1961 - 1966 F-100 & Larger F-Series Trucks
Discuss the Slick Sixties Ford Truck
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1962 F100 4x4 front to rear ratio mismatch questions
If I put lower ratio gears (higher speed) in the rear differential on my 4x4 it seems the rear end will be pushing the truck when in 4x4, but when the rear starts slipping, the front will take over and pull. This does not present a problem in my feeble mind so I am seeking the forum's experience.
Will there be any damage to the truck in 4x4 if I go with a higher speed rear end?
"The rust gods hate and fear phosphoric acid."
It sounds risky to me, but then I've not known anyone to do such.
The normal ratio is lower in the front than in the rear so the front is always slightly pulling when in 4WD. For example, my 1966 F250 4x4 has 4.56 gears in the rear and 4.55 in the front. This causes the front to pull slightly (.01 difference) and the steering will work as expected.
With your idea the rear is always pushing, possibly causing it to push you through corners and overpower the steering capabilities. And this is on loose terrain such as a gravel road. On blacktop or even a sticky patch of dirt it might be enough to overload the front and break something.
For it to work smoothly with significantly different gears it seems like the transfer case would have to be designed to take up some of the slack, sort of like a differential does when cornering, but instead of side to side it would be front to back. But as designed they don't provide for that compensation. Otherwise you are counting on tires slipping at the right times when it is required and then not slip when you don't want it to, like when steering.
I don't think you'd have that control over it. If the tires don't slip then something would have to break. Most likely in my mind would be the transfer case or driveshaft u-joints would be the first to go.
But, it's your truck so you can certainly experiment all you want.
You'll be okay if you're only doing a difference in approximately .01-.02 ratio (4.09, 4.10, 4.11 for example), anything over that will grenade your transfer case or driveline the minute the front and rear both grip anything at the same time.
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