3.73 or 3.90 help
Thread Starter
Racer
Joined: Apr 2010
Posts: 382
Likes: 1
3.73 or 3.90 help
I'm fixing to change my rear gear set up in my vette. I am stuck between the 3.73 gear and the 3.90 gear. I really want to feel the difference in the car, and not just know I have a different gear back there. The car is a 05 z51 6sp. (yes I know of the weak rear diff, and that is getting changed also) The only things I am going to do to the engine is some Kooks long tube headers and x-pipe, already have them at my house, a Vararam intake, also already have it, and sending my intake manifold and throttle body of to get ported, then a good tune. I doubt I'll be going with heads/cam anytime soon, but It had crossed my mind. It really just depends on how much of a difference the gear makes, if I go with the heads cam.
I want to keep the car simple, but fun. I don't DD the car, but I would like it to be useable on the road. I don't do much track racing at all. At least not with the Vette.
I have been told a 3.73 is the best for the z51 trans, then I read guys that have the 3.90 in their z51 and say the 3.73 isn't a big difference from the 3.42 stock gearing. Tires are going to be a set Bridgestone R11 tires, stock size.
Thank you in advance guys!
I want to keep the car simple, but fun. I don't DD the car, but I would like it to be useable on the road. I don't do much track racing at all. At least not with the Vette.
I have been told a 3.73 is the best for the z51 trans, then I read guys that have the 3.90 in their z51 and say the 3.73 isn't a big difference from the 3.42 stock gearing. Tires are going to be a set Bridgestone R11 tires, stock size.
Thank you in advance guys!
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
I have 3.90s in my Z51.
You really should look at 3.90s or 4.10s. I had considered doing 3.73 only because of highway rpms for long trips. I made myself go up a step and I'm glad I did. With 3.90s I'm doing 72 mph at 2000 rpm. For tooling around town that's fine and very usable. It's not bad on longer trips too.
Even 4.10s is 68 mph at 2000 rpm. That's hardly excessive for just bombing around town and while I like a lazy 6th gear, plenty of people do take their car on cruises with 4.10s. In fact my LS1 Camaro A4 with 3.23s turned the same rpm from the factory. So it is very "useable."
For the fun factor go for 4.10s or if you can't get there, 3.90s. Skip the 3.73s unless you are touring and regularly driving 80 mph.
I want to keep the car simple, but fun. I don't DD the car, but I would like it to be useable on the road.
Even 4.10s is 68 mph at 2000 rpm. That's hardly excessive for just bombing around town and while I like a lazy 6th gear, plenty of people do take their car on cruises with 4.10s. In fact my LS1 Camaro A4 with 3.23s turned the same rpm from the factory. So it is very "useable."
For the fun factor go for 4.10s or if you can't get there, 3.90s. Skip the 3.73s unless you are touring and regularly driving 80 mph.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
I have 3.90s in my Z51.
You really should look at 3.90s or 4.10s. I had considered doing 3.73 only because of highway rpms for long trips. I made myself go up a step and I'm glad I did. With 3.90s I'm doing 72 mph at 2000 rpm. For tooling around town that's fine and very usable. It's not bad on longer trips too.
Even 4.10s is 68 mph at 2000 rpm. That's hardly excessive for just bombing around town and while I like a lazy 6th gear, plenty of people do take their car on cruises with 4.10s. In fact my LS1 Camaro A4 with 3.23s turned the same rpm from the factory. So it is very "useable."
For the fun factor go for 4.10s or if you can't get there, 3.90s. Skip the 3.73s unless you are touring and regularly driving 80 mph.
You really should look at 3.90s or 4.10s. I had considered doing 3.73 only because of highway rpms for long trips. I made myself go up a step and I'm glad I did. With 3.90s I'm doing 72 mph at 2000 rpm. For tooling around town that's fine and very usable. It's not bad on longer trips too.
Even 4.10s is 68 mph at 2000 rpm. That's hardly excessive for just bombing around town and while I like a lazy 6th gear, plenty of people do take their car on cruises with 4.10s. In fact my LS1 Camaro A4 with 3.23s turned the same rpm from the factory. So it is very "useable."
For the fun factor go for 4.10s or if you can't get there, 3.90s. Skip the 3.73s unless you are touring and regularly driving 80 mph.
But I wouldn't make such a small change from 3.42's to 3.73's again.
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
My car is currently where you are targeting. Adding gears/headers/tune make the stock car feel like it was a turd. Pull the trigger and enjoy.
Thread Starter
Racer
Joined: Apr 2010
Posts: 382
Likes: 1
Ok So I'm for sure going with the 3.90 over the 3.73. Now onto the 3.90 vs 4.10.
Let me know if I'm right on this.
If I wan't to take more off of my drag time, and am going to drive on the track more, then the 4.10 is the best choice?
If I want my car to feel faster, but still be good on the road, and for everyday driving, then I should go with the 3.90 gears.
Is that about right?
