60 corvette
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60 corvette
Hello...I have a 60 Corvette 283 2x4 4 speed with a 411 rear. At 50 mph my tachometer is at 2800 rpm. I would like to change the complete rear pumpkin
in order to cruise at interstate speeds ( 65-70 ). I am not concerned with high performance. Would a 308 be too dramatic a change?
Thanks in advance for your thoughts.....
in order to cruise at interstate speeds ( 65-70 ). I am not concerned with high performance. Would a 308 be too dramatic a change?
Thanks in advance for your thoughts.....
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I did the same thing a few years ago with a 4:11. I went to a 3:70 then a 3:55 with about a 300 rpm change with each gear. My car is a fuelie and it did not like the 3:55 at lower rpms, so I went back to the 4:11. I’m not sure if the dual quads will like the 3:08 gear like my fuelie. Last year I bit the bullet and installed a 5 speed. Best thing I ever did. 2200 rpm at 70mph now. 
Last edited by Geralds57; Jul 26, 2018 at 09:26 PM.
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My '60 fuelie had a 4.11 in it when I bought it. After driving cross country (literally) with that ratio I swore "never again". I changed to a 3.55 rear gear and it's worked out well and this is the ratio I would recommend.
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My '58 2x4, with a Muncie wide ratio transmission, had a 4.11 which was great around town but miserable on the freeway. I changed to a 3.36 which took a little bit of getting used to working the clutch and gas in first gear but is a huge difference on the freeway. My revs are about 2,000 at 70 mph. I can actually carry on a conversation and the stress level is lower knowing that I'm not over-taxing my SBC. However, if I had to do it all over and still wanted to take the cheap route (versus installing a 5-speed), I'd probably opt for the 3.55 which might be the happiest medium between highway revs and overall around-town driveability.
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I have a 3.08 in most everything except the Cutlass (2.41 posi) and the Chevelle (2.73 posi) and I really like those more Interstate compatible gears. Also, everything I own has a manual tranny and when I am going to slow in town for the engine--------------------------------I simply shift down into a lower gear--------------------------TOO SIMPLE.
I even swapped from 3.70 in the T-bucket to 3.08, and it STILL hauls the mail!
I even swapped from 3.70 in the T-bucket to 3.08, and it STILL hauls the mail!
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I went the 5 speed route. As compared to the original T10 and 3.70s, It’s like having 4.88s and 3.08s. Yes, is a little expensive, but some of the expense can be recouped by selling the original parts. Changing rear end gears isn’t usually free either.
Assuming you have a close ratio trans, a 2.20 first gear and a 3.08 rear is a 6.8 final drive ratio for first gear. That’s pretty steep for a 283 engine. Might work OK for highway driving, but it’s not something I would wanna deal with in traffic.
Assuming you have a close ratio trans, a 2.20 first gear and a 3.08 rear is a 6.8 final drive ratio for first gear. That’s pretty steep for a 283 engine. Might work OK for highway driving, but it’s not something I would wanna deal with in traffic.
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St. Jude Donor '07
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How much highway driving are you planning to do? My 61 has 4:11 and for the 3-4 times a year I drive longer than 100 miles, I didn't want to sacrifice in town driving. But mine is a fuelie. - 3200@70 is what is was built for and happy to doing it.
Maybe guys that run 2x4's can chime in about low rpms and fowling plugs, carb and running rich issues. I have never had a car with 2x4 so I can't give my opinion.
I have thought about a 5 speed, just for the long trips, but couldn't justify the cost for me.
Maybe guys that run 2x4's can chime in about low rpms and fowling plugs, carb and running rich issues. I have never had a car with 2x4 so I can't give my opinion.
I have thought about a 5 speed, just for the long trips, but couldn't justify the cost for me.
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From: Southold New York
I have 3.36 Positraction in my present '61 with a "strong" engine we built when I owned a machine shop - no problems except it still has the car's original "wide-ratio" transmission. Much preferred the gear spacing of the close-ratio box in my '59 with dual-quad 270 hp and 3.70 Positraction. Have several other non-Corvette vehicles with close-ratio boxes and rear ends of 3.42, 3.64 and 3.89. Each has its own personality, but there really is not much difference in daily use. With the tires presently installed on the 3.89 the effective ratio is close to 4.11 which proves a bit "busy" for extended driving.
Returning to the OP's question, with his engine, I was very happy with the 3.70 rear. If a lot of highway use is contemplated, perhaps a 3.55 or 3.36. but remember that a lot depends on tire size and changing tires is relatively cheap and easily reversible.
Returning to the OP's question, with his engine, I was very happy with the 3.70 rear. If a lot of highway use is contemplated, perhaps a 3.55 or 3.36. but remember that a lot depends on tire size and changing tires is relatively cheap and easily reversible.
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I did the same thing a few years ago with a 4:11. I went to a 3:70 then a 3:55 with about a 300 rpm change with each gear. My car is a fuelie and it did not like the 3:55 at lower rpms, so I went back to the 4:11. I’m not sure if the dual quads will like the 3:08 gear like my fuelie. Last year I bit the bullet and installed a 5 speed. Best thing I ever did. 2200 rpm at 70mph now.
Great! Your comment is incredibly timely, as I'm just about to take the plunge for a 5 spd. I also have a 4:11 gears and love it up to about 50-55 MPH and then the constant 3000+ RPM's become mind numbing. 70 MPH at 3750 is just crazy.
So, I'm looking at the TKO-500 and 5rh gear is .68. Trying to calculate this out it seems I would be doing around 2550 in final drive, but maybe I'm figuring wrong. But, your comment about 2200 at 70 MPH sounds wonderful!
Do you have the TKO or ???
Do you have the .68 5th gear?
How about 1st gear, which comes standard as 3:27 to 1, which multiplied times the 4:11 rear gear equates to a 13:43 1st gear factor, if I did that right. Great for the drag strip, but how about on the street. Do you have to shift out of 1st before you're out of the driveway?
Butch
Last edited by Dreaming60’s; Jul 27, 2018 at 02:59 PM.
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When I bought my '60 it had 4:11's but I changed them to 3:55's. The 3:55's are nice but I would not go any higher. Small block Chevys love 3,000 RPM's.
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Great! Your comment is incredibly timely, as I'm just about to take the plunge for a 5 spd. I also have a 4:11 gears and love it up to about 50-55 MPH and then the constant 3000+ RPM's become mind numbing. 70 MPH at 3750 is just crazy.
So, I'm looking at the TKO-500 and 5rh gear is .68. Trying to calculate this out it seems I would be doing around 2550 in final drive, but maybe I'm figuring wrong. But, your comment about 2200 at 70 MPH sounds wonderful!
Do you have the TKO or ???
Do you have the .68 5th gear?
How about 1st gear, which comes standard as 3:27 to 1, which multiplied times the 4:11 rear gear equates to a 13:43 1st gear factor, if I did that right. Great for the drag strip, but how about on the street. Do you have to shift out of 1st before you're out of the driveway?
Butch
So, I'm looking at the TKO-500 and 5rh gear is .68. Trying to calculate this out it seems I would be doing around 2550 in final drive, but maybe I'm figuring wrong. But, your comment about 2200 at 70 MPH sounds wonderful!
Do you have the TKO or ???
Do you have the .68 5th gear?
How about 1st gear, which comes standard as 3:27 to 1, which multiplied times the 4:11 rear gear equates to a 13:43 1st gear factor, if I did that right. Great for the drag strip, but how about on the street. Do you have to shift out of 1st before you're out of the driveway?
Butch