Fordnatics List Archive

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Mail From: Shel Belinkoff <(email redacted)>

For as long as I can remenmber I've heard that, for a given axle, lower
gear ratios equate to weaker gears. This is because, for a given size
ring gear, the lower ratio requires more teeth, and, therefor, the teeth
are thinner. How accurate is this?

I suspect it's inaccurate, and here's why: While thumbing through a
catalog recently, I was looking at the varios ratios that were available
for different axles. What I found was that, in many cases, the lower
ratios actually used fewer teeth on the ring and, simetimes, the pinion gear.
This would lead one to believe that, in certain cases, the lower ratios
were stronger than even the stock or higher ratios. For examples, let's
look at the popular Ford 9-inch:

Ratio Teeth
----------------------
3.50 35-10
4.86 34-7
5.67 34-6
6.20 31-5

Based on these figures, the lower ratio should be stronger than the higher
ratio. What's the truth? Are lower ratios inherently weaker than higher
ratios, but for reasons other than the size or number of teeth on the
gears?

Shel Belinkoff
(email redacted)