Gentlemen,
First, Happy 4th to all.

I have a vibration in the left front wheel. I have replaced a bunch of stuff and still the vibration is there. It starts at about 65mph. It may be doing it at lower speeds and I just don't feel it. Here is what I have done so far.

Had the tires balanced, twice.
Replaced the coil springs.
Replaced the shocks.
Replaced the ball joints.
Replaced the wheel bearings.

What have I missed? There are only 2 things left. It could use a front end alignment. And the pivot bushing for the I beam. Has anyone ever had ones of these go bad? What symptoms does a bad pivot bushing cause?

 

Have you tried swapping the tire with one from the rear? It could be as simple as a tire that is not completely round, or has a belt trying to walk/separate.

 

Oh yeah, I did that also. That was actually the first thing I did. I forgot to put that on the list.

 

Yes, I've had a bad pivot bushing. But the symptoms that I had were a clunk under my feet on bumps and bump-steer where the truck went somewhere I didn't expect when I hit a bump. In addition there was vagueness in the steering, sorta like a worn sector box, ball joints, or tie-rod ends. All of that is caused by the axle being able to move fore and aft due to the worn bushing, which points the wheel in various directions.

But I don't see that causing a vibration. But, it could let a small vibration to build up into a bigger one. IOW, if your balance job isn't perfect it could let things build.

However, what you may be missing is loose belts in the tire. I've had loose belts that caused the balance to go away almost from the first roll of the tire. Apparently the belts shift and there goes your balance. Balance again and they shift again. So I'd swap tires and see if it moves.

Edit: As usual, I'm behind RW. (Or Jim, or Dave, or ......)

 

Vibrations can be tricky. It may feel like its coming from the front because of where you are sitting. A passenger may think/feel it is coming from somewhere else.

I had a rear u-joint failing once , where the noise sounded like it was from the left front wheel (when I had the drivers window open). It was only after I drove with the rear slider window open that I could then tell the noise was coming from the back.

Check the truck over entirely. Look closely at the U-joints/drive shaft.

Put the back end up on jack stands and chock the front tires (and make sure nothing.no one is in front of the truck) then run the truck up to 65mph. Does the vibration still occur?
(Note: sometimes you need weight on the wheel bearing before it will act up).

You may want to try one of these "electronic ears". They make finding the source of noises/vibrations easier.
This model has one clamp (other models have multiple clamps so you can listen to different parts/areas at the same time).

 

I can swap the two front wheels for a quick test drive and see what happens. I've already swapped front to back.

I did replace the u-joints last summer. I haven't thought about putting it up on jack stands and running up to speed. I'll give that a try.

 

Just make sure it is well supported and sturdy. Having the truck come off the jack stands while the wheels are spinning at 65mph would make a mess.

Also be sure to stop the wheels completely before shifting back into park.

Obviously if the truck is still vibrating at 65mph with only the rear wheels spinning, the problem is in a rotating part and not the front end.

Good luck.

 

I have a set of 20ton school bus jack stands. And at my age I am very careful with everything I do. My tranny is manual so I'll be ok. Thanks though for reminding me.

 

Best way i know of testing a U joint is to back the truck up and before it comes t a complete stop put it in drive and step on the throttle some. If the U joint is bad it will cause the whole truck to shake like its coming to pieces. If it doesnt shake then your U joints are fine.

We do this at the shop as a quick easy way of checking for bad U joints.

 

Update:
Well, I put it up on stands and ran it to 75mph with no vibration. So I guess my drivetrain is ok.

I swapped the front tires and no change. I swapped the tires front to back again and no change.

I'm taking Friday off work to see if I can get the front end alignment done.

My neighbor suggested an out of balance rotor. Since the rotor and hub are one unit it could be out of balance and act like an out of balanced tire. I'm ready to try a witch doctor so if the alignment doesn't work I think I may replace the rotor.

 

This is an opportunity to share some of the "old ways" with the younger generation... at one time, tires were balanced by jacking the corner of the vehicle and placing under the tire an electric motor driven wheel, which spun the tire [including wheel and brake drum or rotor]. This was more time consuming and when the tires were rotated, rebalancing was again needed.

Perhaps some of the other "older guys" will remember this!

 

I actually know one older than that. The garage guy would lay the wheel/tire on a balanced pivot. It have a bubble level in the center. He would lay weights around the tire until he got the bubble centered.

 

Hopefully you checked at all speeds as it might not show at 75 MPH. Typically the stock sized tires will show their out-of-balance most around 60 to 65 MPH.

It could be a brake rotor although that's quite unusual since they are pretty uniform and have a machined outer surface. And, even if out of balance a bit they don't hurt the overall balance by much due to their small diameter.

But, there is another possibility. Is the vibration during certain driving situations, like letting off the gas slightly? I had a badly worn set of splines on the rear drive shaft that would only cause a vibration if I was coasting down a hill with just enough throttle to maintain the speed. However, it didn't show up like a tire vibration, but more of an overall "everything" vibration.

 

Had a U joint act like that once before. Never vibrated under a load nor at speed, but the moment you let up off the throttle and coasted between 20 and 25 mph the car would shake very badly.

 

I ran the speed up to 60 waited, 65 waited, 70, waited, 75 and still nothing, perfectly smooth.

It starts at about 60-65 and is there when I accelerate, decelerate, coast in neutral.