19 replies to this topic

[M14esp]

I have recently bought a mk1 copper s which has got twin tanks but on closer inspection it appears to have had the right hand tank retro fitted at some point in its past. Now my problem is do I refit the right hand tank during the resto or do I remove the tank and it's fittings and return it to factory. Any thoughts or opinions welcome cause I can't decide!!

[Cooperman]

With just an original 5.5 gallon tank the range of a Mk.1 Cooper 'S' is abysmal. We used to have to refuel about every 125 miles. Virtually every Mk.1 'S' had twin tanks either as standard if built after the end of 1965 or retro-fitted if earlier than that.

[M14esp]

Hi think it was built oct 65 ? Well that is what everything seems to be stamped? So you would keep the second tank cooperman ? Cheers for response

[bmcecosse]

It should indeed have twin tanks - so if you suspect it has been retro-fitted, you have to wonder if you have a Cooper S.......or just a Mk 1 Mini that looks a bit like a Cooper S.

[M14esp]

It is a definite 's' well according to the log book and all the matching numbers !
Would a heritage certificate tell me if it was a single tank cooper or twin ?

[Cooperman]

An October 1965 registered car could have been manufactured as a single-tank car. The twin tanks were not homologated in time for the 1966 Monte-Carlo Rally and twin tank homologation didn't happen until about March '66 (that's from memory) and one might guess that twin-tank production would have started in late 1965. If the OP's car was made in, say, mid-'65 it could have sat at a dealers for a month or so before 1st registration. It is right 'on the cusp' of twin tank production. A Heritage Certificate will give the actual production date and it may be possible to identify the date of first twin-tank manufacture.
However, twin tanks are desirable in a genuine 'S' due to the high fuel consumption of around 25 mpg if driven as an 'S' was intended to be driven.

Edited by Cooperman, 17 September 2012 - 07:27 PM.

[M14esp]

Cheers cooperman think that has made my mind up you really do know your stuff !

[Artful Dodger]

how much do you want for the right hand tank? Pm me please

[bmcecosse]

I serviced for two B registered (so 1964) Cooper S cars - and both had twin tanks as standard. Were they an optional extra at that time ?

[dklawson]

Roy, the RH tanks and oil coolers were optional on the -S until 1966.

My car is from the summer of '64. Its Heritage certificate lists my car's oil cooler as a factory option. There is no mention of the RH tank... which was on the car when I bought it. The tank was clearly added to my car prior to 1972 when it was exported from Europe to the U.S.

[bmcecosse]

I knew the oil cooler was fitted later - when there too many engine failures with low pressure! But not the RH tanks.......thought they were a fitment pretty much from the beginning.

[Cooperman]

On the ill-fated 1966 Monte the 'works' Group 1 cars did not have twin tanks because they were still a Group 2 option noit a Group 1 standard fitment. The result was that BMC had to send out special re-fuelling crews to put in petrol almost before every other special stage. As a rally fuel consumption for the Group 1 cars was about 14 mpg on the stages and 20 mpg on the road sections the effective rally range was about 90 miles in order to have a 1/2 gallon reserve.
Group 1 homologation of the twin tanks was from around March 1966. Of course, looking at the photos of competition Minis before and after that time won't help as normally the cars were used in Group 2 form, so the optional tanks were OK from 1963 onwards, just not allowed when the cars ran in Group 1 form before that time.

Edited by Cooperman, 17 September 2012 - 11:25 PM.

[pdaykin]

I think the official introduction date for twin tanks was Jan '66 which means very late 65 S may have had them from the factory.

I think an Oct '65 would be too early for factory twin tanks - they were available as an option but I'm told it wasnt a particularly popular factory fit option.

Record quality seems to vary (what is reported seems to vary on the same car too !!!), but a heritage certificate will normally tell you if twin tanks were fitted as "standard". Even if they were fitted as "standard" the certificate still lists them as an accessory.

[Cooperman]

It's the FIA Homologation Papers which define whether an item is 'standard fitment' or an 'optional factory-fitted extra'.
The same applies to the Hardy Spicer drive shaft couplings which were not fitted as standard until late '65 or early '66.
My homologation papers are the 1964 issue and list the twin tanks as a 'Group 2' option.

[ace01]

Twin tanks were an option from the first minis in 1959. My Cooper (61) was fitted with an extra tank, proven by early photos of it. So many early S's had them fitted as an option.

If I recall correctly, the hardy spicers were not homologated by the time of the Monte in 66 and Stuart Turner was concerned that this would be picked up when the strip down of the winning cars took place.