Recently got my first toyota and 4x4 a few months back. Doesn't have manual hubs, so always locked I gather. At any rate I drove it twice the first few weeks in 4L on a few occasions very short distances, such as out of ravines and such. Never noticed any problem, but 4WD is new to me. Last week I parked in a ditch and opted for 4H to drive out on to the pavement. I immediately noticed something didn't feel right. Like a slight thump that increases in speed to about 15 mph to 20 then goes away. I hear a squeak intermittently also, and when slowing down it really vibrates and shakes the front end. I figured u-joint issues, so I greased all zerks., with no change. I notice no slack in any of the u-joints or the double cardan. I pulled the front driveshaft and took it to a toyota pickup specialist and he agreed that it seemed all joints were in great shape. Driving in 4WD with the driveshaft removed was smooth as driving in 2WD. I also notice the truck pulls left when the 4WD is on. It does appear to have a new passenger side cv joint, and the drivers side looks original. I jacked the front end up and rotated the wheels but found no catching, squeaking or slack in the driver cv joint. Im leaning towards the drivers cv as the problem, but since whether in 4H or 4L, the cv's are spinning just the same at the problem speed yet it doesnt seem to happen in 4L. On a side not I checked the front diff fluid level and found it poured out, so it was overfilled somehow. I drained it and put new oil in, and saw no metal in the old fluid. Any advice would be much appreciated.

Miceal

 

Don't drive on (dry) pavement with 4wd.

On a modern "AWD" vehicle, there is a third differential (or a "viscous coupling") between the front and rear drive systems. This allows the front and rear to rotate at slight differences in speed.

"Traditional" 4wd doesn't have that junk. It's designed for times when you need absolute traction (ice and snow and mud, or climbing out of a ditch), and you engage it when you need it, not "all the time." (That's why you have a transfer case shift lever). On dry pavement, it's trying very hard to give high traction, but the slight difference in drive speeds cause one of the tires to skip (or "scooch"). You'll notice this even more while turning.

To me, your experience sounds "normal."

 

Yes, because you are driving in 2WD!

Like Scope said, it sounds normal.

Your truck (unless altered) has automatic hubs (Automatic Disconnecting Differential, or A.D.D.).

In my 4Runner, 4H and 4L felt very different (as somewhat expected). In 4H, the truck would jerk some and shifts (automatic) felt rougher (and were at different RPM's when compared to 2wd and 4L).

 

Oops. Double post.

 

Had a lot of snow and ice here in northeast Ok recently, so the 4WD got used a lot. Definitely seemed to get worse a bit. Replaced an axle, packed the spindles with grease, and got a lot more familiar with the A.D.D. system and 4WD in general. My Toyota mechanic even drove it and said it seemed okay. I finally suspected the cv ball in the front driveshaft and bought one from a friends wrecked Toyota for 50 bucks. Thought I'd at least have an extra to rebuild while still having one to use. bolted the salvage one in and the truck's shaking was gone. My truck has lower miles than the donor, but has a 4" lift. Guess the extra angle wore it out faster.