Re: identifying LSD rear axle on 105/115 cars

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

In AD8-0148 Stuart Thomson asked the FAQ "How can you tell if a 105 series car
has a LSD in it, particularly if the car doesn't run, are there any external
markings on the case??"

 In AD8-0149 Andrew Watry gave the standard answer, in a qualified and
mostly-correct formulation: "The 2000 LSD rear axles used on US models have a
triangular-shaped rib dealy cast into the bottom of the axle, behind the sump,
with the pointy part toward the front if I'm remembering right, and I think a
longitudinal line bisecting the triangle.  There are no similar angled ribs on
the earlier non-LSD axles. I don't know if AU axles are the same, but would
guess so, even if gear ratio is different.  I hear LSD was an option on
pre-2000 axles, but don't know if there's any external way to ID."

 Joe Cabibbo added: "I recently posed the same question to AlfaCentro
Technical Editor Rex Chalmers, and he quickly identified a small finned
protrusion to the front of the differential as the tell-tale sign of a LSD.
For the benefit of others, I will snap a picture identifying this mark later
today and post the URL."

 I would not normally want to disagree with either Andrew or Joe, let alone
Rex Chalmers, but the advices given have nothing to do with differentiating
LSD axles from non-LSD axles, except for the dual facts that run-of-the-mill
pre-1972 Alfas imported to the United States would not have had limited slips
and that most, if not all, 1972 and later 115 Alfas originally imported to the
United States did have limited slips, by virtue of the importer's marketing
decisions rather than Alfa's design or manufacturing decisions.

 Limited slip differentials were a factory option on almost all 105/115 cars,
and standard on some, like the 33 Stradale (a 115) and the Montreal (a 105).
.

 HOWEVER all four-cylinder 105/115 rear axles prior to the 1972 models had the
same differential case and sump, with no differences in form or markings,
whether they had limited slips or not, AND all 105/115 rear axles from 1972 on
had a different differential case and sump, visibly different from those of
the pre-1972 cars, but exactly the same on cars with and without limited
slips. The visible clues which Andrew Watry and Rex Chalmers describe are
sure-fire ways to tell a 1972-and-later axle from a 1971-and-earlier axle. In
the US, that usually (but not certainly) coincides with having or not having a
limited slip. Looking for tell-tale markings on the axle of a drum-brake
Giulia TI doesn't tell you whether the car had the optional limited slip any
more than it tells you whether the car had the optional floor shift or the
optional separate front seats. Looking for tell-tale markings on the axle of a
later car doesn't tell you whether the car had the optional limited slip any
more than it tells you what other options it had. A car built for a particular
market would have had what that distributor picked from the factory options
list, and a car built to order for a particular customer would have had what
that customer picked from the distributor's options list, if any. Limited slip
differentials in the earlier axles would be rare in the US used-parts market;
on the later cars quite a few world-market cars have been brought over and
many have been parted-out. I have seen some information that all 2000 Spiders
and GT Veloces had limited slips regardless of market, but that 2000 Berlinas,
Junior Spiders, GT Juniors, Junior Zagatos, Giulia 1300s, Giulia 1600s, and
Giulia Nuovas were all optional. The odds are that a used-market axle in the
US with the markings Watry and Chalmers mention probably has a limited slip.
But that is odds, not how-you-can-tell.

 (One hedge: the above is extrapolated from several sources but the
source-pile is not unlimited; if somebody can cite facts which blow holes in
my opinions on these maters I will welcome them.)

 And before anybody gets hung-up on the 105/115 distinction, it seems to have
nothing to do with year, displacement, hung pedals or anything like that; the
Giulia Nuova Super was still a 105 in 1976 and the Giulia 1300 Super was
already a 115 in 1970, although the only apparent difference between the two
was that the 1300 was a 115 and the 1600 was a 105. The only explanation I
have heard that makes sense is that the distinction between a 105 and a 115 is
not technical but administrative or programmatic- that the cars envisioned in
one program were 105s, while the additional cars envisioned in another later
program were 115s.

 Cheers

 John H.

Raleigh, N.C.

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