V-8 vibrator

[grouch]

Get your mind out of the gutter. I've got an older Dodge Ram with a high speed vibration. It don't feel it until I hit 75 mph. Anything under that, no problem. Hit 75 though and it feels like I'm running on the rumble strip along the edge of the road. New tires, well balanced, wheels are straight, U-joints look good. It sort of feels like rear drive train, but I was picking up speed going down hill with a trailer. I've since tried it sans trailer and it still will make a al happy. Any suggestions?

 

[Omac]

I would check the drive shaft and the pinion gear in the rear axle.

 

[MO VietVet]

So, you had the vibes before and after the tires? Do you feel the vibes in the steering wheel? In your ass at the seat?

 

[grouch]

So, you had the vibes before and after the tires? Do you feel the vibes in the steering wheel? In your ass at the seat?

The old tires were such I didn't want to run too fast. With the new ones, I had to replace two wheels that were warped. I didn't notice the vibration until going down a hill with a loaded trailer. Coming back with an empty one, I got up to 75 and it started. No easing in, just yes or no vibration. I've noticed the rear u-joint is fairly new. The front one isn't. Once I take care of the ball joints, I'll pull the shaft and test the joints.

I don't feel it in the steering. It's a chassis vibration. Definitely feel it in my butt. My gut feeling is a shaft vibration but I like to ask others opinions as I'm not perfect.

 

[MO VietVet]

Whoever did the rear joint, should have done the front joint as well. Make sure they are "phased" correctly. Check you tube to see what I mean about phasing the u-joints. Likely are phased correctly but does not hurt to check. Also need to have the balance and true checked at a driveshaft shop. A rookie can damage a shaft pretty easily and no matter how many joints you put in, there is still a shaft problem.

 

[grouch]

Whoever did the rear joint, should have done the front joint as well. Make sure they are "phased" correctly. Check you tube to see what I mean about phasing the u-joints. Likely are phased correctly but does not hurt to check. Also need to have the balance and true checked at a driveshaft shop. A rookie can damage a shaft pretty easily and no matter how many joints you put in, there is still a shaft problem.

I'll look for dents and evidence of a lost balance weight. I've run into those over the years.

 

[grouch]

Update. I rebuilt the front end and found a bad wheel bearing. On the truck, it seemed okay but I was doing a lot of other work and decided to replace the bearings while everything was apart. With it in my hand, the left one rolled smooth but the right one grumbled in my hand. I still have a bad u-joint on that axle but the vibration is gone.

 

[Shaggy]

Update. I rebuilt the front end and found a bad wheel bearing. On the truck, it seemed okay but I was doing a lot of other work and decided to replace the bearings while everything was apart. With it in my hand, the left one rolled smooth but the right one grumbled in my hand. I still have a bad u-joint on that axle but the vibration is gone.

At least you found the problem.