[Fot] Rear End Ratios

[Ted Schumacher]

A "rule of thumb" for gearing is you should be at peak revs in top gear 
2/3 of the way down the longest straight.  Thsi allows you to carry top 
speed for a longer period of time.  Ted


On 7/1/2013 9:41 PM, John Hasty wrote:
> OK you guys.  Thanks. What you are telling me is to get off my ass & drive the
> car!  But it is really hard @ 77 to learn too many new tricks. I've only been
> at this 4 wheel stuff for 2 seasons but can bet I am gonna try.
>
> Sent from my iPhone
>
> On Jul 1, 2013, at 8:24 PM, Larry Young <cartravel at pobox.com> wrote:
>
>> 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 at pobox.com> wrote:
>>>> 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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-- 
Ted Schumacher
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