Hi Gang,

Today my truck was delivered. Deep breath. Mostly it is very good, but it has a vibration/noise that becomes audible at around 35-40 mph and builds in relation to speed. RPMs do not seem to affect the noise at all. It seems to be centered under the drivers seat to forward of the firewall. At 65-70mph this is a very loud, throbbing sound, not unlike driving down a rumble strip at high speed.

The driver who drove it from florida sais that he heard the noise and had it checked but was told it was "normal". Right.

Conditions here today were very stormy so I could not really check under the truck, but we are clearing space to get it into the garage in the morning. We plan to jack it up and check everything out for freewheeling and to make sure no u-joints are binding from the suspension lift. If we don’t find anything I plan to have it at a dodge shop on Monday.

Any clues what to look for would be appreciated.

 

well if they did a body lift, I would be checking tranny cooler lines and or a/c lines rattling along the frame/body somewhere. also check tranny shift cable and ebrake cable for rattlin.

 

Sounds like your front driveshaft is binding. When I lifted my Silverado I had the same problem. Turns out when I ordered the lift, I accidentally got the wrong driveshaft. I know it's a completely different truck but same principal. How much lift was it again?

 

6" front, 4" rear. They did a driveshaft mod, changing it to a two piece in order to miss the wheelchair lift, but as far as I know, no changes were involved on the front driveshafts.

 

don't have to extend the shaft for a 6" lift. only thing would have been shim the 2 piece rear shaft

 

It seems to be centered right under the drivers seat, to a little forward.

I also woke up thinking that I did not check it without the wheelchair in the truck - I'll check that today too. Just in case it has something to do with the weight of the powerchair in the dropped floor.

 

No change without the chair in the truck.

I noticed another thing this morning, without all the thunderstorms making noise, I can hear a high pitched squeal too. It sounds like a fluid squeal - maybe the power steering thing I have heard about? It seems to be louder when I drop off the fuel.

 

I spent a little time under the truck this afternoon, and the only possible problem I see is that there is a LOT of metal powder in and around the double u-joint the comes forward from the transaxle. I tried to grease the joint but my needle tip was too flexible and it bent and broke. I'll have to pick up one that is a little stouter and try again. But if all the steel dust there came out of that joint - it's toast.

We just back from a little ride where I put the truck in 4wd for the first time. There was not as much noise under acceleration, but when I dropped off the fuel, that front shaft sounded like it was going to jump through the floor. After a couple miles I took it out of 4wd and now it is much louder at slower speeds.

I think that must be the problem. The question will be if Ram says it was because of the suspension lift, or if it just was never greased at the factory.

 

Have you checked the drive shaft yokes to ensure that they are in phase with one another. Sounds to me like your having vibration from the breakover. If the driveshaft is laying on the ground, you want one end of the driveshaft to be 90 degrees offset to the other end (e.g. one end is N-S and the other end would be E-W)