driveline vibration

A tire with carcus separation beginning can produce symptoms of this sort but front end alignment will not. Incorrect alignment angles produce pull, tire wear, over correction type symptoms but not vibration. This was one of the most common education issues with customers who would come in requesting an alignment due to tire problems, mud in wheels and that sort of thing.

Driveline vibrations are usually not that difficult to separate from front end vibration so let's assume that your analysis is correct, and that the issue is in the drive line.

Transmission problems such as output bushing can create vibrations which are quite speed specific so this check is always part of the diagnosis. Place the vehicle one level surface with appropriate means of preventing it from rolling for obvious reasons.

Engine not running and transmission in neutral to unload the driveline. Try pushing the driveshaft to the side in each direction at the front and watch/feel for movement. There should be only a few thousandths of an inch of clearance in that bushing.

A common driveline vibration is caused by a universal joint which is failing or has been improperly installed. These can be difficult to identify with the driveshaft in place but an initial inspection for rust spreading from any of the universal joint spider boots (the little rubber donuts around each of the four legs of the Cardin type universal). Grasp the ends of the shaft and attempt to twist across each universal joint to detect any movement/slack. There should be none. One can hook a tool through the yolks in order to increase twisting force so long as one does not damage the boots.

Can't recall for sure but think that vehicle has a centre support bearing which is composed of a mount, rubber cushion ring, and bearing. There should be almost no movement, side to side, when trying to deflect the shaft by hand.

Jacking the rear wheels off the ground can allow the driveshaft to be rotated in an attempt to feel a difference in rotational effort or binding but it will likely be easier for you to remove the driveshaft in order to flex the universal joints. Take care when withdrawing the shaft from the transmission that the end of the shaft does not damage the transmission seal. Not difficult but simply needs to be supported.

The driveshaft is hollow so look for any dents or bending and be aware when removing that the length and mechanical advantage can make the shaft surprisingly heavy.

If not sure, the cost of having the universal joints and support bearing replaced are not that great so, depending on age, condition and mileage, I might simply do them. If the driveshaft has a slip spline and yolk which allow two sections of the driveshaft to slide in and out, take care to mark the phasing of the two ends so they go back in the same relation.

Jacking the vehicle to allow it to be run in gear with wheels off the ground can assist in locating the source of the vibration but has some huge risks for the unwary!

An out of balance driveshaft can be rebalanced by adding weights such as placing hose clamps so that the screw is oriented to the light side. In heavier imbalance weights are sometimes welded into place but the weight amount is often determined by clamping lead stock under hose clamps.

One can run the vehicle and use chalk to mark the heavy side since this side will run eccentrically and so chalk moved into close proximity will leave marks on the heavy side. This may be best left to a professional but simply requires time and thought.

I'm assuming that the vibration is a new event so likely an imbalance accented by worn support bearing or universal joint, if driveshaft related.

Typically differential issues which cause vibration also show other symptoms such as seal leaks and noise.

charlestown wrote:
hello i have a 2005 26ft rv on a e450 chassie . i notice a vibration after 30mph and much more noticeable at 50 and 60 mph. i,ve balanced all 6 tires twice they aren,t the problem . im thinking more in the line of the univerals or the center carrier bearings . i bought it this way so i wasnt sure if this was normal considering the size and weight . has anybody experienced a similiar problem with their e 450 chassie and if so what steps were taken to correct this issue . thanks mark from charles town wv

Prolly a flat spotted tire, OR a front end out of line

i dont think a motor mount will cause this vibration , i could tell if i had a broken motor mount , the reason i posted this twice i thought i was in the wrong forum i didnt want it in dingy towing i meant to put it in class c,s im sorry i mad a mistake . i thought maybe somebody has a class c with a similiar problem

You got a pretty good answer from donn0128 on your previous post. Why post again?