[Fot] Lime Rock - Groups for Fri Qualifying/Practice and Sat Race

[Mark Cook]

Henry,

 

Thanks for the info on gearing.  Video was helpful as well for having not
ever driven Lime Rock.

 

Was looking at the Lime Rock HF43 posted race groups.  Question.  Will we
run in Group 5 as a single group for Friday's practice/qualifying and
Saturday's races as well as the Kastner Cup on Monday?  Or, run in multiple
groups, like they have listed below (TR250/6 2500cc in the 2.5 Litre or Over
2 Litre as example)?   I assume multiple groups except for Monday's event.

 

Thanks,

 

Mark Cook

 

https://limerock.com/events/historic-festival/hf-driver-information/

 

HF43 Groups and Classes

 

The following race groups are our tentative run groups:

 

Group 1 - Mid Century GT / Sportscars Under 2 Litre

    Under 1.3L

    Over 1.3L

 

Group 5 - Triumph Feature - Kastner Cup

    Triumph Under 1.6L

    Triumph Over 1.6L

    Triumph Over 2.2L

 

Group 6 - Tin Tops / IMSA RS / Under 2.5 Litre Cars

    Under 1.3L

    Over 1.3L

 

Group 9 - GT / Sportscars Over 2 Litre / Sports Racing Cars

    GT

    Sportscars

    Sports Racers

 

 

 

 

 

-----Original Message-----
From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of yellow04 via Fot
Sent: Thursday, June 5, 2025 12:23 PM
To: FOT
Subject: [Fot] Gearing for Lime Rock

 

If this comes through twice, I apologize. Working through some technical 

difficulties with my mail server.

 

I have been asked by numerous folks about what rear end gear to run at 

Lime Rock. Several of our guys with a lot more laps at Lime Rock than I 

do have chimed in, thanks everyone for your input. Sometimes a picture 

is worth a thousand words, so here's my input.

 

https://youtu.be/xIg5KQwM-pw

 

I clipped a lap from my in-car camera from the 2024 Lime Rock Vintage 

Festival. My tach is plainly visible and I added captions on what I am 

doing with the gearbox. The lap shown is somewhere in the mid-1.05's. 

The camera is one of those Go-Pro knockoffs, so the quality is junk, but 

it got the job done. The sound was cut, if you heard what the camera 

records for sound you would thank me!

 

The gearing I use in the TR250 is a 4:10 R&P, a Triumph gearbox with 

close ratio gears, a stock Laycock overdrive and I am running on Hoosier 

Speedsters with a diameter of 24.2 inches. My shift point is 6000. This 

example should be easy to reference against your race car assuming you 

are familiar with high school math!

 

This is the same setup I used in my old TR4 racer and the TR3, except my 

4-cylinder racers use a Moldex crank, Carillos and a cam that ran to 

7000. With the additional revs afforded by the billet bottom end, I 

don't need the overdrive to enhance the top end. Again, it's all in the 

math.

 

My line through Big Bend and the Uphill are not optimal, but that is a 

conversation for another time.

 

Watch the tack twitch as I crest the Uphill, you know you did OK when 

you get a little wheelspin there!

 

Hope this helps.

 

Henry Frye

KCup chair

860.508.3118

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fot at autox.team.net

 

http://www.fot-racing.com

 

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