There's some Australian displacer part numbers and the UK equivalent in this extract from a factory drawing for the Mini (YDO5) and Cooper S (YDO6).

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Thanks Winabbey,
Approximately what year was this specification written for?
The 1966 S I am restoring has displacers without numbers stamped on the casing, but at least one bag has traces of yellow
paint on the hose and the end strut is about 2mm longer than the usual later struts. I assume it is 21A1693 or 21A1705. Do you know if either of these were
fitted to Australian-built Ss?

Just to revive this post, I have just been researching this having just removed my hydro bags from the subframes. I noted the 21A1477 numbers on the top and assumed my S hydro bags had been replaced at some stage as this was the number for 'normal' use. Once I found this and another thread I realised there is also a model number stamped into the body in the middle. I couldn't see any body numbers until I looked closer and removed a bit of paint. I thought I would add these pics to this post in case anyone else is trying to find out what they have. I have only looked at the rear so far but have the following numbers. 167 21A2014 67 and 258 21A2014 67. From this I gather I have the original correct Cooper S bags and will check the front soon which will also require some paint removal but they should be 21A2012 according to the preceeding information. What I still haven't worked out from all the info is what the first three digits represent? In my case I have 167 and 258 both on the rear. Does anyone have any ideas on this? Unfortunately one of my rear bags has rusted out around the end as shown in the picture so that will require replacing so if anyone has a 21A2014 for sale please let me know. Dr Mini suggested it is OK to put 'normal' 21A1477 type on the rear and keep the spare 21A2014 for the front but if I could find a 21A2014 it would be even better. That is WD40 and not a leek on the dry looking one to see the numbers not that it matters as the end is damaged as shown below.









the damaged one! Bugger. Worked OK on car but needs repalcing.



The info below was from a UK mini forum:

S Hydrolastic units were stiffer than standard units, identified by the coloured bands.

Early Hydrolastic Mini's pre 68:

Normal front – no marking part no 21A 1477
rear - no marking part no 21A 1703

Stiff front and rear 1 Yellow band part no C-21A 1705

Hard front 1 Red band part no C-21A 1819
Hard rear 2 Red bands part no C21A 1821

Late Hydrolastic Mini's post 68:

Normal front and rear 1 orange or green band part no 21A 1804

Stiff front and rear 2 orange bands part no 21A 1811
Hard front 1 Blue or silver band part no 21A 1872 then 21A 2012
Hard rear 2 Blue or silver bands part no 21A 1874 then 21A 2014

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Flute - 68 MK I Cooper S
Member: VMCI #2474
Member: International Mini Model Collectors Club

Coopers had rubber donuts Not hydrolastic???
(English coopers?)


The GT bags I have dismantled havn't had any numbers on them all

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Yes UK 998 Cooper had hydro until discontinued in 1969.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

My mid 67 mk2 S has the blue banded 1872 and 1874 displacers (part number stamped and stencilled) and from some of the comments above the change to silver marked displacers must have happened around that time? my early mk2 S has 2012 and 2014 (stamped and stencilled), and my Clubman GT's have what I believe to be just orange paint dots near the top of the displacer (although I have heard people say they were pink dots?) and they are genuine GT displacers.
Cheers
Rod

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1967 New British Racing Green Mk1 Cooper S, 1967 Lake Green 1275 MG Midget, 1969 Jet Red / Crystal White Mk2 Cooper S, 1972 Gambier Turquoise Clubman GT (ex police), 1972 Camino Gold Clubman GT, 2009 JCW Challenge Edition, Megane RS265, Clio RS220.

So my late 68 S 21A2012's and 21A2014's would lead into your early Mk2 S with the same bags. I can't see any banding or paint marks on mine as they have been sprayed over. Thanks for info.

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Flute - 68 MK I Cooper S
Member: VMCI #2474
Member: International Mini Model Collectors Club

I think I have some photos somewhere I'll try to dig them up and post.
Rod

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1967 New British Racing Green Mk1 Cooper S, 1967 Lake Green 1275 MG Midget, 1969 Jet Red / Crystal White Mk2 Cooper S, 1972 Gambier Turquoise Clubman GT (ex police), 1972 Camino Gold Clubman GT, 2009 JCW Challenge Edition, Megane RS265, Clio RS220.

I have now cleaned up my front bags and confirmed they are 21A2012's with 68 year stamp even though the rears were stamped 67. Interestingly the prefix number prior to the part number are both 23 whereas my rears have 167 and 258. My assumption is that those must be batch numbers and by chance my front are the same and the rears are different. With a bit of a scrub the top rubbers came up like new but I will have to clean up around the edges a bit. As mentioned earlier the tops all have the part number 21A1477 on them. I will continue the hunt for a replacement 21A2014.

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Flute - 68 MK I Cooper S
Member: VMCI #2474
Member: International Mini Model Collectors Club

I wonder if the batch number might be a day of the year number (Julian Code).

To Flute:
I think the corrosion damage to your displacer might be 'just a flesh wound' - it might not "buff out" but I've had a rear one with not so bad rust and was still working. The rusted section doesn't really provide any structural support. Worth trying to reuse.

Thanks for the info Bill B. It didn't leak in the car and worked fine ( I never knew it was in that condition until I took it out) but I thought not ideal to put back in when I am down to a nut and bolt resto but I will definitely keep it in reserve. One problem is the dust cover doesn't stay on properly as most of the lip is gone. I think using one in better condition would be the best way to go if I can get one.
I like the 'Julian Code' theory Morris 1100, that would be highly plausable! Unless someone has one numbered higher than 366 (allowing for leap years in the code) I think you are right! So my front ones were made on the 23/01/68 and rears on the 16/06/67 and 15/09/67. Interesting.
More hydro displacer posts here too.

viewtopic.php?f=2&t=41713&start=15

viewtopic.php?f=2&t=68874&hilit=21A2014&start=15

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Flute - 68 MK I Cooper S
Member: VMCI #2474
Member: International Mini Model Collectors Club

To Flute
The boot retaining lip is a problem. If determined, a made-up shroud to hold the boot could be clamped on with a hose clip.
I was interested to see that your photos show the displacers with stencilled numbers as well as stamped numbers. I've only seen metal stamped numbers and colour bands on silver displacers. I will have a look through my bits for a rear 21A2014. Cannot guarantee if any of them work, but the rear ones tend to survive better except if they get water behind the boot, as yours did.

Was cleaning up my hydro bags today and on the hoses discovered Dunlop markings so thought I should add a photo here of the best one (others pretty faded or invisible) for completeness for anyone else looking at this thread in the future. Not sure if I should re spray the silver bands on the hoses or just leave them original.







This is the gunk that came out of four bags when flushed out. To flush I filled with water and then injected it into the bag with an air hose and then held inverted and put more air in forcing the fluid and gunk out. Did this about 6 times until clear and then filled with radiator fluid and put a rubber cork in from Clark Rubber and store until the rest of the car is ready.







Re paint silver bands or leave?



I would like to blast and repaint the unit too but then I will loose the silver stencil numbers painted on them. Maybe just a coat of clear over them to stop any rust??

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Flute - 68 MK I Cooper S
Member: VMCI #2474
Member: International Mini Model Collectors Club

Anyone got some spare bags to sell please PM me

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1970 MK2 Cooper S