gears
Laughing Gas
Joined: Mar 2004
Posts: 1,243
Likes: 0
From: Maple Ridge B.C. Canada
welcome to FTE.i would not stray from the factory gear ratio differences that much.i could be wrong,(someone jump in to correct me if i am) but i think 3.54 with 3.50 may cause too much driveline binding.you may wind up dragging the back axle to much. i have never tryed it so im no expert.-billy
Laughing Gas
Joined: Mar 2004
Posts: 1,243
Likes: 0
From: Maple Ridge B.C. Canada
all the diffs i have worked on have bin like that.i asked my friend (ford mechanic) he said it was for turning, and so the front axle would always pull the rear axle a slight amount.its like if you have a front wheel drive and you pull the emergency brake on as you are moving,you will still control your steering.but if you could lock up your front brakes and power the rear axle,then you would have trouble controlling your steering.its a crude example, but it gives you the idea of what its like.you will have better control if the front in slightly ahead of the rears rotation.i hope this helps-billy
Junior User
Joined: Sep 2001
Posts: 97
Likes: 0
From Randy (Not arguing one way or the other - just providing a different opinion):
It looks like for street driving you want 1% or less difference. If you have 3.53 in the front you could go 3.50-3.56.
For what it's worth mine came from the factory w/ 3.50 rear 3.54 front.
Originally Posted by Randy
Myth: The gear ratio in the front of a four wheel drive has to be different from the front so the front wheels will pull more.
Response: There have been many different ratio combinations used in four-wheel drive vehicles, but not so that the front will pull more. Gear manufactures use different ratios for many different reasons. Some of those reasons are: strength, gear life, noise (or lack of it), geometric constraints, or simply because of the tooling they have available. I have seen Ford use a 3.50 ratio in the rear with a 3.54 in the front, or a 4.11 in the rear with a 4.09 in the front. As long as the front and rear ratios are within 1%, the vehicle works just fine on the road, and can even be as different as 2% for off-road use with no side effects.
Response: There have been many different ratio combinations used in four-wheel drive vehicles, but not so that the front will pull more. Gear manufactures use different ratios for many different reasons. Some of those reasons are: strength, gear life, noise (or lack of it), geometric constraints, or simply because of the tooling they have available. I have seen Ford use a 3.50 ratio in the rear with a 3.54 in the front, or a 4.11 in the rear with a 4.09 in the front. As long as the front and rear ratios are within 1%, the vehicle works just fine on the road, and can even be as different as 2% for off-road use with no side effects.
For what it's worth mine came from the factory w/ 3.50 rear 3.54 front.
