Line lock help, it's making me crazy!

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Les Gibson

Les Gibson

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Hi all. I'm wondering if any one here has a similar set up to mine that I might draw some knowledge from. My 1976 Arrow (shown in the profile pic) has a full Alston chassis under the body. The Wilwood brake master cylinder is mounted under the driver side floor, attached to the frame rail. The manual proportioning valve is mounted forward of the MC, then forward of that the line lock solenoid is mounted, all plumbed with hard line. There are residual brake pressure check valves mounted in the front and rear brake lines, I'm assuming due to the fact that the MC is mounted slightly below the level of the wheel caliphers. What makes me crazy is the operation of the line lock. It doesn't operate as they normally do, in other words pumping the brakes then setting the line lock, mine works opposite of that, push the button to activate the solenoid and THEN pump the brakes! I have a lot of problems with the line lock holding the front brakes tight enough to do consistent burnouts. I've dialed in more forward brake bias which seems to help but I don't want to take out too much rear brake. Doesn anyone else have a set up like this and how do you get it to operate with consistency? Thank you in advance!
 
You have front and rear brakes, dual master, the proportioning valve should be between master cyl and rear brakes only, with no effect on front brake pressure/application.
The front brake circuit should have the line lock only.
Once triggered, It should hold whatever pressure you apply, also has the ability to accept and hold whatever pressure you choose to add, and continue to hold till button released.
I use mine daily as much as I use my brake and gas .
Not sure I understand your issue ?
I did read your post a coupla times, and am sure this isn't your first line lock ?
 
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Inertia said:
You have front and rear brakes, dual master, the proportioning valve should be between master cyl and rear brakes only, with no effect on front brake pressure/application.
The front brake circuit should have the line lock only.
Once triggered, It should hold whatever pressure you apply, also has the ability to accept and hold whatever pressure you choose to add, and continue to hold till button released.
I use mine daily as much as I use my brake and gas .
Not sure I understand your issue ?
I did read your post a coupla times, and am sure this isn't your first line lock ?
Click to expand...
No it's not my first line lock. When I bought the car spring of last year the previous owner told me about the operation of the line lock. He said press the button and pump the brakes several times before starting your burn out. I said don't you have that backwards? Shouldn't you pump the brakes and then press the line lock button? He said no, not with the brake system this car has. I didn't believe it. So first run I made in the car I did things the traditional way and the car blasted right out of the water. Backed back in and did it the way he told me and it worked. It had me scratching my head as to how it could work that way.

Anyway, the issue is consistency. Sometimes the front brakes don't hold long enough for me to get good heat in the rear tires. I put new brake pads in on all for corners a couple of weeks ago. This past Friday night I had the car out for the first time this season doing test & tune. In 2 of my 3 runs the front brakes barely held. After dialing in more front brake bias on the third run they held long enough for me to get some smoke out of the tires.. it just seems not right to me.
 
Les Gibson said:
The Wilwood brake master cylinder is mounted under the driver side floor, attached to the frame rail. The manual proportioning valve is mounted forward of the MC, then forward of that the line lock solenoid is mounted, all plumbed with hard line.
Click to expand...

Inertia said:
You have front and rear brakes, dual master, the proportioning valve should be between master cyl and rear brakes only, with no effect on front brake pressure/application.
The front brake circuit should have the line lock only.
Once triggered, It should hold whatever pressure you apply, also has the ability to accept and hold whatever pressure you choose to add, and continue to hold till button released.
I use mine daily as much as I use my brake and gas .
Not sure I understand your issue ?
I did read your post a coupla times, and am sure this isn't your first line lock ?
Click to expand...
The proportioning valve needs to be in the rear brake line. Front brakes do most of the braking. You do not want to reduce pressure there. The rear brakes need the proportioning valve so that they do not lock up before the front. I am not saying fixing this will fix your problem, but from your description, I would say it was installed incorrectly.
 
Did you install the line lock or is that how you got it? Is it possible the line lock is plumbed to the rear brake line as some do? Then you hold the button which prevents the rear brakes from getting pressure and you hold the front brakes with the brake pedal. Some guys prefer that setup. Just a thought...
 
MobileCustoms said:
Did you install the line lock or is that how you got it? Is it possible the line lock is plumbed to the rear brake line as some do? Then you hold the button which prevents the rear brakes from getting pressure and you hold the front brakes with the brake pedal. Some guys prefer that setup. Just a thought...
Click to expand...

Excellent thought.
 
MobileCustoms said:
Did you install the line lock or is that how you got it? Is it possible the line lock is plumbed to the rear brake line as some do? Then you hold the button which prevents the rear brakes from getting pressure and you hold the front brakes with the brake pedal. Some guys prefer that setup. Just a thought...
Click to expand...
Yes, good thought. I had never heard of doing it that way. But, I haven't heard of a bunch of stuff.
 
crazydog said:
Yes, good thought. I had never heard of doing it that way. But, I haven't heard of a bunch of stuff.
Click to expand...
I guess it gives you a lot more control to ease out of the burnout, or for having fun with burnouts. LOL
Thinking of switching mine around like that.
 
