Enough is enough, brakes again

Pete · Post by **Pete** » Tue Oct 02, 07 8:11 pm

Hi there, similar posting to Morgan.

Have just fitted new Discs to a car & cannot get the system to bleed up. No pressure on the Drivers side (LHD) caliper. Tried gravity bleeding over 2 days, no change.
Have tried 3 master cylinders, all have the same effect. Dismantled one & there is no seal damage.

Have tried "reverse bleeding" the line in question by forcing fluid up it under pressure to no effect.

Bench bled the Master cylinders so I know there is pressure at the front brake port.

When you operate the brake pedal there is no pressue at the brake line, but you can feel suction when you lift the brake pedal, as if to return the fluid to the master cylinder.

The Back brakes seem unaffected and bleed OK.

I obviously suspect the proportioning valve. If I squirt fluid up the brake line where there is no pressure it comes out the pass side front line.

I cannot seem to "reset" the valve and it won't dismantle - too old and seized. I really do not want to have to replace the valve and the hard lines as I am sure they will round off when I come to disconnect them (been there, done that).

Does anyone have an explanation for this, and have they found the best (read "easiest without raiding the yearone catalogue") solution.

Many thanks in anticipation.

Pete

Anonymous · Post by **Anonymous** » Tue Oct 02, 07 8:29 pm

If you have pressure going into distribution block from master & pressure going out of distribution block to R/H & L/ H front brake lines , then i would be checking a collapsed hose or blockage.

The front lines on mine are taken off the distribution block separatly (two ports), where as the rears are fed off of one port on the dis block , splitting @ the rear axle.

Pete · Post by **Pete** » Tue Oct 02, 07 8:33 pm

Thanks Adam, the hoses are braided steel Goodridge items.
it's a puzzler in'tit....

Mick · Post by **Mick** » Tue Oct 02, 07 9:08 pm

You could try gravity bleeding one at a time, start with the pass rear, crack it open leave it for 10 minutes, look for a drip, lock it off, then drivers rear, pass front and then drivers front.
Mick

Derek · Post by **Derek** » Tue Oct 02, 07 9:17 pm

When bleeding the Drivers side (LHD) caliper, try pushing back the pistons in the caliper with a piece of wood with the bleed nipple open then lock the bleed nipple up and pump the pedal, you may have to do this a few times, I had this trouble a few years back when I renewed the brake fluid.

TrevD · Post by **TrevD** » Tue Oct 02, 07 9:22 pm

all the race guys who run unusual brake setups use a vaccume can to draw fluid through to the calliper as opposed to pushing it through as most of us do, it seems to work even with the master cylinder lower than the callipers. it might be worth seeing if somone local has this kind of kit you could borrow. if you get realy stuck let me know and i will see if i can borrow it for a weekend and pop over to you to see if we can sort it out.

Pete · Post by **Pete** » Tue Oct 02, 07 10:07 pm

Thanks for all the comments guys. Having a dead car on the drive way is not handy at the moment.

I think the Vacuum idea is a good one - I wonder if a Vax would work??

I tried gravity bleeding in all combinations with no luck.

The caliper pistons are all the way back in to the body.

Someone off the board suggested trying to take the brake warning switch element out of the proportioning valve and "centre" the component to allow fluid back down.

Does anyone (DAVE!!!) have an exploded diagram of a "B" body proportioning valave please as I can't get my head around the fact th at you get suck on the pip but no blow

Dave-R · Post by **Dave-R** » Wed Oct 03, 07 9:57 am

The proportioning valve is in the rear line ONLY. It cannot effect the front brakes.

What you are thinking of is the metering valve which was used on early disc brake cars. You can just remove the metering valve if you have modern wheel cylinders in the rears. Somthing like that.

I don't have a metering valve.

I posted some scans somewhere recently. I will find them.

Dave-R · Post by **Dave-R** » Wed Oct 03, 07 10:02 am

These might help. Some more coming in a moment or two.

Dave-R · Post by **Dave-R** » Wed Oct 03, 07 10:04 am

More.

Pete · Post by **Pete** » Wed Oct 03, 07 11:45 am

Spot on Dave, thanks - will read tonight.

Thanks again

Dave999 · Post by **Dave999** » Wed Oct 03, 07 3:38 pm

that switch assembly in fig 8 if it is in a T piece near the cylinder or bolted elswhere i think it is just a warning light switch I don't think it can activly switch off the front or rear circuit however it worth looking at, and the following method could be tried

if it is integerated into the master cylinder (and i know this from experience) it swicthes off a circuit (until you reset it) if the pressure in the circuit is reduced to a certain ratio against the other circuit

undo it by 8mm so the forked end of the plunger under it can't interfere with the T ends of the piston between the springs.

the springs will resturn the piston back to its at-rest position as shown in the piccy

Then bleed. then do it up again and test

I know nout about US cars and Dave's attachment appears to indicate it is purly a pressure imbalance warning light in aT junction somewhere near the place where the pipes go off to the rear of the car..... but its worth a try

I know its there as part of the master cylinder on the Aussie ones, bang between the master cylinder exits for front circuit and rear circuit because i had hours of fun with mine because i didn't know how to reset it.

i do now

Dave

Dave-R · Post by **Dave-R** » Wed Oct 03, 07 3:54 pm

I know that is just a switch. I was short of time so I just posted up all the scans I had from that section of the manual. Hopefully there is something in that lot that will help. Maybe just the text.

Dave999 · Post by **Dave999** » Wed Oct 03, 07 5:12 pm

dave i wasn't saying you had the wrong bit

i just don't know how a remote switch like that works.

its US mopar init

Oz ones are different but the safty switch, when switched results in the same symptoms as Pete and Morgan experience

worth a try was my only point

Dave

Dave-R · Post by **Dave-R** » Wed Oct 03, 07 5:15 pm

I am not even sure which bits we really need out of that lot to be honest. I am going to re-think my own brake system when I get around to it.