3.54 / 3.55 and 4.09 / 4.10 / 4.11 Gears

One of the most common questions about gear ratios is: what is the difference between 3.54 and 3.55 or 4.09, 4.10, and 4.11 gears?

As our Gear Ratio Calculator explains, the gear ratio is calculated by dividing the number of teeth on the ring gear by the number of teeth on the pinion gear. Since this doesn't always end up in a nice even number, we have to do some rounding to get the final gear ratio down to three digits.

Additionally, different axles use different size ring and pinion gears that require a different number of teeth on each gear to make them turn properly. This variation in tooth number combined with a need to round up or down is what causes a discrepancy in gear ratios.



NEW! - Need help with gear ratio variations? Check out the new comments section below!






Example: 4.09 / 4.10 / 4.11 Gear Ratios

The following table contains a list of common axles along with their ring and pinion tooth count and ratios. You will notice that while many of them are identical, a few have a different number of teeth on each gear that results in a minor shift up or down in the final gear ratio.

Axle
Ring Gear Teeth
Pinion Teeth
Calculated
Final Ratio

Dana 30 JK
41
10
4.1
4.10
AMC Model 35 / M35
37
9
4.111111
4.11
Toyota 8"
37
9
4.111111
4.11
Dana 44
45
11
4.090909
4.09
Dana 60
41
10
4.1
4.10
GM 10.5" 14 Bolt
45
11
4.090909
4.09
Dana 70
41
10
4.1
4.11
Dana 80
41
10
4.1
4.11


It is perfectly ok to run 4.09 gears in one axle and 4.11 gears in the other. The general rule of thumb for any 4x4 vehicle is for the front and rear ratios to be within 2% of each other (this amount is easily absorbed within the backlashes in the drivetrain) and the difference between 4.09 and 4.11 gears is less than one-half of one percent.



Compatible Gear Ratio Variations

3.54 3.55


3.90 3.92


4.09 4.10 4.11

4.86 4.88


5.13 5.14





Ring gear ratio data is ©Copyright Crawlpedia.com - Please provide a link back to this page when copying.






Other Ring and Pinion Resources

Differential Locker Comparison
Gear Ratio Finder
Gear Ratio Calculator
Ring and Pinion Setup Specs
Thick Gears and Carrier Breaks





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