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Correct Gearing
I need some info and advise. Now that I have finally got my 428CJ running well I have noticed that I have less low end torque since I switched from my 302 w/ a T-5 to a Toploader Close. I am still running 3:73 rear gears and if the chart I used from David Key is correct my trans ratio are as follows:
1st 2nd 3rd 4th 2.32:1 1.69:1 1.29:1 1.00:1 This ratio reminds me of my 3.25 : 1 gears I had behind my old 302 before I replaced them with a 3:73 set up, slow off the line. Am I expecting too much or should I have gone with a wide ratio trans? Should I change my rear gears to 4.11 : 1 ? What advise is out there on this subject. I intend to drag race and road race some ie: Mid Am N.W. Cobra Club event at Pacific Junction, (between Kansas City and Omaha). Tulsa’s Ford Performance and Shelby’s Meet as well as the Run and Gun in St. Louis. |
I don't really understand the real difference between the Close Ratio and Wide Ratio in terms of performance?
Close Ratio has 28 teeth, Wide has 31. Close Ratio Gearing is: first second third fourth 2.32 1.69 1.29 1.0 Wide Ratio Gearing is: first second third fourth 2.78 1.93 1.36 1.0 I have a 289 but am running a 4:10 rear end. It "flys" off the line! but the sacrifice is about 3700rpm at 70mph with my current rearend gearing. David Kee???? Where are you???? |
It sounds like the key phrase here is "off the line" performance.
With the close ratio toploader, your engine will run at about 17% lower RPM for the same MPH compare to the wide ratio, and your torque multiplication is equivalently less. The wide ratio is better off the line, close ratio is probably better for road racing. |
There is a good site that all you have to is plug in all the gear ratios and tire size in and will give all the RPM & MPH in each ratio is is www.smokemup.com hope it will shed a little light. Ken M.
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Thanks Ken,
That was a big help. |
Clois,
I have an Excel spreadsheet for MPH vs RPM and RPM vs MPH that I would be happy to e-mail to you. It just requires inputting tire diameter, transmission ratios and rear end ratio and will give you output in all gears in increments of 5 MPH and 500 RPM. It also looks very professional thanks to Excelguru. |
Dick,
Would you be kind enough to send me a copy of that spreadsheet? bigwilly@bigwillys.com Regards, |
Spreadsheet
Dick,
Please send me a copy of your spreadsheet to: clharlan@duke-energy.com Thanks. Bye the way are you going to the NW Cobra club meet at the Mid America Motorplex June 1 & 2? |
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