I ordered an 06 250 last week. I ordered the limited slip with the 410's. I will not be doing any off roading. This will be a second vehicle that will get 5-7,000 miles per year. I do live in Mich so I will drive in the snow occasionally in the winter. I will have 4x4 so is the limited slip really necessary for me. I will also not be doing any towing. I want to save the $300 unless you guys in the know tell me it is absolutely necessary. Thanks in advance.

 

Get it all including the limited slip. If you tried to add it later you would spend 5x whatever the dealer invoice shows. You only need it once to pay for it many times over. My boss didnt have limited slip on a sd when he was launching a boat last year , and the tires ended up slipping on seaweed, and the whole truck slid into a lake and he ended up swimming through the window opening to get out. Insurance co totalled the truck out and resold it as a flood vehicle. Possibly avoidable if it was there when he need it. Bill

 

for 2002 f350v10

That makes me just want to keep the order the same. But to get to the heart of my question, if he had been in 4x4 would he have had a problem?

 

For $300 you'd be nuts not to get it. If you happen to be in 2WD mode and the rear end slides out from under you, you'll wish you'd had limited slip.

I have it on my truck (2WD) and absolutely love it. It makes me feel more in control in shaky situations.

 

4 wheel drive without limited slip is actually only 2 wheel drive. One rear wheel will spin and one front wheel will spin. I had a 4X4 without limited slip once and it was a problem.

 

Ok guys I'm convinced. I will keep the order as is with LS. Glad this forum is here for this very reason. Thanks all.

 

corrected thanks to BFR
In AWD vehicles, even this assumes the center diff/transfer case is locking (splitting the torque front and rear). Otherwise, if the center diff is open, you essentially have one-wheel drive. Whatever wheel is spinning will take all the torque and the other 3 will just sit there.

I'm fairly certain that on the Ford SD trucks with 4-wheel-drive, shifting into 4-wheel not only powers the front axle, but also splits the torque so power is shared front and rear.

As others have said though, there are many conceivable situations where you might not have any reason to be in 4x4 and start to have one rear wheel slide - the limited slip rear diff would prevent that.

Good luck.

 

There is no center diff in these truck. Center diffs are on AWD vehicles.

When you put it into 4wd, you ARE putting power to the front driveline.

 

I understand that shifting in 4-wheel powers the front axle (and the front wheels if the hubs are locked ), but how is torque split between the front and rear axle?

Thanks!

 

It is split evenly front and rear. All you are doing is moving the gear in the t-case and engaging the front driveline.

It's not like the Jeep Cherokee's or the Subaru's with the full time AWD. Those vehicle's have center differentials that are always engaged. The computer tells it when the lock up and apply power where it needs to go.

On part time systems, putting it in 4WD splits the torque to both ends.

A VERY clear way (and very expensive) is to get on a slick up-hill section, get your rear tires spinning real good, and drop it into 4wd. Really......................DON'T DO THIS, CARNAGE ENSUES.

 

The transfer cases on the superduties use a chaindrive to run the front drive shaft. They are rocksolid transfer cases and the torque is split evenly between the front and rear driveshafts. There is no "torque split" as is used in some AWD vehicles. When in 4x4, both driveshafts are mechanically locked together and driven together by the transmission.

 

Thanks - that's what I've been trying to figure out. I'm more familiar with AWD systems that have locking center (and front and rear) differentials.

In Ford's part-time 4wd system, when the gears in the t-case are engaged to power the front axle, such that both axles get a 50/50 share of the engines torque, then the most torque any single wheel could "steal" when spinning is 50% thereby leaving 50% for the opposing axle.

I just hope I never get stuck on ONE side of the truck such that both the front and rear wheels on the same side spin! This is why I wish I had a limited slip axle (or better yet, front and rear locking diffs).

Thanks for the help guys - I'll edit my earlier post to clarify.

 

Miescha,

ARB's BABY! Best o' both worlds.

 

BFR: please elaborate on the ARBs. Are they air-locking differentials? Can you give me an idea on cost? How hard to install?


Also, just learned you are overseas on our behalf - my sincere thanks for the work you do. If ever I can be of help to you here in the states, please let me know.

 

ARB's are Air Locking Differentials.

Here's the basic concept. You need the Locker itself, the compressor, and the switch in the cab.

Under normal driving, the compressor is off and the locker is unlocked (open differential). This allows both wheels to spin different speeds and causes no excess wear on tires or drive line components

Now, turn the compressor on, takes about 6 - 10 seconds to fill. Now the system is ready. Hit the swtich for the ARB and a charge of air actuates the locker and both wheels turn together. To unlock, just turn off the switch and you are back to an open diff.

Ahhhh, cost. ARB's aren't cheap. Selectables are about the most expensive of the lockers you can get. There are a few different one; ARB, Detroit Electrac, Auburn ECTED) The only one who makes one for the 10.5 rear end is ARB.

They all run about $800 each. This does not include the install. The install costs more for selectable lockers, as you have to run either air lines (ARB) or electrical lines (Others).

Example scenario for cost on my truck is:
Gears Frt - 167.00
Gears Rr - 197.00
Master Install Kit Frt - 162.00
Master Install Kit Rr - 201.00
ARB Frt - 815.00
ARB Rr - 815.00
Compressor - Free
Labor to install - 1000.00

Total cost for 4x4 with gears, 2 lockers, compressor, and wiring: 3357.00

Definitely not cheap, but worth every penny.

BFR