Vibration through car - driveshaft ??

[Ben]

I'm getting a slight vib through the car at around 4500-5000RPM. I noticed it before because the passenger seat shakes a little but as I'm using the hardtop now its a bit more obvious as there's a slight sound to it too ?

I had the driveshaft off a few months back, but I marked it and I'm fairly sure its back in the same position, however the vibration could've been there before but as i rarely drive at that speed I didn't really notice it, besides I had a few other noises and vibrations to deal with !

So what the problem, driveshaft balance, bad centre bearing or both ??

Is there any point in trying the shaft in a different position ?

Is there a method for ensuring the shaft is fitted correctly, I had the car on a lift when I tightened the centre bearing holder, does that matter ?

I've had all the wheels balanced just to rule that out BTW !

Any advice / suggestions ?

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Benz Dr.]

Bent rim.  No balancing can help you on that one.

 The driveshaft can be out of balance but I've not run into this so far. I've seen plenty of bent rims before though and they tend to be speed related. Unlike a tire out of balance this seems to be at a certain speed - anything above or below and it's not too bad. A tire tends to have a wider range of vibration with a critical speed in the middle.
Dan c
SL Barn


Daniel G Caron

[Cees Klumper]

Benz Dr. is right. I have had a vibration since I got my car 4 years ago. The drive shaft, bearing etc was brand new. The cause of the vibration could not be located. Replacement of the engine and transmission mounts helped a little.
Finally, when I went to get a 4-wheel alignment last year, the mechanic showed me the cause of the vibration: a bent rim. He was able to balance it out for the most part, but not entirely. It's practically gone now, but I know that I need to get a new rim to eliminate it completely.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[Ben]

I watched the tyre guy do the balance and I was watching for rium damage, which I didn't see !

However if driveshaft vibration is not common the maybe I'll swop the rims and see what happens !

Thanks guys !

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Benz Dr.]

I always have them do a rim balance before they mount the tire. Anything that isn't close to zero is suspect.
You can turn the rim slowly and should be able to see the bend - at normal tire balance speed you can't see it as well. The rim edge can be bent in or sideways as well as the whole rim can be out of true with the centre holes. This can't be fixed but the outer rim may be fixed it's not too much.

Dan c
SL Barn

Daniel G Caron

[Ben]

Yeah the more I think about it a rim seems obvious but as i said I looked closely and couldn't see anything amiss. However since they were balanced the problem is less pronounced suggesting issues with the rim !

Now I'm curious though !  IF the centre bearing was gone what would the symptoms be ??

Also that centre support could it be tightened in the wrong place? The holes are elongated for this purpose maybe ?

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Ben]

Just to finalise this topic I managed to discover what was wrong !

having checked and rechecked everything as suggested (thanks guys) I had begun to suspect something in the driveshaft bearing/driveshaft damage or rear axle issues as everything else checked out. However whilst rechecking a rim for damage I had the car jacked up and with the handbrake off I rotated the wheel and heard a funy sound. I innitially suspected a wheel bearing but noticed that there was a slight tight spot when rotating the wheel.

So I removed the wheel and the brake drum and discovered a broken spring which it seems has been the cause as when replaced the problem is totally gone. I reckon the shoe would drop slightly causing a drag but then move again and release, generally rattling around catching and realeasing !

Anyway one new spring a readjustment and "Hey presto" no more vibration !!

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[J. Huber]

Nice detective work Ben!

I have new rear shoes going on very soon -- I'll inspect the 'ol springs while I'm at it!

James
63 230SL