Simple question, Matt. But, like Andy and Mark said, the answer is
not quite as simple.
In general, a lower ratio (higher number) will give you better
acceleration. But you run out of gear in a hurry. A higher ratio
(lower number) will allow you to spend more time in gear before you
have to shift.
As an example, the Austin America drivetrain in my Mini came with a
3.65. I ran it that way until just before the '97 Nats when I put in
a 4.13. Once I got used to the difference, I was pretty happy with
the 4.13. However, with the 4.13, I spent a lot more time on long,
open courses shifting gears. It was great on short, tight courses but
I would have preferred the 3.65 for the longer, more open ones.
In your case, however, there's not that much difference between a 3.82
and a 3.9. That's only .08 difference. For that small of a gain or
loss, I wouldn't bother doing the swap!! 8<{)
BTW: I ran with the 4.13 until two weeks ago when the tranny-side
shaft on the idler gear sheared off flush with the gear face and fell
into the tranny case. When I shifted to second, it got propelled out
the front side of the case like a bullet leaving a gaping 2-inch
hole. I hastily transplanted my spare tranny with the 3.65 and it was
perfect for yesterday's long, flowing course at the dragstrip. I was
able to run almost the whole course at the top of second gear without
ever shifting to third. We ran basically the same course back in
August and I spent too much of my time (with the 4.13) rowing back and
forth between second and third.
As has already been said, the bottom line depends on where you're
going to do most of your running and what kinds of courses you're
going to have to contend with. But, again, I really don't see enough
difference between a 3.82 and a 3.9 to warrant a change one way or the
other.
Of course, opinions are like *ssholes. Everybody's got one and they
all stink!!! 8<{) That's mine!
John (Old Fartz & TLS #37) Lieberman
Matt Murray wrote:
>
> All other things being equal, for an autocross, would one prefer a
> 3.82 or 3.9 axle ratio?
>
> TYIA,
> Matt Murray
>
> mailto:mattm@optonline.net
> mailto:mdmurray@gwns.com
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