Hey all, I'm new here & have been looking through the drivetrain tech section but have been unable to find a similar thread, so here goes.

When in 4wd (it's fine in 2wd), I've noticed a clunking sound and a slight jump coming from the front end approximately every 30 feet of travel, independent of speed (the faster you go, the more often it occurs since it happens about every 30 feet). It occurs while driving in a straight line on dirt roads, and is more pronounced when under load, such as going up steep hills.

The truck is a '97 3.0L 4x4 with floor lever, manual trans, & manual hubs; 210,000 mi, it was lifted when I bought it a couple years ago & this problem has been occuring since I got it. I recently had the front wheel bearings replaced, brake work completed, new tires installed, and one of the manual hubs replaced because it was shot (the mechanic said the other side was ok).

So any thoughts on what this problem could be? Could anyone help a guy out and outline a course of action for this problem?

Thanks in advance for your thoughts!

 

I would test two ways.
Leave in 2WD but lock the hubs and drive it, front axle and driveshaft will be turning but no load from transfer case.

Put in 4WD and leave hubs unlocked and drive it, front axle and driveshaft turning but no load from wheels.

You mention it does it in straight line driving, does that mean when turning it doesn't make the noise at all?

The 1997 Ranger would have had an electric shift originally, the manual shift transfer case was dropped in 1995 as an option, I believe.