Gearing?

[l10tus]

Can any of you racing lads throw any light on the gearing used in racing Elans?

Watching some of the action it appears that the gearing is is way higher than road going cars, as some of the various video action shows cars using gear changes down to 2nd gear on some 'not so tight racing circuit bends', they appear to be doing in the region of 60 - 80 mph in second.

What sort of gear ratios are available and how about diff ratios?

My Sprint ( with its 3.54 diff ratio and 4 speed 3 rail) , is screaming at 50 mph - so much so that it's painfull to drive fast!

I know they probably run 30 or 40 BHP more, but what gearboxes are they using ?

Do any of them use a 'standard type' set up ?

What's the script here?

Q: How come the racers seem to be so 'long legged' ??

Regards,

Phil.

[billwill]

I think the engine cranks etc are strengthened and balanced etc so they can run much faster than the 6500 RPM tops of the road cars.

[elancoupe]

I was once told that some US racers run 2,3,4,5 ratios instead of 1,2,3,4. With the races being rolling starts, 1st isn't really needed.

[StressCraxx]

Gearing depends on the track, both final drive and transmission gears, plus tire diameter can change too. Even cantilevered race tires can "grow" in circumference to provide a slight overdrive effect.

Here in the US, most races are rolling starts. Usually a very tall first, then ratios stepped fairly closely to keep the engine revs in the usable power range. Each gear change up often results in a 1500 RPM drop in revs if the power band is that wide.

The driver wants good acceleration out of the slow corners and yet just touching the engine redline at the end of the straight just before braking.

For example in my Crossle FF Hewland with a 9/31 R&P:
18:34 First = 68.9 mph
21:30 Second = 91.1
22:28 Third = 102.3
24:28 Fourth - gives me a top speed of 115 (with tire growth) at the end of the straight entering the Andretti Hairpin at Laguna Seca.
If I race at Thunderhill, it has a longer straight, so I use a 24:26 4th so I get 125mph before lifting for T1.

Regards,
Dan

[rgh0]

I run a close ratio Quaiffe gear set box with 3.77 diff and 175/60 x 13 tyres.

With a 8500 rpm rev limit I would change down to second for a slow corner and 3rd for a medium corner and stay in top for a fast flat out corner.

This is a good compromise setup that works on both slow and fast tracks --- it gives me around 200 km/h in top at 8000 rpm.on the longer straights

On a tight circuit with shorter straights you could use a higher diff -say 3.9 or 4.1 with the same tyres and rev limit and you would be a little quicker but you would be slower on the fast circuits due to lower straight line speed. changing the diff on an Elan is to much of a pain to be swapping diffs for each circuit

We do normal drop the flag starts so you need to be able to get the car off the line which this combination does well

cheers
Rohan