Line lock plumbing problems

[lapisxj]

I plumbed my line lock into the rear system replacing the Z shaped jumper from the MC to the Porp Valve. Wired everything up, bled the brakes and all works well except that the LL won't hold. You can tell that it is engageing but slipping. I don't know if having the LL upstream from the Porp Valve has anything to do with this or not. Any suggestions?

 

[Bender]

Does your brake warning light go on? Even if it doesn't this could be the problem......

There is a shuttle switch in most proportioning valves that moves if the pressure in both the front and rear brake systems are not fairly equal. The idea behind this is to set off your brake warning light if either system springs a leak.

Chances are the pressure held in by the line lock pushes the shuttle over when you release the pressure on the other side...i.e. if the line lock is holding pressure in the rear through the proportioning valve when you release pressure on the front brakes the shuttle slides over. This movement of the shuttle will probably release enough pressure to make the line lock useless.

I think it has to be beyond the proportioning valve...

But then again that's just a theory. I've never actually tested it.

 

[lapisxj]

No, the brake light doesn't come on

I am wanting to get a double throw switch which will allow one pair of contacts to operate power to the LL and the other pair to make a ground connection so that my brake light on the dash will come on to let me know that the switch is activated.

 

[lapisxj]

turns out the porp valve is upstream of the LL, it still doesn't hold well, probably cause of the drum brakes...