How much more time gets knocked off the 1/4 mile with the 4.10 over the 3.90? And, how much time will get knocked off with the 3.90 over stock?
Let me know if I'm right on this.
If I wan't to take more off of my drag time, and am going to drive on the track more, then the 4.10 is the best choice?
If I want my car to feel faster, but still be good on the road, and for everyday driving, then I should go with the 3.90 gears.
Is that about right?
How much more time gets knocked off the 1/4 mile with the 4.10 over the 3.90? And, how much time will get knocked off with the 3.90 over stock?
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
If I want my car to feel faster, but still be good on the road, and for everyday driving, then I should go with the 3.90 gears.
How much more time gets knocked off the 1/4 mile with the 4.10 over the 3.90? And, how much time will get knocked off with the 3.90 over stock?
Burning Brakes
Joined: Apr 2009
Posts: 1,155
Likes: 0
From: Kansas City MO
here is something for you to compare by.
My 100% stock 2001 TA LS1 with M6 and 3.42 gears got 29 mpg going from KC to California and back.
I put heads/cam/headers/4.56 moser 12 bolt with all of the other BMR goodies. car put out around 430 rwhp on 28" slicks at the dyno. Drove it with street tires from KC to Kentucky and back and still got 24 mpg highway.
After all the engine work and before I put the rear end in (did not do it until I broke the stock rear end at the track) I found a nice road where I hit 188 mph (the trip to california was to go to Granatelli's and get their 200mph speedo for my TA since I was burying it.
After the 4.56's, I found another deserted road where I topped out at around 155mph.
with 4.10's, 4.33's or 4.56's you can actually use 6th gear.
With 3.42's I would go across the 1/4 mile line in the top of 3rd gear
With 4.56's I would go across the 1/4 mile line in the top of 4th gear.
I guess what I am saying is don't be afraid of 4.10's.
My 100% stock 2001 TA LS1 with M6 and 3.42 gears got 29 mpg going from KC to California and back.
I put heads/cam/headers/4.56 moser 12 bolt with all of the other BMR goodies. car put out around 430 rwhp on 28" slicks at the dyno. Drove it with street tires from KC to Kentucky and back and still got 24 mpg highway.
After all the engine work and before I put the rear end in (did not do it until I broke the stock rear end at the track) I found a nice road where I hit 188 mph (the trip to california was to go to Granatelli's and get their 200mph speedo for my TA since I was burying it.
After the 4.56's, I found another deserted road where I topped out at around 155mph.
with 4.10's, 4.33's or 4.56's you can actually use 6th gear.
With 3.42's I would go across the 1/4 mile line in the top of 3rd gear
With 4.56's I would go across the 1/4 mile line in the top of 4th gear.
I guess what I am saying is don't be afraid of 4.10's.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
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
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
1mpg combined city and highway daily driving too.
I would choose 4.10's again. They are more of what you are looking for in gears and there is no difference on the street.
On the drag strip gears make it easier to launch, by quite a bit. 4.10's are notably easier to launch. I would put them in again and I recommend them.
I don't have before and after gears track data. My best with 3.90's was 11.2 and now 10.99 but I put skinnies on my car too to get the 10.99.
I would choose 4.10's again. They are more of what you are looking for in gears and there is no difference on the street.
On the drag strip gears make it easier to launch, by quite a bit. 4.10's are notably easier to launch. I would put them in again and I recommend them.
I don't have before and after gears track data. My best with 3.90's was 11.2 and now 10.99 but I put skinnies on my car too to get the 10.99.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
My top speed at the Miami Mile event was 185, which is 6800 rpm in 5th gear with my 345 street tires. The car would go faster if I raised the rev limiter. Shifting to 6th would have slowed me down, as given my cam I make power all the way up to 6800+.
I top out at about 130 in 4th gear, which is right beyond the traps using 315/35/17 tires (they are the same height at 275/40/17's) for my car.
4.10's are perfect for my car. If I had a blower or a lot more horsepower, I'd have to use 3.90's or taller tires to keep from shifting to 5th in the 1/4.
I top out at about 130 in 4th gear, which is right beyond the traps using 315/35/17 tires (they are the same height at 275/40/17's) for my car.
4.10's are perfect for my car. If I had a blower or a lot more horsepower, I'd have to use 3.90's or taller tires to keep from shifting to 5th in the 1/4.
Burning Brakes
Joined: Jun 2004
Posts: 1,200
Likes: 14
From: Playa Vista CA
Don't waste your money on such a small difference with 3:73's. Go 3.90 or 4.10. If your car is not for the track and you don't need to maximize trap speed with a specific gear & HP I would go 4.10 and enjoy driving the car even with the z51 gearing. Don't fear the gear!
