3.07 vs 3.55
Thread Starter
4th Gear
Joined: Feb 2014
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3.07 vs 3.55
I love to cruse and thinking about changing rear differential from 3.07 to 3.55. I also have a 700r trans in my 1980 c3 already. I am looking for a few opinions to help me with this decision.
Racer
Joined: Oct 2020
Posts: 416
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From: Atlantic Beach, FL
In my other car, I have a TKO-600 with a .68 overdrive, which is pretty close to the 700r .70 - I'm running a 3.50 gear and I've been very happy with it in town and on the highway. I would highly recommend going to the 3.55 gear or even 3.70 if you're not going to be on the expressway much.
Le Mans Master
Joined: May 2002
Posts: 5,086
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From: Lebanon Township New Jersey
It's simple arithmetic. 3.55 divided by 3.08 equals 1.15. So whatever rpm you're cruising at now, multiply by 1.15 for the new rpm, at the same car speed. In other words, rpm will increase by 15%.
Is my vette stock?? HAHA
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Do it!!!! it will be a lot more fun than you think. I went from 3.55 to 3.70 and loved it. Now I have a 4.11. Going from 3.07 to 3.55 will be a huge upgrade, its like adding 50 extra foot pounds of torque at low rpm, you might want to get a neck brace. With a 700r4 first gear of 3.06x3.55 you have a 10.86 final drive ratio...good drag racing gearing
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Thread Starter
4th Gear
Joined: Feb 2014
Posts: 4
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Do it!!!! it will be a lot more fun than you think. I went from 3.55 to 3.70 and loved it. Now I have a 4.11. Going from 3.07 to 3.55 will be a huge upgrade, its like adding 50 extra foot pounds of torque at low rpm, you might want to get a neck brace. With a 700r4 first gear of 3.06x3.55 you have a 10.86 final drive ratio...good drag racing gearing
Race Director
Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
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And engine wear? I've been spinning mine well over 3,000 RPM for hours on end for the last 30 couple years. Yes I freshened it up about 5 years ago. but still at Std bore. original crank and rods. It's a 350 Chev. good oil and proper maintenance and considering the miles per year most of these get driven.
Just not a real concern.
Just not a real concern.
Is my vette stock?? HAHA
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From: Im not allowed to tell you
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700r4 has overdrive.....if you are worried about gas mileage and rpm you bought the wrong car
Le Mans Master
Joined: Apr 2011
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From: Hermosa
Only so much the tires can do to keep from spinning. Unless you run some kind of drag radial you’ll just burn more rubber above 3.55 from a start. Unless your looking for the acceleration after launch, then by all means 3.73, 4.11 whatever.
The 3.55 is a good all around ratio with street tires. Or at least is has been for me. I still have can’t hook up at launch with my th350 and 3.55. Shift to second at full acceleration breaks loose as well. So with the 7004r lower 1st gear, lots of wheel spin.
The 3.55 is a good all around ratio with street tires. Or at least is has been for me. I still have can’t hook up at launch with my th350 and 3.55. Shift to second at full acceleration breaks loose as well. So with the 7004r lower 1st gear, lots of wheel spin.