foot brake leave pressure switch, location and RPM

[Dragsinger]

Racer,

for those of you who leave at a low RPM, activated by a pressure switch in the brake line.

Which switch? part number?
What RPM?
Do you employ the MSD low RPM adjustable chip?
What is your method to disable the switch down track?

Thanks for any help.

[Eric Merryfield]

Originally Posted by Dragsinger

Racer,

for those of you who leave at a low RPM, activated by a pressure switch in the brake line.

Which switch? part number?
What RPM?
Do you employ the MSD low RPM adjustable chip?
What is your method to disable the switch down track?

Thanks for any help.

Both my cars that have them, Dakota and Dragpak are in PA, I am sort of torn as to whether the brake pressure switch is better than electric......I don't recall the part #, it was a commercially available pressure switch.

The Gremlin has electric two step switch on petal like most, you launch have a snack shift a couple of times and then at 1,000 feet turn the switch to turn off the two step switch.......pretty foolproof......I have a brake pressure gage in the Gremlin for optimal staging....

The Dakota, well its got the brake pressure switch, and if you want to see drama, imagine what fun it is to have a leak with one of these....right as you are getting close to staging.....

If you go the brake pressure switch route, yes it need to integrate into the MSD two step, and do yourself a HUGE favor and right down the brake pressure its releasing at.....if you have to do any work, you have to reset it and its a fair bit of trial and error, and knowing what you had at it, will save your bacon.

You might suffer from periodic, insta launch if you are not careful, lets say you have the switch set at a tree killing 900Lbs, you stage it at 1000lbs, waiting for a really slower car you might relax just a touch, and insta launch.....time trials, qualifying no harm no foul elims like gulp, a final and you are liking the gremlins setup a bit more. You really need that brake pressure gauge for playing with these. This is with the Dakota, 3200-3300 launch. Re the down track, if you are jamming on the brakes with over 900lbs of force at the stripe, that's a problem.......

Eric

[Alan Nyhus]

I use this one:

https://www.transducersdirect.com/pr...sure-switches/

After the burnout, I power it up with an illuminated toggle switch. When the set pressure is reached, a green light comes on so there's no surprises when the throttle is opened.

Hope this helps. -Al

[Tom Goldman]

I have used the pressure switch Folk Race Cars sells and also the one that Alan listed the link to .
Both work , the Transducers Direct one is way cheaper and I think easier to adjust .
I used the 250-1000 psi set point version.
I incorporate a safety switch in the 2 Step circuit by using a micro switch on the shifter to open the circuit when the shifter is not in 1 st gear .
E-Shift is a little trickier ,I use a relay activated by the controller to cut out the power in 3 rd gear.