Maybe we can figure it out... Broncobran, can you turn off traction control and let us know if it still spins both tires?

Another good article on Limited Slip Differentials... http://auto.howstuffworks.com/differential4.htm

Dunesgirl, I still think you are describing an open differential, but maybe I am misunderstanding. I apologize if so.

 

This is correct. BRONCOBRAN68, you can go to the dealer and compare the letter on the stiker that identify your diferential with a nother truck with 3.74 Limited option. It should be the same letter.

 

I'm not 100 % sure but a 3.73 Limited should be a B6 axle on the door sticker.

 

Another cool article... sorry, I am an engineer so I find this stuff interesting... back to reading...

http://auto.howstuffworks.com/28000-...-explained.htm

 

I realize I'm dredging up an old thread, but came across this video that shows very well what a limited slip differential does in uneven traction situations. It may be on a Tundra, but a limited slip is a limited slip (although I recognize that some limited-slips are better than others). Watch this Tundra come into the ditch, and when the shot pans to the back, you can see both tires simultaneously, as well as see that the tire that had the most resistance on it would stop spinning several times while the one that had the least resistance spun continuously. Tundra had no forward motion either.

clicky for youtube video

 

I still think, any '09 with the electronic locker will not also have L/S in it. I have nothing to base this on personally, but if you ever look at a diff, the L/S portion takes up most of the innards of the gears. Electronic lockers I have seen look to be about the same size. It would be nice to have L/S when lock locked, but I highly doubt it. And FWIW, an open diff can burn 2 strips of rubber if the conditions are weak, like the wet looking picture previously showing both tires smoking. Similarly, a LSD can also spin 1 tire if there is too much friction modifier, or the conditions are beyond its capabilities. So to base this judgment on weather or not 1 or 2 tires spins when the electronic locker is somewhat silly, not absurd, but not definite either.

By my interpretations of Ford's words quoted earlier. Working like a regular differential to me means open.

 

I believe there several on demand type lockers that when unlocked act as LS differentials.

 

FYI - I recently asked a ford tech. on justanswer.com if the 09 FX4 has a LS diff. when in 2wd. Here is his response

"The ELD is always an open differential. It has no clutches. It is only a locker when in 4high or 4low and only below 40,ph. Any speed above that and it disengages on its on and then re-engages once back under 40mph."

I got to trust any mechanic with a nickname of "moose"


http://www.justanswer.com/profile.as...2499435&FID=24

 

here is another good video comparing open, LS and locker

http://www.youtube.com/watch?v=y6_kO...eature=related

 

That last video never shows a limited slip diff. At least not according to the narrator.

 

lol i like the way they brake in the f150 and roll back as it's about to pull it's self out of that rut. Talk about try and make the other trucks look bad. LS would def help in that Situation though. Plus you notice the diffence in the rut they are in. The rut is a lot less agrresive than on the other trucks and they attack it at a different angle than the rest.

 

That was with the traction control off. It is not possible to spin the tires for more than a second of so with traction control on. It cuts engine power as soon as slip is detected. This was a slow speed burnout. Both tires kept going just like there was a spool in there.

Oh and I spoke with the ford regional tech director for my district and he said it is a limited slip when unlocked.

 

I really dont think they would make a mistake like that in the manual and on there website. The diff dont even have any clucth plates either so i would love to know how they make a LS with no clutch plates? I would take the infomation from the manual and online over any time i believe a tech. A ford tech told me my truck needs to be serviced every 12k miles! They even spoke to someone higher up after the computer system said 5k and they also said 12k.

 

It never says anything in the manual about an open diff. It says the ELD performs like a standard axle when unlocked. It also says the lsd performs like a standard axle. It never says it is an open diff when unlocked. Maybe my truck was an accident or maybe my locker is stuck but I am the second guy to be able to keep both rear tires spinning unlocked.

 

Ok this is taken right from the workshop manual, now the FX4 DOES NOT have a LS diff, it has a standard open rear diff, and is currently the ONLY model that you can get the ELD. any other model will have a LS rear diff.

An Electronic Locking Differential (ELD) is also available which electronically locks the differential side gears to the differential case which will allow maximum torque to both rear wheels. The operator controls the differential with a dash mounted switch.

The ELD system consists of the following components:

ELD coil, located at the rear differential
Rear differential
Mode Select Switch (MSS) (unique for ELD equipped vehicles), located on instrument panel
The ELD system, which is optional on Electronic Shift-On-The-Fly (ESOF) equipped vehicles, allows the operator to lock the rear differential side gears when in 4H or 4L mode. ELD operation is requested by pulling out on the MSS when in 4H or 4L mode.

The operator can switch between 4H mode without ELD or 4H mode with ELD at speeds up to 30 km/h (19 mph). In 4H, the ELD will disengage at speeds above 40 km/h (25 mph) and will automatically reengage at speeds below 30 km/h (19 mph).

To engage or disengage the ELD while in 4L range, the vehicle speed must be less than 90 km/h (56 mph).