Well, this one's got me. My '99 323i has an annoying vibration that is amplified between 55 and 65 mph. Everything is new on the front of the car, except the strut tower pivot bearings, but I know they aren't causing THIS problem--no way.
I ran a search in the forums about this problem, and found several possibilites. The shocks in the rear are original, but would not cause this issue. I got 4 new BFG Ultra High Performance Traction T/A tires on the car, and the 4-wheel alignment is dead-on. The car does not pull or anything.
The brakes are also brand new, all around. No pulsation in the pedal.
I've had the car up in the air, absolutely NO play in any ball joint, bushing, pin, tie rod, or anything under the car. It's all tight.
Which leads me to the driveshaft. I have had the driveshaft out 3 times. The Bently manual says to try rotating 180 degrees @ the splines, and also maybe 90 degrees at a time at the final drive flange at the pig. Did this, didn't help. Second time I had the driveshaft out, I replaced the flex disc @ the rear trans. flange, the center carrier bearing assy., and lubed the splines. I also checked the u-joint play and center splines, no excessive play noted. I do have some play in the rear trans. flange in the tail piece of the transmission, which to my understanding there is a repair kit for? It seems a bit sloppy to suit me. But I tried the new parts, no change.
Third time I took it out I tried another series of rotation and I also aligned the entire drivetrain with precision instruments per the Bently manual. After installation and a test drive, the vibration is still there.
I also get the clunky downshifts, and when I go into reverse, there is also a large clunk. The rear axle shafts appear to be straight, and as I said, no bearing problems iminent. There are no missing balance weights on the driveshaft. Center splines are lubed well.
Before I go ordering a $700 driveshaft assembly, is there anything else I should do? Are these drivetrains THAT fussy? I suppose that's a good thing, but what a pain in the ass.
Comments/suggestions would be greatly appreciated. I HATE F!@#%* vibrations.
Officer: "I see you set the table for four." Groucho Marx: "That's nothing--I set my alarm clock for eight."