'08f150stx

I am curios about switching gear ratio's. My truck is stock, 3:55 open rear end. I would like to switch to an aftermarket limited slip diff. but would like to change gear ratio's if I go through the expense of changing the diff. I have found a 3.90 to a 4:10. I would like to still be able to drive on the highway occasionally but mainly do short trip city driving. Tire size will probably go up one size from stock. I know 3:73 probably would not make enough of a difference, especially if I go up in tire size to warrant the cost. All I really want is more torque. Got any thoughts on gear ratio's?

dereku

3.73 and slightly larger tires would prolly be great. But the 4.10 will give you some more oomf

'08f150stx

Thanks Derek.

dereku

I have a 4.6 too and I know it is slow. It could probably use the 3.73 in stock form. I have the 20s with 275/55s and it lacks some low end speed.

Also look into an aussie locker or lockrite.

They are cheaper than a full limited slip and work about the same just less refined.

'08f150stx

Yes it is slow on take off especially. I guess it is about getting the rpms up quicker to begin to get the engine into the torque curve. The 3.55's are great at 65 mph with the stock tire size, but increasing the tire size will only make the engine work harder to get into the torque curve. So the gears I saw were between 250 and 300 per set. So $600 for gears, $600 limited slip diff (eaton or detroit) but don't know about the labor. I am guessing 1800 to 2000 total installed.
http://www.diffsonly.com/