Help Please....Problem Front Brakes

I've just drained all the brake fluid from the front caliper of my '99 WR400 and for the life of me can't get the bluddy thing to bleed properly. I fill the master cylinder (not to the top) then bleed the brakes as per the manual but can't even get any pressure up. The brake lever just goes full travel. Dunno what to do. Haven't had this happen before and any ideas/fixes would be a big help.


[ November 26, 2001: Message edited by: Pip ]

route your brake pipe so that the highest point is the mastercylinder and not the loop at the top of the pipe.

fill with fluid.

remove the caliper.

pump open both pads and watch air and fluid re-enter the m/c. pump the brake up (checking the fluid levels) and then leave it with a strap pulling the lever hard to the bars.

leave overnight.

undo strap and more air will vacate.

now pump open the pads to their limit once again.

you now have perfect brakes.

re pump to close the pads.

now undo the banjo bolt, quickly place pipe at correct angle and re-tighten.

quickly open pads again to limit.

pump brakes up again.

you're done.


Another trick, the infamous Clark Mason shared w/ us, is to pump the fluid in from the bottom. I used this trick while working on a Honda Quad that I could not bleed (brakes still on the machine).

I used a turkey baster with a length of tygon (clear flexible) tubing attached to it. I held the turkey baster high up with the end of the tubing attached to the bleed valve which was open. Very gingerly, I squeezed the baster bulb (otherwise it would have popped right off due to the back pressure/resistance for the fluid to pump into the brake system). Like a charm, TREMENDOUS amounts of air came out of the reservoir. Realize, you may have to remove some of the fluid out of the master cyclinder if it gets too high.

Any loops in the brake line should be removed to allow the fluid to rise up naturally to dispell the air.

I did bleed the brakes normally after this to ensure everything was satisfactory.

Sounds like something I used to do on my mountain bike (hayes hydraulic brakes) only I used a SYRINGE with a tube added to it instead of a turkey baster.

Just make sure the system is open at both ends or you end up spraying fluid all over everything when the pipe pops off of the bleed valve!!! Did I say that happened to me ? Did I ?

The problem may be that the rubber bladders in the master cyclinder either are worn or have a hole in them. I had the same problem with my 99's rear brakes. No pressure no matter whaat I did. I finally broke down and took them apart and found that the washers were almost totally gone. The parts come in a rebuild kit that cost only a few bucks. It only took about a hlf hour to take everything apart and put it back together again. Just follow the directions in the owners manual. Hope this helps.

Thanks guys,

Just finished work so I'll try the "backflush method" first and see how that goes. Again thanks for the help.

Phil :)

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