Intermittent Vibration

[Gisdan]

Hi Guys, just seeing if anyone has experienced anything similar. I've recently replaced the donuts & centre support bearing on my '77 Alfetta sedan & had the engine out at the same time. Since then the car has run with some vibration, but the odd thing is it varies from run to run as to how coarse this is. Sometimes it's barely noticable & others more pronounced. The car gets used regularly i.e. several times a week so it's not tyres out of round & the change can occur between driving in the morning & coming home in the evening. Wondering if it might be the engine mounts?

So would appreciate any thoughts or suggestions that we can look at from the accumulated knowledge & experience on the forum.
Thanks
Dan.

[Mick A]

Hi Dan,

There is a spherical bearing that locates the two halves of the tailshaft. Sometimes this is tricky to line up and people often make the mistake of forcing it together, which dislodges the bearing and it doesn't sit in the bush.

I don't know if you did it yourself or a knowledgable Alfa specialist, so that is my guess based on the information you have provided, also assuming everything was fine and no vibration before the tailshaft was removed.

-Mick.

[Beatle]

Is it speed or RPM related?

[Gisdan]

Thanks Mick, no vibration before removal & change of donuts, I will check that bearing when next under the car.
Beatle, not specifically speed or RPM, you can tell if it's going to be smoother or coarse as soon as it's started i.e. at idle.

[Mick A]

It's not that simple you need to pull the tailshaft out and apart to check it.

[Mick A]

If it is a tailshaft problem, it will be RPM related and consistent with certain revs.

It's all a bit hard to diagnose here as nobody can see the car. . Probably best to take it to a specialist for a diagnosis.

[carlo rossi]

if you dont mark and number the bolts as they come out
then you will have issues of this kind particularly if it was forced back in as was said earlier by choderboy
when it came out was it all marked ?

[Mick A]

You don't need to mark the bolts, only note location of washers, which should be on the head side of the bolt.

[Neil Choi]

This is the spherical bearing which joins the two halves together as indicated by Mick, hope this helps.

[Gisdan]

Thanks Neil, Mick & everyone with suggestions. Much appreciated. Gives us some things to check on when I've got the time to pull the propshaft out / apart. I know the spherical bearing went back in but fairly sure no real care was taken over it's centering etc.
Cheers, Dan.

[Neil Choi]

Mine went back together fine too, with new bearing and donuts.   So now off to get balanced.  Spinning at 7500rpm unbalanced is a bit of a worry.

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[Neil Choi]

Didn't have problems fitting spherical bearings in the middle or tailend so should be good.  Though the old shaft had a broken bit that holds the tail bearing in place such that the bearing came off inside the rear donut.

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