Mercedes W115 vibration

Blue850

I've got a "thrumming" vibration in the Merc, pretty bad at 30mph, smooths out at 40 and between 50-60 returns with a vengance, smooths out again over 60 but I can hear /feel a thrumming in the whole car. Car is an auto but is changing gears ok.

Had the car on a 2 post lift last and the whole thing was rocking at 40 with the wheels off the ground. flexi joints and central bearing appear to be in good condition and looks like the propshaft has been changed.

any ideas?
If its an out of balance prop, who can balance them?

MercMad

It most likely IS a prop shaft problem but I would check simple things first !

The fact that you see the car wobbling whilst on the lift would tend to rule out things like bad tyres or bent rims, but no harm in checking them out also !

You mention the driveshaft appears to be new, obviously someone had that problem and could not figure it out.

The rubber doughnuts can be fitted incorrectly, not obvious, but if you look closely they will appear slightly strained. Also the transmission output flange can become damaged if someone at some point did not tighten the flex discs bolts properly. Whilst checking this push and pull on the transmission output flange as the central nut holding this to the output shaft, its a slotted nut, and it can come loose.

Finally these cars have a central bearing and if this is fitted or tightened incorrectly the driveshaft will be minutely too long ! You should put it on the lift again and loosen the bearing support, normally two 13mm bolts. Then put the car back on its wheels and roll it back and forth, dont lift it again, unless of a four poster ramp. Crawl under it and nip them up ! If you see any grease nipples, grease them !

Let us know how you get on !

Dades

Thought I'd throw this out as it reminds me of a prob I had when I got my SL this year.

I had a vibration/rubbing that appeared a certain ranges, only to disappear again. After inspection (or so I was told) it turned out the exhaust had been remounted too close to the steering box after the last work had been done on it.

May your issue be a minor one!

Blue850

From searching the 'net, it could be anything.. its definitely in the drive train somewhere as in neutral its ok no matter how hard its revved.
We'll start at the back wheels and work our way in.
Not looking good for Mosney though unless I get the brother to bring the Kadett Coupe

Spit62500

MercMad is dead right - eliminate the simple things first. Does the back wobble on the lift with the wheels off?

Propshaft Services in Dublin (off the Naas Road) will balance it (the name's a dead giveaway!)

I know that its not exactly around the corner from you but if its the prop then they're probably where you want to go. They balanced my Amazon prop when I put in an overdrive with the front prop section from the donor car. It's been perfect since.

There are stories of people balancing props with jubilee clips but I'd imagine that it takes a lot of patience and some luck.

If you have it on a lift it might be possible to detect a prop wobble with something held close to the prop as it spins (usual disclaimers about injury).

Hifive

I had a vibration on part throttle, not coasting, or balls out, just when trickling along. Had a good root underneath the car this week, when I was re doing the Waxol (great fun by the way I came out looking like a chimney sweep!) and found one of the exhausts was very close to part of the body work and had obviously been in contact with it. Loosened all the exhaust clamps and bet the sh1t out of it with a lump hammer, sorry tapometer , and low and behold no more vibration.
As your vibration is when your on the gas, could it be, loose or worn engine mounts, causing the exhaust or some other rubber mounted component touching the body or chassis when provoked?

Blue850

Thanks for the replies. Hopefully I'll have it sorted in the next few weeks. Got wind of an old Merc saloon sitting in a driveway, not too far away, covered in green mould. The guy who saw it reckons its an upright headlamp model and also found out where the green Fiat 850 in Irish Vinatge Scene's Laid to Rust is. Might do some spares hunting tomorrow.

MercMad

Actually yes I forgot to mention the rear gearbox mount, it can get soft and you get some vibrations, but not a harmonic type !

Best of luck !

MercMan Ben

Hi there,

the prop shaft comes in two parts and sits on splines, where it can be disconnected. If it had been removed in the past and wasn't put together exactly how it was, the prop shaft is out of balance and the problems you are talking about occur.

All the best,
Benjamin

Blue850 wrote:

I've got a "thrumming" vibration in the Merc, pretty bad at 30mph, smooths out at 40 and between 50-60 returns with a vengance, smooths out again over 60 but I can hear /feel a thrumming in the whole car. Car is an auto but is changing gears ok.

Had the car on a 2 post lift last and the whole thing was rocking at 40 with the wheels off the ground. flexi joints and central bearing appear to be in good condition and looks like the propshaft has been changed.

any ideas?
If its an out of balance prop, who can balance them?

Blue850

Thanks again. I think i'm going to have love hate relationship with this Merc. I was looking for chrome wiper blades for it yesterday at Mosney, all the 114s there had a hook type fitting on their wiper arms and I could only find "push in" type blades, got home to discover my one has push in type arms:rolleyes:
anyway going to look for this parked up one tonight

MercMad

Hi there,

the prop shaft comes in two parts and sits on splines, where it can be disconnected. If it had been removed in the past and wasn't put together exactly how it was, the prop shaft is out of balance and the problems you are talking about occur.

All the best,
Benjamin

........yes thayts most likely your problem right there ! I should have thought of that. I had that before with a Pagoda I should have remembered !!

Blue850

Are you talking about where the front and rear shaft meet, at the universal joint?
BTW the parked up W114 turns out to be a W123, at least I've been saved a 40+ mile trip to see it.

MercMad

Yes its right where the centre bearing is. You will see the spline there and one side just slides out from the other. You are supposed to mark it, scribe a line or paint a mark, before separating the two halves !

Maybe take a close look in case some previous mechanic did mark it all up correctly !

Are you going to check out the W123 anyways ??

Blue850

I'll probably go for a look , but its of no interest to me, whatever chance i have of bringing home a 115 for spares, if I bring home a dead 123 I'll be divorced:D

8~)

...s'cuse me; what's the mention of a W123? Got details?

Blue850

PM'd

corktina

would it be the Taxi-meter rattling at all at all? :-)