Is it possible that the line lock is plumbed backwards? I thought that they had an inlet and outlet. And the cars I work on have the adjustable proportional valve on the rear brakes
 
Pretty sure it is controlling the car by blocking pressure from the rear. This is why it is inconsistent. The holding force is only what your foot is applying and you aren’t applying it enough. Try and push the button then drive it like it doesn’t have a line lock. Apply all the pedal pressure you need, remove your foot when you want to move. When done let up on the button. Heard of people plumbing it that way, the brake lights operate as they should. I actually tried it and it didn’t work. Redid it the traditional way.
 
MobileCustoms said:
Did you install the line lock or is that how you got it? Is it possible the line lock is plumbed to the rear brake line as some do? Then you hold the button which prevents the rear brakes from getting pressure and you hold the front brakes with the brake pedal. Some guys prefer that setup. Just a thought...
Click to expand...
this was the way the car was built before I acquired it. The line lock is definitely plumbed into the front brakes. I'm fairly certain that the proportioning valve is plumbed in the rear brake line. My guess is the residual pressure valves in the front and rear brake lines may be having a effect.
 
Sterling said:
Is it possible that the line lock is plumbed backwards? I thought that they had an inlet and outlet. And the cars I work on have the adjustable proportional valve on the rear brakes
Click to expand...
It's certainly possible. I have a spare solenoid exactly the same as the one installed in the car. I'll double check to make sure it's not plumbed backwards.
 
I had one that acted funky brand new. Replaced it and no issues. It was inconsistent on holding power.
 
I plumbed a line lock up on a Dakota and it would only lock the rear brakes no matter how I plumbed it to the master cylinder.I bypassed then removed the factory proportioning valve then it work as it should.
 
Solved the issue. I had swapped the rear tires from side to side before opening day. Just a habit I had gotten into over the years. Apparently these Goodyear tires, even though they don't have directional arrows on the sidewalls, are directional. First test run at Winterport Dragway this past Sunday was the closest I've ever come to wrecking on track. Rear end was extremely light and dancing back and forth. Got out of it at the 330 and coasted the rest of the way. Got back to the trailer and decided out of desperation to swap the rear tires back to their original position, which is a pain in the backside on this car as it requires disconnecting the shocks so the rear will drop enough to clear the fenders. Also dialed in a little more front brake. Went up for second test run and all was well! Did good burnout, car launched good and went straight down broadway. Who would of thunk it! 60' and ET were a little off from the end of last season so did some more investigating and found broken plug connector on #2 plug wire. I always carry a spare set of wires so I decided to swap them all, and while doing so discovered most of my spark plugs were only in finger tight! I recalled that when I was putting new plugs in a couple weeks ago the shop inspector ( my hound Olive) came in and was criticizing some of my other work so I never went back and torqued down the plugs! It's not easy having a task master shop inspector! Anyway, since there's no racing here in Maine for Memorial Weekend going to tow over to New England Dragway on Saturday and run with the big dogs in their weekly points program. Should be fun!
 
Inertia said:
Well done Les .
Stay safe .
Click to expand...
how are u doing something stupid. they are diff get uor mod instructions . but the lock out goes only front setn of wheels . stay away from rear it has to work after bleeding complete sys . take out set pump brakes set lock rev and let go. that is switch to front lock out. pumping brakes is to set front befor u lock at lockout switch or the stuff u have is fcked,
 
charles mill said:
how are u doing something stupid. they are diff get uor mod instructions . but the lock out goes only front setn of wheels . stay away from rear it has to work after bleeding complete sys . take out set pump brakes set lock rev and let go. that is switch to front lock out. pumping brakes is to set front befor u lock at lockout switch or the stuff u have is fcked,
Click to expand...
u put what u have only on line to front brakes. but make it to where they front brakes work with out using lock so u can stop if that does not work u have a fck system.
 
FWI
On a factory car, that runs four same-sized tires, the front brakes do about 85% of the work.
On my hi-perf street car, I found that, as the rear tires got swapped ever bigger, I could dial in more and more rear brake, until eventually with 295s, the Rear now has Zero proportioning; and I actually gutted that part of the Combination switch.
My line lock is plumbed and wired the usual way; namely; into the front brakes and powering up the solenoid after pressurizing the front lines, which locks the front brakes on.
As an aside, I also wired an on/off switch in parallel to be used as a hill-holder, as my car has a manual trans.
My street-car has 235/60-14s up front so on burn-outs, those 235s have no problem holding the car, even on clean, dry asphalt.
Jus saying .....

If you have a factory combination valve, there is a shuttle valve inside it. On the one end of that valve is the front brake system. On the other is the rear brake system. The job of that shuttle is to ground out the brake warning lamp on your dash to light it up, in the event of a failure of one of the two systems. This action also stops the flow of brake-fluid in the failed side.
Now, If someone took that shuttle valve out, or if the isolation seals on the shuttle have failed, then inside that valve there is no longer any isolation of the two systems. This renders your dual system, back into a single system, which I'm sure is a bad thing, especially if it was done on purpose.
Jus saying.......
 
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