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Re: [Fot] Rear End Ratios

To: Kas Kastner <kaskastner@gmail.com>, FOT@autox.team.net, John Hasty <jhhasty@gdhs.com>
Subject: Re: [Fot] Rear End Ratios
From: Larry Young <cartravel@pobox.com>
Date: Mon, 01 Jul 2013 19:24:02 -0500
Delivered-to: mharc@autox.team.net
Delivered-to: fot@autox.team.net
References: <CEE0CDB1E81B4383A7382EC87AB7818B@gdhs.local> <51D1DFEE.1070909@pobox.com> <CAGiQU1Csf7nJG9EJzd01egNO_at9YFfvj=RRcKY3au7AWatBYQ@mail.gmail.com>
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130620 Thunderbird/17.0.7
I would also consider using the OD in in other than top gear. Quick 
shifting overdrive is sometimes more convenient in a tight and busy 
situation.  It can also give you better gearing by splitting gears. At 
Hallett there is one very tight turn and with a close ratio gearbox, 
first is too low and 2nd is too high but 1st overdrive is just right.  I 
didn't have an overdrive the one time I ran at VIR, but I was so busy 
during the lead up to the the straight, I had wished I had an overdrive, 
which only required the flick of a switch.  That was one data point that 
lead to me to reinstalling the overdrive.  Again at Hallett, the 
overdrive was really only needed on the straight (maybe), but I noticed 
my son, Tom, would use it all over the track. It is just more convenient.
Larry

On 7/1/2013 3:25 PM, Kas Kastner wrote:
> That 4.55 will make you fly up the hill to the start line and off a 
> lot of the slow corners.  Live with it.
>
> *Never be beaten by equipment.*
>
>
>
> On Mon, Jul 1, 2013 at 1:00 PM, Larry Young <cartravel@pobox.com 
>
>     John,
>     A 4:1 rear with overdrive (0..82) is 3.28.  Unless you've changed
>     it since I had it, it has a 4.55 rear, which gives 3.73 in
>     overdrive. This is close to the standard top gear of 3.7 which
>     most racers run.  You must be making good power to reach 6200 at
>     the end of a long straight.  I think there is something like a 4.3
>     R&P ratio available, but I think I would stick with the current
>     setup and live with 6200.  Some guys spin there motors a lot
>     higher than that
>     Larry Young
>
>     On 7/1/2013 11:57 AM, john hasty wrote:
>
>         The overall ratio we have in the TR3A is 3.7 achieved with a
>         4.1 rear end
>         and overdrive.  At VIR, Road Atlanta, Savanna and Mid Ohio,
>         all with long
>         straights, we are turning 6200 at the end of each of them.
>          Elkhart Lake has
>         longer straights and we are concerned that we might need a
>         taller rear end
>         gear.  If we put 3.7 rear end gears in we would have an
>         overall ratio of
>         3.66 which I believe would produce 800rpm less or the same as
>         turning
>         7000rpm with the 4.1. I can't turn 7000 with a stock crank so;
>           Does anyone
>         with experience at Elkhart have a suggestion?   What do you
>         run there?
>         Thanks guys/gals......
>
>         John H. Hasty
>
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