Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Hoist!]

I mounted dual 6 piston differential bore PM Calipers on the front and a 4 piston DB PM Caliper on the rear. We went nuts trying to bleed them, before getting a handle and pedal. I have it decent now, but it's still squishy and gets firmer when I pump the brakes. I shouldn't have to pump the brakes at all. It should have a firm feel like before. Anyone have a good method of bleeding these systems, besides the conventional "pump the handle, hold, open & close bleeder, and repeat" system? This has made me nuts for years, but get it done eventually. But these PM's seem to be even more stubborn. I don't have a Mighty Vac, and have never had much success with it anyway. These HD master cylinders kinda suck. I'll probably be changing them also. But I don't like the squishy feel or having to pump them while braking, and would like to correct this before my trip to HS. Any ideas? Thanks!

Hoist!

[Twolanerider]

This is one of those "patience, [gr]asshopper" kind of things.  Just be glad you're not doing it with DOT5.

On bikes I've always had best luck, and pretty good luck, with an initial gravity bleed.  It helps tremendously if you fill the calipers before you mount them too.  Then for the initial bleed just fill the reservoir (and keep it topped off as need be) while leaving the bleeder open.  Then let gravity do its job and carry it through.  Once that's done finish off with a slowly pumped bleed "normally."  Though often times a good slow gravity bleed is enough.  I'll usually do this with the calipers dismounted and laid in such a fashion that a bleeder farthest from the master cylinder is also at the lowest point.

[hogasm]

Howie I have one of those 29.99 brake bleeder kits from Wall Mart. The one you hook up air to. Works like a charm.

[Twolanerider]

Howie I have one of those 29.99 brake bleeder kits from Wall Mart. The one you hook up air to. Works like a charm.

One thing to be careful of with those being supplied by a small reservoir.  Perhaps not always, but the suction under air pressure can cause enough turbulence in the little master cylinder reservoice that fluid gets splattered all over the place.  Just make sure the master cylinder reseroir is covered.

[Hoist!]

Thanks, We did it off the bike and on it, we gravity drained it for a little bit. It was done at the dealer and Alex spent a lot of time with it. There's only so much time they let him spend. Those Might Vac things never worked too good for me. Can these be power bled with a compressed air bleeder? I was gonna ride it this weekend like this, and if I don't pop the rest of the air out and get a firm handle, I'm bringing it back up to Alex to spend more time with it. If I have to go back, I'll be doing it with him this time! Will another Brake Fluid besides HD work any better? Thanks again!

Hoist!

[Midnight Rider]

Howie....when I put the PM's on my bike, I had a hell of a time getting them bled too.  On the rear, take the caliper OFF and hold it as high as you can get it with the bleeder up, of course.  The rear was pretty easy on my bike doing it that way.  Another thing to look for is to make certain the bleeder is firmly seated...after much frustration, I discovered one of mine needed to be tightened down pretty firmly to get it to COMPLETELY close off to the atmosphere.  After getting it seated well initially, then you can do things normally.  Allowing the fronts to gravity bleed for a couple of HOURS helps...just get you a couple of beers and a few ciggies and keep the reservoir topped off.  Then you just have to do the old pump and squeeze 'till you get a relatively firm lever/pedal.  The PM's have a different "feel" than the stockers.  They feel slightly squishy, but only to a point, then firm up nicely.  Get them as good as you can get them, then ride the bike to seat everything in well, then do a final bleed just to be sure.  I think the different feel is due to the differential bore for the pistons.  In the end, you will like them, but it does not feel the same as the stock calipers.  It's more of a progressive pressure, if that makes any sense.

[Midnight Rider]

One other thing...I bought one of the brass vacuum do hickeys that is supposed to pull from the caliper bleed.  Either I'm retarded (highly probable), or I couldn't get the damn thing to do a better job than just letting gravity do it's thing.  So that was 30 or more bucks blown up a wild hogs a$$.

I used Valvoline Synthetic fluid (dot 3 and 4 compatible, but it's not DOT 5)...by the time I was done, all lines had been flushed with the new stuff.

There's just a lot of air in there, buddy, and the way the lines route doesn't help matters.  Get some clear tubing if you don't already have it, and you'll see the teeny/tiny air bubbles coming out.

[Hoist!]

One other thing...I bought one of the brass vacuum do hickeys that is supposed to pull from the caliper bleed.  Either I'm retarded (highly probable), or I couldn't get the damn thing to do a better job than just letting gravity do it's thing.  So that was 30 or more bucks blown up a wild hogs a$$.

I used Valvoline Synthetic fluid (dot 3 and 4 compatible, but it's not DOT 5)...by the time I was done, all lines had been flushed with the new stuff.

There's just a lot of air in there, buddy, and the way the lines route doesn't help matters.  Get some clear tubing if you don't already have it, and you'll see the teeny/tiny air bubbles coming out.

Thanks Terry! I never had any luck with those Mighty Vacs either. I have PM's on my Pro Street, and know and like their feel. That's why I replaced the SERK stockers. I didn't have this much trouble with the single front brake. The duals are a PIA! I'm gonna bounce it around this weekend over the city bumps. I'm taking Neal, Sue and Steve on a Tour of the city on Sun. I'll aim for some good bumps and hope I can knock the rest of the air out. If not, I'll try bleeding some more next week. Otherwise, I'll supply the Beer and the DOT 4, and you, Don, and I can bleed all over the Stagecoach Parking Lot! Thanks for the input. Have a great ride and It'll be nice seeing you again in Memphis!

Hoist!