Shift Point Question???
Thread Starter
Burning Brakes
Joined: Jul 2006
Posts: 826
Likes: 22
From: Chicago Area
Shift Point Question???
80 Z28 with a replica built ZZ430 block and 700R4 trans:
I was messing with the shift points late this summer and it was shifting at about 6000-6200 from 1-2 but from 2-3 it would NOT shift until I let off the pedal a bit. Once in a while even after hitting 3rd...it would want to drop back to second severlly over reving the motor. I brought it down to about 55-5600 so if I just stomp on it and not use the slap shifter, it will shift nice and not over rev. Do I want the car to shift at max HP/TQ rpm based on my dyno numbers (5800ish) In other words...am I losing time on the track if I shift it above the 5800? I don't race it much but when I want to wax a ricer, I was just wondering where I should shift it. I had it at the track once before messing with it and with a sloppy 2-3 shift (not shifting unless I backed off the pedal a bit) my best time was a 13:29 with radial T/A's. If I remember right...I was shifting high. Could I have shaved off more time if it would have shifted at 5800-6000? have not raced a lot... but had a blast that day...
Thanks
I was messing with the shift points late this summer and it was shifting at about 6000-6200 from 1-2 but from 2-3 it would NOT shift until I let off the pedal a bit. Once in a while even after hitting 3rd...it would want to drop back to second severlly over reving the motor. I brought it down to about 55-5600 so if I just stomp on it and not use the slap shifter, it will shift nice and not over rev. Do I want the car to shift at max HP/TQ rpm based on my dyno numbers (5800ish) In other words...am I losing time on the track if I shift it above the 5800? I don't race it much but when I want to wax a ricer, I was just wondering where I should shift it. I had it at the track once before messing with it and with a sloppy 2-3 shift (not shifting unless I backed off the pedal a bit) my best time was a 13:29 with radial T/A's. If I remember right...I was shifting high. Could I have shaved off more time if it would have shifted at 5800-6000? have not raced a lot... but had a blast that day...
Thanks
Melting Slicks
Joined: May 2001
Posts: 2,131
Likes: 4
From: May help you? You can sure as hell try!
You should shift past the HP peak so that the RPM's fall just below HP peak for the next gear. The object is to stay as close to HP peak as possible while going down the track. You can figure your RPM drop and shift points based on the gear ratio's of your transmission.
Nice Z28. My friend had a red one like that while we were in college. He also had a '78 around the same time. The '78 was surprizingly fast for a car built during the dark days of the smog era. It had a 4 speed and 3.73 rear axle. Unfortunately, the '80 was a bit of a stone but nothing some good hipo parts couldn't fix. It was a nice cruiser, though. My buddy now has my old '69 Z-28 that he just finished a total rotisserie resto on.
Nice Z28. My friend had a red one like that while we were in college. He also had a '78 around the same time. The '78 was surprizingly fast for a car built during the dark days of the smog era. It had a 4 speed and 3.73 rear axle. Unfortunately, the '80 was a bit of a stone but nothing some good hipo parts couldn't fix. It was a nice cruiser, though. My buddy now has my old '69 Z-28 that he just finished a total rotisserie resto on.
Thread Starter
Burning Brakes
Joined: Jul 2006
Posts: 826
Likes: 22
From: Chicago Area
Originally Posted by LemansBlue68
You should shift past the HP peak so that the RPM's fall just below HP peak for the next gear. The object is to stay as close to HP peak as possible while going down the track. You can figure your RPM drop and shift points based on the gear ratio's of your transmission.
Nice Z28. My friend had a red one like that while we were in college. He also had a '78 around the same time. The '78 was surprizingly fast for a car built during the dark days of the smog era. It had a 4 speed and 3.73 rear axle. Unfortunately, the '80 was a bit of a stone but nothing some good hipo parts couldn't fix. It was a nice cruiser, though. My buddy now has my old '69 Z-28 that he just finished a total rotisserie resto on.
Nice Z28. My friend had a red one like that while we were in college. He also had a '78 around the same time. The '78 was surprizingly fast for a car built during the dark days of the smog era. It had a 4 speed and 3.73 rear axle. Unfortunately, the '80 was a bit of a stone but nothing some good hipo parts couldn't fix. It was a nice cruiser, though. My buddy now has my old '69 Z-28 that he just finished a total rotisserie resto on.
