How hard and how much would it be to change to a limited slip rear diff? I have an 02 4x4 with a 3.55 ratio. Is this overkill? Seems like it would be nice in the snow without using 4x4 just on the streets.

 

Why would you buy a 4x4 truck, or any truck for that matter, without LS?

 

not very hard, the cost is the major factor, if you can find one used out of wrecked truck ,you can save some $$$$$, the benifits of a limited slip out weigh the cost. ive done some old rear end changes and it turned out well, i'm not uptodate on the newer rear diff's, i'm running a 3.73 Lts, not bad on milage, but i do alot of towing , if your lucky you'll find a whole axle,(check the tag)and change the whole assembly,and not worry about setting the gears(important).check the tag on the front axle for the ratio.

 

I had an Eaton brand limited slip placed in my 03 supercab. The part cost $400 and the shop charged $200 for installation. It was worth it.

 

I have got a 2002 f-150 2x4 The axle code is U so this is the 3.55 rear differential, does anyone know the eaton part number for this type of upgrade, I don't know a whole lot about axle technology, but I do know some people who do. I would be able to get their help in the replacement procedure, but I just don't know which eaton posi-limited slip part is needed.

btw does the eaton have any improvements over the stock ford diff??

thanks,
//John

 

John-

The axle code for a 3.55 is not U. This is your trans code... a 4R70W. A 3.55 rear will be either an H9 for a factory limited slip or 19 for an open style under the axle block on your door jamb sticker. The site has a reader under the tech article section. All Ford axle codes are 2 digit codes. Double check your codes.

-Kerry

 

You can find gobs of used Ford 9.75 LS's on ebay, for super cheap.

Putting in a LS is not hard, but time consuming for the DIY'er, however I dont reccomend this for the weekend wrench turner.

I paid $40 for a 9.75'' Ford LS unit that came with spacers, ring and pinion and bearings (was from a 01 f150 wreck with 10k miles)

Prolly the most important item to have is a large shop vise and a large torque wrench.

The hardest part is swaping the ring gears from your open carrier to the LS carrier and removing the bolts, an impact wrench works best for this.

I put in my own LS in, with all new seals, (pinion too), oil, LS additive, shipping, etc, all came to about ~$150. But it took me about two 5-9 nights (i had got the wrong seals).

If you are really serious about doing this, I can post some directions to follow.

 

as I am more of the weekend nail (and beer) pounder, and not the wrench turner, I'll probly look to a garage or some gear head buddies of mine, but I will definitely look to ebay,

Thanx for the tip!

 

My mistake, I must have not taken my medication <evil grin> Anyway the u is my tranny, but axle code is 19 Thanks for all the information so as I see it I should find myself the 9.75 LS diff. After hearing that it takes the average gear head several hours to do this, I will probably take the parts to my mechanic and have him do it it'll be worth the 200 dollars considering it just took me 2 hours to change the spark plug wires on this thing. You practically need a phd to figure out that darn clip between the engine and firewall.

//John