Axle Ratio
Thread Starter
6th Gear
Joined: Sep 2014
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Axle Ratio
I have a C4 with a 436 cu.in. SBC and Tremec TKO 5 speed. I am setting up to race World Speed Trials. We are timed at the 1mi. mark and the 1 1/2 mi. I would like to know how to figure the best rear axle ratio to use. Any suggestions will be greatly appreciated.
Thread Starter
6th Gear
Joined: Sep 2014
Posts: 6
Likes: 0
Thread Starter
6th Gear
Joined: Sep 2014
Posts: 6
Likes: 0
American Iron Restorations
Looking for 215MPH in the mile or better Tremec TKO 5 speed Just need to know rear axle ratio to use. Should be turning 6600rpm. Thanks
Last edited by american Iron; Dec 31, 2014 at 09:48 AM. Reason: Forgot rpm
Thread Starter
6th Gear
Joined: Sep 2014
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Team Owner
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What do you actually have for a flywheel weight?
http://www.cargister.com/calculator-...l_ratio_teeths
Use actual tire dimensions and not the tire sizing option for accurate results.
Questions?
Thread Starter
6th Gear
Joined: Sep 2014
Posts: 6
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American Iron Restorations
This calculator might do well for your particular needs. I've done the math a couple times and have found no reason to dispute the "numbers". A plus to this calculator is that you can SEE the RPM drops between shifts that should help you calculate just exactly what you might want to change. A tire change vs. a rear gear change sometimes does wonders. Something that some don't realize is that the "RPM loss" between shifts isn't affected with flywheel weight choices. Flywheel weight considerations could be of some concern for you but that's a different conversation.
What do you actually have for a flywheel weight?
http://www.cargister.com/calculator-...l_ratio_teeths
Use actual tire dimensions and not the tire sizing option for accurate results.
Questions?
What do you actually have for a flywheel weight?
http://www.cargister.com/calculator-...l_ratio_teeths
Use actual tire dimensions and not the tire sizing option for accurate results.
Questions?
Team Owner
Joined: Sep 2003
Posts: 25,365
Likes: 2,731
I believe that most frequently that tire is mentioned to be 26" - try some calculators and then use maybe 97% for a rolling dimension to use in the calculator that I linked to. I like the flywheel weight and I'd think it a plus for MPH at the 1 and 1 1/2 mile runs. There may be other thoughts but MPH and longer than 1/4 mile results I like it. Are these standing or rolling distances? You may have mentioned and I just overlooked but I thought it easier to maybe ask than go back.
You want "rolling" dimensions to do this accurately NOT advertised height or dimensions. There's a couple ways to calculate "rolling" accurately.
You want "rolling" dimensions to do this accurately NOT advertised height or dimensions. There's a couple ways to calculate "rolling" accurately.
Thread Starter
6th Gear
Joined: Sep 2014
Posts: 6
Likes: 0
American Iron Restorations
I believe that most frequently that tire is mentioned to be 26" - try some calculators and then use maybe 97% for a rolling dimension to use in the calculator that I linked to. I like the flywheel weight and I'd think it a plus for MPH at the 1 and 1 1/2 mile runs. There may be other thoughts but MPH and longer than 1/4 mile results I like it. Are these standing or rolling distances? You may have mentioned and I just overlooked but I thought it easier to maybe ask than go back.
You want "rolling" dimensions to do this accurately NOT advertised height or dimensions. There's a couple ways to calculate "rolling" accurately.
You want "rolling" dimensions to do this accurately NOT advertised height or dimensions. There's a couple ways to calculate "rolling" accurately.
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
That 255/50R16 tire is 26" tall....
A 3.54 rear gear is going to give you potentially 212 MPH at 6600 RPM.
A 3.45 is potentially 217 MPH.
Both in 5th gear of course.
http://www.csgnetwork.com/speedcalc.html
Will
A 3.54 rear gear is going to give you potentially 212 MPH at 6600 RPM.
A 3.45 is potentially 217 MPH.
Both in 5th gear of course.
http://www.csgnetwork.com/speedcalc.html
Will