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Clutch switch for launch/flat shift in micro question

VB242

VB242

I.M. Weasel
Joined
Sep 21, 2011
Location
Driving the No Malarkey Bus
I have a clutch switch from a cruise control and would like to use it for launch/flat shift. I understand that I use vref and either flex or spareADC to get the signal but the switch is normally closed with the pedal up. Is there a setting I can't find that will let me wire directly to the switch or do I need to use a relay and operate it with the switch?
 
VB242 said:
I understand that I use vref and either flex or spareADC to get the signal but the switch is normally closed with the pedal up. Is there a setting I can't find that will let me wire directly to the switch or do I need to use a relay and operate it with the switch?
Click to expand...

No, you understood it wrong. The switch needs to ground the SpareADC to Sensor Ground. You need a normally open switch, the software is written for normally open switch. I like SLS141, it has both normally close and normally open plugs.

http://www.msextra.com/doc/pdf/html/Microsquirt_Hardware-3.4.pdf/Microsquirt_Hardware-3.4-29.html
 
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Ok thanks, I was looking at the spare adc diagram, not the flex diagram. I should be able to use a 5 pin relay with n/c-n/o contacts, it will just be active until I press the clutch in.
 
I've been vaguely pondering doing this on my car (since the launch/flat shift wire is just hanging out of the MS3X harness, mocking me).

I wasn't sure what would work best for a switch position. Seems like a switch that triggers when the pedal is all the way up might be too slow for launch control - since the clutch has already grabbed halfway through the pedal travel, before the ECU gets the signal to unleash all the boosts. Would that make for a bog? Or does it all just happen so fast that it doesn't matter. Putting the switch where it gets tripped when the pedal all the way down might work better for launch control, but that would not be very good for flat shift - you'd be on full boost/full power for the last half of the pedal travel down to the floor, and if you don't push it all the way down you'll zing it.

Probably way overthinking this - top out switch is probably fine. Gives the clutch that .3 second to grab before the engine lights off.
 
Not only that but you may find the switch isn’t in an optimal location. My switch was way to high initially and the clutch had to be nearly all the way out to engage, so, you either dump the clutch or you sit on your launch limiter for the first 10 feet or so.
 
You don't need to ground it to sensor ground. I grounded mine to the stock fuse panel ground point and it's been great for a couple years.

I put a brake switch in a modified cruise control switch bracket. All you should need to do is make the hole a slot so the switch can sit farther away from the pedal.

You may want to put another switch in line with the clutch switch so you can turn launch on or off. I used a spare port in the dash switches to do that.

The only relay in my clutch switch circuit controls the dash switch arm light.
 
t8fanning said:
You don't need to ground it to sensor ground. I grounded mine to the stock fuse panel ground point and it's been great for a couple years.

I put a brake switch in a modified cruise control switch bracket. All you should need to do is make the hole a slot so the switch can sit farther away from the pedal.

You may want to put another switch in line with the clutch switch so you can turn launch on or off. I used a spare port in the dash switches to do that.

The only relay in my clutch switch circuit controls the dash switch arm light.
Click to expand...

Exactly what I did in my 240, then adjusted the switch until it was where I liked it. Worked great.
 
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