Leaky Master Cylinder ???

[70bigblockdodge]

Whatever the depth of the hole in the piston, make the push rod stick out no more than that. Sounds like yours is too long if not releasing

 

[live4theking]

Thanks guys. This is the project for this evening.

 

[PH27L7]

The pushrod is the easiest & cheapest to deal with. If not that I would suspect the MC has weak return springs or the piston is sticking in the bore. It could also be a booster malfunction where it is not properly releasing vacuum.

 

[live4theking]

I ended up shortening it by a1/4 turn. It seems to have made a big difference. I need to run it a bit more to know for sure.

 

[live4theking]

I'm still fighting with this issue of the brakes holding when applied. I have noticed that it is more prevalent when the car is cold, first run of the day. After minutes of driving it isn't as bad, but is still there.

I was told that the Midland Ross booster requires 20 inches of vacuum to operate properly. I work with a number of gear heads and they all basically think that that much vacuum isn't going to happen. It makes about 16 or 17 inches at best.

How much vacuum do you think is required?

 

[Davea Lux]

I'm still fighting with this issue of the brakes holding when applied. I have noticed that it is more prevalent when the car is cold, first run of the day. After minutes of driving it isn't as bad, but is still there.

I was told that the Midland Ross booster requires 20 inches of vacuum to operate properly. I work with a number of gear heads and they all basically think that that much vacuum isn't going to happen. It makes about 16 or 17 inches at best.

How much vacuum do you think is required?

You do not need much over 12" vacuum for that booster. Try backing off the travel rod about 1 turn and see what happens.

Dave

 

[live4theking]

Thanks Dave. I've adjusted the rod so much that I can almost do it with my eyes shut.

The crazy thing is if I hook the pedal with my toe and pull it up the brakes release instantly. I've checked for tight spots in the pedal mechanism and found nothing. In this old thread there was mention of a valve inside the booster not releasing properly. I really know nothing about how they operate.

The mechanic that inspects it for me is into old cars. When I was talking with him he said anything 15 inches or more is great.

 

[Davea Lux]

Thanks Dave. I've adjusted the rod so much that I can almost do it with my eyes shut.

The crazy thing is if I hook the pedal with my toe and pull it up the brakes release instantly. I've checked for tight spots in the pedal mechanism and found nothing. In this old thread there was mention of a valve inside the booster not releasing properly. I really know nothing about how they operate.

The mechanic that inspects it for me is into old cars. When I was talking with him he said anything 15 inches or more is great.

Has the booster been rebuilt yet?

Dave

 

[live4theking]

Yes, by booster Steve. He's the one that told me 20 inches of vacuum was required. I had been talking with him about it through FB messenger.