4wd engagement leads to pulling to the right

[mrmauser98]

I have a 98 k1500 5.7/4l60 that has a rough country 6in on some crappy 36in tires atm.

The issue I'm having is if I engage 4wd hi(haven't tested low) the truck will pull to the right bad. I've only engaged it on a dry road and yes I know that's not recommended but I'm just testing the system before we get some snow here in Indiana. I feel like if we get some snow the way this thing pulls could be a bad time.

I haven't had this truck to long and I've had to put some parts in it, here's what I've done so far.

Replaced the CV axles with some extended length duralast ones, the tie rods had a lot of play so I replaced them all. Truck needs and alignment since doing them but it drives fairly straight in 2wd. When I was in the front end nothing stuck out to me as being bad, the brakes and wheels looked fairly new.

I tested the 4wd know when I got it and was pulling before I replaced all the stuff as well. Really just looking for some advice as to what to check out next ?

 

[Sean Buick 76]

If possible I would Jack the truck up on all 4 corners onto stands and carefully test the truck to see if the power is being transferred to both front wheels or only the one. I suspect that only one side of the front diff is engaging.

 

[GrimsterGMC]

Sounds like your front diff actuator isn't working, the transfer case is engaging sending drive to the diff and left wheel but the actuator isn't connecting the right axle so no drive to that wheel.

 

[mrmauser98]

If possible I would Jack the truck up on all 4 corners onto stands and carefully test the truck to see if the power is being transferred to both front wheels or only the one. I suspect that only one side of the front diff is engaging.

I'll do that tomorrow, I'm a little confused about the actuators. So the truck being a 98 should have the updated electric actuator correct?

 

[Sean Buick 76]

I don’t know the difference between the early or late actuators however on the early style I had in my 91 it was a floor shift connected to an electrically activated plunger thing that poked into the front diff to lock it in. When that actuator failed in -30 weather I added about 3/4” of a broom handle and replaced the broken actuator jamming it into 4x4 manually. Then a week later I was able to swap out the actuator to get it back to functional.

The way to test the actuator was to removed it from the diff and switch back and forth to 4x4 and see if the plunger would extend or not.

 

[Schurkey]

If the actuator doesn't engage, neither front wheel gets power unless the differential is severely screwed-up.

The left-front wheel is perpetually connected to the differential, it can't be disengaged. However, with the actuator not engaged, the differential side and spider gears whirl around uselessly. The differential is not a "posi" or "locker". No--or very little--power is transmitted even with the transfer case engaged.

My '97 has the motorized actuator, my '88 is thermal. I don't know when GM switched, and I don't know if they switched on every application at the same time--like maybe 8-lugs got the motorized unit before the 6-lugs, perhaps.

Have you verified that there's decent, clean lube in the front differential? The front differentials take very little lube, and they're known for leaking. If the differential is run "dry" long enough there may be enough internal friction from failing bearings or whatever that the side and pinion gears don't whirl around so nicely any more. That's the only way I can think of that would transfer torque without the actuator being engaged. But I've been wrong before.

 

[Sean Buick 76]

I agree that the front diffs are fully open. What would happen if the actuator was partially engaged would only one side of the diff get spun? I’m not sure. I do know that if one of the CV joints is broken you could get some funky issues as I had a CV break once.

 

[Schurkey]

Thinking about this some more, I bet the steering/suspension is wiped out. When the front wheels pull...they pull the alignment out of spec and the vehicle self-steers to the right.

I'd be looking at control arm bushings, and steering linkage--tie rod ends, idler arm, pitman arm--first; and then EVERYTHING on the front steering/suspension after that--ball joints, play in the steering gear, wheel bearings...ANYTHING that could be loose and affect the alignment.

 

[mrmauser98]

Thinking about this some more, I bet the steering/suspension is wiped out. When the front wheels pull...they pull the alignment out of spec and the vehicle self-steers to the right.

I'd be looking at control arm bushings, and steering linkage--tie rod ends, idler arm, pitman arm--first; and then EVERYTHING on the front steering/suspension after that--ball joints, play in the steering gear, wheel bearings...ANYTHING that could be loose and affect the alignment.

 

[mrmauser98]

It was finally almost in the 30s here today so I pulled it into he garage, and lifted all the wheels off the ground. It's goes into 4wd front driveshaft is spinning, however I can stop either wheel with my foot by dragging it and the other side will continue to spin, at one point I had both about stopped by dragging my foot. I pulled the actuator out and reconnected and it seems like it pops right out instantly it is the electric one.

I didn't hear any bad noises, while under it. However I did find a used front diff by a local guy for $100 so I'll probably go that route.