Limited Slip Differential for a 4x2 Truck Questions... please read and advise...

In my opinion, limited slip differentials are only useful when you are in a situation where your rear wheels are on surfaces with significantly different traction. For instance one wheel is on ice and the other is on dry pavement, or one wheel is in a mud hole and the other on firm ground, or one wheel is unloaded because of very unlevel terrain. Without the limited slip differential, the traction of both wheels is limited to the traction provided by the wheel with the least traction (Total traction = 2 times the traction of the wheel with the least traction). With a limited slip, the traction available is equal to the traction of the two individual wheels. In cases where the traction available is the same or nearly the same for both rear wheels, there is no advantage to la limited slip rear end, and there is one disadvantage - with a limited slip axle, in situations where there is limited traction available to both rear wheels, you can easily break both rear wheels loose. When this happens, the rear end will fishtail and can be difficult to control. All of our farm tractors have manually applied rear differential locks. I have never had these be of any use. In any situation where I have broken one wheel loose, applying the differential lock just insures that both rear wheels are now spinning, which results in a quick burial of the tractor in the field.

In your case, a limited slip might be useful on a boat ramp because there are times when both wheels will not be on surfaces of equal traction. On the other hand, I've never had any trouble pulling boats out of the water with my F150 with an open rear differential. Unfortunately my F150 will get stuck on wet grass (my Father says it is because the tires are too wide). However, I doubt that a limited slip would do much good in my case. Whenever I have stuck the F150 it was on a mostly uniform surface and if I had a limited slip, both rear wheel probably would have spun. If you are really worried about the traction on boat ramps four wheel drive is nice - particularly if you are launching on a shallow ramp that forces you to back your rear wheels into the water.

Ed

Todzilla wrote:

4x4 is really best for boat ramps. Those buggers can be greasy.

Even in a limited slip, if you are starting out and one wheel slips, it will spin. There has to be a little load to shift it. A slight tap with the brake pedal will get both moving.

This also works in a open diff vehicle. If one wheel is spinning, you can bang on the brake pedal which loads up the spinning wheel to the torque point the other side will grab. It works really well, but needs some practice to make work easy.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Todzilla wrote:

"Todzilla" wrote

You may want to check into what these "Vehicle Dynamic Control" systems do. And if the limited slip diff is offered on these two trucks as an option? Lately, on the high end GM trucks with what they call "StabiliTrac"....they use the ABS brakes to perform the same functions as limited slip diffs and transfer cases with either clutches or viscous couplings. In other words.....when you get wheel spin, instead of a mechanical component transferring torque to the non-spinning wheel, the ABS system stops the spinning wheel which automatically sends power to the non-spinning wheels. Perhaps the Nissan and Toyota are now using a similar system.

Ian

Ian,

Yes, both vehicles offer a similar brake system. I knew that it applied brake force to the spinning wheel, but I didn't realize that triggered the other wheel to spin. That corresponds, however, to what the gentleman mentioned earlier about the brake tapping treatment earlier. Thanks for the input everyone, I'm learning quite a bit. What I'm thinking now is that I won't get the optional limited slip for now... I can always add it to the truck later if it becomes an issue. How does that sound???

Adding it later would require replacing the differential. You may get an entire axle from salvage more economically. As for pulling boats up boat ramps, it depends on the ramp (and the boat obviouisly). I really doubt you would "need" limited slip and if you did, you can probably find another boat ramp that works better for you. I've pulled a 20' inboard (3800 lbs) for many years with an old Cougar having open differential. There has been the ocasion where one wheel would slip, but I have never been stuck. If the ramp is wide and no one else is beside you, going up at an angle helps.

"Todzilla" wrote

Yep...applying the brakes manually works in a similiar fashion to what a limited slip/locking diff does. By the way, braking the spinning wheel does "trigger" the other wheel to spin, but not because of any particular new magic or new technology. It's simply because of the way a differential works. The reason that one wheel spins is because the other is being held (stuck) and so all the torque flows to the spinning wheel. By holding the spinning wheel, you force the other wheel to start moving......it has no choice.

Ian

Thanks for the input everyone, I'm learning quite a bit.

You need a real truck, not a Toyota or Nissan. :-p

Seriously, a true limited slip differential and true limited slip / locking transfer case give much better real-world offroad performance than ABS/traction/stability control systems. The latter are adequate for on-road use, and maybe even better because they don't require you to alter your driving style as a limited-slip differential can under certain circumstances (it makes the vehicle more prone to oversteer on slick surfaces). So decide based on how you really intend to use the truck- 99% on-road, then go with the electronic system. Offroading? Then look for real hardware, not software, to perform the needed functions.

Well, I think I'm going to take the plunge on the Titan. I will NEVER have this vehicle off-road (unless something really crazy happens), so I'll go without the Limited Slip.

No offense to domestic truck buyers, but I'll put the Titan up against ANY of them. I've driven them all... and this is the HULK of 1/2 ton trucks. If you see one on the road, don't challenge it to a race... ;-)

Thanks again to everyone... this has been very educational and I'm extremely grateful.

Are you KIDDING? I'm already looking for one to uh... challenge (in my head, I'm thinking 'humiliate' :-) At least Nissan saw fit to put a reasonbly sized engine in their attempt at a truck, unlike Yota.

"I'm already looking for one to uh... challenge (in my head, I'm thinking 'humiliate' :-)"

All I can tell you is that you better bring something modified, because there is NO factory 1/2 ton truck that can touch it 0-60 or

1/4 mile. That includes the infamous "Hemi" Ram. The Dallas truck challenge for the Titan was just conducted the other day where they line the trucks up and run em through all the obstacles and down the drag strip... there was the Ford, Dodge, Chevy, and Toyota in their biggest, baddest configurations. The results were not pretty... HULK SMASH PUNY TRUCKS!!! ;-)

Thanks again to everyone...

Yeah but will it outrun a Corvette or a Mustang Cobra? If I want a drag race vehicle, I wouldn't want a truck. If you want to prove it is a good truck, I know the perfect person to test it...(but not me). Send one down and make sure it has a fifth wheel setup.

Ed