What gear ratio to use?

[HOWDY69]

I have decided on a Truetrac for the 1969 F250. Should I change the rear end gear ratio while I am at it? It has a 9.6 CR FE410 with a 4.10 Dana 60 32" tires. Mostly daily driver, not much towing, more interested in fun factor than mileage.

[jschreiner]

With a 32" tire 3.50 would be the highest I would go. A 3.73 gear with 32" tire is almost like having 3.25 gear. Jay

[averagef250]

I'd keep it 4.10.

[HOWDY69]

The Fordfe site recommended the following link.

http://www.richmondgear.com/calculators.html

I played around and it looks like the 4.10 is a good ratio.

Street Performance with 4.10 gr and 31.7 in tires
55 mph 2390 rpm
60 mph 2607 rpm
65 mph 2825 rpm
70 mph 3042 mph
75 mph 3259 mph

Drag Performance
Current setup: 92.8 mph
4900lbs, 305 hp, 4044 rpm, 31.7 in tires, ideal gear ratio 4.11
With headers: 97.6 mph
4900lbs, 355 hp, 4254 rpm, 31.7 in tires, ideal gear ratio 4.11

[ima71 trucks are older]

if you use it in town a lot, stop and go traffic and the like 4:10 will give you the best milage.