balancing nuts

["John Hertzman" <johnhertzman@domain.elided>]

I am not about to question whether Rich Hirsch found what he said he found-
added nuts, of different weights, added to the bolts which attached the rear
giubo to the clutch yoke - but I am curious about the dynamics. I didn't go
under my Milano to look, but I assume it is similar in principle, if not in
detail, to the Alfettas. On the Alfettas the giubos are fastened with three
different types of bolts. At the flywheel there are three bolts with two flats
on the heads (which presumably register against the crankshaft flange) with a
stepped shank for the portion which is a press fit in the flywheel. The
threaded section extends about 5 mm beyond the nyloc nuts, maybe barely long
enough to carry an added balancing nut but such a nut on the flywheel bolts
could affect the balance of the flywheel, not of the driveshaft.

The twelve bolts attaching the giubos to the four ends of the two driveshaft
sections have round heads, and splines which lock into the driveshaft yokes.
They are not listed in alternate lengths. The nyloc nuts on these bolts, in
situ, leave about 2 mm of threads exposed, hardly enough for an added
balancing nut although undoubtedly enough to allow washer thickness
variations.

The three bolts attaching the rear giubo to the clutch yoke have hex heads and
no visible distinguishing characteristics, so presumably they could be found
in different lengths, although only one is listed in the parts book. BUT, as
with the flywheel bolts and nuts, I can see how added weight here would affect
the balance of the clutch yoke and the clutch, but not how it would affect the
balance of the driveshaft. An unbalanced driveshaft would distort the elastic
giubo, the bolts and nuts attaching the giubo to the shaft would have an
eccentric orbit, but the clutch yoke and its bolts and nuts would not be
flopping around.

So, I am missing something. A nut balancing strategy would suggest that the
twelve bolts attaching the giubos to the driveshaft flanges would be long
enough to accommodate nuts as needed, but they are not. They are long enough
to accept thicker or thinner washers, or longer nuts, or nuts with a larger
hex, but none are offered.

I don't have a better explanation for the added nuts on Rich's car; it seems
an odd way to balance the clutch. If one of the engineers on the list wants to
have a shot at it, I will be interested in any further thoughts or
observations.



John H.
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