Line Lock ~ Drag Racing

[xxxJohnBoyxxx]

Can anyone tell me if a line lock can be installed on a BMW 318is without messing up the ABS function?

When I stage with my clutch all the way in when I rev to 4,000 the car creeps and I'm going to red light soon because of this so I need to figure it out. Parking brake is unacceptable.

I actually would like a line lock with rev limiter so I can lock fully staged and mash the gas full with the limiter holding it at 4,000, preload the clutch and as soon as I let off the button both limiter and front brakes are released for a nasty launch...

[pdxmotorhead]

The Line lock is just a valve in the brake line. Note for staging you need two one for each front brake. I'd pull the ABS fuse when racing. They also don't release as fast as you would think. There is a very slight delay. There are also two types, one is held closed by electricity, one is cocked by the electrical signal and you have to pump the brakes to release it.

Hope this helps...\
Dave

[xxxJohnBoyxxx]

Originally Posted by pdxmotorhead

The Line lock is just a valve in the brake line. Note for staging you need two one for each front brake. I'd pull the ABS fuse when racing. They also don't release as fast as you would think. There is a very slight delay. There are also two types, one is held closed by electricity, one is cocked by the electrical signal and you have to pump the brakes to release it.

Hope this helps...\
Dave

Dave isn't there one pipe off the master cylinder I can tap? One for front and one for back, I ignore back...

[tiFreak]

Originally Posted by xxxJohnBoyxxx

Dave isn't there one pipe off the master cylinder I can tap? One for front and one for back, I ignore back...

I'm pretty sure most modern master cylinders are set up with one line for the RF and LR brakes and one for the LF and RR brakes, that way if you lose a line you'll still have one front and one rear brake

[Xenocide]

Originally Posted by tiFreak

I'm pretty sure most modern master cylinders are set up with one line for the RF and LR brakes and one for the LF and RR brakes, that way if you lose a line you'll still have one front and one rear brake

Correct. Each brake has its own line to the ABS unit.

[xxxJohnBoyxxx]

I don't think my master cylinder has 4 lines going into it. I think it has 2...One for the front brakes which branches to the 2 lines in the ABS and one to the rear brakes the branches into two lines in the ABS.

If I put the line lock on the front line coming out of the master cylinder then both front brakes are locked. Question is what will the ABS do about it??

[Xenocide]

ABS shouldn't care....assuming you have no ASC, it just monitors the wheel speed sensors. Not 100% sure on that but I know our cars have VERY simple ABS units.

[pdxmotorhead]

Ok just went and checked.

MC has 2 lines to ABS pump. From the pump there are 3 lines, 1 to the rear and 1 to each front caliper.

The S13 Nissan I work on has 3 lines off the master 1 to each front and 1 to the rear.

I wonder if you could use the ABS pump for the line lock, Override it so it puts the pressure on the front for you. It would react way faster than any line lock.

I would try between the master and ABS first. It looks pretty easy just build 1 new line and there is a nice roomy spot just below the master cylinder. Otherwise it looks pretty easy to put a pair of line locks right off the ABS pump.

Will be interesting to see how it reacts if you lock the front and do a burnout.
Will it pump the rear brake? or release pressure on the front in response to the difference between the front and rear speed sensor.

I'd do this in a wide open space....

Dave

[xxxJohnBoyxxx]

Here is the setup I'm thinking about. Install the line lock solinoid in the MC front brake line. Setup a relay to turn off ABS when the line lock button is active.

I think this will allow: push brakes on hard and push button the front brakes will be locked and the relay will disconnect ABS to not interfere with the locked front brakes or throw a ABS code. After I leave hard the ABS will come back on-line for panic braking

ASC ~ what is that?? J/K I got rid of that 2 years ago, no ice down here and with a boosted motor it was always engaging plus the ASC TB was a restriction in my intake track so it had to go, I'm 3" from turbo to throttle body and 3" from down-pipe out the flowmaster 50 series. I've never liked driving a car with traction control. I do like ABS for daily driving, I have been in situations and panic stopped where the ABS helped a lot

[pdxmotorhead]

Ya know, there is a thought there, if you could work the connection that activated the original traction control to control boost, so if the rear starts spinning it would feather back just a tad you would launch like crazy. Spin is the enemy and there is a reason the classes like top fuel don't allow traction control and have to do it all with the clutch tuning...

Hmm.

Dave

[Jean H.318TI]

get a 2 step launch control and WOT shift box.

[mohaughn]

Early Ti's all have three channel ABS, the rear brakes share the same line from the ABS. If it was a four channel system, we would have speed sensors on each wheel.

I think the very late 99 models may have a 4 channel as BMW started changing cars to the 4 channel setup in the late 90's, but I've never actually looked at one to see if it is different.

Most of the linelocks I've seen sold for BMWs have two input/outputs. So I think they are intended to be put after the ABS pump. Hurst makes one for like 150$.