Best Gear Ratio

[tyly]

ok when i got the vette, the previous owner put 4.11's in it. The gear ratio is a lot of fun when your not driving fast, it accelerates really quick. But when i take it on the highway it sounds like it is going to blow. I cant go quite as fast as most of the other cars on the highway, and i dont know where it really tops out at becuase the spedo was never recallibrated. What i want to know is what would be the best effective gear ratio to use? The tires on the vette are 245 60 R15's...if thats any help....thanks for any help

 

[67HEAVEN]

tyly,

Welcome to the

To answer your question accurately, it would help to know your engine and transmission combination.

However, moving to 3.55:1 or 3.70:1 gears would certainly help your highway rpm's a great deal.

 

[tyly]

thanks

yea...i was looking in a magazine and it suggested maybe getting 3.73's or 3.91's...would you mind if i asked what you have in yours?

 

[67HEAVEN]

thanks

yea...i was looking in a magazine and it suggested maybe getting 3.73's or 3.91's...would you mind if i asked what you have in yours?

3.08:1, but I also converted to a Richmond 5-speed transmission, which changes everything about how the drivetrain works.

I wouldn't want the 3.08:1 with the old Muncie 4-speed.

Here's how I arrived at my decision. I made the comparison sheet to help determine if 3.08:1 worked for me.

Use something like this to work it through for your car.

 

[tyly]

wow...thank you very much...i will definitly use that...i appricate it

 

[waterboy1976]

Ive got 3:55s in my 73 with a 4speed.....it cruises nice at 70mph and have had it as high as 95 with no blowing....

 

[Chas]

3:55 w/automatic in my 73...runs nice at 70 mph ,it seems like it could shift one more gear....but also seems like it can handle it for hours on end at that speed and not have a problem at all.
I had the factory 3:08 i think and bumped to 3:55...also going this setup he was able to put in the proper gear and has my speedometer within 1 mph.
Chas

 

[67HEAVEN]

thanks

yea...i was looking in a magazine and it suggested maybe getting 3.73's or 3.91's...would you mind if i asked what you have in yours?

Do you have the M-21 or M-40 transmission? By the way, 3.73:1 and 3.91:1 gears are not Corvette gears. Here, for example, was the choice in rear gears in 1967 under RPO G-81, and the number installed in production cars:

• 3.08: 1,981
• 3.36: 8,189
• 3.55: 2,410
• 3.70: 5,662
• 4.11: 2,061
• 4.56: 5

 

[GTR1999]

You should consider a few things before buying parts that might not work.
Decide what you what for a gear and tranny 1st thing. Then if you think you're going to change the gears then you'll have to see what type of 411's were installed. If they are stock then you have a 4 series carrier and will need a 3 series carrier to run 273,308,336,355,370,373,390,or some 411's. Now if you have a 3 series with a 411 gear set then it's not too bad, about $500-$800 difference!
The GM 370 gear sets aren't bad if you can find one. The Richmond gears sets can be a noisey setup, Yukons set up good but they're made in Pakistan or India? I used them but I wouldn't recommend hammering them after hearing some stories. The best gear sets are Tom's and they offer the 373 set which is stronger then the 370 that eveyone else sells. They are back ordered now probably until next year so if you can find a set you'll pay big. I used a set last month and they were $375 for just the set! I think they were the last ones left on the market,but I have one set here.
So again before you buy anything think about what you want from the car.

 

[Hib Halverson]

ok when i got the vette, the previous owner put 4.11's in it. The gear ratio is a lot of fun when your not driving fast, it accelerates really quick. But when i take it on the highway it sounds like it is going to blow. I cant go quite as fast as most of the other cars on the highway, and i dont know where it really tops out at becuase the spedo was never recallibrated. What i want to know is what would be the best effective gear ratio to use? The tires on the vette are 245 60 R15's...if thats any help....thanks for any help

To answer this question properly, we need more information.

1) Which transmission is in this car?
2) What are the basics of the car's engine set-up?

 

[Evolution1980]

700R4 with 3.08 rear end gearing

I posted pics in another thread here on the CAC of my dash (Speedo / Tach) while driving on the highway. Click Here for the link.

I have a 700R4 and 3.08 rear end gears. The car has nice grunt off the line and I certainly am not complaining about my cruising RPMs. Check the pics in the link...

 

[Hib Halverson]

With the 700R and 245/60R15s, I wouldn't go any lower than 3.55 and, even then, you'll be spinning the tires a lot. If it were me, I'd go 3.36.

 

[thesurvivor]

My big block '73 has 3:36's behind a 4 speed. Runs 2400rpm at 60 mph....use to deliver almost 20 mpg before I "tuned" the carb. Now it delivers a shot in the seat and great smiles.....

 

[jhoog59]

Thats exactly what I am looking to do to my 81. This may sound stupid but what kind of highway gas mileage do you get with that setup.

 

[Tepot]

thanks

yea...i was looking in a magazine and it suggested maybe getting 3.73's or 3.91's...would you mind if i asked what you have in yours?

I've got 3.55's in mine and I think it's perfect. takes off fast and Highway is not problem. when I floor it, I almost get to 100 MPH before shifting from 3rd to 4th gear and it's not a problem.