2 Step Question?

[art leong]

I've got my 2 step (launch control) working fairly well (I think?). It holds the rpms from about 3300 to 2800 against the footbrake.
My problem is the car surges (creeps) a little bit (3 inches in 5 seconds) when on the button against the brakes.
When I try to lower the rpms it just widens the surging.
My converter flashes to 5100 and it is a hard hit converter made to be used with a transbrake.
I can work on the 2 step a bit more with timing retard, or pull some fuel out.But I don't know how it will act when I let go of the button.
I've never used a 2 step before. Is the surging normal? It the rpm range normal? Will putting in a soft hit converter help?
This testing has been done in my driveway with no heat to the brakes. So can I expect it to hold a little better arfter a burnout?

[Brandon Peterson]

I usually leave around 3000 to 3500. With a converter that flashes around 5200.. my car wont hold at 3000 in the lanes without creeping a bit but on the starting line it is a totally different feeling and it should easily hold.... I also use a pressure switch not a button don't know if there would be any difference....we tried at first using it wired into the brake light switch but felt there was a lag on the releasing of the two step

[Rich Biebel]

A 2 step does not normally move anywhere near that many rpm. Maybe 100 but no way 500. Something is not right if your saying the rpm moves that much when the rev limiter is activated...

If you car moves there is not enough brake pressure or your brakes are not good...

I never used a rev limiter on any car without a trans brake.

I did set my Firebird stocker up with an adjustable low rpm rev limiter chip and a button for use with the footbrake with a finger button before they were prohibited. I tried it in the pits one day and hated it.....never used it on the race track. No way it would hold the car without being hard on the footbrake even with the 2 step activated at 3000 rpm.....I did not like the feel of it....

[Rsmith38]

On my comanche (R/SA) with conv stall at 4900 I have a 3000 chip in 2-step. Any higher and it will pull through the lights. Aerospace front disks and Jeep rear disks. My thinking is the surging is the problem - if your RPM stayed at 2850 - where the 2-step starts dropping cyls - it probably wont move forward - but at 3500 it sure will creep.

[Chad Rhodes]

art, are you seeing that rpm variation on the tach or are you logging it and its doing that? i use the two step in my DFI and the tach will do some crazy stuff, but if you read the data logs its a pretty flat line, maybbe a 50-75 rpm variance.

[art leong]

Originally Posted by Chad Rhodes

art, are you seeing that rpm variation on the tach or are you logging it and its doing that? i use the two step in my DFI and the tach will do some crazy stuff, but if you read the data logs its a pretty flat line, maybbe a 50-75 rpm variance.

This is from the datalogger, I think the tach needle would have an effect if I was using the tach to figure it.
I'm wondering if it's a 4 cylinder thing. With an 8 cylinder if you cut one cylinder at a time your cutting 12.5% of the power. When I hit the button I'm taking out 25%.
When in neutral the motor stays within 75 rpms when the button is activated. But with a load on it. It gets cranky.
My brakes are stock discs (bonded pads) in front and back. I can't use larger or aftermarket brakes because I need to run 13 or 14 inch wheels (to keep wheel height to 20 inches)
The converter was made for a transbrake application. I'm wondering if I went to a softer hit converter. If it would be easier to hold on the line.

[Mile High]

I wouldn't worry about it until I took it to the track and tried it. The starting line is alot different than your driveway. I change converters on mine once tried it at home and it started pushing, took it to the track and all was well. I prefer a pressure switch to operate the 2 step.

Jeff

[gmonde]

X2 on taking it to the track first before any changes are made gmonde

[art leong]

My brakes are single piston 54mm front and 34mm rear. I have a pressure gauge and am able to get to around 1400 pounds of pressure.
Should that be enough?

[Mile High]

Maybe the brakes aren't strong enough. I don't have a brake pressure gauge. The starting line is alot different than your driveway. With my converter change I lowered my launch rpm from 3400 to 2700 and dropped front tire pressure 10 lbs. to cut a light. I have Wilwood discs up front and stock Ford drums on the rear. Don't need no stinkin' transbrake.

Jeff