How can this happen?

[Shawn.L.Turbo]

Went to pull away last night, after truck has been sitting all day in the freezing cold. Parking brake was on. I had left it in 4WD.

Started 'er up, pulled off the parking brake, and went to back out. It didn't want to move... as if the wheels were frozen to the ground, which has happened MANY times, so I thought no big deal. I just slowly let out the clutch in reverse, and it really loaded down the engine.

It kicked and bucked as I backed up about 4 feet. Went to go forward, and noticed the rear end was pushing around to the front. At least one or both of the front wheels were completely locked up. I guess the front brakes had frozen.

Here is the question:

In 4WD, how can the front wheels lock up compeletely, but the rear wheels still turn?
Maybe I don't understand enough about transfer cases.

I think the front rotor got iced real bad and then froze up solid. That's my hypothesis at the moment as to the cause.


Ideas?


Shawn

 

[Hale on wheels]

I could be wrong, but I don't think the front diffs on these trucks are limited slip, so the front will only apply power to the easiest wheel to turn.

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Cody Hale
01. 5 2500, QC, 4x4,Auto
Gig'em Aggies!

 

[Lil' Dog]

The transfer case chain drives the front drive shaft to the rear so one of the wheels should have turned or the 4wd lock on the front axle slipped out when you shut the engine down and lost vacuum. The collar that locks the passenger wheel to the diff is vacuum actuated and may have relaxed during the shutdown period.
But to have the brakes seize on like that is not that common. I would soak the calipers in penetrating oil and work them around to try to avoid this in the future. The coating of oil should keep the water out next time. I use anti-siezure compound on all the sliding surfaces on my calipers to avoid this problem.

J-eh

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Jason Hoffman
Lil' Mack - 89 D250LE 5 Spd 3. 54 Reg Cab. K&N,"tweaked pump", BD Injectors, Banks Pyro/Boost, 3. 5" Exst tail section straight. E&M Custom seats. Bosch H4, PIAA 80W/80W HdLites. 100W Drv,55W Fogs. 237,500 miles (380,000 Kms) 7850 Hrs.
Cummins Power Booster member.
The Original Turbo Diesel

Lil' Mack Pics

 

[Deezul1]

I learned years ago in Idaho do not leave parking brake on in freezing weather as the wet that gets in to the drums can freeze your brakes together and trying to power out can damage brake components

 

[Steve St.Laurent]

Hale on wheels could be right. You could have had one front wheel locked and the other front would turn. The differential in the front axle is an open diff, if you took your rear driveshaft off and put the truck where one front tire was on ice and the other one on dry pavement the only tire that would turn would be the one on the ice - hence the reason for lockers. A lot of people don't realize that if you don't have a locker in the front and rear that you actually have 2wd, if you have a rear locker only you have 3wd, lockers front and rear and you finally have 4wd. It could be worse though, 2wd trucks with no locker are actually 1wd (been there - stuck with only one tire on ice and no way to move)!



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-Steve St. Laurent - President of the Great Lakes TDR
'98 QC LB (CMNSPWR), 4x4, ISB, 5sp, 4. 10 LSD, TST Powermax, 275hp RV injectors, SW fuel pressure gauge, BD exhaust brake, Isspro turbo temp monitor, front Draw-Tite receiver, rear Draw-Tite class V receiver, BFG 285/75R16 AT KO's, (all the common stuff clipped)

 

[Amianthus]

That same thing happened to me this morning. With the exception of the parking brake thingy. Anyway, it's happened before. I attributed it to ice freezeing up the brake drums to the backing plates, tires freezing to the ground, etc. My Ferd did this also. I haven't noticed any problems yet. I wouldn't worry too much about it. Although the emergency brake logic is sound advice.

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'99 2500 ISB QC SLT (No Leather!), 4x4, 5sp, 4:10, 275inj. , PE, PE-EZ, 4"exh. , Pac-Brake, A-Pillar gauge pod w/boost and pyro, Line-X, V-1, lights, siren, lic. plt. frame says "Diesel Fumes Make Me Horny!", and much more goofy stuff.