Quote:
Originally Posted by Ken300D
I have the same issue on my 1984 300SD. It doesn't really do anything when I am driving it unloaded, but when you get weight in the trunk to the extent that the back lowers, then there is this vibration as you start out.
I've had my issues with driveshafts before, and I think the problem is the driveshaft U-Joint. The single U-joint on these cars doesn't really flex very much, and over a long time tends to wear in one position. I have found that with the driveshaft out, you can feel where the U-joint develops something like a "center-detent" where it catches in place where it is worn.
So when you load the car down, you're exercising that U-Joint out of its normal worn operating area. And you get the vibration.
I can see how it might also be the center driveshaft support bearing.
In either case, the work involved is a high price to pay (either in parts money for a driveshaft, or labor effort to replace the center bearing) to resolve a minor vibration. I'm just living with mine until it gets much worse than it is now.
|
... the u-joint is not affected by how low the vehicle is... you have independent rear suspension, and the diff is bolted to the frame of the vehicle... it could still easily be the u-joint, but more likely it's from the additional load from either weight in the car, or wind resistance at speed due to the rear being lowered, and losing the natural rake "spoilage" of the air.
either way, since it's more noticeable with a load, it could be,
1. Tires, just balancing does NOT determine if loaded they vibrate... try swapping front to rear to see if the vibration "moves"
2. Differential wear
3. worn axle joints
4. u-joint and or center bearing
5. flex discs allowing more travel than usual
6. broken frame parts allowing vibration
7. all of the above
8. None of the above
9. I've also noticed brake calipers being seized causing a vibration after a longish drive...