Line Lock/Roll Control won't release?

[hpfiend]

OOPS forgot to mention this is on a 70 AMC Gremlin

 

Hey all-

 

Previous owner had installed a biondo line lock which would not release after removing power requiring that he crack open a line to release the wheels. We reinstalled it and no surprise the same thing happened. We bypassed it and the brakes worked as before. Thinking the line lock was the issue we bought a new one from JEGS. Same deal. We don't have the inlet and outlet mixed and are completely adding and removing power (no switch yet). It is easier to blow through in the reverse direction so we are thinking of trying it that way for the heck of it.

 

We have it installed directly from the outlet of the master cylinder to the line lock and then from that to the front brake line tee. One side immediately goes to the drivers side wheel after the tee and the other side goes through a differential brake pressure switch and then to the other wheel. The brake pressure differential switch is not supposed to block or restrict flow only indicate when brake pressure is higher or lower front to rear and set a light. We do not have it wired. Maybe this is the issue?

 

The front rubber brake lines have been replaced a few years ago.

 

The pedal seems to be very hard with limited travel and high off the floor with or without the line lock. It is a manual brake setup, it will not go to the floor- something else bottoms out (probably the master cylinder push rod). The previous owner said he replaced the master cylinder as well.

 

It was drums all around from the factory, previous owner put disc in front and wilwood proportioning valve in rears to balance rear drums. It now has 4 wheel disc (8.8 rear) with wilwood valve still installed. No factory proportioning valve is installed.

 

Any ideas?

 

I am going to pull a number off the master cylinder and see what it is but I am not sure how to proceed. The drum/drum m/c is supposed to have a check valve and no residual pressure release. My dad thinks the brake differential switch is causing it and that we should tie in after it?

 

Thanks!

[Richard Cranium]

I'd say that if the brakes work correctly without the line lock, then it's not the pressure differential switch. If it is the differential switch, then wouldn't the drivers side wheel release while the passenger side stays locked?

[hpfiend]

I'd say that if the brakes work correctly without the line lock, then it's not the pressure differential switch. If it is the differential switch, then wouldn't the drivers side wheel release while the passenger side stays locked?

 

Thanks for your reply Rick. You are correct it wasn't the pressure differential switch. Apparently the previous owner had flipped the lines on the master cylinder and there was some internal proportioning valve/check valve within the m/c not allowing the line lock to release pressure.

 

The large reservoir is for front disc brakes, the small reservoir is for rear drum brakes typically. He had them the opposite way. We swapped the lines at the master cylinder, bled the brakes and it works like a charm now. Will probably have a new biondo racing line lock for sale here soon.

 

Thanks!