i locked my hubs in this morning when i left work because we got some snow. was fine until i hit the highway once i put it in 4 th gear i got some really bad vibrations. this is just with the hubs locked but not in 4wdr. truck felt like it was gonna fall apart. so i pulled over unlocked them and everything was fine again. anyone know what would be causing this? may have been from around 60 kms it started but wasnt to abd a low speeds

 

my guess would be a weight fell of the front driveshaft causing it to become unbalanced, this is assuming youve had the truck up to that speed before with the hubs locked in

 

or the slip-yoke on the front drive shaft between the t-case and front diff is shot; see if you can wiggle it around by hand

it should have a little movement, but not a lot

you could also try putting some grease in it if you haven't already; they can get wobbly when they dry out, but drying out is what tends to make then go bad

I only know this cause mine would probably explode if I did over 30mph mine's gotta lot of movement and vibration, but I never have the hubs locked in unless I'm venturing off the road, in which case I very rarely hit 15mph

 

i've driven it with the hubs locked before when the weather was bad without this problem. i just went out and checked doesnt seem to be any play in the front driveshaft. think i will avoid taking it to work tonight since its storming and dont wanna use the 4x4 and break something.

 

how's you CV boots?

 

i am also having the same problem as 87toyy. So should i just grease the u joints? Or is there a way to grease the slip yoke? And how would i be sure that there isnt a weight that has fallen off, as yoterr suggested.

 

yes you can grease the slip yoke; there's a grease fitting on the shaft like the fittings on u-joints and steering components

as far as the wieght, normally, you can see a "clean" spot where the weight use to be applied but fell off

 

Mine doesnt like going above 55 in fwd, ask me how i know

 

my guess is that you went 55 in fwd

 

hmm. strange. i went outside and looked at the slip yoke and it really doesnt have all that much play in it. and there is a weight still on the drive shaft that is closer to the t-case. I will try greasing the slip yoke and everything in that area and see what happens.

 

so we had a storm today and had to take the truck up to the store in 4x4. it worked fine. take it out of 4x4 with the hubs still locked in and i get the vibs.

 

u-joints!

 

You can narrow down the source of the problem by temporarily removing the front drive shaft. If the vibes remain, it is in the CV joints. If it goes away, it is probably in the driveshaft. While the shaft is out, you can feel the u-joint and CV joint for smooth operation.

 

and if the vibrations turn out to be coming from the driveshaft instead of the CV's, what would you recommend i do to solve the problem?

 

take it to a driveline shop and have them replace the u joints...

 

Yes, figure out what is wrong with the shaft. Usually fairly easy to feel the way the various joints move by hand. If they feel gritty or stick and slip, that is a sign of wear.