Yank Shift Extension Question
Thread Starter
TECH Junkie
Joined: Dec 2005
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Yank Shift Extension Question I have a Yank SS4000 torque converter(4L60E) and I will be shifting around 6500 to 6600rpm. The shift extension should be around 5700rpm. So does the shift extension act as if the torque converter had a 5700rpm stall after the initial launch?
Just wondering as I enter the data for my drag race simulation program. With a 4000 stall entered the rpm will drop back after the 1-2 shift and 2-3 shift to 4000rpm. In reality the motor will probably drop back to around 5700rpm. It makes quite a difference in et if I enter 5700rpm stall versus the 4000 stall. I know the launch part (60') then becomes messed up.
One reason for doing this is to see where I should set the shift point when shifting from first to 2nd gear. Maybe I need a new drag race simulation program.
Just wondering as I enter the data for my drag race simulation program. With a 4000 stall entered the rpm will drop back after the 1-2 shift and 2-3 shift to 4000rpm. In reality the motor will probably drop back to around 5700rpm. It makes quite a difference in et if I enter 5700rpm stall versus the 4000 stall. I know the launch part (60') then becomes messed up.
One reason for doing this is to see where I should set the shift point when shifting from first to 2nd gear. Maybe I need a new drag race simulation program.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Typically, a run with a Yank SS4k starts like this.....Brake stall to whatever you feel. i like to bring it off idle slightly, about 1500-2k. Light goes green you floor it, rpms raise to 4k and the car blasts off, rpms hold at 4k until the speed catches up. Then when you are at the correct speed for 4k rpms, the speed and rpms climb together in unison. At your shift point (say 6500), it shifts and the converter drops back to around 5600. Your speed is not appropriate for that much rpm because the converter is letting the motor slip. So rpms hold at 5600 until the speed catches up, and when it does, speed and rpm pull together in unison again until the next shift where the same situation happens again. You will FEEL the shift extension, the car pulls the best in that area.
For a stock converter car, after the shift, the rpms fall to around 4300 or so, and immediately rpms and mph climb together, they never separate, if one is moving up, so is the other.
An example of a Yank SS 4k. Close lane ss4k, far lane equally modded M6.....
http://www.youtube.com/watch?v=Fzj1jwCkAaA
For a stock converter car, after the shift, the rpms fall to around 4300 or so, and immediately rpms and mph climb together, they never separate, if one is moving up, so is the other.
An example of a Yank SS 4k. Close lane ss4k, far lane equally modded M6.....
http://www.youtube.com/watch?v=Fzj1jwCkAaA
Typically, a run with a Yank SS4k starts like this.....Brake stall to whatever you feel. i like to bring it off idle slightly, about 1500-2k. Light goes green you floor it, rpms raise to 4k and the car blasts off, rpms hold at 4k until the speed catches up. Then when you are at the correct speed for 4k rpms, the speed and rpms climb together in unison. At your shift point (say 6500), it shifts and the converter drops back to around 5600. Your speed is not appropriate for that much rpm because the converter is letting the motor slip. So rpms hold at 5600 until the speed catches up, and when it does, speed and rpm pull together in unison again until the next shift where the same situation happens again. You will FEEL the shift extension, the car pulls the best in that area.
For a stock converter car, after the shift, the rpms fall to around 4300 or so, and immediately rpms and mph climb together, they never separate, if one is moving up, so is the other.
An example of a Yank SS 4k. Close lane ss4k, far lane equally modded M6.....
http://www.youtube.com/watch?v=Fzj1jwCkAaA
For a stock converter car, after the shift, the rpms fall to around 4300 or so, and immediately rpms and mph climb together, they never separate, if one is moving up, so is the other.
An example of a Yank SS 4k. Close lane ss4k, far lane equally modded M6.....
http://www.youtube.com/watch?v=Fzj1jwCkAaA
Thread Starter
TECH Junkie
Joined: Dec 2005
Posts: 3,092
Likes: 11
Thank you for the explanation. That is how I envision it. My question would be after the shift to 2nd gear the motor rpm only drops to say 5600rpm. Would that not be equal to a 5600rpm stall? I am trying to duplicate that on a drag race simulation computer program. Maybe I just need a new program.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
No, that is shift extension. Different stalls will have different shift extensions, as well as shift rpm changes shift extension. Its all relative to getting a stall thats right for your package. Typically, the bigger the stall the more extension it can handle. And example, with a 3200, rpms dropped to 5k after a shift, changed to a 4k, and it only drops to 5500. You could FEEL that 500 rpm difference. I couldn't live without it now.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
All the info on that track outing is here:
https://ls1tech.com/forums/multimedi...pics-vids.html
First passes on this converter, even though its almost 2 years old.
https://ls1tech.com/forums/multimedi...pics-vids.html
First passes on this converter, even though its almost 2 years old.
