4.10 or 3.90
Former Vendor
Joined: Jun 2007
Posts: 655
Likes: 5
From: Daleville Indiana
What do you plan on doing with the car? Is it a base model or Z51? Make sure that you upgrade the case of the differnential when you get a differential. The 05 differentials are very weak if you didn't already know that.
http://forums.corvetteforum.com/c6-f...ferential.html
http://forums.corvetteforum.com/c6-f...ferential.html
Thread Starter
Racer
Joined: Jun 2009
Posts: 374
Likes: 0
From: Houston Texas
I'm well aware of the rear end issue... Scattered the original less than two weeks ago and am upgrading. Its the base model, which has the 2.66 first gear. I dd the car so I was thinking 3.90 gears for just a little more accel.
Last edited by Schoolteacher; Jan 24, 2011 at 10:48 AM.
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
Both are going to feel much better than the 3.42s. 4.10s offer a little more performance, 3.90s slightly lower highway rpm if you do a lot of highway cruising. With the base model, I'd do 4.10s; you'd still turn lower rpms on the highway than my Z51 with 3.90s.
Burning Brakes
Joined: Jun 2007
Posts: 823
Likes: 0
From: Seguin Texas
I was thinking the same thing. I have base gears and think a 3.73 would be nice for this car. It only needs a bit more gearing IMO. I don't want to turn 1st into a useless without DR's gear. Maybe, 3.90 but no more. I have a mustang GT DD with lots of mods and steep gears. They suck to shift at 15 mph from1st to 2nd and have to rev the motor high in every gear. Had to get DR's to hold any traction with it.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Go for a ride in a car with the gearing/trans combo you want. The worst thing you can do is make a decision based on posts from people who dont have the gears you're asking about. I have a Z51 with 2.97 in first with 4.10's out back. I also have a 17lb boost and nitrous and yes it hooks. I had 4.10's when it was a H/C nitrous car at sea level. I wouldnt have changed that.
Get the facts based in first hand experience. Dont go by a guy sitting in his chair with a calculator.
Today, a guy with 3.42's on an A6 went 9.75 in the 1/4 on 13psi. Thats trans and gear combo is even steeper than mine in first and it works. Not having the right tire is a poor excuse to handicap gearing as a bandaid to traction. You may as well simply start in second gear if you think that works.
The proper formula: Gear your car for trap speed and stop adding power when the tire you run cant get it to the ground anymore.
The improper formula: Get as much power as you can with street tires and use tall gears to handicap your ability to get the tq to the ground.
Get the facts based in first hand experience. Dont go by a guy sitting in his chair with a calculator.
Today, a guy with 3.42's on an A6 went 9.75 in the 1/4 on 13psi. Thats trans and gear combo is even steeper than mine in first and it works. Not having the right tire is a poor excuse to handicap gearing as a bandaid to traction. You may as well simply start in second gear if you think that works.
The proper formula: Gear your car for trap speed and stop adding power when the tire you run cant get it to the ground anymore.
The improper formula: Get as much power as you can with street tires and use tall gears to handicap your ability to get the tq to the ground.
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
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Former Vendor
Joined: Jun 2007
Posts: 655
Likes: 5
From: Daleville Indiana
Based on what you have said I would recommend 3.90 gears. You can do calcuations for trap speed and whatnot, but it really comes down to what you are doing with the car. The 3.90 will give you a great boost in acceleration and will run less rpm down the highway. You are using the car as a DD so that would be my recomendation.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
I have had 3.90's for years and now 4.10's with the Z51 trans. I find the 4.10's made a notable difference at the drag strip, making the launch easier, which helps the clutch live (49000 miles and 433 launches so far still gets 1.5's at will).
I don't notice any difference in highway or around town from the 4.10's vs 3.90's. Both are about the same, and both feel nice and peppy.
I'd recommend the 4.10's. They give you more of what you buy gears for. and mind you, I used to wave the 3.90 flag...until I got 4.10's.
I don't notice any difference in highway or around town from the 4.10's vs 3.90's. Both are about the same, and both feel nice and peppy.
I'd recommend the 4.10's. They give you more of what you buy gears for. and mind you, I used to wave the 3.90 flag...until I got 4.10's.
Melting Slicks
Joined: Jun 2006
Posts: 2,164
Likes: 3
For the street or drags I'd go with 4.10 with a base trans, for roadracing I would be a lot more hesitant to mess with the gearing.
Race Director
Joined: Dec 2006
Posts: 12,385
Likes: 2,906
From: Fort Worth, Texas
I have had 3.90's for years and now 4.10's with the Z51 trans. I find the 4.10's made a notable difference at the drag strip, making the launch easier, which helps the clutch live (49000 miles and 433 launches so far still gets 1.5's at will).
I don't notice any difference in highway or around town from the 4.10's vs 3.90's. Both are about the same, and both feel nice and peppy.
I'd recommend the 4.10's. They give you more of what you buy gears for. and mind you, I used to wave the 3.90 flag...until I got 4.10's.
I don't notice any difference in highway or around town from the 4.10's vs 3.90's. Both are about the same, and both feel nice and peppy.
I'd recommend the 4.10's. They give you more of what you buy gears for. and mind you, I used to wave the 3.90 flag...until I got 4.10's.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
http://xse.com/leres/ss/calculator.html
But the short answer is, if you're using 275/40/17 mickeys you can go about 130. Then, if you mod the car faster than that, you can always go to bigger & taller tires, which you would probably want anyway if you are going faster than 130.
Racer
Joined: May 2010
Posts: 499
Likes: 5
From: Bensalem PA
Thanks Joe! According to the calculator with my tires and 4.10's at 7000 rpms at the top of 4th I should be at 134mph. After the cars done it should be traping 130-132mph so they should be fine for me.
Burning Brakes
Joined: Jun 2007
Posts: 823
Likes: 0
From: Seguin Texas
The OP's intentions for his car may be diiferent than others who only want top drag strip performance. He may also want to keep using run flats. Not everyone thinks the same...but according to some we all should want the same thing out of our own car. Oh wait! I had an opinion and didnt get permission first.
Last edited by Fuego; Jan 26, 2011 at 06:32 PM.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
The OP's intentions for his car may be diiferent than others who only want top drag strip performance. He may also want to keep using run flats. Not everyone thinks the same...but according to some we all should want the same thing out of our own car. Oh wait! I had an opinion and didnt get permission first.
The OP's question, 3.90's or 4.10's indicates he or she has made the decision to put in higher (numerical) gears for whatever reason. My answers are based on that premise.
I've had both so I offer my thoughts.
4.10's are more of what you put gears in for. There is no difference in street driving or realistic fuel mileage between 4.10 and 3.90. Same for road course use. No difference 4.10 vs 3.90. The only difference is in drag racing, and 4.10's are better for launching and the launch is so key in drag racing. The only reason to not get 4.10's is if you are going to have so much power you'll be at 135+ in the 1/4 for your chosen tire size, which would require a shift to 5th. Then you might consider 3.90's. Or taller tires, same effect.
Burning Brakes
Joined: Jun 2007
Posts: 823
Likes: 0
From: Seguin Texas
Very true but I was referring to my way or the highway. Just putting a different "spin" on things if this is their first exp. with modding. I question the NEED for many to mod the gears at all. I know it's faster in the quarter, but we dont all want the same thing. Again, just putting out a different view. He did want opinions after all.
Last edited by Fuego; Jan 26, 2011 at 07:08 PM.
