For reference, my TR-4A was always quicker at long tracks (Road Atlanta and
Elkhart Lake) with the overdrive gearbox. I used the Dolomite Sprint close
ratio gears. But even with these, when geared properly for the long
straights, second gear was too tall for the tight corners, and first gear
(2.19) was too low. My times improved by about a second a lap by going to
a lower rear end gear (4.3 instead of 3.45) and using the overdrive. The
4.3 gave me a very strong second gear in the tightest corners (e.g. turn 7
at Atlanta) and the overdrive gave me essentially a fifth gear.
-----Original Message-----
From: Gt6steve@aol.com [SMTP:Gt6steve@aol.com]
Sent: Wednesday, January 26, 2000 6:34 PM
To: RodsINTOMG@aol.com
Cc: FOT@autox.team.net
Subject: Re: Racing with overdrives
In a message dated 1/24/00 7:19:51 PM Pacific Standard Time, RodsINTOMG
writes:
<< >>
Steve,
I'm curious. I can't guess why you would want to race vintage with an
overdrive gearbox. First, they are about 25 lbs heaver than a standard
gearbox (at least in the MGB). Do you seriously run out of gears on the
race
tracks that you race? Do you get up into the dangerously high RPMs like
6,500 or 7,000 or more on the straights of the tracks that you frequently
race?
I have an MGB with and early standard gearbox converted to close ratio
with
an MGA twin cam gearset. I run a 3.9 rearend on long tracks like
Thunderhill
and either the 3.9 or the 4.3 on tracks like Sears Point with the 4.3 on
tracks like Laguna Seca.
I know that the MG car company ran very tall gears and perhaps an
overdrive
in the early '60s at places like LeMans with the long 2 mile plus
straights.
But vintage, where do you need it?
It seems to me if you have your car camed correctly you should make most
of
your power at the top of the RPM band (say 6,000 to 7,000) and thats where
I
would want to be at the end of my longest straight in top gear. Simply
adjust the final drive to do it.
I'd like to hear your thoughts and those of anyone on the list on this
subject.
>>
Hi Rod, Sorry it's taken me so long to respond.
My GT6 is running a 3.89 rear which works out about perfect for most of the
western tracks at the end of the straightaway as you said. I'd like to be
running a 4.11 to launch out of the tight twisties a little better. Vegas
comes to mind as a 4.11 track. My thought was to exploit the OD as a way
to
legally have a five speed to accomplish this. That's my official story.
The truth?? A friend just bought a five speed cheater box for his GT6 and
it's galling the HELL out of me to think he has an advantage.:-}}
Thanx for your observations and take that flamesuit off. Bye, Steve
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