Hey all, its been awhile since I've sold my E34 and posted here. Since I've been very much lacking stimulating automotive conversation beyond clear corners, wheels, and oil type discussions on the other board, and because I have an extremely confusing vibration problem, I've come here to throw myself at your guys feet for help. Since you all actually work on some of your cars, I was hoping someone could shed some light on this. This is for my E46 (which has a driveline very similar to the small 6 E34 525i, actually). The E46 is a 2001 330Ci with a 5spd manual.
Okay, holy crap, I am completely, thoroughly, and utterly confused. I've been having a rear end vibration for some time that I asked about here but didn't get any responses. I did my test of lifting the car and running the engine tonight, and I got very strange results.
With the wheels on - MEGA vibration, way worse than driving the car. Nothing until about 40, then a pretty big peak (probably the biggest) at 45, then a little less at 50, then another peak at 70, slows down a bit at 80, and then gets progressively worse from 90mph +. Heres an odd thing - when driving the car, the worst vibration is at 82mph, where there is the least with the wheels off. When driving, there is very little vibration at 45mph.
With the wheels off - very, very, very little vibration, but I can still feel something slightly. I can also notice what I THINK is a slight bit of runout on the rotors radially, then seem to be not rotating perfectly round, but its not completely obvious. Could be an optical illusion.
Now, here's the part. I put the car in 5th, let off the clutch, and let it idle at 20mph. With the wheels off, there is a noise like what you would think the inside of a windmill sounds like. Its a clinking, clunking, metal gear noise thats rythmic, but random, if that makes any sense. I had my GF rev the car up to 40-50, and it does SEEM to get a little worse, but its very hard to tell. If you put your ear directly next to either wheel hub, it seems to come from the hub. If you stand behind the car, it seems to come from the differential.
As crappy as a busted differential sounds, I'd rather pay $200 for a used diff than $400 for a rebuilt driveshaft. I am just at a complete loss, I'm very confused by these symptoms.
A little more information about the tires. I got a flat a little while ago, Costco finally got my new tire in. The flat was on the LR. I had them put the tire that was on the RR on the LR, and the new tire went on the RR (to balance out the camber wear and because the RR wears the fastest). Both wheels balanced to 0.00 on their 2 position machine, but it wasn't a roadforce machine. Also, the vibration in the car didn't seem to be affected by this tire change at all.
Any ideas? I'm thinking either the differential is all sorts of broken, the wheel bearings are shot (although there is no play in the wheels that I can tell), or the CV axles are messed up somehow. I want to throw tools at the wall at this point. Thanks for all the help.