Line lock not holding????
Thread Starter
Melting Slicks
Joined: May 2001
Posts: 3,270
Likes: 26
From: Winchester VA
Cruise-In V Veteran
Line lock not holding????
I put a line lock on my 85. Originally tried to plug one front outlet and run a single line into the line lock and two out. This is a Hurst line lock "roll control". I found that I was blowing some fluid out of the reservoir cap, cap never blew off. So I decided to go with an 86 master cylinder, which made the pedal feel better, not hard to do, but the lock is still not holding and to a lesser degree, pressure is still pushing fluid through the cap.
I noticed that the lines supplied with the installation kit are smaller than the rear feed brake lines, which is a single output. What I mean is the 85 master cylinder had two seperate small output lines for the front. There is now one small output, will this cause a backpressure into the reservoir? Can someone with a 86-89ish tell me what size their front brakes master cylinder output line is?
I noticed that the lines supplied with the installation kit are smaller than the rear feed brake lines, which is a single output. What I mean is the 85 master cylinder had two seperate small output lines for the front. There is now one small output, will this cause a backpressure into the reservoir? Can someone with a 86-89ish tell me what size their front brakes master cylinder output line is?
Melting Slicks
Joined: Aug 2003
Posts: 3,395
Likes: 393
From: Lakeville MI
Re: Line lock not holding???? (RainDelay)
Are you applying the brakes first, and then activating the line lock, and then releasing the brakes? This should hold pressure in the front axle circuit, but not the rear.
If you're activating the line lock first then applying the brakes, you should be unable to build any pressure in the front brakes (unless there is a check valve to permit braking through the line lock, a good idea in case you forget and really need to stop). The fluid squirting in the reservoir occurs because you're building pressure before the tmc (tandem master cylinder) compensation port is fully closed by the lip seal. This is normal for the first few mms of tmc stroke, but be careful if your line lock is active since high pressure with a short stroke can damage the lip seal by pushing it into the comp port.
Other possibilites include fluid leaks and/or air in the system.
If you're activating the line lock first then applying the brakes, you should be unable to build any pressure in the front brakes (unless there is a check valve to permit braking through the line lock, a good idea in case you forget and really need to stop). The fluid squirting in the reservoir occurs because you're building pressure before the tmc (tandem master cylinder) compensation port is fully closed by the lip seal. This is normal for the first few mms of tmc stroke, but be careful if your line lock is active since high pressure with a short stroke can damage the lip seal by pushing it into the comp port.
Other possibilites include fluid leaks and/or air in the system.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Re: Line lock not holding???? (tequilaboy)
The fluid squirting in the reservoir occurs because you're building pressure before the tmc (tandem master cylinder) compensation port is fully closed by the lip seal.
BTW, 85 has independent front brake circuits. Guess I'd need two linelock systems to avoid needing a new MC?
