Heyall....
I am stumped on this one, so any thoughts or suggestions would be much appreciated.

Truck:
1993 Dodge Ram 250 - Cummins Diesel - 2 inch suspension lift - 35 inch tires - DANA 60 front axle.

The Problem:
When I am driving in 2WD, all is perfect. If I lock the front hubs (diff engaged with wheels), nothing changes, all good. When I pull the stick into 4WD, then it gets bad.
The truck will immediately begin to track off. If I gas it a little bit, it will veer sideways, and if I lift off the gas, it will veer back. There is no vibrations or anything like that, but its jumping all over the road, and feels like the front and rear tires are not tracking together.

So far, I have taken measurements to make sure everything is aligned. I found that my front axle was not perfectly parallel to my rear. I made some adjustments at the front, and brought it up square. It was off my about 1.75 inches measuring from the end of the axle. I then checked the wheel alignment and brought the 2 front wheels in parallel to each other.
Upon test driving, everything was perfect as normal in 2WD, and just like always, as soon as I kicked in the 4x4, she started getting unstable.

There is nothing lose in the steering. All the ball joints, tie rods etc are all good. The diff is limited slip. I DO NOT have any kind of steering stabilizers. Everything in the front end is stock with the exception of 2 inch skyjacker leaf springs and the big tires. Its as if one wheel is pulling more than the other... seems very odd.

Please, any ideas or things to look for would be great. I am totally stumped on this one... and I would really like to have 4WD before the snow flies...

THANKS!

 

Just a thought... is there any chance that my limited slip diff might be locking up or is stuck locked?
Just hypothetically, what would be the effect of running a spool in the front diff? Would that feel similar to what I am experiencing?
Just trying to run through the possibilities.
... Then again, if I unlock just one hub, its not really any better... so the diff locking up cant really be the problem... {sigh}

 

have you owned this truck for a long time? I hear posi's in the front could cause issues with turning in street driven type of 4x4 kinda sounds to me like maybe one axle is spinning faster than the other when its locked into 4x4 mode.

 

I have owned it for a year, its been a problem since i got it. However its so bad i cant even drive in a straight line... Not just turning. However when i turn on loose snow or mud, i can feel the truck want to slip sideways instead of following the tire tracks some of the time.
Are you suggesting my gearing is off? Or that the power lok is causing wheel speed to be off? Anything i can do as a test?

 

I'm really not sure how to test it to figure out what it's doing. is there a vacuum setup on your front end to disengage the axles? or is that what the locking hubs are supposed to do? I've heard that posi's can cause trouble cornering because sometime's they won't unlock ( ex: like if your on the gas hard i think) so then both of your front wheels are trying to go the same speed when one of them needs to go slower. my guess is one axle is locking and the other one isn't because it only happens when you send power to it and it sounds like the tires might not be turning at the same speeds. Is there a shop in your area that u trust that specializes in transmissions and axle's? or a place that specializes in 4 wheel drives, honestly as much as i try and do stuff myself in the case your describing I'd be tempted to take it in and have them take a peek. be sure to put a post up here to let me know what ya find out!

 

Ok so here is my update. I had my dad over for the weekend, so I had him turn the wheel while I went underneath and looked for anything that seemed off. First off, I found 1 tie rod end that has a bit of a click, but nothing visual. Then I found that half of my dag link is separating badly. There is a lot of slop there. I just replaced it about 6 months ago.
What I am going to do is buy a new drag link, as well as install a drop down pitman arm that will give me a better angle with the 2 inch lift. I will also do both tie rod ends while I am under there. Im hoping this will help. It would make sense if one wheel was trying to pull in a different direction.
Waiting for parts now. I will update when I get results!

Thanks for the help thus far!

 

Check the gear ratio from front to back, I bought one once with 2 different ratios and it acted that way, also had one with a broken spring center bolt on the front but that had leaf springs.

 

Hey, thanks for the reply.
I got all my new parts in. I installed 2 new tie-rod ends, as well as a drop-down pitman arm, and a new drag link. Everything looks good. I confirmed my alignment was good, and took it out for a test drive.
NOTHING has changed. If I accelerate hard, then the truck will pull to the side a little, but the worst is still if I take my foot off the gas quickly, especially when in a lower gear and the engine is slowing the truck... then the truck lurches dangerously to the side.
I am will look into confirming my gear ratios are the same. That would be good start. What exactly were your symptoms? Did you have the same side to side lurching?
I do have leaf springs also... I put them in last year, so I know everything is good there. Has anyone ever heard of axle wrap in the front axle? Is that a possibility? Im just trying to think what the hell could be going on up there.

 

Just to add to that, last year I was trying to diagnose some drive line vibrations, so I removed the rear drive shaft to see if the vibes were eliminated. When I did this, I drove the truck in 4X4, but obviously only the front wheels were driving. I was in snowy conditions, but this is what I found:

1) The truck DID lurch side to side, just the same, thus concluding that mismatched gears is not the issue.

2) When making a slow turn on my lane way, the truck wanted to drive off the road, indicating that the diff was either locked, or locking up, which may or may not be normal in those conditons.

I would like to avoid going to any drive line specialist or mechanic until I have exhausted all options... I have never been to a mechanic before, I dont want to start now!

Thanks!

 

Here is the latest update:

Last night, I decided to start running some tests and looking for more causes of what appeared to be some form of torque steer. As 90% or more of torque steer issues are a result of loose steering and suspension components, I decided to start there. As stated before, I have just replaced tie-rod ends, drag link, and installed new drop-down pitman arm.
I had my wife start working the steering wheel to see if everything looked good. All my steering linkages looked great, everything tight, alignment good. Then it occurred to me that I was watching the axle shifting when she turned the wheel. It appears that there is some slop in the front left leaf spring shackle. The leaf springs, bushings, spacers and bolts are new as of 8 months ago, however it appears that the bolt is actually moving within the shackle itself.
The movement was about ¼ to ½ inch.
My father disagrees that this could cause my issue, but it makes too much sense. When I give the truck gas, the axle shifts in one direction. When I slow down, it shifts back. Very straight forward. It also would not be an issue when in 2WD, because the axle would be in a constant pull backwards, and would never be pulling the truck forwards.
I do not know the extent of the issue, but I am going to drop the front of the leafs down and inspect further when I have the chance. Worst case is I need to replace the shackle. If I am lucky I can simply use a larger bolt.
Fingers crossed on this one, im hoping it is actually this easy.
Thanks for all the help so far.


Cheers.