Shifting on Time

SGSST109E · 02-13-2009, 10:23 PM

I have been shifting by RPM for years. I want to try shifting by time to see is it would work better on my car. Would like to hear opinions on shifting before the TS come on, after the TS is on etc.

Lou SG2340 · 02-14-2009, 07:07 AM

Being in high gear before the stop closes will soften the hit on the tires when the stop opens. I turn the stop on at .02 and shift at .04. Shifting after the stop goes thru its cycle is no different than shifting by rpm.

SGSST109E · 02-14-2009, 10:35 AM

Have you ever tried shifting before the stop?

Lou SG2340 · 02-14-2009, 01:19 PM

Quote:

Originally Posted by SGSST109E

Have you ever tried shifting before the stop?

No when I shifted by RPM I shifted after the stop opened. In my opinion the point of shifting by time is to shift after the stop closes. In shifting by time, when you close the stop & shift will depend on car weight, HP, & other veriables.

In my opion the car is more consistant & you will be on the stop for a shorter period of time by shifting by time while the stop is closed. Lou

GaryGoFast · 02-14-2009, 03:32 PM

How heavy is the car?
Does it have a 2 or 2 speed trans?
Whats the 1st # in the stop?
Air or Electric Stop?
Slow or fast car for class?

Super Street 2800 lbs., if your at or slightly above 2800 with a 2 speed trans, air stop, 4200 stop rpm, I shift at .75 and thats just after the car settles ON the stop. Heavy car low stop RPM = Bad thing for convertor.

Lou SG2340 · 02-15-2009, 07:25 AM

First started shifting on time at 2500lbs 9.90 at 150 mph. T. stop is air 1 stop. PG trans 8" 6200 stall convertor.
Present car is 2260 lbs with same motor combination. 160 mph . Go on stop at .02 shift .05.Convertor slipage is 75 to 55% while on stop. Never had a convertor or trans problem while at 2500 lbs. Convertor in car has 300 passes on it slips 8% at finish line. Stop RPM is 4100. Lou

jmarkaudio · 02-16-2009, 09:57 PM

By shifting on time while on the stop you don't hit the tires as hard when the stop comes off. That may help on a marginal track.

SGSST109E · 02-17-2009, 11:59 AM

I agree but it hasn't been and issue on my combination. Just looking to make it more repeatable.

dak · 02-20-2009, 01:17 AM

Gary.. your post said low RPM heavy car = bad for the convertor.. 8" convertor?? what if you go to a bigger convertor..like a 10"?

I know that I limit RPM on the starting line and use that setting as my stop RPM.. The 8" convertor goes 5800 but I limit it to 4400..

If you had lots of motor.. (like a lot of guys) do you really need a loose convertor?

don R · 02-24-2009, 11:47 PM

I think shifting on time is more consistent. I believe time gets the shift closer to the same point on the track every pass. If there is a little more or less tire slip I think you will see less difference in the pass.

02-13-2009, 10:23 PM	#1
SGSST109E Member Join Date: Jun 2007 Location: NJ Posts: 342 Likes: 54 Liked 124 Times in 58 Posts	Shifting on Time I have been shifting by RPM for years. I want to try shifting by time to see is it would work better on my car. Would like to hear opinions on shifting before the TS come on, after the TS is on etc.

02-14-2009, 07:07 AM	#2
Lou SG2340 Member Join Date: May 2008 Location: Disputanta Va (30 minutes from VMP) Posts: 122 Likes: 0 Liked 0 Times in 0 Posts	Re: Shifting on Time Being in high gear before the stop closes will soften the hit on the tires when the stop opens. I turn the stop on at .02 and shift at .04. Shifting after the stop goes thru its cycle is no different than shifting by rpm.

02-14-2009, 10:35 AM	#3
SGSST109E Member Join Date: Jun 2007 Location: NJ Posts: 342 Likes: 54 Liked 124 Times in 58 Posts	Re: Shifting on Time Have you ever tried shifting before the stop?

02-14-2009, 03:32 PM	#5
GaryGoFast Senior Member Join Date: Nov 2003 Location: New York Posts: 804 Likes: 0 Liked 1 Time in 1 Post	Re: Shifting on Time How heavy is the car? Does it have a 2 or 2 speed trans? Whats the 1st # in the stop? Air or Electric Stop? Slow or fast car for class? Super Street 2800 lbs., if your at or slightly above 2800 with a 2 speed trans, air stop, 4200 stop rpm, I shift at .75 and thats just after the car settles ON the stop. Heavy car low stop RPM = Bad thing for convertor. __________________ Gary Federico S/St, S/G 1814

02-15-2009, 07:25 AM	#6
Lou SG2340 Member Join Date: May 2008 Location: Disputanta Va (30 minutes from VMP) Posts: 122 Likes: 0 Liked 0 Times in 0 Posts	Re: Shifting on Time First started shifting on time at 2500lbs 9.90 at 150 mph. T. stop is air 1 stop. PG trans 8" 6200 stall convertor. Present car is 2260 lbs with same motor combination. 160 mph . Go on stop at .02 shift .05.Convertor slipage is 75 to 55% while on stop. Never had a convertor or trans problem while at 2500 lbs. Convertor in car has 300 passes on it slips 8% at finish line. Stop RPM is 4100. Lou Last edited by Lou SG2340; 02-15-2009 at 07:26 AM. Reason: added stop rpm

02-16-2009, 09:57 PM	#7
jmarkaudio Junior Member Join Date: Apr 2008 Posts: 83 Likes: 0 Liked 0 Times in 0 Posts	Re: Shifting on Time By shifting on time while on the stop you don't hit the tires as hard when the stop comes off. That may help on a marginal track.

02-17-2009, 11:59 AM	#8
SGSST109E Member Join Date: Jun 2007 Location: NJ Posts: 342 Likes: 54 Liked 124 Times in 58 Posts	Re: Shifting on Time I agree but it hasn't been and issue on my combination. Just looking to make it more repeatable.

02-20-2009, 01:17 AM	#9
dak Junior Member Join Date: Mar 2003 Location: west coast Posts: 26 Likes: 0 Liked 0 Times in 0 Posts	Re: Shifting on Time Gary.. your post said low RPM heavy car = bad for the convertor.. 8" convertor?? what if you go to a bigger convertor..like a 10"? I know that I limit RPM on the starting line and use that setting as my stop RPM.. The 8" convertor goes 5800 but I limit it to 4400.. If you had lots of motor.. (like a lot of guys) do you really need a loose convertor?

02-24-2009, 11:47 PM	#10
don R Member Join Date: Dec 2005 Location: Illinois Posts: 109 Likes: 0 Liked 0 Times in 0 Posts	Re: Shifting on Time I think shifting on time is more consistent. I believe time gets the shift closer to the same point on the track every pass. If there is a little more or less tire slip I think you will see less difference in the pass.