Help with new gears

[MudManNM]

I want to put some 4:56 gears in my 91 Explorer EB. I am looking for some helpfull info on what to buy, how hard it's going to be to install, and places on the web that I can get the gears. Any help suggestions would be great. I have a 6.5 inch superlift, 2 inch body lift, and 36 inch tires, 4.0 V6 semi-stock moter. I looking for a little more beef to push it all. Any one have any other suggestions? I plan on dropping in a V8 351 from my Mustang next month to give it more power. How will this effect my gas mileage with the new gears? I know the motor is going to eat gas like it's going out of style but with the new gears will I need the motor? I need some help....I plan on dropping in the motor next month. Thanks!



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Scott
91 EB

 

[Tom Wilk]

Hey Scott,

I can't tell you much about swapping the engine except that it sounds like a MAJOR project.

As far as getting the gears installed, you should definately let a pro set up the differentials. There are quite a few things that can go wrong when changing the ring and pinion. You need to adjust not only the position of the pinion, but also the ring gears, as their surfaces must meet properly or you will either wear the gears out very quickly or break off teeth. Tolerances for these are a couple of thousandths of an inch. So, let someone with some experience do that job. It wouldn't hurt to watch, though if you get the chance. There can never be enough experienced ring and pinion people in the world.

Also, this would be a good opportunity to install a limited slip, or better yet, a locker, at least in the rear. That way, you'll only pay once for the rear end setup.

As far as the 4.0 L, change the gears first and then decide if it is adequate for the task. Don't forget to recalibrate the speedomoter for the new gearing/tire size. If it still seems a bit weak, there are people here that have made various amounts of modifications to their 4.0's to increase power.

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Tom

 

[QTRMILE]

Although I can't help you much with the gear install (I assume its a 4x4...) but I love engine swap challenges!

I've always found the best gears to buy are the Ford Motorsport units, as they install with a minimum of hassles. Other brands require you to change shims and can be much more of a hassle to install (at least in REAR differentials, I'm still in the dark with regars to the front...) I would find a reputable shop, make sure you get references and check them out. A lot of places either won't install stuff you bring in or charge you more. They understandably want to make a little profit on the sale of the gears.

One hint that has worked well for a lot of us drag racers: seek out a Ford mechanic and see if you can get him to do the install after hours or in his/your garage.

As for the engine swap, I think Tom is right. Get the gears done and see what you think. The gears will go a long way in overcoming the pronounced lack of umph in the 4.0. If you think you want to go the engine swap route, drop me an email or post here and I'd enjoy kicking some ideas around with you.

Good luck, Rob aka QTRMILE

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no Explorers, but plenty of Fords:
'82 Mustang GT 351W
'82 F250 351W
'91 Mustang LX 5.0
'78 Mustang II pro street