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Cooper Citroen Type Gear Boxes


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#1 Stefan Schmidt

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Posted 07 December 2013 - 13:36

Can anybody help me.. I have learn that the F1 Coopers such as the Cooper T51 were fitted with Citroen Type gear boxes before they used the awful Colotti gear box.

 

My question is now, which Citroen Gear Box was in use and in which way was in modified?

 



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#2 Allan Lupton

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Posted 07 December 2013 - 18:13

 

Can anybody help me.. I have learn that the F1 Coopers such as the Cooper T51 were fitted with Citroen Type gear boxes before they used the awful Colotti gear box.

 

My question is now, which Citroen Gear Box was in use and in which way was in modified?

 

Well the four-cylinder Citroen of the day was what we in the UK called the Light 15 or Big 15 and my understanding was that the gearboxes came from those.

The normal gearbox was a three-speed job so I think one modification would have been to make it four speed, possibly at the expense of reverse.

Since the gearbox in the Citroen is ahead of the engine and the Cooper has the gearbox behind the direction of rotation may have been wrong but I can't remember. If I have that right I can't remember if the gearbox was just modified to be installed upside-down or a new bevel pair were made to run with the big bevel on the other side.



#3 Bloggsworth

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Posted 07 December 2013 - 18:41

IIRC the Coletti box was only used by the teams Moss drove for, as Cooper wouldn't allow Moss to use the ERSA gearbox (Presumably to try and make the Moss cars uncompetitive with the works cars). The design of the Coletti box was OK, it was machining errors which caused the unreliability.

 

I think the F3 Cooper's box had reverse, it's nearly 50 years since I last drove one. The FWD to RWD change was accomplished by just turning the diff over from left to right. Limited ratio changes were effected by splitting the box at the diff housing and changing transfer gears, which, of course, change all the ratios relative to the diff ratio - In effect one was really only changing top gear to achieve max revs on the longest straight. Sounds easy, it wasn't, the gearbox was probably heavier than the "A" Series engine, and single handed, took hours, whereas changing ratios in a Hewland Mk9 could be done in about 20 minutes.



#4 Dick Willis

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Posted 07 December 2013 - 23:49

Have a look at the Crosthwaite and Gardiner website where you will find exploded views of the gearbox.



#5 Roger Clark

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Posted 08 December 2013 - 00:06

Well the four-cylinder Citroen of the day was what we in the UK called the Light 15 or Big 15 and my understanding was that the gearboxes came from those.
The normal gearbox was a three-speed job so I think one modification would have been to make it four speed, possibly at the expense of reverse.
Since the gearbox in the Citroen is ahead of the engine and the Cooper has the gearbox behind the direction of rotation may have been wrong but I can't remember. If I have that right I can't remember if the gearbox was just modified to be installed upside-down or a new bevel pair were made to run with the big bevel on the other side.

Surely the four cylinder Citroen of the day was ths DS which had a four speed gearbox -probably similar to the Light 15's though.

Cooper modified the Citroen gearbox with strengthening ribs on the casing, step up gears to allow the engine to be mounted lower in the chassis and higher grade steel in the gears themselves. As stated above, the works team didn't use a Colotti box. They switched to their own 'box in 1960.

#6 Allan Lupton

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Posted 08 December 2013 - 09:27

Surely the four cylinder Citroen of the day was ths DS which had a four speed gearbox -probably similar to the Light 15's though.

Cooper modified the Citroen gearbox with strengthening ribs on the casing, step up gears to allow the engine to be mounted lower in the chassis and higher grade steel in the gears themselves. As stated above, the works team didn't use a Colotti box. They switched to their own 'box in 1960.

The DS may have been 4-speed but it had a hydraulic-operated semi-automatic change system.

The L15 gearbox was a two-shaft job with the input shaft above the diff, so mounting it upside-down lowered the input shaft - can't think where step-up gears would be used.

I can't find a drawing of that gearbox except in my books, posting which is all too difficult.



#7 Roger Clark

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Posted 08 December 2013 - 09:53

The DS may have been 4-speed but it had a hydraulic-operated semi-automatic change system.

The L15 gearbox was a two-shaft job with the input shaft above the diff, so mounting it upside-down lowered the input shaft - can't think where step-up gears would be used.

I can't find a drawing of that gearbox except in my books, posting which is all too difficult.

There was, of course, the ID a simplified DS with manual gear change.  however, I think you're right about the origins of the gearbox: the first Climax engined cars, the T39 Bobtail had a Light 15 derived gearbox.  A Paris firm, ERSA, produced a four speed conversion and this was used by Cooper at Francis Beart's suggestion.  This is from Cooper Cars, page 121.  Doug also describes the step-up gears (page 154) introduced for the 1958 Mark III or T45.