asinine rear ends

["Luke Kowalski" <lkowalski@domain.elided>]

chip asks:

>. I am thinking of installing a 410 differential on my '79 Spider to
>lower the high end rpm's when I am driving on the interstate.  I did
>some major modifications to the engine when I rebuilt it about two and a
>half years ago (11mm cams, 10.4 pistons, Webers carbs, oversized in and
>ex valves and all the normal rebuild stuff).  It definitely has a lot
>more power, but the gearing of the car seems to be wrong.  Will changing
>the diff. help in attaining more interstate speed?  How much will the
>low end suffer?  Are late model Spider gearboxes the same as my '79
>gearbox?

I have a 74 Spider. It has had similar engine work, apart from my Spica
being "Ingrammed", instead of swapped for Webers. I also found that my car
was not as drivable on the American Interstates as a later Spider with the
different rear end. Thus, I have swapped the ratios. I went from a 4.56 to a
4.10 (the latter can be found in any 82 or later US Spider). Now, first and
second gears last longer and the revs are reasonable at highway speeds.
Sure, it is no longer a killer track car, but I only use it for weekend
touring.
If I could go back in time, I would probably leave everything (including the
motor) stock, but as long as it was modified to my tastes, I went all the
way.
If you do the same, your 0-60 will suffer, but the car will be easier to
drive, in my opinion.


thx
luke, San Mateo, CA (work and home, but for how long?!)

74 Spider (now a bit higher in the front and level, no longer scraping curbs
with the Integras)
82 GTV6 (sacrificial lamb for a buffing operation this weekend)
95 164 LS (next in line for swirl removal, not getting much pavement action
with the new, shorter commute)
98 Audi A6 Q (buffed and happy, got all the scratches out!)

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