Re: Alfetta Sedan Project - Drive shaft vibration

[James Montebello <jamesm@domain.elided>]

On Fri, 4 Oct 2002, Daegrigg (Don) wrote:
>The question.  There is a pronounced vibration/buzz when you spool
>up the engine like a thousand angry bees that get more angry with RPMs.
>I have confirmed that I have a bad passenger side transmission mount -
>not replaced yet.  Could this be the problem.  Hard to believe this
>mega buzz is normal for the car.  I've tried the hose clamp approach to
>balancing the shaft as mentioned in Pat Braden's ' Bible.

My '78 Alfetta also buzzes/vibrates some, but only around 2000-2500rpm.
By 3000, the vibration is pretty much gone, and it's very smooth at
3500-4000, where it typically runs at freeway speeds.  It also seems
to be worse when cold, but this may be my imagination.  I replaced the
motor mounts, which didn't seem to help this much (they needed changing,
anyway).  It's not really harsh vibration, but it's noticable.

On my car, the donuts aren't broken (light surface cracks on the front
only).  I haven't yet tried a serious check of the center support.
A simple grab and shake showed no play.  I haven't yet tried the
hose-clamp balance trick.

Bad transmission mounts usually don't show up as vibration, but rather
as clunks or jerks when getting on or off the gas.  Awhile back, someone
did mention that the pilot bearing at the front donut could be worn,
which will show up as vibration.

I have to fix my very rusty exhaust before I really do any work on the
vibration, as the noise of the exhaust itself somewhat masks the vibration
(and hides other noises, too).  This appears to require nearly complete
fabrication, as the stock parts appear to be NLA, and I'm not going to
gamble on Stebro again.  Fortunately, there's a really good exhaust shop
near me.

james montebello
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