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Re: [Fwd: Ring and Pinion Source]

To: jfcowan@earthlink.net
Subject: Re: [Fwd: Ring and Pinion Source]
From: "Robert M. Lang" <LANG@ISIS.MIT.EDU>
Date: Thu, 30 Sep 1999 15:51:20 -0400
Cc: triumphs@autox.team.net
Hi John,

You may not have completely read the orignal message. The orignal message
was actally not from John but another person. And that person was none
other than ex-triumphs list participant Nick from NorCal.

At any rate, to answer your question, a lot of racers like the 4.55 setup
because it gives them better acceleration. Less than 4.88 and more than 4.30.

The 4.30 and 4.10 are okay for road racing, but nowadays the power bands
are so small, you have to go for gears. Unless you also happen to have a
set of "close ratio" Dolomite Sprint tranny gears (or the ultra-rare Kas
Kastener gear sets from the 60's).

The reason for this is simple, but not completely obvious. The road racing
rules for SCCA Production class, for example, allow for the stock 'box with
internals from any source (my paraphrasing) or an alternate box (Jericho,
Saenz, etc.) as long as the alternate 'box doesn't have an overdrive top
gear. So, with a stock TR 'box and stock-ish gears and an A type overdrive,
well, you have 7 speeds. With the 4.55 gears, you can really pull out of
the hole. Note that I have not read either the '98 or '99 Prodution Car
Specs rulebook, so this might have changed. At any rate given the
availability of optiona internal  gear ratios (not available) and fixed
tire/wheel sizes (PCS limits "big TR's to 23 X 9 15 slicks), there's only
one place to play with the gearing - the differential.

I'll also point out that a minor drawback to getting too much "gear", I
have a 4.88 for example, is that you have absolutely no top end. My "race
car" has a 4.88 diff, and by my calculations I limited to about 86.5 MPH
(more or less) at 6500 RPM's. I gotta build a motor that'll spin to 8K
RPM's and I gotta get an A-type overdrive or a Jericho box... _someday_.

Later,
rml

p.s. if you ever tired of that 4.30 gear set, drop me a line. ;-)

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