front and rear diff swap

[rusty 91]

Ok so heres what i got. I got a 98 explorer sport that acording to the door code it has 4.11 gears with a limited slip, and my new explorer is a 01sport it has a 3.73 open diff, both 4x4. I do tow things with my car and that limited slip is much better in the snow thats y i want to do it. Has any one done this before or got advice, or am i just being to ambitious when i can just take the linited slip part out and put it in the 01 and live with the 373 gears. Opinons and thoughts plaese

 

[2TimingTom]

Should work just fine.

To verify the axle ratios, jack up the rear axle, put it in neutral and spin the tire 1 revolution and count how many times the driveshaft goes around. You may want to put a piece of tape on it so you can see it easily.

99% chance your gears are what your door tag says, but before you dive into such a time consuming project, 20 minutes spent doing this might just save you.

 

[Aiezzi]

Just swap the axles all together it will make your life way easier instead of pulling the gears from the diff and resetting them into the other axle. I'm sure it has been done many times and is fairly simple to do.

 

[rb142]

You can do it, but unless you are towing some heavy loads I wouldn't recommend it. You will really notice the hit in fuel economy. But it is a lot easier to do a swap than to do a full rebuild on that diff to put the limited slip in. (No, you can't just swap out that part.) Limited slip 3.73 setups are plentiful in parts yards and easy to swap in.

 

[intelisevil]

Limited slip 3.73 setups are plentiful in parts yards and easy to swap in.

I'd leave the '98 as is and swap a 3.73 LS into the '01.

 

[1997XLTRollover]

You can do it, but unless you are towing some heavy loads I wouldn't recommend it. You will really notice the hit in fuel economy. But it is a lot easier to do a swap than to do a full rebuild on that diff to put the limited slip in. (No, you can't just swap out that part.) Limited slip 3.73 setups are plentiful in parts yards and easy to swap in.

^Before we make assumptions, although I have a feeling you may be right on this one...

OP What size tires are you running? Are you running stock size tires or are you running something larger in diameter? If you have 32's like myself going from 3.73's to 4.10's will drop your tach at almost the exact same RPM as a stock tire with 3.73's so would actually help keep your fuel economy in check.

EDIT: In all fairness I went from 3.27's to 4.10's in my Mustang and saw no change in fuel economy. In fact my city mileage went up a bit. It's all relative for every application.

 

[2TimingTom]

I was geared at 4.56 with 30s for awhile and didn't see my mileage drop.

 

[intelisevil]

If you have 32's like myself going from 3.73's to 4.10's will drop your tach at almost the exact same RPM as a stock tire with 3.73's so would actually help keep your fuel economy in check.

EDIT: In all fairness I went from 3.27's to 4.10's in my Mustang and saw no change in fuel economy. In fact my city mileage went up a bit. It's all relative for every application.

Sorry but your math is backwards. Going from 3.73's to 4.10's will INCREASE your engine speed at any given road speed.

32" tires, 3.73 axle ratio, top gear 4R70W (.70), 65 MPH = 1782 RPM - Driveshaft turns 3.73 times for every tire rotation.
32" tires, 4.10 axle ratio, top gear 4R70W (.70), 65 MPH = 1959 RPM - Driveshaft turns 4.10 times for every tire rotation.

http://www.crawlpedia.com/rpm_gear_calculator.htm

Going from 3.27's to 4.10's in your Mustang would have increased your RPMs at any road speed by about 20%. I would think you'd see a noticeable drop in fuel economy unless you were lugging the engine with the previous gearing.

 

[1997XLTRollover]

Sorry but your math is backwards. Going from 3.73's to 4.10's will INCREASE your engine speed at any given road speed.

32" tires, 3.73 axle ratio, top gear 4R70W (.70), 65 MPH = 1782 RPM - Driveshaft turns 3.73 times for every tire rotation.
32" tires, 4.10 axle ratio, top gear 4R70W (.70), 65 MPH = 1959 RPM - Driveshaft turns 4.10 times for every tire rotation.

http://www.crawlpedia.com/rpm_gear_calculator.htm

Going from 3.27's to 4.10's in your Mustang would have increased your RPMs at any road speed by about 20%. I would think you'd see a noticeable drop in fuel economy unless you were lugging the engine with the previous gearing.

Not if you're running 29" factory size tires with 3.73's and then jump to 32's with 4.10's. RPM is almost identical

Oh and as far as the Mustang, as I said it's all relative. With 3.27 gears the engine was not fully in it's powerband so I had to stay in the gas more to keep the car going. With 4.10's it was slightly out of its powerband (fairly high RPM for cruise) but I hardly had to have my foot on the gas so the extra RPM balanced out. RPM doesn't matter as much as actual engine load when it comes to fuel injection. That was more of a carburetor issue.

 

[intelisevil]

Not if you're running 29" factory size tires with 3.73's and then jump to 32's with 4.10's. RPM is almost identical

That statement I can agree with, previously it sounded like you already had the 32's and then changed your gearing, causing the RPMs to drop.

Oh and as far as the Mustang, as I said it's all relative. With 3.27 gears the engine was not fully in it's powerband so I had to stay in the gas more to keep the car going. With 4.10's it was slightly out of its powerband (fairly high RPM for cruise) but I hardly had to have my foot on the gas so the extra RPM balanced out. RPM doesn't matter as much as actual engine load when it comes to fuel injection. That was more of a carburetor issue.

As I suggested, it sounds like you were lugging the engine with the 3.27s.

rusty 91: Are you still around or did we scare you off? Another plus of doing a junkyard swap into the '01 is that you always have the '98 to run around and get more parts as needed!

Good Luck,

 

[1997XLTRollover]

That statement I can agree with, previously it sounded like you already had the 32's and then changed your gearing, causing the RPMs to drop.



As I suggested, it sounds like you were lugging the engine with the 3.27s.

rusty 91: Are you still around or did we scare you off? Another plus of doing a junkyard swap into the '01 is that you always have the '98 to run around and get more parts as needed!

Good Luck,

Well the 3.27s are factory stock on all 99-04 mustang gt's but yeah it must have been a little bit.