Author Topic: S2 Gearing  (Read 1542 times)

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Offline andall

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S2 Gearing
« on: Wednesday,July 19, 2017, 12:32:45 PM »
This topic may have been raised before, but:
I've driven my newly acquired S2 at normal traffic speeds on the Norfolk A and B roads near my home and have come to the conclusion that top (4th) gear is far too low. The speedo reads 50 mph when the engine's doing 3000 rpm. Based on that, 6000 rpm would be 100 mph. OK, it's not a laid-back cruiser, but i expected it to be a bit less deafening and not so low-geared. This led me to consider a Renault 5-speed gearbox conversion.
Can anyone please corroborate the mph/rpm values I saw, and by how much would a 5-speed box drop the revs? I was pleasantly surprised at the torque from my non-standard 1647cc motor so feel that it would cope with taller gearing very well.
Is a 5-speed box my only option, or can the final drive ratio be changed easily? Forgive my ignorance in advance...

Offline LotusJoe

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Re: S2 Gearing
« Reply #1 on: Wednesday,July 19, 2017, 12:52:37 PM »
Looks more like top speed at 6,000 RPMs would be 90 MPH
Joe Irwin
3927R TC Special
(The Classic Barn Find)


Offline 4129R

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Re: S2 Gearing
« Reply #2 on: Wednesday,July 19, 2017, 01:09:45 PM »
When in Norfolk are you? I am NR20 5SF.

Alex.

Offline BDA

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Re: S2 Gearing
« Reply #3 on: Wednesday,July 19, 2017, 01:21:09 PM »
A Renault NG-3 may be easiest swap to make. I would give Richard at Banks a call.

Offline 4129R

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Re: S2 Gearing
« Reply #4 on: Wednesday,July 19, 2017, 01:32:21 PM »
I have 2 x 4 speed boxes sitting in my garage. You can check out the ratios if you want. You cannot be too far away from me.

Offline jbcollier

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Re: S2 Gearing
« Reply #5 on: Friday,July 21, 2017, 02:34:36 PM »
They are what they are.  You can lower the rpm somewhat with a 5 speed.  From the archives:

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Quote from: jbcollier on Friday,February 19, 2016, 01:24:43 PM
Top gear ratios compared:
4th gear 336:  1.03 x 3.56 = 3.67
5th gear 395 early: 0.91 x 3.78 = 3.44
5th gear 395 late/365/NG: 0.86 x 3.78 = 3.25
5th gear some NG3: 0.78 x 3.78 = 2.94

For the sake of comparison,  if you were cruising along at 4000 rpm in 4th with a 336 or 352,  then the equivalent road-speed with the various 5-speeds would require these rpms:

Rpm .... overall ratio
4000 @ 3.663:1 = 336 & 352 in 4th
3771 @ 3.454:1 = 395-00 in 5th (it's a close ratio 5-speed, not a over-drive 'cruiser')
3591 @ 3.289:1 = 365-07  (stock Europa Twin Cam Special)
3552 @ 3.253:1 = 395-11,  -04 thru -09,  -12,  -21,  and NG3-025
3233 @ 2.961:1 = NG3-064 (but it has a very low 1st gear and poor intermediate spacing).

Note that in 5th, there's negligible difference between the Europa's 365 5-speed, and the 395-11 or -21.

Tim Engel
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The Europas are not relaxed cruisers.  My 0.91 5th gear equipped car revs quite high at 80 mph.  I have fitted a 0.86 5th gear but haven't been out on the highway yet.  I expect a modest rpm reduction but not by a huge amount.