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Bleeding brakes- on Avanti


avantey

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The brakes on my Avanti are giving me fits and rather than hijack Unimogjohn's or Avanti Rescue's threads I figured I would start one here. All of the system is new or freshly rebuilt now with SST lines, new hoses and fittings, one rear cylinder new, one rebuilt, both front calipers all rebuilt. After four nites of work we finally found the problem and got a good high hard pedal with a lot of bleeding. However the battery was low so I could not start the car and check the pedal when running.

Well, I decided before I put the wheels back on to try this just to be sure so I just did that and I am back to square one! With the vacuum booster working the pedal goes right back to the floor! What in the world is going on with that? Does it mean air is still in the system?

Thank you for any help here. A lot of people here know a lot more than me on most everything it seems! But I keep trying and learning from you all......

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Are you pressure bleeding with a bleeder ball system?

Or are you just having someone press the brake pedal?

I always fill the MC and bleed it on the bench.

Then put it on the car and then press the pedal down, once and lock it there with a rod made for that purpose.

Then go to the farthest cylinder from the MC, and open the bleeder valve with a box end wrench so as to observe

fluid and or air bubbles .

Next Repeat the process until that cylinder shows NO air bubbles.

Now (after checking the fluid level in the MC), push the brake pedal and hold down with the rod. Then bleed the next farthest cylinder.

Repeat until all the cylinders show only fluid when bleb.

Too many people think you need to pump the MC a few times before bleeding a wheel cylinder.

That is the best way to put air bubbles into the system.

Drum type brakes should have the shoes adjusted to operating clearances, before starting the bleeding attempt.

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Guest carlnut50

This is a long shot but be sure you don't have the wheel cylinders upside down with the bleeder below instead of on top. A friend put left caliper on right side and vice versa on a 72 chevelle and the bleeders were much lower that way. It gave him fits until he got me to help with the problem.

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Thanks for all the ideas! The cylinders cannot go on backwards as the bolt patterns prevent this. I ended up with a very firm pedal until I started the car, then the pedal went south in a hurry. I kept bleeding all corners and ended up with a pedal that went half travel and firm at 2/3. On another thread it was asked if the brakes worked at this point and they do. Then I adjusted the plunger on the vacuum booster so I have 1/4 travel to engage and 1/3 until firm. I may adjust further but thanks for all the ideas! I am not sure if my solution was the best or if I like the feel of the pedal yet but I am going to drive it and try it this way.

Thanks again,

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