2 step & pressure switch
 

Has anyone ever had an issue with your 2 step not turning off clean during the launch?

I have developed a studder during the launch.

It shows the O2's going rich almost like it's a ignition thing.

Re: 2 step & pressure switch
 

I assume you have a data recorder in the car. We bring the
12v signal from the pressure switch / 2 step into a digital input
Then you can see the 12 v drop and rpm increase. Our O2 sensor goes
rich on the hit also.I assumed it has to do with the vacuum secondary
in the carb
David

Re: 2 step & pressure switch
 

Yes, a bad Pressure switch can cause this. I would change it out .

Steve Teeter. Stk/SS 620

Re: 2 step & pressure switch
 

David, I do have a Racepak. I will order the 12 volt event sensor.


Steve, good point. I will change it out while I'm at it.

Thanks,
Mike

Re: 2 step & pressure switch
 

Some pressure switches have buna type o-rings or wetted parts. Buna rubber is not compatible with brake fluid. EPDM rubber is compatible with brake fluid. Virtually all brake o-rings, seals, etc are edpm rubber. Not sure as to what extent that has with the switch, but I know one person who had a switch go bad and his had buna rubber parts.

Re: 2 step & pressure switch
 

I get your using brake pressure switch but are you using one in conjunction with a button on the brake pedal. If you are that's the first thing I would get rid of.

Re: 2 step & pressure switch
 

What is the switch to buy?

Re: 2 step & pressure switch
 

I was doing research on switches and most have buna rubber. I think there is a place on the east coast that has epdm rubber pressure switches. I think that it is saved on my work computer. I will check and see.

Re: 2 step & pressure switch
 

If someone could share what brand pressure switch they have had good results with it would be greatly appreciated!
Thanks,
Mike

Re: 2 step & pressure switch
 

I use a Harley brake lite switch, no problem in the 5 years it's been in place.
I've also used Napa SL147 and SL143, both VW brake lite switches.

Grant

Re: 2 step & pressure switch
 

I would think a brake lite switch would trigger
at a low pressure Ours is set at 700 psi
David

Re: 2 step & pressure switch
 

Anyone come up with a part number. McMaster Carr has a switch 3427K5, but it is the Buna rubber.

Re: 2 step & pressure switch
 

I use one from transducers direst p/n TDPS8. adjustable, 250-1000 psi, 1/8 pipe thread. It works perfect, but looking at the data sheet, it has a buna N diaphram. Contact them and ask for something similar with viton.



513-583-9491


SALES@TRANSDUCERSDIRECT.COM

Re: 2 step & pressure switch
 

Call Folk Race Cars. They sell what's called the Ultimate Brake Pressure Switch. Easy to adjust to different brake PSI requirements. Two wires.
( Has three but the black wire is not used). 150.00?.

Steve Teeter Stk/SS 620

Re: 2 step & pressure switch
 

What brake fluid are you using with these switches?
Thanks,
Mike

Re: 2 step & pressure switch
 

I'll have to dig up the part # but I just use a 2 wire brake pressure switch that has pipe threads. Listing is probably for and old Ford car.
Just found my spare switch, it's an S194 from Carquest.