I remember years ago there were some here using a line lock in dragsters to hold the car from moving at all when the line lock was applied.

I didn't really think much of it at the time. But we bought a car that has one. It even kind of messed us up with backing up with a pro brake.

I figured I would disconnect it, but wondered, are others using these? Thoughts?

I've always ran gear backlash on the tight side for anything without a line lock.

Put it on a car years ago, its aggrivating to say the least. If your trans is built right you don't need it in a dragster, door car is another story.

We found troubles backing up and slows RT down some which is easily adjusted in the box but i think its unnecessary.

quote:

Originally posted by Triple Nickel:
Put it on a car years ago, its aggrivating to say the least. If your trans is built right you don't need it in a dragster, door car is another story.

We found troubles backing up and slows RT down some which is easily adjusted in the box but i think its unnecessary.

How much did it slow RT's? We noticed we were using less delay than my car has by a good amount.
I may just snip the wire.

Why not add a toggle switch to turn off the line lock when backing up?

I had one years ago and found it made my lights more inconsistent, it was a short hard tail car….

This is an interesting topic. We just disconnected ours on our dragster because we were having some inconsistent reaction times. Our thinking was if the brake pressure varied from pass to pass, the rear brakes may have some variation in releasing. We have yet to get it back out to prove the theory, but did notice a difference in the one pass we made with it unhooked. Worked out to be about .017. I want more data for an accurate grouping before I say yes that was it though. Keep us posted here as I am interested in what you see in your car. In a door car it is hooked to the front brakes, so any variation wouldn't really be seen in vehicle reaction.

I had to wire one in for a friend of mine. I used a separate switch to back up with a diode so it didn't activate the linelock.

Maybe its because I stage carefully, but I had a few seasons of getting a handful of LB3A's. It would always happen when I got on the two step at the second bulb. I had a very good racer explain to me that the stage beam is so small and since my car isn't taking a "set" forward due to the linelock, the vibration flickers the beam and redlights me. Disabled my linelock and the problem went away.

Great input. Thank you!

I run one in both dragsters.

Whenever I drive a dragster without a line lock I can feel the car “settle” when I hit the transbrake button and let off the brake. Does it settle the same every time? I don’t know. But I know that with a line lock the car doesn’t move a whisker. This is not a transmission setup issue (although I suppose a transbrake could mask that too) as all cars are going to have slack in the drive train from rear end backlash, splines in the axles, etc. If you’re worried about reaction time issues due to different brake pressure just run the line lock on one of the rear wheels.

The backing up problem is solved with either backup button and a diode (have on my wife’s car) or a DPST backup button which I wired on my car. I wouldn’t put an extra switch in because that’s something to forget to flip on or off.

Ran one in my old door car. Used a diode with a separate button to back up. You can get a bag of 10 on Amazon for $10 or $11.

quote:

Originally posted by Bucky:
Thoughts?

Yea, fix your trans!

If ya got one rock'n in and roll'n in,it ain't doing the same thing twice in a row, I know. Because I purpose built a PG in 2016 for .370 Pro Tree racing, to take a big bite when the trans brake was set. It failed because it wouldn't do the same thing twice in row.

This is when I believed everyone who said 370 Pro Tree was an impossible task for a 3200 lb car on a 28 x 10 bias, with a small block.

If ya wanna 370 Pro Tree race with a heavy doorslammer staged shallow, start off with a JW Pro Tree Brake, there's none faster on the planet.

In a heavy door car, I have to have a line lock connected to the transbrake every time. In the exact same car my buddy does not.

The only difference we can find is the way I stage vs the way he stages. I bump the brake so much faster than him it bounces the rear end, and must put the chassis in a bind.

After hooking up the line lock, I have been more consistent on the tree than I have ever been in that car, so it definitely helped me. I've hooked it to the box in every car after that, and don't see why you wouldn't really.

Heavy door car here, 3216 lbs. and the line lock is NOT wired into the trans brake and there is no reason to. This car, my cars, are “stupid consistent” and their transmissions function/operate correctly.

That said, consistency starts and ends with the knucklehead wearing the brain bucket!

If you have a car that moves or twitches after you set the brake and pick up the throttle, your trans. is not what it should be

Pump is poor, or various other possibilities...

I have 2 transmissions and neither moves.....

If it moves, fix it...

A door car with stock type suspension might benefit from using a Line Loc with the trans brake.

I've had it on at least 1 car and just used diodes to prevent back feed on that car

On another car I had a switch on the dash for the LL along with another switch that turned on an idle stop solenoid....Used that for S/G racing.....raise the idle and stick it in there "John Force style"

Had one trans that jerked a bit as I matted it.....NFG !!.....put a Dedenbaer pump in it, problem solved....no line loc

i think one of the biggest issues is just going in a idle, I like going in at about 1400 so the pump pressure is higher than at idle so I never have to worry about it. I always ran one in the door cars but still did the same thing.
To each their own but I do believe if your trans is rocking in the stage beams you need to fix that first.

Another reason to use a SLE which we do in both cars.

I had a trans that would rock at trans brake engage. replaced the pump with a Dedenbear, same thing, change pressure spring (210), same thing. I was using the linelock and going in at 1400RPM as a crutch to stop the rolling. What was the fix was changing to a Sonnex Smart-Tech Ratio-Style Servo Kit 2882110K. Now i can roll in @ 900 rpm with the linelock disconnected. Best $200 I ever spent on a trans.

https://www.sonnax.com/parts/4...atio-style-servo-kit


Joe