Bleeding front brake 1978 GS1000

[jskellington]

Just installed Russell steel-braided front brake lines for a single disk GS1000. Followed instructions, primed the lines with an eyedropper filled with fresh DOT3, torqued the banjo bolts and now I'm having a devil of a time getting the air out of the lines. I've tried the usual method with no success. Then I attached a vacuum pump to the bleeder screw. Got some sputtering small amounts of fluid interspersed with lots of air, but haven't been able to draw out a steady column of brake fluid.

The sky's blue, the air's warm . . . I wanna get back on the road. Anyone got any ideas?

Thanks,

Jack

[KEITH KRAUSE]

A fellow GS'er made a topic that may help you.
Go to the "Tips and Tricks" section and look for "Priming the front Master Cylinder". If you try it, do us a favor and let us know if it worked .

[Anonymous]

the vacuum bleeder should work well if you are getting a lot of air where is it coming from. don't have the bleed screw too loose, can suck air around thread. if you have someone to assist get them to slowly pump lever about 1/2 way in a few times while you keep up the vacuum. if your vacuum bleeder is o.k you should no get extra air only what is in the system.. that all i tell you from this distance
ozman

[QuaiChangKane]

This might help:

I just changed out my front master cylinder for a Katana unit. To drain the system, I used a 1/2 qt. Mason jar. Easy enough, just attach som clear hose, loosen the bleed screw, and pump until no more fluid comes out. But watch the hose, because when it's almost empty, it will suck air back in if you pump and release while the bleeder is open. So pump and hold, loosen the screw, tighten the screw, pump and hold, loosen, tighten, etc.

I had a stall when I got the new m/c put on - it wouldn't pressurize. Then I realized that the same holds true when pressurizing - if you pump and pump and pump while the bleeder screw is open, you'll just suck air back into the lines. So, pump and hold, open the screw and let the air out, then close the screw, THEN release the handle, pump and hold, open screw, close, pump and hold, open, close, etc. - Just don't release the handle until you've closed the bleeder screw - and make sure you don't suck the master cylinder dry while you're pumping away (you'll just suck up more air)!!!. After figuring this out, it was just a few cycles before I had usable pressure.

I saw a vacum bleeder, but couldn't justify the cost. I used a 6-dollar bleed kit from the auto parts store - it was a 2' length of clear hose, and a 4 oz. plastic bottle with a hose inlet in the cap, plus a magnet mounted to it. The magnet will fit right onto the frame, and the bottle will fit between the header pipes. This way, the bottle stays higher than the caliper and all air bubbles will rise into the bottle instead of staying around the bleeder valve (to be sucked back in when you loosen the screw).

After doing the first caliper, I bled the old fluid out of the second caliper, then bled the anti-dive. Since the front fluid looked like Log Cabin syrup, I bled the rears, too. Not as good as an SS brake line swap, but definitely better feel. Plus, I'm not using a 20 year old front m/c any more, and the new one has a 4-position adjustable brake lever.

Sorry for the wordy post!!!!


-Q!

[jskellington]

Well, as usual, my brake-bleeding problem was entirely self-created, so as I stand before the jury of my fellow GS riders, this is my confession:

I am a complete idiot.

In about the third consecutive hour of pumping the Mityvac (if nothing else I've developed a lethal grip) and continuing to draw huge bubbles and paltry amounts of brake fluid out of the bleeder screw, it occurred to me that the air had to be coming from the master cylinder. In particular, my attention focused on the diaphagm, which had turned itself inside out from the suction, forming a kind of bowl into which I (massive cringe) dutifully poured additional brake fluid when required. Meanwhile, below the diaphagm, the hole at the bottom of the master cylinder reservoir happily gulped huge amounts of atmosphere.

Worse, this was pointed out to me by a CB-1 riding friend who came by for dinner.

Anyway, the humiliation has mostly dissolved. My brake fluid has gone from an evil coffee color to something like expensive tequila, the brake lever is firm and I'm about to punch the starter button and go test the feel of those steel-braided lines . . .

. . . but before I go, thanks to everyone for taking the time to offer intelligent suggestions to this dimwitted mechanic. This forum is great!

Jack

[QuaiChangKane]

Ride-on, Jack.



We'll have to hook up sometime - I pass through Oakland at least once a week....



-Q!