clunking in 4wd - driving in straight line

[ccanuk]

Hi there

I took my 94 XLT out for a spin on sunday, and when I was in 4wd HI and driving in a straight line I could hear a clunking and feel it through the body even while driving in a straight line on dirt/gravel...

is this normal or is something binding up... I recently had the drive system checked out and they said there was no slack, but they were a bit rusted and would need to be replaced in a few years...

any idea?

 

[MrShorty]

How often does it clunk? At one time I had mismatched tires (front was different make/model than rear) on my BII, and I would occasionally get a good clunk from the drivetrain releasing tension built up from the different tires. It was also hard to shift from 4H to 2H. Do you have any difficulty shifting into 2H?
Other big possibility is something wrong with the hubs (especially if you still have the auto hubs). If one of the hubs isn't fully engaging/slipping, it can cause a noise.

 

[ccanuk]

it clunks about once a tire rotation... it has the same tires all around, though they may have a little more wear on the rear set.

I don't think it's the hubs either, the clunking sounds like it's comming from the rear, and it can be felt through the whole body of the vehicle... I do have auto hubs though...

 

[Bashman]

Have you checked your u-joints? A clunking/binding is not normal in a straight line.

 

[ccanuk]

the shop said they were ok... maybe I'll get them to take another look

it's only when I'm in 4wd that I get the clunking though so I don't think it is the Ujoints in the rear...

 

[ccanuk]

Previous owner says the front has a higher gear ratio than the rears... from factory... is this possible?

 

[CodePoet]

ummmm i wouldn't think so...you could check maybe by getting the truck totally off the ground (all 4 wheels). start it, put it in drive (or 1st if you have a manual) and get out and watch...wouldn't be a huge difference but you might be able to tell. From the factory though the gears should be the same front and rear. Did the shop check the u-joints on the drive shaft, the axle shafts (cv's) or both? This problem sounds so much like that kinda problem. I replaced my rear u-joints last weekend...it's really not to hard and not expensive

cp

here's a pic of the axle shaft...maybe it could be that u-joint, instead of the two on the drive shaft? Sorry to include the d28 in there too