Guys, is limited slip really neccessary or desirous to have on a 4x4?

I can understand LS in a 4x2, but if you can engage the 4x4 when needed, is LS needed for a 4x4 truck?

I may have found a truck I want and the only option missing is the LS.

 

What limited slip does with 4x4 is allow you to get really really stuck. In a low traction situation ALL wheels pull when in 4x4. A 4x4 withouth limited slip can actually be considered a 4x3 because only one of the rear tires will pull.

 

OK...that confused me a little.. First you say that a 4x4 with LS can get you really stuck...

Then you say a 4x4 without LS is actually a 4x3...


Is this a good or bad thing... I don't understand.

 

i think what he meant to say is that the LSD allows you to get really stuck and still get out. LSD is a good thing. i personally wouldn't buy it without it, but only you know how you will use your truck. i say be patient and get one with the LSD. you can read about differentials here:

http://auto.howstuffworks.com/differential.htm

 

It really depends on what you want the 4x4 for. If you want it for " It looks cool and the occasional dangit I'm stuck and need to get out" then no LS would more than likely be fine. If you need 4x4 to get around because you travel in some nasty places then a LS would be a help.

LS works by transferring rear axle power from the wheel that is spinning (losing traction) to the wheel that is not spinning (has traction). Therefore, if you "burn out" (spin the tires) on a limited slip differential (or posi traction in "My Cousin Vinny") both rear tires will be spinning. Without limited slip only one tire would spin.

What I meant by the really get stuck commit is that with a 4x4 with limited slip all 4 tires are attempting to get traction. With that you can dig really nice holes. Hence when you get stuck you are really stuck (time to find a tractor stuck).

 

I can honestly say that I do not intend to go off roading with this truck and will only occasionally tow a boat and go where there is snow or ice.. (I live in central TX)...

Therefore, it sounds like I wouldn't need it, but that it would be handy for resale value maybe...

 

Most people wouldn't know to ask during resale. But, I did get it on mine.

 

Forget the resale, I don't even check to see if ones got limited slip when I apraise them. It sounds like you don't really need it. I have a lot of people that don't like limited slip and won't take it and I have a lot of other people that say they have to have it, but it doesn't matter at all for resale.

 

Total Agreement

 

Is there any additional maintenance to having a LSD?

 

Plus AdvanceTrac is better than the Limited Slip. Oh yeah, it's not available for the 04 F-150. Maybe 2005 with side curtain airbags?

 

No. The only maintainence is to change differential lub at 100,000 miles which isn't a bad idea anyway and may be a part of normal (Non-LS) readend maintenance.

AdvanceTrac is "better" but only because it uses the ABS wheel speed sensors to since when the wheels are slipping. It also works on the front wheels unlike a standard LS. AdvanceTrac greatly enhances overall vehicle stability.

As far as a direct comparison to a LS rear end, if you understand how AdvanceTrac works what you figure out is as opposed to mechanically sensing the wheel slip it uses the ABS sensor tp determine if the wheel is slipping. If AdvanceTrac senses wheel slip, it uses the wheel brake to the slipping wheel to cause the opposite non-slipping wheel.

Therefore, the big reason it is better is that it works with the front wheels as well to keep them from slipping

 

Yes but it is also Traction control. I heard that it lets th 3 ton Expedition move with just one wheel on the ground. For those of you who don't know, AdvanceTrac sends torque to the wheel(s) with most traction. It can also apply brakes when needed and cuts power form the engine when needed. Now thats impressive, plus it dects understeer and oversteer, and keeps the vehicle on the drivers intended course, and the driver doesn't have to do anything. Also prevents the the vehicle form rolling over.

 

Advancetrac is a stability control system. Its job is to preven spin outs and controls yaw using the ABS system. A feature included with advacetrac is traction control that is whats been discused. Many vehicles have Traction control and advancetrac is an option on top of that. Traction control applies the brake to a spinning wheel to send power to the other side. If both wheels are spinning it retards engine timing to cut power, if thats still not enough it cuts fuel to different cylinders until traction is regained. It is very nice on slick roads, but isn't good for perfomance. Ask anyone who drag races Mustangs what step one is and they'll tell you its turning off the traction control as if you hit it you loose too much power for too long of time. Thats where limited slip has an advantage. Some vehicles have both (Mustang for example)

 

An interesting way to look at it is with a 4x2 regular axle you know for a fact one wheel will turn, so you spend an extra $3000 for a 4x4. Since the front is also a reguar axle you know for a fact that one of those wheels will turn. Now you know for a fact that two wheels, one in the front and one in the rear, will turn. Is it woth another $285 to know for a fact that three wheels will turn at any give time.l

On the other had, on flat pavement in 4H it's very hard to spin the wheels even in the snow.

The only down side to not having LS on dry roads is when you have the 5.4 with the 3.73 axle. It's tough to keep one wheel from spinning on right turns and in the rain. My 99 was that way, and many times traffic would start off, but I would just sit and spin. Even more so with the 300 hp three valve engine I would expect.