Thinking of an Upgrade

[joefnh]

I have a 03' 4.0L 4x4 and am thinking of upgrading my rear differential as a way to solve the infamous rear end whine. I have 160k on it and it is becoming quite loud at this point.

How hard would it be to upgrade the rear differential to a limited slip style? Would it be easier to purchase a used limited slip form a junker then rebuild it or can I convert the non limited slip model that is in there now?

Thanks in advance.

--Joe

 

[Elessar65]

Go to a junk yard and just get a whole solid axle from a 2nd gen. Should be fairly simple to swap it in, no steering or anything like that to worry about. Then you can have all the comforts of a 3rd gen without the sissy IRS

 

[my pos mounty]

Joe, I see your from New Hampshire. Try www.carworldused.com
Recently I replaced my D4 LSD with 3.73.
They have 10 of them at $98.00 a piece

Search for 1999 mercury mountaineer AWD 5.0, will list them.
Your looking for a D4 LSD.

 

[jrford]

uh, with IRS a solid axle is not going to work. Maybe swapping guts if it fits. But really you need one from '02-05 like you said, just make sure the gears are the same. On the '06 what you can do is try and find a JY with both and compare an '06. It might be the same, i wouldn't think ford would re-engineer it. . .
On a side note i had one in my hands its not heavy at all. . . reasonable shipping i would think.
Half of me would want to just swap and fill and see what happens. . but it looks like its a PIA to swap it out and an once of prevention might help in the long run, i'd be very tempted to take it to a gear shop and replace the seals and check it out. It should be a lot cheaper it if you hand carry it in.

 

[my pos mounty]

Yeahhh, uhmm, I was a little... "well lubricated" last evening and will refrain from answering here under those conditions again. Friends dont let friends post drunk, you'll look awful dumb the following morning. All i remembered between reading it and writing my response was "rear diff" and " wanting to upgrade to a 3.73 LSD".
My apologies

 

[91EX4x4]

I have a 03' 4.0L 4x4 and am thinking of upgrading my rear differential as a way to solve the infamous rear end whine. I have 160k on it and it is becoming quite loud at this point.

How hard would it be to upgrade the rear differential to a limited slip style? Would it be easier to purchase a used limited slip form a junker then rebuild it or can I convert the non limited slip model that is in there now?

Thanks in advance.

--Joe

Unless you buy an aftermarket insert (locker) for the factory carrier, you will need to buy a factory carrier that has a limited slip. I'm not 100% positive about the explorers (I do Tbirds with IRS) but you will likely need to make sure the carrier you get is for IRS. The side gears in the IRS carrier should have provisions for circlips to hold the CV axles in place instead of C-clips like on a straight axle. If you use a solid axle carrier without the circlip provision you will be able to get the CV axles in, but if they lock in place, you won't be able to get them back out without a major fight and disassembling a lot of the rear end.

I'm pretty sure your diff will need 31 spline side gears, so you will need to get a carrier out of an explorer. One out of an 03/04 Cobra "should" interchange. Not the whole differential, just the carrier. If you get a carrier from a solid axle, you can have the bevel for the circlip machined into the side gears. It's not ideal, but it's cheap, and it works. I actually have a Ranger limited slip carrier in my Tbird with machined side gears. It took the guy about five minutes to chuck them in a lathe and cut the bevel.

-Rob

BTW, the 3.73 gears in my tbird were used from an IRS exploder. We got pretty close to the original wear pattern when we set them up and it whines loudly about 45 mph. It's ok, I couldn't hear them after I changed the exhaust.

 

[Elessar65]

uh, with IRS a solid axle is not going to work.

Sure it will, just like puttin one under the front of a truck. Just needs some grinding and welding and fabrication. Lol.