Hi ya'll I've been lurking around on this forum for a while just never posted anything and I was wondering if ya'll can help me solve this problem. I have a 93 Dodge Ram 150 RWD 5.9L single cab. I got this truck about a year ago and have not had any problems with it other than basic maintenance. Ever since I have had the truck though it has had a violent shimmy/vibration in the steering from around 55-80mph and I'm also feeling it in the cab. It seems the vibration is definitely proportional to how fast I am going. I have recently got new tires and had the tires balanced and aligned I don't know how many times. I have had new shocks put in, new control arm bushings, had my ball joints, u-joints, and suspension checked out multiple times and they say everything is fine. I am starting to think it might be the drive shaft. From what I hear though if it is in the drive shaft you get the vibration when you accelerate or slow down. The u-joints look fine and I'm not getting any funny noises coming from them either. So any ideas? Thanks.

 

Does it happen past 80 too?

 

i would first look at the drive shaft to see if any weight have fallen off. how are the bearing in in the rotor/ rear end.

 

Yes it does happen past 80, still does it all the way up to 90 too.

The bearings in the rotor are fine. I had a look at those when I took off the rotors to get them turned last week. The ones in back I'm assuming are fine since no vibration is coming from back there. Everything seems to be coming from the front. I'll take a good look tomorrow morning at the drive shaft to see if i find anything.

 

I had a look at the drive shaft this morning, everything looks fine, no lose weights on there, andthere is no play. The u-joints are a little rusted but doesn't look like any abnormal wear and tear on them.
The pinion seal on the rear differential is still seaping through ever so slowly but I have known that since I have had the truck and I check the oil in it every few months and its still full since I have checked it recently. So I am pretty stumped.

 

I think you need to find a better alignment shop. A good alignment shop will find your problem. Don't tell them you want an alignment just give them the symptoms and let them test drive it. There is no reputable mechanic out there that would experience violent vibrations in the steering wheel at 55 MPH during a test drive and still look you in the eye and tell you everything is fine.

 

Tire could be out of round or have a slipped belt.