Shaking at Highway Speeds.

[ctgriffi]

I've got a 2WD, 4.0, '94 XLT Ranger with about 172K on it (original motor and A4LD), and I'm getting a pretty fast, intense vibration when I reach between 60-70mph. Seems to be steadily worsening.

I jacked it up yesterday and checked out the ball joints and tie-rods on both sides, and, honestly, I can't see any unwanted movement in those joints. I did notice that my passenger-side front wheel bearing seems a hair loose, and I'm going to pull that apart this weekend to adjust/repair.

I know that driveshaft problems can cause something like this, so I took a look at that, too: I couldn't see/feel any looseness in the U-Joints, but the frame-mounted center support might be a problem. When I yank on the shaft near there, I can see about 3/16" amount of play in the rubber bushing inside of the support. Thoughts?

Also, the tires aren't in great shape either - a couple of them are pretty wonky, thanks to my RA bushings going bad, until I replaced them several months back. Still, it was driving fine for a good while after that - up until about 2 weeks ago, so I don't think this vibration is tire-related.

Thanks for the help!

 

[martin]

vibration that occurs in the sixty to seventy mph range is more often than not tyre related. Balance weights get knocked off, especially if you go off road.

 

[ctgriffi]

Thanks, Martin. Yeah, you might be right about that, although I do zero off-roading. I think I'll fix that front wheel bearing and, if necessary, look at getting 2 new front tires mounted and balanced.

Any more thoughts out there?

 

[legoms013]

Could be a worn carrier bearing. Could be just crappy tires that don't balance, check to be sure the wheel weights are still there. I'm betting its the carrier bearing though if thats where the play is then you need a new one [bearing].

 

[ctgriffi]

Checked/adjusted the front wheel bearing that seemed a little loose. I couldn't see any damage at all to the cages, roller, etc. I cleaned it and repacked it anyway, of course.

I did have 2 tires that were in bad shape, Martin - one was really bad! I put the 2 half-way decent tires on the back, and had two brand new tires mounted/balanced on the front.

I'll take it to work tomorrow and see how it does at highway speed. If the problem still exists, I guess I'll look at the carrier bearing, legoms013. Where/what is it anyway? (Thanks for the tip)

 

[legoms013]

Its a funny looking rubber bushing mounted on a cross member in the midpoint of your 2 piece driveline. You described how there was play when you grabbed here and it moved around, the rubber part is the bushing that will need replacement. My hunch is at high speeds the driveline is just bouncing all around inside due to there being a gap (the play you refer to) and as time goes on this rattling/bouncing around inside the bushing makes it get worse.

 

[ctgriffi]

Drove into work today and the truck felt MUCH better. I don't think I'm feeling any of that vibration, so it seems that the new front tires probably did the job.

I will keep an eye on that carrier bearing, like you mentioned. Here's a Timken replacement I found on AZ.