Hello all, I am new to this site but I have been a visitor for many years and have saved thousands of dollars in labor with the help of all of your Q's and A's. Anyways i have a 92 f150 with a 4.9 and manual locking hubs. I have searched the threads and could not find an accurate description to my problem, I was recently driving on loose gravel and locked in my hubs and shifted to 4H, when i got in and tried to turn and accelerate it acted like it didnt want to move. And when i gave it enough throttle, it hopped and jerked around very badly. I know that it is normal to have some jerking in 4wd but i have never had it happen so bad that it felt like something was about to break, especially in deep loose gravel. Was wondering if possibly it could be a hub issue?? If anyone has any ideas or suggestions to what this may be i would appreciate any responses.

 

Just to clarify, the gravel was not close to deep enough to get stuck.

 

Has 4x4 worked correctly in the past? Are the tires the same size front to back? Has a differential been changed? If so maybe they don't match ratios.... Have you had the truck long, maybe a previous owner did some swapping...

 

Jack up the front and while in 4 wheel drive slowly spin each wheel and also try to turn side to side. Sounds like you have a bad axle u joint

 

Well, my grandpa owned the truck since 96. And about 15 years ago we did change the rearend. But the 4wd worked good after that. I got the truck in 2016 and the 4wd was working normal as far as i could tell. It had the normal hopping sensation when i would turn the wheel tight, I try not to use the 4wd very often. And the tires are 31X10.5 all the way around with very close to the same amount of tread. I was concerned when i felt how hard it was to accelerate with the wheel barely turned. Thank you for your guys' time. I will lift the front end and try that and double check everything

 

Mudsport 96, what should i look for while spinning the wheel in 4wd? Just any loose play? Will it possibly make noises? Thank you for your reply

 

Does the truck roll smoothly when going straigjht forwards and back in 4WD? If not then the front and rear gear ratios don't match.

 

Conanski, yes the truck does roll smoothly straight front and reverse thankfully. Does that possibly rule out that the gear ratios may be wrong? I believe my f150 is a 3.08 gear.

 

With the hubs locked and the truck in 4wd, do i have to jack the front and rear to allow the front wheel to spin by hand? I just tried it but the front wont spin with the back tires on the ground. I apologize if these are stupid questions,

 

This sounds like stuck axle joints as noted above. It typically causes heavy steering too, even in 2x4. Have you noticed any wandering or hard to turn issues lately? The last time my truck did this, I locked the hubs, and drove circles on gravel until the steering was normal again (break up the rust), to get me by until I could make the time to change the front axle U-joints. Not using 4x4 regularly, counter intuitively, often leads to this condition as the grease doesn't get distributed within the joints and they corrode.

If you put the front end on jack stands, rotate the wheels by hand with hubs unlocked, they should turn freely. Then turn the steering wheel and repeat, wheels should still turn freely. Lock both hubs. If the joints are OK, the wheels should still turn by hand pretty easily whether the steering wheel is straight or turned. If the joints are bad, the wheels will be very hard to rotate when the steering wheel is turned.

Edit to answer latest post: Just disengage the 4x4 at the transfer case to do the tests.

 

I havent noticed it being hard to steer lately, i just replaced the steering gear about 5,000 miles ago because i lost power steering while turning right only. Since then the steering has been normal, but with the hubs locked in, it is quite hard to spin the front wheels by hand compared to the rear. But i dont see any slop in the axle u joints. As I am in my garage right now troubleshooting with all of your replies, again, thank you all for helping me, a complete stranger.

 

*correction* with the transfer case disengaged and the hubs locked, the front wheels spin very easily
any possibility that this could be a bad hub issue?

 

Not likely, hubs either lock or they don't. Front axle U-joints on the other hand seize up often. My test for them is one side at a time, turn the steering full lock one way and jack a wheel off the ground, that wheels should spin freely when the hub is both locked and unlocled... if it doesn't you have a seized u-joint. You don't want the other hub locked when you do this or the t-case in 4wd.

 

The concern with the U-joints isn't slop, it is being rusted & bound up. Tight, not loose.

Please clarify your above posts by answering yes or no to the following two questions:

Are the front wheels easy to turn with the hubs locked (& transfer case not in 4x4) with the steering wheel straight?

Are the front wheels easy to turn with the hubs locked (& transfer case not in 4x4) with the steering wheel turned?

Conanski's method of locking only one hub at a time is a good point in that it will allow you to isolate which side is bound up.

 

Yes easy to spin while straight, with hubs locked. and yes easy to spin while turned with hubs locked using that method. I am beginning to fear that it may be a gear issue