I have a full float 4.10 LS rear axle in my v10 van. Today I got in some mud at a friends house and that LS would not drive both wheels. I was three inches from the concrete and one wheel just sat there and spun. I applied the brake, hit the accelerator a bit and let the brake go. Tried just putting it in reverse, unless they don't work backwards?
I am frustrated. This is the second LS I have had that does not work like intended, any input on how to make it kick into both wheels driving, or what I might have done wrong, or what ford isn't giving us in the LS rear axle.
Thanks for replies,
Got my buddy to pull me out 3 inches, useless!
Andrew.

 

Not familar with your set up but most LS diffs use small clutches inside the housing next to the spider gears. If those clutches are worn then you can lose the "limited" part of the limited slip diff. Some are easy to rebuild and can be done without removing the diff. I have done this on Fords 8.8 diff but as i said I don't know your setup.

 

I am assuming it is a dana rear end, you will have to pull the carrier out of the diff to replace the clutches that prevent the axle gears from spinning, this makes it so that in order for the axles to rotate at different speeds they must override the clutch pack. example: turning a corner, it is not a locker or a spool (both axles locked together).

I have one out of a Dana 70 I can take a picture of later.

the trick to making a worn LS diff stick is to drain the fluid and refill with an in-expensive correct weight lube and DO NOT ADD the LS additive, and DO NOT USE a lube that already has the additive in it. this additive causes the clutches in a good LS to slip and not "chatter" on a corner. without the additive the clutches will grap better. If you have a tire airborn LS provide little help.

If you rebuild it I would suggest adding an extra steel behind the clutch pack to provide extra spring pressure, Sox and Martin did this to their 9" fords by adding a steel beer can bottom behind the springs, I added 3 extra steels in my Ford 9" when I rebuilt it, with 13" slicks I toasted the stock one in one burn out at the track, after it started to go. after the rebuild it was like a locker for the first 100 miles.

jack both wheels up in park and spin the tires, you should not be able to turn it with all your might, if you can but it is difficult than it's worn out, if you put it in neutral and the wheels spin opposite of each other than I think you had a fast one pulled over you and its a open diff or it is very very worn out LS, and is basically just an open.

 

Thanks for the reply, I am running Mobil 1 synthetic 75/140 with Ford additive in the rear and that is probably why its not working. Too much friction reducing oil.
I don't like the grumble without the additive.
I tow a lot and will put up with the LS not working in favor of better lubrication.
I have been into this diff for carrier bearings myself and its definately LS. I was just wondering if there is some special trick I need to do to get it working in a stuck situation. Some have said to put the brake on and that will help engage it, I wasn't sure if I was missing something. I have had several of these rear ends and only one ever helped me out of a slippery slope.
Appreciate your reply
Andrew

 

The clutch type LS is easiest to use b/c it is always doing it's job, applying the brake could maybe slow down an over speeding tire and help the clutches grab but the best way i have found is to, keep the rpm's down and stop and restart the wheel spin repeatedly, once the clutches start to slip they seem to stay slipping, and if you spin the crap out of them your likely to toast them real quick.

It is normal for a LS rear to make a "wrrr, wrrr, wrrr," on a corner, the chatter feels like bind in a 4X4, the tires don't want to spin differently and they skip or bind, or it binds and then the clutches slip, if it is smooth it's working properly.

My dad works for verizon business and we own 2 4X4 dakotas, both whine on corners, several more of his coworkers trucks whine too. one of his coworkers took his truck into the dealer so many times for the wrr wrr wrr that they ended up giving him an open rearend.

 

I installed LS in both my E-350 Dana 60's.In ea case,the instructions were speciic..not to use synthetic fluid...reg lube plus the additive only.I havent had a bit of trouble in over 400,000 combined miles.

 

My 8000 Lb Ext 99 E-350 with 140,000 miles will roast both back tires on the pavement, I swapped the Motorcraft synthetic at 100,000 with Royal Purple, it requires no additive, yet I've never had an issue from my gears, just leaking caused from poor venting, I believe my vent tube is blocked.