Another brake bleeding thread

[mach1mustang351]

I know, there is info everywhere on bleeding the dreaded integrated brakes.  For the last few nights I have been trying to bleed the brakes on my 1979 1000SP.  I have done everything I can think of and have ran a quart of DOT 4 through it and i still have air. I wanted to give a run down and hopefully I'm missing something easy.

I started by filling the rear master cylinder and putting my vacuum pump on the brake valve to get fluid up to that point. Once there I cracked the line to the rear caliper, the front caliper and at the bleeder screw until I got fluid. 

I then disconnected the line at the rear caliper and applied vacuum to the line until i got fluid. I then reconnected to the caliper.  I disconnected the front hose at the hard line and applied vacuum to the hard line until i got steady fluid. I reconnected, and then disconnected at the caliper and vacuum bleed the hose.  I reconnected the caliper.  I then setabout bleeding the calipers.

I managed to get a steady stream of fluid through the rear but the front has been more problematic. I have tried pumping the brakes and manually bleeding, I have tried vacuum bleeding, I have tried both at the same time, I cracked the line at the caliper again to make sure I still had fluid there (I do). The last thing I tried before I ran out of fluid and gave up for the night was I unbolted the caliper from the bike and raised it above the handle bars and tried bleeding it up high. All I get is a steady stream of bubbles though the clear line and it never gets better.

As stated earlier. The rear caliper and the valve are bleeding steady fluid its just the front caliper that is fighting. Could there be something wrong with the caliper?? Everything was rebuilt as part of the Guzzi's refresh before getting back on the road.

My next idea would be to make some kind of pressure bleeder out of the old master cylinder cap and see if I can gain an advantage there.

Any ideas appreciated.

[blackcat]

"....I have tried vacuum bleeding..."

Hmmm....I purchased the one from Harbor Freight and it pumped the lines out in both bikes/car in a blink. 

[tris]

Slack gland nut somewhere
Porous hose,
Bleed nipple that allows the vac bleeder to suck air in via the thread?
New slave cylinder seals faulty or in the wrong way around?

Push the pistons all the way in and hold them there - less volume to bleed

[SPScottNT]

Bleed nipple that allows the vac bleeder to suck air in via the thread?

This.

Do you have a firm lever?  Does it feel like there is air in the system when you push the foot lever?

[mach1mustang351]

This.

Do you have a firm lever?  Does it feel like there is air in the system when you push the foot lever?

Feels like there is air when I push the brake lever. It has firmed up some but still easily travels down
To the mechanical stop.

[SPScottNT]

Rats.  I was hoping it was something as simple as that....

One question for you:  Do you have the F08 front caliper and the slightly larger F09 rear caliper?

One question for other SP owners with the same set up (F08 and F09 calipers):  Is the foot pedal firm?  Looking at the master cylinder piston area to caliper puck area ratio in that set up makes me think the pedal would not feel all that firm.  The linked system on a Cal II or Lemans III uses the same master cylinder, but F08 calipers front and rear (and feels firm at the pedal - I'd think the F08/F09 setup would have to feel different).

Of course, that is all moot if you had a firm pedal before the brake bleeding.

Scott

[injundave]

On my T3 I used two pumper type oil cans attached to the bleed nipples at the front caliper and pushed fluid back to the master cylinder. This was after going through the same as you have with the same results at the rear caliper. When I had clear, new fluid flowing into the master cylinder I then bled the front caliper in the usual way which took out the last tiny air bubbles and had good pressure.

YMMV

Dave

[Two Checks]

Doues yours have a bleeder under the seat on the L frame rail? If so bleed it 1st.

[mach1mustang351]

Doues yours have a bleeder under the seat on the L frame rail? If so bleed it 1st.

It does have that bleeder. I bleed it there first. I was going to try the back pressure bleed but my wife decided to inviteme out for pizza and beer and apparently I'm "too drunk to get brake fluid and work on my bike" oh well maybe tomorrow. 

[Chuck in Indiana]

I use a re purposed Cajun injector (cheap, Guzzi content) and push fluid from the caliper to the master. Conventional bleeding should get it from there. After you get some pedal, if you have time, hanging a 20 lb or so weight from the pedal overnight will get the last of the air. The whole process is documented in the Lario Rehab thread. 
This is *assuming* all parts in the system are good.

[BrianK]

Have you yet tried bungeeing the brake lever to the handlebar overnight?  If not, give it a shot.  It might amaze you.

If it helps, try it again and while it's in that position, use the plastic handle of a screwdriver to gently tap-tap-tap the caliper and up the lines all the way to the MC.

Both help those sticky little air bubbles that just hate to leave to travel up (gravity is your friend) from the caliper and brake lines into the MC.

Good luck. 

[rodekyll]

Since nobody has mentioned it and because this situation just happened to me, I'll suggest either the banjo sealing washers are leaking air or the m/c is leaking air.  Either of these can suck air without dripping fluid.

[mach1mustang351]

I put another out into it today. I installed a new bleeder in the caliper thats fighting me. I messed with it and got no where. I noticed that when the bleeder was shut, there were still bubbles coming through the bleeder into the clear tube. I installed the old bleeder and the same deal.  I have tied down the brake lever and will try it again tomorrow

[Mike Tashjian]

Bleeder screws will leak air around the threads and let you believe there is a problem.  Try wrapping those threads with teflon tape to stop the air leaking through the threads.  That will let you concentrate on the problem at hand.   Mike

[twhitaker]

I noticed that when the bleeder was shut, there were still bubbles coming through the bleeder into the clear tube.

If you have bubbles when the bleeder is shut those bubbles are not coming through the bleeder. They may be drawn in between the hose and the bleeder but not through the bleeder.

[tris]

If you have bubbles when the bleeder is shut those bubbles are not coming through the bleeder. They may be drawn in between the hose and the bleeder but not through the bleeder.

Wot he said 

New pipe me thinks

[mach1mustang351]

I GOT IT!!!!

So here was the fix. I ignored it a couple days and cleaned the garage up. Between working a lot, tackling car and bike projects and fixing the house, the garage was wrecked. We are in a better place there now. I started from scratch basically. Started at the master, cracked the lines and worked toward that PITA left caliper.  I decided to become confident in my assessment the caliper was holding the air. I then removed the caliper and bleed about 3 cups of fluid through the directly from the brake hose (caliper disconnected completely) just to be sure. I reconnected the caliper and bought it up high, by the handle bar.  I pumped the brake until the pads were almost touching. I held the pedal down, cracked the bleeder and pushed the pistons back in. I did this about 5 times to make sure the air was pushed out of the caliper. I bolted it back on and pumped it up.... I had brakes!!!! I then bleed out all the bleeders again, just to be sure. And the pedal stayed solid. Its all over!!

I may get to take it on its maiden voyage this week!!