'96 1500 Vibration between 65-75 MPH

I have a 1996 Ram 1500 318 with automatic transmission. It has over 180,000+ miles on it and had the engine rebuilt at around 160,000 just for good measure. It's still running on the stock transmission (no rebuild, numerous fluid changes) and besides normal wear and tear has not had any major problems.

Recently, I have been having problems with a vibration that shakes the truck at around 65-75MPH. It doesn't seem to be affected by the RPM of the engine, just the speed. I have had the tires rebalanced, shocks replaced and the front end checked out fine with nothing showing a major problem. I've even had the tires checked, replaced spark plugs and replaced the wires. I still can't seem to find this elusive vibration.

Has anyone else had something like this show up on their truck? Any suggestions?

Many thanks!
Greg

It is possible that your bushings on your rear end may be going. I had vibration and a lot of other fun problems on my 1990 D-150 till I rebuilt the rear end suspension. With the replaced leaves and the extra leaf I put in, she doesn't squat back on accelearation, better acceleration, etc... Have a mechanic check, I found out mine when I though the transmission was going out, turned out the rear suspension was toast.

How about the U joints? If worn, that would cause a vibration.

Hmmm. Either might be a possibility. It really feels like it is coming from the front end. I'm starting to wonder if my shocks are causing the problem since it almost feels like it's bouncing. Do either of you have experience with Pro Comp ES1000 shocks?

Is that a 4x4?

No. It's 2 wheel drive.

Could be the shocks, if they're not dampening any small vibrations you could feel it. Does the steering wheel vibrate, or do you feel it more in the seat?

Both actually. And it only happens after about 65 MPH, and doesn't really care what RPM the engine is at.

When you say tires checked, do you mean spin balanced or static. Is it possible a belt has slipped in tire? This was was problem with early steel belted tires and produced the conditions you describe. I know the tire industry has fixed this but it still shows up occasionally. Look at sidewall of tire for "ripples".

That's probably what it is, a slipped belt.

I'll take a look tomorrow and let you know. These tires are fairly new so I never thought of it. Just curious, but wouldn't this show up if I had the tires balanced?

If you had them "static" balanced they slap the tire on a platform and add wieghts till bubble is centered. If you had them spin balanced a bad belt might show up. Did you do all four or just the front? You could try rotating tires front to back on same sides to see if condition changes. Also I never looked, do Dodges have a midship bearing on driveshaft? I had a Chevy P.U. that the rubber bushing that supports the midship bearing went bad on. Produced vibration at speed, and I couldn't figure it out till shaft fell off.

I had a belt slip one time, was fine when balanced but a couple weeks later was thudding at anything over 50. Guy @ the tire store didn't believe me, he said it was my rim so I had him take the tire off and spin the rim by itself. It was perfect.

So if it is the tire, try and isolate which one is bouncing, maybe have someone drive next to you to tell you which one is moving around....

Sorry about the delay. Had a cold that set me back a few days.

I took a look at the tires and nothing. I even had the tires rotated to see if it would make a difference, but no change.

Any ideas?

I've thought a little, since you have new shocks and have had the alignment checked on the tires, then I would think about the wheel bearings. Have they ever been replaced? After 160K they're likely a little loose and that could allow enough play to make the vibration you're experiencing.

Also if you have a steering damper, it may be going south.

Interested to hear the solution.

suspension or could even be your motor mounts but i highly doubt that if its un-afected by rpm speed.