Changing Automatic Transmission Shift Point-Drag Racing
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,841
Likes: 46
From: Laurel MT
Cruise-in I Veteran
Cruise-in II Veteran
Cruise-In III Veteran
Changing Automatic Transmission Shift Point-Drag Racing
Hello!
I have a good customer who is drag racing his new C7, Auto, Z51 Coupe. This past weekend was his first at racing the new C7.
He has asked for our assistance in changing the shift points. He told me that he was hitting the rev limiter before the automatic shifted to the next gear. He doesn't want to use the paddle shifter. Any suggestions from any of you?
Thanks.
I have a good customer who is drag racing his new C7, Auto, Z51 Coupe. This past weekend was his first at racing the new C7.
He has asked for our assistance in changing the shift points. He told me that he was hitting the rev limiter before the automatic shifted to the next gear. He doesn't want to use the paddle shifter. Any suggestions from any of you?
Thanks.
Melting Slicks
Joined: May 2001
Posts: 2,596
Likes: 120
From: East Tennessee
Most likely not hitting the rev limiter. although it sounds like it.
GM is using fuel cut to let the trans shift faster, and make it live longer. You can tune it out but its not going to make a huge difference in 1/4 mile times just by shutting that off. But if you do actually raise the shift points/limiter that may help some, going to take some experimenting. At the risk of blowing his warranty of course.
GM is using fuel cut to let the trans shift faster, and make it live longer. You can tune it out but its not going to make a huge difference in 1/4 mile times just by shutting that off. But if you do actually raise the shift points/limiter that may help some, going to take some experimenting. At the risk of blowing his warranty of course.
Le Mans Master
Joined: Oct 2005
Posts: 5,051
Likes: 889
From: Tampa Florida
Hello!
I have a good customer who is drag racing his new C7, Auto, Z51 Coupe. This past weekend was his first at racing the new C7.
He has asked for our assistance in changing the shift points. He told me that he was hitting the rev limiter before the automatic shifted to the next gear. He doesn't want to use the paddle shifter. Any suggestions from any of you?
Thanks.
I have a good customer who is drag racing his new C7, Auto, Z51 Coupe. This past weekend was his first at racing the new C7.
He has asked for our assistance in changing the shift points. He told me that he was hitting the rev limiter before the automatic shifted to the next gear. He doesn't want to use the paddle shifter. Any suggestions from any of you?
Thanks.
Intermediate
Joined: Nov 2013
Posts: 32
Likes: 0
From: Fort Worth Texas
I currently have a 2LT/Z51 and I have run it at both 1/8 and 1/4 miles tracks.
Ive tried using launch control.. doesnt do well.
Putting it in Sport mode til the TC light comes on in the Screen and on the Analog Speedometer gave me the best times.
With just straight out runs, It was going to 6800-7000 before shifting. As far as I could tell, I never hit the limiter.
If I had to guess.. I would say he was in Manual mode sport. Tell him to leave it in D and just use Sport Mode.
I could be wrong, but thats what it sounds like to me.
Ive tried using launch control.. doesnt do well.
Putting it in Sport mode til the TC light comes on in the Screen and on the Analog Speedometer gave me the best times.
With just straight out runs, It was going to 6800-7000 before shifting. As far as I could tell, I never hit the limiter.
If I had to guess.. I would say he was in Manual mode sport. Tell him to leave it in D and just use Sport Mode.
I could be wrong, but thats what it sounds like to me.
Le Mans Master
Joined: Aug 2004
Posts: 5,259
Likes: 16
From: Monroe Township New Jersey
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
St. Jude donor in memory of jpee '14
The short list: 
Track mode, let the car shift by itself. Drive thorugh or back into the water box and do a burn out to heat the rear tires rememebr not to get crazy with a long burnout. Just take the slack out of the converter and nail the gas.
Track mode, let the car shift by itself. Drive thorugh or back into the water box and do a burn out to heat the rear tires rememebr not to get crazy with a long burnout. Just take the slack out of the converter and nail the gas.
