Mass Carnage

97singlecab

97singlecab

New member
Joined
Mar 12, 2008
Messages
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How fast can you drive in four wheel drive?? I finally got my new automatic install working and went out to test drive the truck. I four wheel drive launched and was going over 120 since that is as high as the speedometer goes. When I let out of the throttle the transfercase exploded and the front drive shaft came out of the vehicle and disapeered in the ditch. The bolts for the front straps are twisted and broke off in the yoke and the flange is still bolted to the t case with the ears broken off it. It was a pretty crazy ride to say the least. I have a 241dhd to put back in it but now I need a front drive shaft and front yoke.
 
Ouch. I usually click mine back in to 2wd once I'm in 2nd gear. It won't disengage till I let off the throttle but at least once I do let off it disengages. I'll bet that had to be loud as hell inside.
 
It was extremely loud. I thought for sure the pistons had dropped out of the motor. It has a deep ats aluminum pan on the tranny that took a pretty good whack but didn't really hurt it. I was just out looking at it and only two of the bolts on the front yoke are broke off the other two along with the cap are still in the yoke. My buddy that was helping me put the front shaft in, I wonder if two of those bolts weren't tight. Just proves you should always put your own wrench on and check **** when you do big jobs like that.
 
Sorry to hear you found out the hard way, but these trucks are not meant to be going 120+MPH in 4x4.

Joe
 
So I went back out of town where this happened and found the drive shaft and all the pieces that came out. The strap that holds the cap on is twisted like the drive shaft torqued out of it or something. I'll try and post some pics later hopefully.
 
I hit well over 120 mph with my truck on a regular basis in 4x4. As long as you are going straight it wont hurt it. You definately had something else going on there.

Sorry to hear about the carnage, it always sucks when something breaks
 
There is no reason that 120+ in 4wd is going to hurt anything. Like you said, some of the bolts could have been left loose. You are probably want to replace the front yoke too, when the u-joint exits like that under load it tends to tweak the yoke which will load the strap a lot more than it should be, and then this will happen all over again.
 
I agree the speed alone shouldn't have caused it.

I bet that scared the crap out of you. I've never lost a shaft, but I know several people that have and "fun" was never used in their stories. Well, my brother thought pogoing his Ford was fun, but that's just him, and a whole nother story.

I'd think about a set of loops, or at least a front loop. That wasn't near as bad as it could have been. Fortunately no one was hurt.
 
Have to remember too that since '02 the front shaft in every Dodge Heavy Duty 4x4 is spinning at all times, in 2wd AND 4wd.

I'm going to go for a u-joint failure, or loose bolt on this one...

Merrick
 
PM member "chipmnk" I believe he had a heavy duty front drive shaft built for the truck he crashed and I don't think he's sold the shaft yet. He had the shaft built for 1000HP.

Lavon
 
Mcummings my truck is a 97 so the front does not spin all the time unless engaged. I agree with you guys that the speed alone didn't do it, i'm still checking things to see what might have caused it but haven't come up with anything. I checked the front axle but it doesn't appear damaged at all. The t case came out of a truck with almost 300k miles on it and some one told me that maybe the chain has some slack in it so when I let off it unloaded more than usual??? Or maybe it was just time for that t case, it came out of a twin turbo 12v that was making alot of power for a while so maybe it was weakend by him and finished off by me. I sure would like to know what caused it though before I run it up to that speed again.
 
I also put my new 241dhd t case in last night that is out of a 2000 24v. And found out that there is no way to put my speedometer gear in this t case, since 24v getting the vss signal from the rear diff. Is there any way to convert mine that you guys know of. Or do I just need a different t case.
 
some thoughts

Although you may have had a couple of things not in your favour ie worn parts, not any one of them would cause all by themselves the incident you describe

"so slack chian in the transfer case, bad universals, bad mounts for the trans and transfer case, slop in the gears in the axles, and a built transmission with no give" would be my guess

however, and race car guys, myself included will tell you never ever let off suddenly at speed - the over torque on parts is phenomenal, and in this case is likely the straw that broke the camels back.

I have seen race vehicles in 2 wheel drive do a 360 and crash when letting off suddenly after a run because the entire drivetrain basically locks up for a second which locks the tires momentarily

I personally did a 360 at over 120 mph from the same thing - ie the rear basically locked from engine braking, the tires skidded, and hang on mumma. Lucky for me and no help from me (happens too fast) the car wound up facing the right way and coasted to a stop unscathed.

the answer - always click into neutral as you let off the fuel - thats why your shifter has a reverse lockout - so you cant over shift into reverse at speed.

If you dont have a good race shifter - get one.
 
I think your absoulutely right seeker1056 I did let out pretty fast. And might have been a little over anxious to romp on the truck after installing all the new parts. I also was completely not ready for how fast my truck turned out to be. Once I started spraying nitrous and trying to watch my 60 psi boost gauge max out and look at egt's and make sure the overdrive button wasn't off and if the convertor was locked and four wheel drive was engaged. Basicly 120mph came at me really fast and I wasn't ready at all. I am pretty happy that I didn't wreck the truck though atleast.
 
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