Mity Vac II

I took the advice of a previous TT discussion and purchased a Mity Vac II to bleed my wr 400 brakes. It was a hard part to find in Canada at a wopping $90 Cdn compared to $26 US.

After replacing my orignal pads with aftermarket EBS's, I found the brakes soft and in need of a good bleeding. The old fashioned way was not giving me the feel I desired until I used the Mity Vac II. The Front brake works like a charm but the rear is still soft.

The instruction that come with the pump are not clear on the PSI to use and if you should close the valve after so many seconds of vacume assist bleeding. Am I supposted to leave the Valve open and continue bleeding or am I supposted to close the valve and bleed like normal? The book is not very detailed.

Can anyone tell me there hints and tricks with the Mity Vac II?

Or am I stuck with spongy rear brakes?

I bought a Mity vac on my last trip to San Diego. Purged my brakes last night but I had a bunch of bubbles enter the pipe every time I pumped her up. I read in a mail that tefloning the threads of the zerc/nipple is recommended. Is it to excatly do that ie eliminate sucking bubbles.

The only way I could purge either of my brakes was to apply the mity vac get some vacuum and then pump the pedal or lever to get some fluid flow.

Yes, definitely teflon tape the threads to eliminate air bubbles entering the stream! I think it also makes a difference depending on what aqdapter you use to connect the hose to the nipple. The caps never work for me. I use one of the cone-looking thingies that plugs into the nipple. That seems to provide a better seal.

To test the connection, pump the vacuum up to the top of the scale. It should hold pressure easily. If it doesn't, check the connection and/or use a different connector until it can hold pressure for a reasonable time (~30 sec before you have to pump it again). Once you get the connector sorted out, keep the pressure up by pumping it every 30 sec or so and just crack open the bleed nipple a little at a time. Pumping the pedal/lever also helps. I pump the pedal/lever while watching the reservoir for bubbles. Once bubbles stop coming into the reservoir, then I start with the vacuum pumping/bleeding. Remember to keep an eye on the reservoir because that thing sucks it dry quickly.

The Teflon tape only helped a little. A Mechanic at one of the shops used to use the Mity Vac until he purchased a Air Comp which is the ultimate way to bleed the brakes. He told me to Squirt a little lube oil into the Mity Vac so that it lubes the seals. It worked pretty good and now it keeps it's pressure build up. Another hint is to take small Zip Ties and secure your connection, being careful not to brake your plastic snibbs. Zip tie the bleed hose to the bleed screw for extra sealing just to make sure no air gets in.

Pump your brake and hold it down.

Pump it to the Max and just barely crack your bleed screw.


Last step.

Replace your resevoir cap and bleed one more quick time.

My front and rear brake are now working awsome. I can now pull front brake stands with ease when the other WR's can't.

Bleed away.

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