My ('08 Lariat SCrew 4X4 5.4L) has a limited slip rear, what about the front? I'm thinking about putting synthetic oil in the diffs, I know I have to use an additive for the limited slip clutches in the rear. Do I need anything of the kind in the front?

 

No limited slip in front. You don't want it in the front as it can cause problems when turning.

 

I could understand a locker doing that. Didn't know the limited slip would cause the same problem.

 

how do you figure? The hubs are unlocked when not in 4wd. IE the two wheels can spin at different rates with no ill effect.

 

it is my understanding that when one looses traction, in 4wd or not, the other will engage. if not im sorry that is just my understanding

 

It will have a tendency to go straight in slippery conditions due to the LS, where an open will turn at the 2 different rates. A LS hasd nothing to do with a locker. The clutches keep both tires spinning even when one loses traction, up to a point. They are not "locked" together. In slippery conditions, the clutches are far more likely to not allow the wheels to turn 2 different speeds.

 

yes, in the rear of the truck that is correct. But these trucks have vacuum hubs. IE when not in 4x4, there is no power applied to the wheels.

 

I see that you have a '99. Do the newer models ('04-'08) also have vacuum locking hubs? It was my understanding that on the newer models the front hubs were always locked, and that the front axle, differential, and drive shaft were always spinning with the turning of the tires. The only place that they were disconnected from the drive train while in 2wd was the xfer case. When put in 4wd the xfer case engages to supply power to the front drive shaft...

Like I said, that was my understanding of how the 4wd system in the newer models worked, but I could be wrong...I actually hope that I am wrong, that's a lot of drag that the truck has to push all the time which would cause worse gas millage and unnecessary wear and tear on the components.

 

The 97-99 do not have hubs. All locking is done at the diff and TC. 04 up have hubs again, and lock at the hub and TC. In neither case is the front driveshaft always turning. On 97-03, the front axles are always turning, but no connection at the diff.