I have a 1994 E150 cargo van. It has 219K on the clock, and the drivetrain is all original, 4.9L/auto. For the past 25k miles or so there is a vibration in the driveline that is directly correllated to driveline load. I have turned the van off at speed and the vibration goes away. It is not a constant vibration at speed, only when the throttle is in just the right amount such that the load is right, it will vibrate. A little more or a little less throttle and the vibration will go away. It will vibrate at any speed over about 20 mph if you get the throttle right.

I crawled under it today to take a look. The u-joints look prett good. The rear leaf springs look odd, they are not a smooth arc but are actually higher on the axle than on the ends, probably from loading the van down with too much weight. I also noticed that the pinion angle points above the driveshaft. This seems to compliment the overloading issue seen on the leaf springs and point to the rear of the van being too low. new springs will raise the rear and probably fox the pinion angle relative to the driveshaft.

I pushed on the tire and rolled the van backward a bit while it was in park. I watched the pinion hub and noticed that there is quite a lot of slop in the gears, and the pinion appears to have some side to side play in it. Now we're getting somewhere.

I think the van was overloaded a few times and the leaf springs were deformed enough to make the rear sag a bit. The van sits level, if not 1/2" lower in the rear when you compare the fenders/tires. Once the leaf springs were "smashed" the pinion angle was incorrect, and that caused a torsional vibration to ring through the gears (no pun intended) that led to excessive wear. Now I have a lot of gear wear, quite a lot of spring sag, and a bad vibration at the right load.

Can someone help me identify this rearend? The tag says "S738G", "08 883 H30". Is this an 8.8"? How about gear ratio? I could pull the cover and count if this isn't enough information. Thanks!

 

On a E150, it should be a 8.8

With 219K, have you ever changed the gear oil??

From what you write, the pinion bearing could be shot. And with the play your talking about, the pinion is flopping around on the ring gear. First thing is to pull the cover and see what you find, any metal shavings, not good, check the ring gear for wear spots.

Your also said the springs are over stressed.

The easy fix, for both the axle and springs is to visit your local junk yard and see what you can find, it just might be a better fix to replace the axle and springs as a whole unit, if you just replace each, you need to use New U-bolts, don't reuse the old axle U-bolts.

Try this link to see if you can find a axle in your area - http://www.car-part.com/