Joe
Joe
Burning Brakes
Joined: Jun 2004
Posts: 1,200
Likes: 14
From: Playa Vista CA
MPH@6500 RPM 3.42 / 3.90 / 4.10
1st 50.9 / 44.7 / 42.5
2nd 73.1 / 64.1 / 60.9
3rd 105.8 / 92.7 / 88.2
4th 151.2 / 132.6 / 126.1
you can go here to figure the rest. http://xse.com/leres/ss/calculator.html
Plenty of 1st gear with either. Top speed I am not sure but with 4.10's 5th gear will do 177 at 6500RPM. I think 6th will still be drag limited. High enough that you may still never see it or at least rarely. I wish we had an autobahn here.
Joe
1st 50.9 / 44.7 / 42.5
2nd 73.1 / 64.1 / 60.9
3rd 105.8 / 92.7 / 88.2
4th 151.2 / 132.6 / 126.1
you can go here to figure the rest. http://xse.com/leres/ss/calculator.html
Plenty of 1st gear with either. Top speed I am not sure but with 4.10's 5th gear will do 177 at 6500RPM. I think 6th will still be drag limited. High enough that you may still never see it or at least rarely. I wish we had an autobahn here.
Joe
Last edited by Joezone914; Jan 29, 2011 at 12:41 AM.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
MPH@6500 RPM 3.42 / 3.90 / 4.10
1st 50.9 / 44.7 / 42.5
2nd 73.1 / 64.1 / 60.9
3rd 105.8 / 92.7 / 88.2
4th 151.2 / 132.6 / 126.1
you can go here to figure the rest. http://xse.com/leres/ss/calculator.html
Plenty of 1st gear with either. Top speed I am not sure but with 4.10's 5th gear will do 177 at 6500RPM. I think 6th will still be drag limited. High enough that you may still never see it or at least rarely. I wish we had an autobahn here.
Joe
1st 50.9 / 44.7 / 42.5
2nd 73.1 / 64.1 / 60.9
3rd 105.8 / 92.7 / 88.2
4th 151.2 / 132.6 / 126.1
you can go here to figure the rest. http://xse.com/leres/ss/calculator.html
Plenty of 1st gear with either. Top speed I am not sure but with 4.10's 5th gear will do 177 at 6500RPM. I think 6th will still be drag limited. High enough that you may still never see it or at least rarely. I wish we had an autobahn here.
Joe
I use first gear all the time in my daily driver...every time I take off!
Top speed with 4:10's, 345/35/19's and 6700 redline is 185. If you wanted to raise redline or put on taller tires you could go 200 if you had the space to do it. Takes more than a mile and a half to go 200 with only 450 rwhp I can tell you.. Spinmonster did it on a closed track, but I think he had nitrous which means you need a lot less track than you do n/a.
Here is proof of the 185 on the Miami Mile event last year.
Last edited by Joe_G; Jan 29, 2011 at 09:15 AM.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
You won't be able to tell in vids. Look at the fast list....all the fast manual guys have 4:10's. That should tell you something. Trust me I had both, get the 4.10's.
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
I have 3.90s in my Z51.
You really should look at 3.90s or 4.10s. I had considered doing 3.73 only because of highway rpms for long trips. I made myself go up a step and I'm glad I did. With 3.90s I'm doing 72 mph at 2000 rpm. For tooling around town that's fine and very usable. It's not bad on longer trips too.
Even 4.10s is 68 mph at 2000 rpm. That's hardly excessive for just bombing around town and while I like a lazy 6th gear, plenty of people do take their car on cruises with 4.10s. In fact my LS1 Camaro A4 with 3.23s turned the same rpm from the factory. So it is very "useable."
For the fun factor go for 4.10s or if you can't get there, 3.90s. Skip the 3.73s unless you are touring and regularly driving 80 mph.
You really should look at 3.90s or 4.10s. I had considered doing 3.73 only because of highway rpms for long trips. I made myself go up a step and I'm glad I did. With 3.90s I'm doing 72 mph at 2000 rpm. For tooling around town that's fine and very usable. It's not bad on longer trips too.
Even 4.10s is 68 mph at 2000 rpm. That's hardly excessive for just bombing around town and while I like a lazy 6th gear, plenty of people do take their car on cruises with 4.10s. In fact my LS1 Camaro A4 with 3.23s turned the same rpm from the factory. So it is very "useable."
For the fun factor go for 4.10s or if you can't get there, 3.90s. Skip the 3.73s unless you are touring and regularly driving 80 mph.
Thread Starter
Racer
Joined: Apr 2010
Posts: 382
Likes: 1
Thank you for all your help.
Does anyone have a z51 with 4.10 or 3.90 gears close to Dalton GA that I could go for a ride in?
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
Well it only makes sense that the 4.10 gears would be faster, but that doesn't help me that much because I'm not just going to track it. Infact, I will prob only track it 5% of the time. and drive the rest.
Thank you for all your help.
Does anyone have a z51 with 4.10 or 3.90 gears close to Dalton GA that I could go for a ride in?
Thank you for all your help.
Does anyone have a z51 with 4.10 or 3.90 gears close to Dalton GA that I could go for a ride in?
I would sooner just keep the 3.42s before I'd put 3.73s in, especially in a Z51 car.