Re: synchro problems and brake pedal height

[cbrown@medicine.adelaide.edu.au]

Re: synchro problems and brake pedal height

in V6.28
>Costel wrote:
>
">> - - When downshifting, "toe" the gas pedal.  In other words, blah, blah,
blah...
..And since we are talking synchros, can somebody explain why Alfas have
problems only with 1st and 2nd gear synchros.  Why not 3rd and 4th, since
they have exactly the same synchros?  Is it something intrinsic to the way
a gearbox works (i.e. 1st and 2nd harder to synchronize) or is it just the
Alfa design causing the problem?"


For fuck sake, don't you people read? - I am inclined to respond at first
impulse. But that would possibly be construed as marginally offensive to our
fellow with the question. It is not tolerant I hear you mutter.  Well mutter
away . And to our questioner, relax. Yours is merely an example of a broader
malady. 

As in all research, check your assumptions, check then recheck your sources,
recheck what you think you have checked, and then really think about what you
want to know. Then frame your question. 
 

 I refer you to Llyod Clonan's posting V6.26, 2 days ago, maybe you missed it,
maybe its myopia,  and for the sake of really underlining the point I'll reprint
LLoyd's short explanation re synchro's. Perhaps that might discourage needless
repitition.

From: "Clonan, Lloyd" <Lloyd.Clonan@dsto.defence.gov.au>
Subject: Alfa33 1st gear synchromesh problems

It appears to me that no one really understands the Alfa 33 or
Alfasud or 105 or 116 gearbox first gear synchromesh. Synchromesh when selecting
first gear from neutral on all Alfa models mentioned,  up until the Alfa 90 and
/ or GTV6 with the "Isostatic" change mechanism was very bad.   The reason for
this is that there is no synchromesh when effecting this change,  due to the
omission of the "brake shoe" on the inside of the synchronizer of first gear. 
If you study carefully the  exploded view of any or all of the abovementioned
boxes you will notice that 2nd, 3rd, 4th, and 5th gears all have two "brake
shoes", but 1st gear has only one, meaning that the box was designed for
synchronised shifting from 2nd down to first but not when shifting from neutral
to 1st.
    This was changed when Alfa adopted the "isostatic" gearchange
mechanism, by the inclusion of a second "brake shoe" with a spring separating
the two. This system worked somewhat better but still not 100%.   The only
successful way to select 1st gear from neutral is , as suggested, to select
another gear (usually 2nd, although this will increase the wear on the 2nd
synchro), and then slip smoothly into 1st.
        I hope this has shed some light on the problem. Dare I say "
They all do that. "


Chris Brown
Lloyd Clonan

AROCA (SA Div.) Technical Committee