We have been getting alot of rain here in Austin the past couple of days, and I switched on the 4wd a couple of times just to see how it drives in the wet. My buddy told me not to drive on the street with the 4wd on, that it will mess it up. Is there any truth in that? Is 4wd on these trucks for off road use only or what?
Correct... Because the front/rear axle essentially "lock up" the drive line when the truck is placed in 4WD, the truck requires some slippage like loose gravel, mud, etc... If you were to continue to drive in 4WD on drive pavement, eventually the driveline would become so tight, you would cause damage to one or more components...
4WD on our trucks is NOT like "all wheel drive" found on most SUV's... AWD vehicles employ clutches in their drive train to transfer traction to individual wheels so they will "slip" the appropriate axle if additional traction is not needed...
A simplified explanation, but if I were you, I wouldn't use 4WD on raods where the tires are not subject to some slippage...
Best Regards,
Les
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2000 F-250 XLT SuperDuty, 4X4 Off Road, SuoerCab, SWB(142), V10/3:73LS/4R100
1999 Skyline Nomad (27') Model 2700
Just to add a bit a wet road is not enough for slippage.
I will confess that yesterday I used my 4x4 on a wet street(a lot of rain in Houston as well lately). I was at a stop light and needed to jump around a beater next to me, we were both first in line at the intersection. I knew the roads were wet and the concrete was old and worn. I also new that a LWB CC and the v10 would break the tires loose and I would go nowhere if I gassed it. I flipped the switch to 4x4 and gased it off the line. Wow..you can really feel the fronts pull since the truck doesn't lurch back as in 2wd. I got around the car and flipped it back to 2wd and was on my way.
Another thing you might not realize is that the gear ratios between the front and rear ends are not exactly the same (like 3.55/3.54). Not exactly sure why this is done, possibly to improve traction (?), but the difference in revolutions would be enough to jack up your drive train over time if the shorter gears were not allowed to slip enough to catch up. And, of course, your transfer case is attempting to spin both drive shafts at the same speed (also to improve traction), which causes jumping while steering -- this would be even harder on things on pavement...
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2001 E350 PSD, Deep Emerald Green, 3.55 LS, Premium package, dual alts, rear A/C. Quigley 4x4, Transfer Flow rear tank (27+26), handicap mods, custom interior, Reunel tire carrier w/ Hi-Lift, Sportsmobile nerf bars (black), Amsoil lubes and Dual-Gard bypass oil filter, Amsoil air filters, Eclipse/JL Audio sound system w/ Sirius & 120GB Neo Car Jukebox (MP3 player), J&J stainless grill, Reunel Stainless bumper, 12000# Warn winch, PIAA lights, Bilstein shocks, Ultra Magnum wheels, Michelin tires (265/75-16), Correctrack rear wheel spacers, Bushwhacker flares (painted), Velvet-Ride spring shackles, p/s filter, external tranny and coolant filters, Wicked Wheel, Autometer gauges(5), 203 thermo, BRV+, removed air intake heater, Optima Yellow Tops, "Harpoon" mod, DP-Tuner, 4" exhaust w/ Aeroturbine, Airdog, HX-mod.
Next on the List: a blown tranny!
fellas, I was under the truck the other day and the tag on my front dif listed as 4.30
same as the rear end. What gives??? [img]images/icons/crazy.gif[/img]
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2001 F250 XLT 4X4 V-10 CC SWB 5-Speed 4.30LS with lots of
addums on it, dipped in Toreador Red Clearcoat Metallic. Oh Yeah still temporarily assigned to california.
I've heard the diffs "used" to be different (full-time 4WD) by .01, but I'm not sure about the new trucks. Not sure why it was done. Probably has to do with front/rear tracking?
The front and rear diffs MUST be the same ratios. If the transfer case engages and tries to spin the front driveshaft at 3.73:1 and the rear at 4.30:1 the T case will explode/fall apart/rupture/grenade...you pick the term.
The only exception I know of is the occasional mud bogger who will have his front end ratio higher than the rear to spin the front tires faster than the rear tires for more "grab" in the goo. This is ONLY done when in the mud pit and as soon as the driver is almost out, he backs way off the gas to try not to do what I mentioned in the above paragraph.
Dan
I have heard of some older Broncos, Scouts, or something having the 3.55/3.54 or 4.11/4.10 gearing. I don't know if that is true or not. That slight of a difference would probably be fine.
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2002 F350 4x4 CC V10 4.30
Custom Y pipe, Flowmaster 70, SCMT
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