caliper pistons to stick in the bores. I didn't bench bleed the MC (big mistake) and it took 12 ounces of fluid to get them bled but I've got a killer rock hard pedal now the first squeese. I had a good hard pedal with the stock lines but the Goodrich SS lines and fittings sure look trick and they won't funk out on the inside like the stock rubber lines. The original stock lines looked good on the outside but when I blew them out they were full of brownish funky fluid also. I can speak from this experience, it's a waste of time cleaning and rebuilding the calipers without rebuilding the MC and replacing the lines as you will only have to do it again because of all the crud in the system. You can pay now or pay later, but you gotta stop.

[greg maz]

I know it's coming...
as TC said, I have the old system failure, you need to keep pumping.
It is now a problem of cash flow.
How much and where?

[Dan Hodges]

Brakes And Tales Of Woa

I know it's coming...
as TC said, I have the old system failure, you need to keep pumping.
It is now a problem of cash flow.
How much and where?

I purchased the caliper rebuild kits from a Yamaha dealer and they were $56.00 ea.(per side). The MC rebuild kit was a few bucks more than one of the caliper kits but I can't remember how much however the diaphragm was $18.00 by itself. I also purchased a new Yamaha brake light switch just for good measure because my switch is the original. I used the Goodridge coated stainless lines and they were $23.00 ea. from Dennis Kirk. The adapters are $9.99 ea., the banjo bolts are $5.99 ea. and the one double banjo is $7.99. The copper crush washers are $4.00 per pack of 6. Last year I installed a new rear MC I got from my dealer which was the last new Yamaha rear MC in the world for this model I suppose that you could buy as they stopped making them some time ago. Brakes are a pain and are one of those unglamerous things that no one likes to deal with but they are one of the most important aspects of your bike. Mention is made that my top MC looks new from the outside and wasn't nearly as funky on the inside as the rear one was and I suppose this is because the front one is on the handlebars and doesn't see the water from the road like the rear one does. I cleaned the bore of my original front MC with a cleaning kit that was designed for one of my shotguns using the nylon brush and cloth bore swabs of the kit and it turned out slick. The nylon brush is course enough to remove the old funk that seems to accumlate in the end of the cylinder bore yet is not so still that it scratches the aluminum. After finishing my cleaning I checked the MC bore with my dial bore gauge and it was dead nut on after which I installed the new Yamaha rebuild kit and now it's new again and ready for years of more cruising the highways and byways. Save your money, get your parts and do it right the first time.