flush brake fluid, which bleed screw to use?

[debby]

Brutus needs fresh brake fluid. The old stuff looks like used motor oil. I think PO was more into polishing than turning wrenches. I suppose that's why he bought a Hardley

The front is easy enough but on the rear caliper there's two bleed screws, one on each side. Would I need to use both screws (if so, which one first)? Or just use one (if so, which one)?

Debby
Brutus - 79 GS1000N
Suzy - 77 GS550B

[tfb]

Use both bleed screws. I don't think it makes much difference which one you bleed first (unlike front brake set-ups with 'antidive' units, which should be bled in a proper sequence).

What you have on the rear of your bike is a twin-piston caliper, hence the two bleed screws. Use both of them to flush fresh fluid into each piston cavity.

Mike.

[Mr. Jiggles]

I just did mine after changing my brake line to stainless steel braided. Yes, use both bleeders. I also kept awater spray bottle on hand to quickly wash off spilled brake fluid.

[rodcwer]

Just make sure you have clean fluid coming out of both screws

[tfb]

To minimise brake fluid spillage, you can use clear tubing pressed over the tip of the brake valve screw, with the other end into a glass jar or whatever, while you use an 8mm (or 10mm, depending on your bike) ring spanner to open and close the screw while pumping the brake lever, etc.

With the clear tubing, you can also clearly see when the fresh brake fluid has come through, as well as if there are any air bubbles still coming out or not.

There will still be a little mop-up of fluid needed, as a small amount will leak past the thread of the screw while it's being opened and close in the process. But you certainly don't have to put up with it dribbling everywhere, over the pads, the calipers, the disc, the floor...

Mike.

[Anonymous]

An additional bleeding technique that I used (on the front) was, after the usual flush and bleed procedure, to close the bleeder screw(s) and maintain pressure in the system for 12 hrs or so. I wrapped a small bungee around the brake lever and left it overnight. Wound up with a rock-hard lever and excellent response. That was 7 yrs. ago and the front brake is still firm and effective. No idea what this procedure does, except maybe percolate any remaining air out of the fluid.