Lotus Elan

"English" final drive ratios

PostPost by: Frogelan » Mon Aug 28, 2017 1:38 pm

Good afternoon from France !

Having read many previous threads on this subject, as I have been looking for ratios to make my S2 comfortable to drive (on our wonderfully fast roads here in the EU ;-) ), and have come across a firm that was certainly new to me who offer a wide range of "English" crown wheels and pinions.

NTG are a manufacturer in Abroath, Scotland (not China) and sell parts directly to the public and have the following CW & P's in stock:

7/31 4.43:1
7/33 4.71:1
7/34 4.86:1
7/36 5.18:1
10/33 3.30:1

10/34 3.4:1, available in 10 weeks.

All above are available at ?355.00 inc. VAT (currently 20%) but transport is additional.

I asked NTG about the 3.44:1 ratio (which seems to be ultra-unobtainium) and NTG could run off a set, but to make this financial viable, sufficient interest (deposits!) would be needed.

The pricing would be 1 set would be circa ?2,600.00, 10 sets ?690.00, 30 sets ?355.00 all inc. VAT.

The link to the company (with whom I have no personal link or financial interest) is as follows:

http://www.ntgear.co.uk/ford-english-7- ... d-pinions/

The chap to ask for is Gordon Strachan.
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PostPost by: nmauduit » Mon Aug 28, 2017 1:54 pm

if 3.3:1 is readily available and moderately priced why not going for that, as it is only 3% lower than the 3.4:1 ? 3% final ratio (or more) may be accommodated by tire wall height in (the unlikely) case that ends up being too long...

just my 2 cents
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PostPost by: Frogelan » Mon Aug 28, 2017 2:08 pm

The 3.44:1 is the highest FIA homologated ratio for the Elan under form 170.

http://historicdb.fia.com/car/lotus-elan

This means that if you are competing at Spa Francorchamps, the Nordschleife or Le Mans, this might be a low cost option unless you have a very good deal with your engine builder... :D
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PostPost by: nmauduit » Mon Aug 28, 2017 3:02 pm

Frogelan wrote:The 3.44:1 is the highest FIA homologated ratio for the Elan under form 170.

http://historicdb.fia.com/car/lotus-elan

This means that if you are competing at Spa Francorchamps, the Nordschleife or Le Mans, this might be a low cost option unless you have a very good deal with your engine builder... :D


in your case you may then need to decide whether you want "to make my S2 comfortable to drive" or to be "competing at Spa Francorchamps, the Nordschleife or Le Mans" ...

as for racers, I'm not sure many of them use lower than 3.77, which would already mean about 150mph at racing redline on Le Mans tires...
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PostPost by: Frogelan » Mon Aug 28, 2017 3:21 pm

Several points:

- I did my calculations based on the Avon CR6 ZZ tyre, not Dunlop L sections which are probably larger
- I'm not sure the engine needs or can rev beyond 7500 rpm in top!

Chacun ? son go?t !
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PostPost by: Craven » Mon Aug 28, 2017 3:26 pm

Not forget you will alter the other 3 gear ratio?s as well!!
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PostPost by: 2cams70 » Mon Aug 28, 2017 11:51 pm

The 2.0 litre Ford Escort had a 3.54:1 English axle fitted as standard. Fairly rare in the UK/Europe since the 2.0 litre engine was only in RS2000 models but still reasonably common in Australia because the 2.0 litre engine was an optional and quite popular fitment in even entry level (non RS2000) Mk2 (1977-1981) models. Both manual and automatic 2 litre models had the 3.54 ratio.
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PostPost by: Davidb » Tue Aug 29, 2017 2:41 am

Burtons sell a 3.54:1 I have one in my car and still wish I had a 5th gear!
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PostPost by: Bombay Racing Green » Tue Aug 29, 2017 6:35 am

Thanks for the info.

It's nice to see that there is still some engineering companies left in Arbroath. I might stop by and get one on my next trip to Aberdeen. There might be time for an Arbroath smokie as well!

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PostPost by: Mazzini » Tue Aug 29, 2017 7:29 am

Davidb wrote:Burtons sell a 3.54:1 I have one in my car and still wish I had a 5th gear!


Are you running a close ratio (2.5/1) box? I have this set up in my S3 and I can live without a fifth gear.
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PostPost by: promotor » Tue Aug 29, 2017 3:48 pm

I and a very well known diff re-builder have had recent dealings/enquiries/experience of these crownwheel and pinions and they are to be used for track use as they have been found to be too noisy for road use in some people's opinions.
The intended use has been confirmed by Gordon Strachan at NTG.

A number of the crown wheel and pinions have been returned to NTG due to the noise issues - as I understand it the issues were to be looked at but I'm not sure if the issue has yet been overcome (or even if it can be overcome?).

These were initially designed to be used in some form of track racing where noise wasn't much of an issue.
Last edited by promotor on Tue Aug 29, 2017 10:24 pm, edited 2 times in total.
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PostPost by: Davidb » Tue Aug 29, 2017 3:52 pm

Mazzini wrote:
Davidb wrote:Burtons sell a 3.54:1 I have one in my car and still wish I had a 5th gear!


Are you running a close ratio (2.5/1) box? I have this set up in my S3 and I can live without a fifth gear.


Yes I have the 2.5:1 first gear-and an alloy flywheel which made pulling away difficult for my co-driver in a recent rally although I have no problem with it.

A 5th gear would make fast cruising much quieter and more relaxing.
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PostPost by: elansprint71 » Tue Aug 29, 2017 7:29 pm

Davidb wrote:Burtons sell a 3.54:1 I have one in my car and still wish I had a 5th gear!


Me too! :)
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PostPost by: msd1107 » Tue Aug 29, 2017 7:58 pm

Davidb wrote:
Burtons sell a 3.54:1 I have one in my car and still wish I had a 5th gear!


Very true. Depending on the state of tune of your engine and if you have a FHC or DHC, you can use a 3.55 with a 5th gear of .833 like the Voights conversion had, giving an effective final drive ratio of close to 3.0.

I too used the 3.55 with a c/r box and found it delightful but I ran out of revs following a Ferrari.

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PostPost by: Mazzini » Tue Aug 29, 2017 8:25 pm

msd1107 wrote:
Davidb wrote:
Burtons sell a 3.54:1 I have one in my car and still wish I had a 5th gear!


Very true. Depending on the state of tune of your engine and if you have a FHC or DHC, you can use a 3.55 with a 5th gear of .833 like the Voights conversion had, giving an effective final drive ratio of close to 3.0.

I too used the 3.55 with a c/r box and found it delightful but I ran out of revs following a Ferrari.

David
1968 36/7988


I have a tuned Q420 spec engine in my S3 which I suppose makes a bit of a difference.
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