Serious Oscillation -- '72 280se 4.5

[autozen]

Although that model has the upgraded drive shaft flex disc that even an idiot can't put on backwards, it still could be coming apart. Get the car in the air and carefully fondle each of the 12 bolts that hold the drive shaft in place. Don't just look at them: try to turn each one by hand. Inspect the two discs for signs of coming apart. Also check the center bearing for excessive movement, although your description doesn't sound like center bearing to me. If you don't find anything wrong with the driveshaft or any of the mounts, etc, there is one other possibility that you don't want to hear. I have seen a few cases where the problem was in the transmission. Also how old are the tires? When tires go for years without much use, they may look like new, but they are unravelling internally.

Good luck,
Peter

[kpb]

autozen -- thanx for the additional tips. I have yet to get out to the garage this AM but truly intend to do so in the coming minutes. The tires, according to PO, are ones he had put on and he owned it 5 years (during which time he drove it 4K mis.) I doubt they are old enuf to unravel but they did not strike me as topnotch rubber eiher. (cannot recall the brand)

You are so right, I DO NOT want to even contemplate tranny issues. Will post as my investigation progresses. Whatever this oscillation is, I noticed it on my test drive and queried PO about it. of course, he never noticed it. If it hasd just stayed at that initial level, I would not be so concerned but in the past few days it has gotten severe, thus I am not driving this beast until I locate and correct. I do not want it to spew parts going down the road.

[psfred]

Drumming only on acceleration? Put a new tranny mount in it. Only takes a few minutes, and it's not expensive ($30). Drumming on acceleration is diagnostic for a bad tranny mount.

Peter

[kpb]

Hey all, have many tips to follow-up for this matter, BUT, I am hoping the problem was discovered this AM. I initially suspected the flex disc but a simple eyeballing last week did not indicate anything amiss. After reading the autozen/Peter idea, I looked again today (while lying on the garage floor since the car is not on jacks nor do I have a lift available -- hell, I don't even have a floor jack!) and discovered the front disc is shredding!!

Hopped online and ordered one (along with other sundry bits of stuff) and hope to replace as soon as the piece arrives. I have seen reference to a rear flex disc and this seems logical, why only have it at the front of the shaft? But, with my limited visibility under there, I have not spotted a second disk. When I had the butt on ramps last week I did not really look for a flex disk but presume I would have noticed it as I was studying the differential and trying to comprehend exactly how all the pieces interrelate. Is it there?

[JoeyTheB]

Had similar problem - minor shuddering under acceleration
from stop to 40 mph.

Visual inspection of flex disc showed mild cracking, enough to decide to replace - previous posts suggested it may be causing problem.

Upon removal of tranny mount, found the old one was completely sheared on one side !

Tranny mount by itself is pretty simple, but flex disc/motor mounts presented a bit more of a challenge - at least for me anyway.
See previous postings on the issues (search flex disc).

Good luck!

Joe
"joey the bee"

[psfred]

I think there is a u=joint in the rear instead of a flex disk -- the diff moves on the W108, unlike later models.

Get a tranny mount, too -- why do the job twice?

Peter

[kpb]

Hey jtb and peter, thanx alot.

jtb, I had previously discovered your thread and already had it printed out and filed in my 280SE notebook for reference. Thanks again for the info and encouragement.

peter, although I inexplicably failed to order a tranny mount along with the flex disc (even after reading many posts about the mount and it's ease of replacement) I called back and a second order with the mount is headed my way. I used IPS out of Boise, Idaho. The too cool deal for me is that they shipped from their warehouse near Cincinnati (2.0 hrs away) so I will probably get one-day delivery!! I submitted my online order about 9AM yesterday and when I called back at 3PM to add the tranny mount, my first order was already on the truck! You are also correct on the rear u-joint. DUH, no wonder I did not notice a flex disc.

I also have pending an order for the service CD. Is it best to await its arrival or is the flex disc and tranny mount straightforward enuf to go with the info from this forum? There is quite a bit of info on each.

BTW, upon further inspection of the disc, I am relieved to have parked the car when I did. It is next to demolished, huge cracks, frayed fabric strings -- just ugly. What is the likelihood that I damaged anything else?? Seems like tranny mount would have taken most of the abuse. Only drove it 2 miles with the really severe vibes.

As always, your patience and advice appreciated.

[autozen]

kpb,

Sorry I misled you on the rear disc. Although I new car prepped these cars and did the initial 500 mile inspections at the dealer, I haven't been under one for years. My special tools for replacing the sliding joint in the rear axle are going to rust. At least I steared you in the right direction on the front disc. The only damage you could have done would be to the flange on the trasmission or the driveshaft if any of the bolts were loose. Take one of bolts and stick it each of the 6 holes and see if the fit is the same. If you wollowed out any of the holes, you have to replace the part. You can tighten it all you want, but it won't hold. Also upon assembly the bolts are inserted from the rear and the washer always goes against the rubber and not the flange.

Good luck,
Peter

[kpb]

peter -- you didn't mislead, I'm just making sure of what I have and/or need for this job. I have been known to miss the obvious.

Thanx especially for the tips on checking the holes and also the proper sequence/location of the washer, these are the types of details which I am notorious (at least in my own mind) for overlooking and having to re-do.

[autozen]

kpb,

You are a refreshing and rare breed. Everyone posting on this website gets paid for what they do. I am assuming that none will work over time for free. I normally charge $80.00/hr for my time,but I enjoy helping people who want to learn, and I am sure that Steve Brotherton, Gilly, and all the other professionals out there volunteer the time just to hear someone say thank you.

Thanks,
Peter

[kpb]

peter -- not to get overly touchy-feely, but...if I am giving my professional advice, which encompasses years of focused experience, for free (which I do often) I most certainly appreciate a sincere "thanx." The way I grew up, just seems like the right thing to do.

Onward -- my parts, including the late-ordered tranny mount appeared toay -- YEE HAH!! Hopefully, tomorrow my damn job (I'm self-employed) will not buirden me so much as to prevent the accomplishment of the necessary repairs. I cannot wait to ride in this beast again...

[autozen]

Well, you are definitely not a Californian which is a state filled with millions of rude and impatient A holes.

Peter