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Re: Clutch

To: ccrobins@ktc.com
Subject: Re: Clutch
From: WSpohn4 <WSpohn4@aol.com>
Date: Sat, 9 May 1998 15:50:12 EDT
In a message dated 5/09/98 9:38:27 AM PST,  ccrobins@ktc.com writes:

<<   I've done some racing myself and one thing I know is that if you
 don't finish, you can't win.  In my view there's a line between
 "spirited driving" and abusing the machine.  I've known guys that
 believe they need to run along at 5K instead of shifting up.  Go figure.
 --  >>

I have friends that have race cars that have the same problem. One guy that
has a very well built MGB engine is convinced that he is going faster because
he shifts at close to 7000 rpm (sounds mean, I suppose). I get a blank look
when I explain to him that his engine has a power peak at around 6000 (he has
a crossflow head - cast heads will often peak lower ) and that the fastest way
around the track is to shift at or slightly above the power peak, ie around
62-6500 in his case, as with his CR trans, with a 1200 or so rpm split between
gears, he will be dropping back to about 5000 or so, right on his torque peak.
I can't convince him, and so far he has resisted my suggestions to go out and
do a couple of laps doing exactly as I suggest and look at the times (I have
done just this and know that there will be little if any difference in times).

As the difference in heat production and wear between 6000 and 7000 is
substantial, he is wearing out his engine to no avail and overburdening his
already taxed cooling system. (Ask me - I know, as my Twinkie peaks at around
7000 - stock was 6700!!, and you can shift to advantage at up to 7500 or so if
you want to go quickest. The guys running low rear ends sometimes use up to
about 7800 on competition Twinkies)

On a related note, when I started racing (in the same car as I have now) back
in the Dark Ages (well, the early 70's actually), we still did standing
starts, and I used to hate it, because you would put many races worth of wear
and tear on the driveline and especially the clutch all in one drag style
start, and also because every few races, someone would stall his car right in
front of you on the grid, inviting you to drive over the top of him or into
the guy beside you. I was relieved when they stopped this traditional but
unsafe practice. The only thing it did prove to me was that my A was faster
from a standing start into the first corner than a racing Lotus 11. Torque, I
suppose, and a strong pressure plate.

Bill S.

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