Re: [A/S] Ford 2004-2005

[Rick Kunath <k9ao@xxxx>]

It's a part-time 4wd system, and as such can't be used on dry pavement, 
so it won't do anything while highway towing. But, I'll second Hunter's 
recommendation to get it if you can. Grass and mud in parking places are 
easy to handle if you have 4wd, and you'd be surprised at how often 
you'll actually use it. Engaging it *before* you get stuck is a really 
good idea.

Another good option is a limited-slip differential in the rear. Get a 
gear-type if you can, as the "Positraction" clutch type limited-slip 
units lose their ability to act as a limited-slip after the clutches 
wear. If you've got more than 20,000 or 30,000 miles on a clutch-type 
differential, your "Positraction" ability is pretty likely minimal. They 
also require wheel-spin (so you're already half-stuck) to work, and only 
work at slow speeds. The gear types like the Torsen and Tru-Trac don't 
have this problem. I've got a lot of miles on my Ford supplied Torsen, 
and it still works as well as the day I drove off the lot. I don't care 
for the feel of the Detroit Locker type of disengagement axles. The gear 
type like the Torsen applies traction control at all speeds even around 
corners, and is nice and smooth in it's action, even at a crawl. Even a 
brand new "Positraction" type clutch unit can't do that. Remember to 
pick an appropriate axle ratio.

I see from taking a look at the Ford Fleet info that the F-250 and F-350 
are only available with a clutch-type ("Positraction") limited-slip 
differential, or with an open differential. The F-450 and F-550 are 
available with either the Tru-Trac or the No-Slip differential. The 
Tru-Trac is a smooth gear-type unit and is operational at all speeds 
even while turning, while the No-Slip is a quieter version of a Detroit 
Locker type that disengages the lock during a turn (not as desirable.) I 
don't know if the gear types are available as a special order, but since 
I am also looking to replace a leased truck this spring, I'll be taking 
a closer look. I know that Ford will sometimes build up special 
vehicles. I had my last truck modified as per special specifications for 
me prior to purchase. I don't know if this is generally available or 
something limited just to the Detroit area. I do know that the changes 
were done at the Ford factory shop.

A clutch-type limited-slip option is better than none, but I prefer the 
more capable gear type units. I'll probably have another Torsen 
aftermarket unit installed if I can get it, or something similar, from 
Ford directly.

I tend to want to push the envelope a bit and run late into the season, 
so sometimes I see snow. I am not retired and still have fixed deadlines 
so I can't always do the optimum thing and sit out bad weather. 4wd does 
help if you have snow or slush on the road, but driving under these 
conditions isn't something you'd want to do if you could possibly avoid 
it. You have to make your own call on safety and your driving abilities 
and experience. The Thanksgiving Holiday here was an example of this. We 
had unseasonal snows here and you might have found yourself stranded 
somewhere without 4wd. Safest would have been to sit tight, but I'd 
still rather have the option.

Rick Kunath
WBCCI #3060