there's a helicopter under my car!

this isn't good...

i knew i had to replace the flex disc on my 73 280SEL so i went ahead and ordered the part. on my way to pick the part up today my car started to vibrate under acceleration.

i had to drive about fifty miles today with the thing vibrating like mad. what kind of damage am i looking at here? since i knew this vibration wasn't good, i gently used the accelerator but there was quite a bit of 60mph freeway driving done.

will my poor baby be ok? did i throw anything out of balance? did i destroy any bearings?

any other light you can shed on the subject would be appreciated.

thanks.

[skalie]

I've got no idea what a flex disc is, but vibration at certain speed has usually been attributed to universal joints or engine mounts in my experience.

i doubt the problem is joints or mounts, the flex disc is toast. besides, the vibration was coming from under the car.

this wasn't at certain speeds this was at all speeds. when i accelerated the thing shook.

i'm replacing the flex disc tomorrow, i just wanted to know what kind of damage could have been done by the vibration.

i know someone here should be able to shed some light on this...

[psfred]

Oh no, something ELSE I have to replace!!

Not like my 280 runs yet, anyway, still working on the JB Weld.

Check the rubber bushing for the center bearing. If you can move the driveshaft very much, replace it. You will get tremendous vibration if it is bad, since the driveshaft is orbiting around instead of spinning. Sounds like the bad muffler from hell.

Other than that, don't think you did any real damage, but check also the centering sleeve on thr front of the driveshaft. You may have killed the plastic bushing in there, allowing the shaft to go off center there, too. Not too hard to replace, but you will need to completely remove the driveshaft to do so. Drill through it, put a pin of some sort in, then take two levers of some sort (prybars or large screwdrivers) and pry the old one out, then tap the new one in. I am assuming the driveshaft on the W108 is the same as the W115 -- make sure there is a plastic bushing in a sheetmetal sleeve before you drill, and that you have the correct replacement!

You will appreciate the new flex disk!

Peter

[MikeTangas]

Just don't drive it any more unitl you get the disk replaced and the center bearing checked. You do not want to throw the drive shaft in one of these cars - or I might be able to pick up yet another for a song, or maybe just by humming a couple bars.

i want to check the center bearing, but i don't know what i am looking for.

where is the center bearing? it is obviously attached to the drive shaft, but is it a part of the drive shaft? is it at the tranny end or is it near the rear of the car? what do i look for?

i will be taking the car to my trusted mechanic after i swap the flex disc. if i can do the center bearing myself i will attempt that too, but i don't have the part right now.

all other advice given before i start wrenching is appreciated!

thanks.

[psfred]

you can't miss it -- driveshaft goes through the bracket, and you have to take it off to get the flex disk out anyway. It's just in front of the single u-joint.

If you can move the driveshaft much in the rubber bushing, it is shot, replace it. The bearing will grind, hiss, or roar, rarely vibrates if bad.

If the driveshaft is off center on the bad flex disk, you need a new centering sleeve.

Peter

[Rackne]

Dont forget to exactly mark the two sections of drive shaft before taking them off the car for exact alignment when they go back together or it will be off balance, vibration will then become a way of life. The center bearing is at the junction of the two sections as I recall.

[omegabenz]

marking the shaft is a good idea, I screwed that one up one time.

damage...my friend has a 300TD with a V8 500 Euro engine in it, and I wrote before that he snaped the drive shaft and it went through the floor board and hit my brothers arm. He is ok, but thats what can happen.