Strange problem occurred today. Truck is 2011 Platinum Screw, ecoboost, 3.55 limited slip diff. I was at a red light and wife was asking how the 4 wheel drive works. I turned the **** to 4 wheel high and explained that we were in 4 wheel high. She asked about the 4 wheel low so I shifted to neutral switched to 4 wheel low and pulled forward to show her the difference in how the truck felt. I stopped put transmission in neutral switched back to 4 wheel high. The light turned green and we drove off. The truck felt like it was in 4 low. Then a loud clicking / chattering sound started coming from under the truck. If you have ever heard an automatic transmission that is put in park while still moving this was the type of sound it was making. I stopped and put truck into 2 wheel drive and it started acting normal again. I was never over 10-15 mph when all this happened. I tried to repeat the problem in a parking lot without success. I did have something else strange happen while trying to replicate the problem. When the truck was in either 4 high or 4 low and I was turning the rear tire would scrub loudly. It scrubbed the same way my jeep does when I engage the rear locker and make a tight turn. When the truck is in 2WD and I make the same turn I got no scrubbing. I didn't think the limited slip diff would act any different while in 4WD vs 2WD. What the deal here?

 

You should never engage 4wd on dry pavement! You you expireinced at the light was most likely the transfer case not shifting from 4 lo to 4 hi so there was grinding in the transfer case. You sometimes need "unload" the tranny and transfer case to get them to switch from lo to hi.

In the lot, in 4wd on dry pavement you will get wheel hop and chirp from the front and the rears. Yes, the limited slip could kick in and scrub the rears.

 

long story short... read the manual on how to use your four wheel drive. It actually sums it all up pretty well, including that it shifts best while rolling without load (coasting/cruising)

 

I have read the owners manual. The owners manual doesn't say anything about why the limited slip differential would act differently in 4WD vs 2WD.

 

Are you even sure that it was the rears? You may have just heard the fronts but thought it was the rears. Are you sure you dont have a locker in the rear?

 

It also could have been the TC kicking in braking the rears and activating the LS. Being in 4wd on pavement and doing circles will send the system haywire, not to mention that it is not good for the driveline.

 

Like Rescue has said... i don't think your limited slip has had anything to do with this. You were playing with the four wheel drive on pavement and it makes the driveline to crazy bad things, including funny feelings, funny noises, and tire screeching. I mean, don't worry, you didn't break anything, but it's normal....

 

Thanks for info and reassurance it's normal.

 

You have to be at a forward moving speed when engaging into 4wd high according to the manual..If you are parked or stopped and engage it and then drive it the linkages do not line up as smoothly as if you are rolling..I wasn't aware of this until I read several posts and then read my owners manual very closely..It clearly states to be at a forward moving speed of..Most guys just let of gas pedal when switching over and it engages smoothly..