Limited-slip rearend - Diesel Forum

dgreen1069 · 03-11-2006, 05:41 PM

Have any of you guys replaced the crappy Ford limited-slip rearend on your X's? I find that mine is no better than a completely open differential. The only way I can get it to apply any real torque to the wheel with traction is to use my parking brake. I wish Ford used the same differential as GM....they get a true locker.

FamilyRide · 03-11-2006, 09:03 PM

Sounds like they are hit or miss. Mine works great. The one in my Expedition was a good one too.

hockeymaine · 03-11-2006, 09:19 PM

Mine is a pain too. I have had the opposite problem. Mine wanted to lock going around corners. Seems like a fine line as to proper amout of friction modifier additive.

dgreen1069 · 03-11-2006, 09:49 PM

Does the modifier make the differential more or less loose? Maybe all I need to do is add some.

toalpi · 03-12-2006, 10:33 AM

[ QUOTE ]
Does the modifier make the differential more or less loose? Maybe all I need to do is add some.

[/ QUOTE ] You need to take some out. The easiest way to take some out is to start with new gear oil and don't put any of the additive in. Also it is "true" that the G80 (in the gmc) does lock (sometimes with damaging results) but only after one tire spins 100 rpm faster than the other tire. So it is a "locker" that requires some slipping/spinning to take place. Not really what most people call a "true locker".

dgreen1069 · 03-12-2006, 01:04 PM

I know what you are saying, but the G80 would allow you to drive up a ice covered hill as long as one wheel was on dry pavement. Try that in a Ford and you wouldn't move more than a couple of inches. I think I'll try draining my fluid and starting fresh. Does the rear take anything special or will synthetic gear oil work just fine?

FamilyRide · 03-12-2006, 05:19 PM

[ QUOTE ]
Does the rear take anything special or will synthetic gear oil work just fine?

[/ QUOTE ]

Ford uses synthetic.

Pitracer110 · 03-12-2006, 08:25 PM

I just installed a detroit locker in my 01' X. No traction problems or one tire spinning problems there. [img]/ubbthreads/images/graemlins/cool.gif[/img]

kd5fyx · 03-12-2006, 09:39 PM

My 01 X Limited came with every option except the Limited slip. In my Jeep days I ran the old dynatrac. I'm thinking Detroit for my X because of its legendary durability. Where did you get yours and how did the install go. I haven't broken down a rearend in twenty years. Thanks, Jeff

Pitracer110 · 03-12-2006, 10:03 PM

Got the Detroit from randys ring and pinion. Around $580 I think. Also got their master install kit. Everything I needed was there to do the install. if you have all the right tools I would say its not that hard. I did the install at a buddys house whos garage might as well be a professional shop. So a wide selection tools and time are what you need. IMO

Nick

kd5fyx · 03-12-2006, 10:38 PM

Thanks Nick,

I have a shop and a full set of tools from 1/4 to 3/4 drive and air. But I loaned out my Dial indicator and Digital calipers last year and still haven't got them back yet (some day i'll learn). Sooo, did you have to reset backlash and such or just pull the axle shafts out enough to remove the diff and install the locker to the ring and then back together.

Thanks again, Jeff

Pitracer110 · 03-13-2006, 08:43 PM

I cant say for sure because I replaced everything. I changed over to the 10.25 from the 10.50, and also changed from 3.73's to 4.30 gearing. Went with the 10.25 stuff to get the larger outter pinion bearing. The specs for the new gear set called for 11-16 thousandths. My stock set was set at 22 or 23 when I cracked it apart. I thought this was on the loose side. I dont know what ford calls for stock to be. My stock diff only had 33k on it at the time. I think after seeing this if I were you at the very least I would check it after the install.

Nick