4 replies to this topic

[Monte Busa]

OK, somewhat non-std braking system on my car - dual Girling KAD bia box, bought it used in very good condition. No leaks in plumbing, but cannot get either front or rear circuit to firm up after multiple bleeding session - one with positive pressure bleeder, and three with 2 person pedal pump and crack bleed valve method - all 4 corners run clear fluid with no bubbles, but the pedal goes down to the floor with almost the same resistance as when the cylinders were empty...any ideas?

Could both cylinders be worn / in need of rebuild? Wouldn't they leak if so?

Cheers in advance,

Aric

Edited by Monte Busa, 30 August 2008 - 04:46 AM.

[Guess-Works.com]

I always find that when having issues with brake systems and bleeding... the easiest way to diagonose the fault is to take a methodical piece by piece look at the system...

so from the master cylinder, undo the first pipe, and insert a bleed nipple... and then check you can get a hard pedal...

Proceed through the brake system until you find the failure point...

[Grayedout]

And of course the age old question.....are the calipers on the correct sides so the bleed nipples are at the TOP ??

[dklawson]

Greyedout beat me to the caliper question/suggestion. I'll add, if you've replaced the rear shoes, they have to be on in the right order or you'll never get a firm pedal. While on the subject of shoes, proper adjustment is for you to be able to spin an elevated wheel and hear a bit of drag. The wheel should then stop in about one revolution. It should not continue to spin and spin and spin.

Regarding the bleeding method, you're in MI. A number of the guys I grew up with use a two man bleed method of "pump-pump-pump-hold... crack the bleed nipple. That won't work on a lot of British cars, particularly early Minis with rear brake proportioning valves on the rear subframe. If you pump the brakes up hard before cracking the bleed nipple, it shuttles the proportioning valve closed so little or no air is driven out of the rear lines. The two man method that works is a person in the drivers seat pushing the pedal down slowly when you have just cracked the bleed nipple open. As the pedal approaches bottom, they call "down" and you close the bleed nipple. Once closed you call "release" and they let the pedal back up and call "up". The cycle then repeats.

Others have good luck with gravity bleeding but that means babysitting the reservoir so it never runs dry. Some swear by pressurized bleeders but I've never used one. I use a bleed hose with a check valve in it and this is similar to bleeding brakes where "Speed Bleeders" have been installed in the calipers.

[Monte Busa]

I figured out the problem on the front brakes - I had the Girling master pushrods adjusted so that they were not travelling far enough past the inlet to the reservoir - now the fronts grab like stink and seems very firm indeed.

I think I have a bit more work to do on the rears as with full brake pedal force, though the pedal feels quite firm, I can still (with good effort) spin the rear wheels (the car is on jackstands right now). The handbrake brake actually grabs harder....hmmm...come to think of it, the bleed nipple on the rear wheels cylinders is on the bottom on Minis...how are they expected to bleed?

Thanks for the suggestions all.

Cheers,

Aric

Edited by Monte Busa, 31 August 2008 - 04:45 AM.