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80 series brakes spongy

Posted: Tue Feb 13, 2007 9:17 am
by squarebear
i have a 2 in lift a while ago i replaced the front and rear brake hoses .after doing so the pedal has been spongy ive bled all the lines numerous times but to no avail could it be the porp.valve and do you have to ajust the rod from the diff housing to the valve after you lift it.

Posted: Tue Feb 13, 2007 1:11 pm
by gtir300
Maybe your master cylinder needs an overhaul, the seals could be worn casuing fluid to weep past them!
I think mine need doing, as my pedal is a bit spongy and fluid has discoloured quickly! (No loss from the system tho!)

Posted: Tue Feb 13, 2007 3:02 pm
by Chucky
Get underneath the cruiser and check the brake hoses while some else pumps the brakes. You are looking to see if the brake hoses flex (Bulge) out when the pedal is depressed. If they do then this would explain the spongy feeling.

If this dont work then I'd check the master cylinder. If thats all good then I'm all out of idea's :D

Posted: Tue Feb 13, 2007 6:01 pm
by dumbdunce
check also the soft lines at both front calipers. If, when you replaced the hoses and bled the brakes, you allowed the reservoir to empty, it's possible there is air trapped in the master cylinder - bleed the cylinder by cracking the flare nuts on the master cylinder and 'tappling' the pedal - push it only 2 - 3 cm on the pedal to just move the pistons slightly. If, when you bled the brakes after replacing the hoses, you made long strokes on the pedal and thus on the master cylinder pistons, you may have slightly upset the seals in the cylinder, and it will never feel good again. Early 80's can be difficult (ie near impossible!) to bleed, you can also try reverse pressure bleeding - use a windscreen washer pump/tank (grab one from the wreckers), fill it with brake fluid and fit the hose over the bleed nipple at each caliper and pump the fluid back up to the master cylinder. it will take some time. you will also need a method for drawing off the fluid as it builds up in the master cylinder - get a couple of big syringes from the chemist.

good luck on your mission

DD

Posted: Fri Feb 16, 2007 9:33 am
by squarebear
thanks ill give all a go master cyl is the only thing i havent replaced

Posted: Fri Feb 16, 2007 4:17 pm
by g35me
You have to lift the rod to the proportioning valve by the same height as the body lift.

Posted: Sun Feb 18, 2007 9:23 pm
by squarebear
well i did the front calipers ,pistons were dirty and replaced master cyl brakes were still spongy,so i ajusted the proport. valve rod and that fixed it got good brakes at long last . thanks to all who replied