Hey everyone,

So I have this odd vibration that I think is coming from the rear suspension on my truck. The truck is a E99 supercab shortbed, 7.3l with 76,000 miles, completely stock (havn't bought the after-market goodies yet, except for the 6637 kit from Clay which is on the way).

So at first I thought it was a wheel weight came off, but Ive driven a car with a wheel weight gone and the car will vibrate worse as the speed increases. THIS vibration in my truck doesnt do that, it happens no matter the speed. and it comes and goes.

The truck drives down the road, no problems, no vibration. then I drive over a crack in the road, or a pot hole, or a bump, etc, and it will start to vibrate. steering wheel will not vibrate, truck still tracks down the road, but you can feel it in the seat, and the rear view mirror will wiggle and make vision blurry. I hit the next bump and it goes away. then hit the next bump and it comes back. doesn't get better or worse with speed. and only goes away with "hitting" something.

What's puzzleing me is that it's not getting any worse, truck tracks right down the road and everything is normal... minus this vibration.

Anyone have any ideas? I'd perfer to not have to live with this, so thats why I'm asking.

Thanks for your help, and sorry for the longish post,

-Jon

 

if you had tire mounted recently something might have got in there. i had this happen before but it would depend on where the weight landed in the tire but never got worse just not a constant vibration. if you take off your tires and roll them around listen real close to see if you hear anything rolling around in there.

 

Very weird. Definately sounds like a moving part, like the drive line or axel. Have you checked for leaks at the wheels to see if maybe a bearing is acting up?

I'm pretty much at a loss here.

I'd definately check the tires like he said, hope you find the problem!

 

I did buy the truck recently and they put new tires on it. I'll check for something in the wheel.

But as far as I can tell there are no leaks to speak of. I was kind-of thinking that it could be shocks only because I know that the stock ones are on their way out (11 years in New England and their rough roads + salt can't have helped). I'm thinking that the valving may not be able to handle the "hit" anymore and keep the suspension from vibrating. Possible caviation from old/broken valving in the shocks. But I don't know I could just be over analyzing it.

Any other ideas to take a look at?

thanks for your help,

-Jon

 

driveshaft carrier bearing (if equipped). May only start shaking when you hit a bump.

 

u joints can come and go before they are too bad.

 

My truck doesnt have a carrier bearing, so I don't think its that.

But if it's U-Joints, how do you really tell that they're on their way out? From the look of them I don't believe they have been changed, or at least havn't been changed in a loong time. So this could be the issue. An axel hitting a bump and then "wrapping" can cause stress on the joints causing them to vibrate.

So how do you tell if they're going out? and what should I get as replacements if this is the issue? MotorCrafts or something else?

Thanks,

-Jon

 

If they dont have grease fittings, they may be orig. The best way is to pull the driveshaft and move the joints around by hand. See if they move smooth and freely. If they are loose or worn, they can move sideways or up and down and become out of center causing a vibration. If you replace them....be sure the new ones have grease fittings.