Re: premature donut failure

["Mark Battley" <m.battley@domain.elided>]

Tom Sahines wrote:

>......The most overlooked component is the bushing in the end of the drive shaft
>that mates with the transmission output shaft. This bushing centers the
>drive shaft to the transmission output shaft and if either the bushing or
>the shaft are worn there will be unnecessary stress on the donut causing it
>to fail.......

Thanks for the info Tom.

I have the same problem - the last donut lasted only about 12,000 miles, and
it is trashed. The gearbox mount was replaced when I did the clutch 12,000
miles ago. The engine mounts and the shaft centre support/bearing are
probably original (150,000 miles), and are definitely tired, so I'll replace
those anyhow. 

Not surprisingly there is slop at the front bush (hard to measure, but maybe
1mm side to side?). How tight should it be? Are there any specs on
tolerances? There was grease in there (I put it there last time it was out),
and the rubber tube is there, but the car has done a few miles...

Until very recently (presumably as the donut finally failed), it didn't have
any significant driveshaft vibration problems. 

Mark Battley
Auckland, New Zealand.

1973 Alfa Romeo 2000 GT Veloce
1989 Fiat Uno Turbo 
1989 Fiat Croma
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