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 S.IV Overdrive Conversion
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jetglo

United Kingdom
17 Posts

Posted - 18 Nov 2018 :  21:00:30  Show Profile  Reply with Quote
Has anyone retrofitted a Series 4 with an overdrive unit?
I would be interested to know what parts and modifications would be required.
Thanks
Bob

pruyter

Netherlands
320 Posts

Posted - 18 Nov 2018 :  21:25:34  Show Profile  Reply with Quote
You need obviously a gearbox/overdrive combination, an overdrive stalk, an overdrive relay and a shorter propshaft although you could shorten your existing propshaft. Of course you need also some wirings and as an extra the overdrive warning light on your dashbord.
In WSM 124 is shown how to wire the overdrive system.

Regards,

Peter
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jetglo

United Kingdom
17 Posts

Posted - 19 Nov 2018 :  06:54:25  Show Profile  Reply with Quote
Thanks Peter.
I will have a look at that article.
As I already have an overdrive unit, do you know if it is feasible to fit it to the existing non-o/d gearbox? Also is the rear mounting frame in the same position? The propshaft and wiring are not an issue for me.
As I understand it, it would not be essential to change the rear axle drive ratio.
Bob
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pruyter

Netherlands
320 Posts

Posted - 19 Nov 2018 :  07:22:33  Show Profile  Reply with Quote
Hi Bob,

Your existing rear axle driving ratio (3.89) is in fact an advantage! My Series IV had the original driving ratio which is standard 4.22 and I have changed it to 3.89 which is standard for a non overdrive model.
To fit an overdrive in a standard gearbox you need another main shaft and it requires a lot of work, so my advice is: stick to an exisisting combination gearbox/overdrive.
The mounting frame in the rear is no problem at all, you don't need to change anything here.

Regards,

Peter
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jetglo

United Kingdom
17 Posts

Posted - 19 Nov 2018 :  08:15:08  Show Profile  Reply with Quote
Thanks Peter.
I’ll have to try to find a suitable gearbox......!
Bob
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pruyter

Netherlands
320 Posts

Posted - 19 Nov 2018 :  08:59:00  Show Profile  Reply with Quote
The best ones are those from John Roseby and Graham Howard. This ones are completely overhauled and John Roseby is without any doubt the well known specialist when it regards gearboxes and overdrives.
The forum of SAOC gives you all the information you can imagine.

Regards,

Peter
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jetglo

United Kingdom
17 Posts

Posted - 20 Nov 2018 :  14:31:24  Show Profile  Reply with Quote
Thanks for the information Peter,I have made contact with John Roseby.
Kind regards
Bob
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pruyter

Netherlands
320 Posts

Posted - 20 Nov 2018 :  21:02:51  Show Profile  Reply with Quote
Your welcome!
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jetglo

United Kingdom
17 Posts

Posted - 21 Nov 2018 :  07:21:44  Show Profile  Reply with Quote
In the absence of the correct part, does anyone happen to know if there is an alternative steering column overdrive stalk switch that can be modified to fit the Rapier? The one I have has turned out to be incorrect and entirely unsuitable.
Thanks
Bob
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pruyter

Netherlands
320 Posts

Posted - 21 Nov 2018 :  09:54:02  Show Profile  Reply with Quote
You could try the overdrive stalks that were fitted to the Arrow (Hunter) range of Rootes cars. In principle it is the same stalk, but it looks a little bit different. Perhaps this stalk could be mended to fit your series Rapier.
By the way: did you try to approach Mike Langley for a stalk or Ebay? For instance last week I bought a spare overdrive stalk for my Rapier from Ebay.

Regards,

Peter

Edited by - pruyter on 21 Nov 2018 09:57:35
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bigt80

United Kingdom
1051 Posts

Posted - 01 Dec 2018 :  20:51:03  Show Profile  Reply with Quote
The club has plenty of 'Arrow' 'self-cancelling' o'drive switches in stock. Cheers. G
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jetglo

United Kingdom
17 Posts

Posted - 12 Dec 2018 :  08:45:28  Show Profile  Reply with Quote

John Roseby has just completed the overhaul and assembly of my spare gearbox and o/d unit: a super job of the highest quality.
Thanks for your advice on this.
Cheers
Bob

Edited by - jetglo on 12 Dec 2018 08:46:40
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