Instructor
Joined: Apr 2005
Posts: 245
Likes: 16
From: nj
For you guys drag racing. You should go around the water and back in. Also this is critical. Do not do a burnout in the tracks left by the normal drag cars. You will only be heating the outer most part of the tire. If you do enough burnouts you will see exactly what I am talking about as it will show the wear on the tire quickly. Real drag cars have wide tires with very narrow rears. This make the center of their tires very close especially when compared to a Corvette. Even a car running a standard width rear and 8-12 inch wide wheels will also suffer from this. Now if the track is a well maintained facility and they replace the concrete at the burnout box on a regular basis this should be a non issue. I do know though that this was a problem even at a place as well maintained as E-Town in NJ. With the wide deep tread street tires you do not want to drive thru the burnout area as they will carry water and release it as you go down track and may cause the rears to loose traction. They are on the edge so it doesnt take much.
good luck
bob
good luck
bob
Former Vendor
Joined: Mar 2004
Posts: 3,442
Likes: 18
From: Winchester CA
Most likely not hitting the rev limiter. although it sounds like it.
GM is using fuel cut to let the trans shift faster, and make it live longer. You can tune it out but its not going to make a huge difference in 1/4 mile times just by shutting that off. But if you do actually raise the shift points/limiter that may help some, going to take some experimenting. At the risk of blowing his warranty of course.
GM is using fuel cut to let the trans shift faster, and make it live longer. You can tune it out but its not going to make a huge difference in 1/4 mile times just by shutting that off. But if you do actually raise the shift points/limiter that may help some, going to take some experimenting. At the risk of blowing his warranty of course.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
Former Vendor
Joined: Mar 2004
Posts: 3,442
Likes: 18
From: Winchester CA
Scraping the splitter.
Joined: Jun 2005
Posts: 8,111
Likes: 1,029
St. Jude Donor '13-'14-'15
On my 11.4 pass, it actually tapped the limiter on the 2-3 shift. The timeslips support this, as that pass had a trap speed of 118.9 mph compared to 120.x on a hot-lapped pass a few minutes later. This is why I feel the car will eventually run an 11.3.
While I agree that's it's a VERY unlikely event, it can happen.
S.
While I agree that's it's a VERY unlikely event, it can happen.
S.
Former Vendor
Joined: Mar 2004
Posts: 3,442
Likes: 18
From: Winchester CA
Melting Slicks
Joined: May 2001
Posts: 2,596
Likes: 120
From: East Tennessee
On my 11.4 pass, it actually tapped the limiter on the 2-3 shift. The timeslips support this, as that pass had a trap speed of 118.9 mph compared to 120.x on a hot-lapped pass a few minutes later. This is why I feel the car will eventually run an 11.3.
While I agree that's it's a VERY unlikely event, it can happen.
S.
While I agree that's it's a VERY unlikely event, it can happen.
S.
Raising the shift point and the limiter and shifting a little higher may eek out a little quicker ET, havent seen anybody spend any time trying on a stock car though. Maybe in the fall when the weather gets a little cooler and the cars get a little older
Scraping the splitter.
Joined: Jun 2005
Posts: 8,111
Likes: 1,029
St. Jude Donor '13-'14-'15
I haven't played around with manually shifting it. There is probably little if anything to be gained.
S.
Melting Slicks
Joined: May 2001
Posts: 2,596
Likes: 120
From: East Tennessee
Burning Brakes
Joined: Jan 2014
Posts: 1,078
Likes: 262
From: swoyersville pa
i agree, he is not hitting rev limiter
Most likely not hitting the rev limiter. although it sounds like it.
GM is using fuel cut to let the trans shift faster, and make it live longer. You can tune it out but its not going to make a huge difference in 1/4 mile times just by shutting that off. But if you do actually raise the shift points/limiter that may help some, going to take some experimenting. At the risk of blowing his warranty of course.
GM is using fuel cut to let the trans shift faster, and make it live longer. You can tune it out but its not going to make a huge difference in 1/4 mile times just by shutting that off. But if you do actually raise the shift points/limiter that may help some, going to take some experimenting. At the risk of blowing his warranty of course.