This one has me stumped... I am usually prity good at figuring these things out.. But not too sure where to start on this one.. The truck is a 99 Dodge Dakota ext cab, 4x4, 5 spd w/ the 5.2

What it is doing:
The truck has a very rapid/quick vibration. At slower speeds and normal highway speeds it is not in-your-face bad, but definatly noticable. But once the truck hit 75-80 mph+, it really seems to jump out at ya and is VERY noticable both by feel and hearing. If I let off the throttle and let it coast (even when going 80+mph) it deminishes considerably. If I give it throttle, even to maintain my 80+mph speed, it will return..

All this started to occure when I did the front brakes (rotors/pads). I am confident I did the brake job correctly (as I have dun MANY brake jobs in the past) and I am fairly certain the brakes are not the cause. I do NOT feel ANY pulsating in the brake pedal while driving or braking and the brakes feel great.

However, I did have a tuff time removing the old rotors. I had to wedge a pry-bar between the back of the rotor and the knuckle to apply constant pressure, while I smaked the rotor a couple of times to free it up.. Did I damage the wheel bearing or something? Seem unlikely, considering the vibration goes away some when coasting and I would have to belive a wheel bearing could handle more abuse than what I did..

The front CVD boots all looked good, no cracks, I could not feel any play when yanking on them..
The rear drive shaft has recent (last summer) joints and I could not feel and significant play..
The front drive shaft has stock joints and again, I could not feel and significant play..

Any help would be greatly appreciated

I finally have some extra cash to fix her up and give her some much needed service. But I would like to figure this problem out first.. I have a set of Edelbrock IAS shocks waiting to go on, I did all the sway bar bushings last month (still need to fint the rear links?), I am planing on doing the exhaust soon as well.. But I want to sort this problem out first, just in case it brakes the bank

Again, thanks in abvance for any advise!

BTW, when can I find the rear sway bar end links cheap? My local dealership wants $80+ for the two

 

Driveshaft u-joint is my first thought. Starting after doing the brakes may just be a coincedence. When the truck is parked get under it a wiggle the driveshaft, if there is any play in either u-joint then it's bad and needs to be replaced.

 

I replaced the u-joints in the rear last summer and there was no play in either the front or rear axles (aside from some very minor back-lash movement)..

 

I would take a look at the bearings. Although you wouldn't think what you did would have caused damage, if the vibe/noise started after your troubles removing the rotors, that would be the first place I looked. Last thing done before the trouble is usually a good place to start.

Also, what about wheel balance. Could you have lost a weight?

Good luck.

 

check you motor mounts to see if they are loose....while your at it check the tranny mounts too

 

I am going to get under the truck today and have a closer look at the drive-train..

Also going to jack-up the front end and see how the front wheels spin. I am assuming if the wheel bearing is bad, I should feel some grit, play or noise?

I am reluctant to think it is the tires out of balance. Becuase the vibration goes away quite a bit while coasting (even though I am going the same speed as when it usually vibrates).. Never the less, I will swap the front tires w/ the rears and see if that has any effect on the vibration..

If a motor mount or trans. mount were bad, wouldn't it make a clunking sound?

Like I said, I am going to get under her today and poke around..

Thanks for the sugestion, I will look into them all just to rule them out..

 

Problem found and solved.. Thanks to all who posted sugestions..

Turns out it was the rear U-Joint. The same U-Joint that I replaces last year! I must have installed it incorrectly.. On the bright side, I had the parts sitting on my shelf. The rear U-Joint uses two different size bearings (small one on the drive shaft and a larger one on the diff). So when I bought them last, I actually had to buy two different sets. The parts I used today were the other half