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Grrrr brakes again
(03-29-2017, 04:53 PM)Duncan Mach72 Wrote: Just started to have a brake issue which might be the proportioning valve.

The stock system was working fine and then I employed an experienced mechanic (a first for me, usually do my own work) to fit a line-lock. He installed this after the prop valve in one front leg, fitted a T-piece after it to get to both fronts then plugged the other leg at the valve. This is the recommended way & he says he has done 5 before with no issues.

The system would not bleed properly so eventually (after a week of trying things!) he put it back to stock so I can have the car back while we have a re-think. However even back to stock he could not get the front brakes back to a safe condition! He drove it 20 miles to my house very carefully because as he said he did not want a customer to drive it in that state.

Going to eliminate the stock prop valve & go with the adjusting type in the rear circuit. Will let you know what happens.

I don't know which proportioning valve you have, but what I did was to take the proportioning spring/plunger out of the valve and left the pieces that control the brake light. I did this becase I added an adjustable proportioning valve for the rear brakes.

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
4-wheel disc brakes
I think I may have found the root of my problems. The previous owner had the calipers powder coated. I remember him telling me they had a lot of trouble bleeding the brakes. Since then it's never had air in. I started wondering if the calipers had been swapped left for right. So I took the wheel off and saw that the bleed nipple is pointing upwards from the side of the caliper and didn't look like it was quite at the highest point. I checked the workshop manual and found a picture that clearly shows the nipple pointing backwards from the top. I removed them last night & will refit correctly & bleed tonight.

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