Re: alfa-digest V8 #67 - 105 GTV Differential

[AlfaNeely@domain.elided]

In a message dated 09/21/2001 8:08:20 AM Central Daylight Time, 
owner-alfa-digest@domain.elided writes:



> Date: Thu, 20 Sep 2001 21:13:05 -0600
> From: Lawrence.Gowin@domain.elided
> Subject: RE: 105 GTV Differential
> 
> > My '71 GTV has a bit of differential noise.  I swapped the rear end from a
> > late 70s Spider a couple years ago to replace a very noisy non-LSD stock
> > unit.  Are there different gear ratios with the later Spiders that may
> > give better acceleration or top end over what I have now?  Will all the
> > later rear axles bolt right in?  I've never heard its more economical to
> > rebuild the existing unit, so I figure I'd swap it for the best newest
> > rear end I could.
> > 
> > Cheers,
> > Lawrence
> > '71 GTV
> > 
> >


       Rebuilding the Alfa rear end is a pain.  It is hard to set up the ring 
and pinion as there is no rear opening to run carbon paper between the teeth. 
 Plus all settings changes require that the left side axle be removed.  It is 
just a pain that most people avoid by finding good used rear ends.
       All spider rear ends will interchange from the 1600 Duetto through the 
end in 1994.  That is, they all bolt up the same.  However, 1750 and earlier 
rear ends were a bit lighter weight.  And the early ones had left hand 
threaded studs on one side.
       Gear ratios changed with the Bosch cars from 4.56 (41 & 9 teeth) to 
4.10 (41 & 10).  That would have been in 1982.  I have never owned a late 
Spica spider, so some of them may have gotten the 4.10 rear end in 1980 or 
1981.
       The 4.56 rear end will give more acceleration and your 71 speedometer 
will be more accurate.  As far as top end goes, it depends on how your engine 
pulls at top end.  Your car will run up against a wall of air and the engine 
may be able to overcome it with RPM rather than torque.  Who knows until you 
try it.
       It may be academic.  You cannot run wide open all that often anyway.  
On the race track, the lower gears will surely be better anywhere but Road 
America.  I rarely even get into fifth gear on the track in a four cylinder 
Alfa.
       The 4.10 will reduce wear and tear on your engine and it may give 
better gas mileage.

Ciao,
Russ Neely
Oklahoma City

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