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Brake bleeding help. Bad MC? Maybe one side of it?

1965GTFB

Member
I've been working on a 66 vert for a friend/former co-worker whose husband just passed away on memorial day after a battle with cancer. They bought the car off Ebay out of W. Va. It definitely was worked on by a redneck or two. Lots of wrong fasteners, some missing parts like the center floor pan brace, tranny kick-down cable, etc. Was a 6 converted to a V8 with what looks to be a 68 or later engine by the valve covers.

He asked me to start on it about a week before he passed, get it safer for her to drive where ever she might want to. Right now I'm fighting with getting the brakes right. He bought all new front and rear suspension form M+, that was easy. New front disc brake kit from CSRP, was drum, that was easy. I checked the rear brakes, good thing, and it had 2 left side adjusters and other problems. Got all new rear brake parts including the hose. Can lock of the front brakes but the pedal seems way too low. After a LOT of bleeding, plugging the master to check it, I think it is a rear wheel cylinder problem. Watching the wheel cylinders and shoes with the drum off they finally move really late in the pedal travel. I'm thinking they are too narrow thus requiring too much pedal travel to move the shoes. The axle tag is REALLY rusty and near impossible to read so I took my best guess that it was a 66 rear end when getting the new cylinders. From looking at the Centic web-site it looks like the only difference between a 65 and 66 WC is a minor bore size difference (65 is 29/32 or 7.25/8 and 66 is 7/8). Could not find any detail specs for WC widths. Couldn't be a '67 or later rear end could it, because aren't those too wide for a '66.

Any thoughts.
 
Re: Need to find correct wheel cylinder for this rear end.

Did the master cylinder get changed from a drum/drum version to a disk/drum?
 
Re: Need to find correct wheel cylinder for this rear end.

"Midlife" said:
Did the master cylinder get changed from a drum/drum version to a disk/drum?

That sounds like the problem....improper master cylinder.
 
Re: Need to find correct wheel cylinder for this rear end.

"AzPete" said:
"Midlife" said:
Did the master cylinder get changed from a drum/drum version to a disk/drum?

That sounds like the problem....improper master cylinder.

MC should be fine, it came with the CSRP kit.

I may just be still fighting getting ALL the air out.
Any tips or tricks welcome.
 
Re: Need to find correct wheel cylinder for this rear end.

Got the front disk brakes reversed left to right, so that the bleeders are not on top?
 
Re: Need to find correct wheel cylinder for this rear end.

The old fashion two person method of pump and bleed always seems to work.

Any chance the lines are reversed on the master cylinder. Some have specific locations based on bowl and bore volume.
 
Re: Need to find correct wheel cylinder for this rear end.

Ted,
Are you still seeing air when bleeding?
 
Re: Need to find correct wheel cylinder for this rear end.

This is on a 66 that had original 4 wheel drum and single MC before adding the CSRP kit and all new rear brake parts including hose to axle.
All the parts are in the right places.
Calipers towards front of car, bleeders on the outside on top.
Two person bleeding wife/lovely assistant on the pedal.
2 or 3 pedal pushes with no air bubbles.
MC small chamber to adj prop valve then to rear brakes, large chamber to original distribution block then to front brakes.
Original hole for rear brakes in dist. block is plugged with plug that came in kit.
No leaks at any connections.
Plugged ports on MC and pedal was high and hard.
Can lock up the front tires when test driving.

Problem is:
Lots of pedal travel before braking starts.
Pedal travels 3" before it firms up.
Noticed when bench bleeding that the last 1/2" of piston travel back out can take up to 10 seconds, does that most of the time when on the car too but some times not.
The rears come in really late, watching with the drums off they don't move until after the pedal is firm and more pressure is applied.

Could one side of the master be bad?

Dennis from CSRP has been very helpful spending lots of time on the phone with me.
Next going try his suggestion of removing calipers and holding them at different angles while bleeding.

Any one ever used one of the pneumatic bleeders that you hook up to your compressor? I have the Harbor Freight hand pump model.

Been through 3 big bottles of fluid. I'd be happy to find some simple thing I screwed up but every thing looks ok.
 
Re: Need to find correct wheel cylinder for this rear end.

Next going try his suggestion of removing calipers and holding them at different angles while bleeding.
yeah... I don't know if I'd do this. likely to push the pistons out. pads might hold them in, or you could take the rotors off and have them between the pads. still...
 
Re: Need to find correct wheel cylinder for this rear end.

"midpack" said:
Next going try his suggestion of removing calipers and holding them at different angles while bleeding.
yeah... I don't know if I'd do this. likely to push the pistons out. pads might hold them in, or you could take the rotors off and have them between the pads. still...
Going to use an old rotor or a block of wood. Maybe even take the pads out and a bigger block of wood.
 
What happens if you adjust the rear prop valve to full open. Maybe remove it from the line completely as a trial.
 
If the system is suspect, and you have the M/C out of the car, might I suggest rebuilding the proportion valve and distro block? The kit's that Scott has for sale are complete with new seals and components...
 
The Adj prop valve is new in the CSRP kit. The dist block is the orig 66 drum block, so no moving parts, nothing to rebuild.

Just finished the rebleeding with the calipers loose. Even adjusted the rears until they were locked up, still no change.

Dennis is sending a new Master, hope that's it.
 
Does the "new" master have a built in residual valve or is there one in the line to the rear brakes? The residual valve keeps the shoes from retracting too far in a drum brake application.
 
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