Just IMHO -- for autox the lower gears work better. Thing is, since every
event is a new course you can't tune to the track like you can road racing.
I have a 4.55 in my Spitfire. I'll go to one event and do the whole course
in 2nd, another and I'm rowing back and forth 2nd and 3rd. And you never
know which until you get there. Changing rear ends is too complex and time
consuming for tuning for an autox course. So you learn to row when you need
to. Sometimes short-shifting. Shifting is only a waste when you spend so
little time in the new gear as to have made it not worth the trouble, but if
you can get a couple of seconds or a couple hundred feet in the new gear,
shift! And then learn how to smooth out your 3-2 downshifts (it's not really
double-clutching but a little throttle blip helps)
My 4.11 hasn't been in the car since the last time I road raced at
Hutchinson (airport course), which was in the '80s sometime. Even on
dragstrip tracks like Memphis and the old Wentzville circuit, the 4:55 was
overall better. At Hutch, the 4.11 was worth 4 seconds a lap over the 4.55.
At Hallett, the 4.55 was worth 4 seconds over the 4.11. In autox, with the
4.11 I could hardly get going and I'd give up a ton every time I needed to
accelerate. I also used to run on 21-inch tires, now I'm on 20s (so's
everyone else) for the gearing change. BTW, my local AX site is an
ex-airport runway too, which tends to faster-speed courses.
--Rocky Entriken
----- Original Message -----
From: "Robert Lang" <lang@isis.mit.edu>
To: <fot@autox.team.net>
Sent: Tuesday, July 14, 2009 9:19 PM
Subject: [Fot] Stupid Gear Question
> Hi,
>
> I recognize that the answer to this question is more or less "find the
> longest straight and gear up/down 'till you hit the redline just before
> the brake point...
>
> But here's the question anyway - I bumped up the power in the TR6
> autocrosser this year. There's enough bump (and it's not completely tuned
> yet) that I can pretty much spin the wheels at will in 2nd, or so it
> seems. I also observe that the rears are running hotter than the fronts -
> this is new territory for me, it's always been the other way 'round.
>
> At any rate, shifting in autox is mostly a waste unless you consider the
> effects of running the motor to beyond the $$$ indication on the rev
> counter, SO - if you're gear too low (numerically higher) - say 4.33 - and
> you happen to have a spare diff with 4.10 gears, would an increase in
> available power combined with the higher gear (numerically lower, 4.10 in
> this case) balance things out so you don't have to row through the gears
> as much?
>
> What I get with my gears spreadsheet is 4.33 and 6200 redline == 62 MPH in
> 2nd whereas 4.10 and 6200 == 65 mph... hmmmm, maybe still too low to avoid
> the upshift to third on occasion (we run airport autcorsses in our
> regions, so we can see some speeds in excess of 80 in prepared cars.)
>
> Just curious what anyone has to offer on the matter.
>
> regards,
> rml
> ---------------------------------------------------------------------------
> Bob Lang NER/SCCA | This space for rent
> Solo Chair 2009 TR6 40 F Prepared | Triumph!
> Voice:781-438-2568 FAX: 617-258-9535 | Cell: 339-927-4489
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