Are the hydrolastic displacers all the same or is cooper S different? Also what is the best way to check the displacers for leaks? Thanks, I have a 1970 mini cooper S under restoration.
P7676

Cooper 'S' hydrolastic bags are different to other Mini bags. I think it's the valving.

Cooper S bags (most) have the rubber cone about 10mm below the top lip of the displacer body.
On Deluxe, K or Matic displacers it is over 20mm below the lip.
So I suspect the rubber cone part of an S bag is thicker, but no I have not cut any up to check.
Yes the S valving is different.

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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.

Here's a list of the unit numbers for different hydro units that I found on the web:

FRONT:

Part# Application Body# (not exact numbers)

21A1477 Cooper to 830000
21A1804 Cooper to 1025600
21A2008 Cooper 1025600 on
21A1872 Cooper 'S' to 1025600
21A2012 Cooper 'S' 1025600 on

REAR:

Part# Application Body# (not exact numbers)

21A1477 Cooper to 830000
21A1804 Cooper to 1025600
21A2008 Cooper 1025600 on
21A1874 Cooper 'S' to 1025600
21A2014 Cooper 'S' 1025600 on


SPECIAL TUNING!

Part# Application Front/Rear Colour Band

C-21A1693 Rally front 1 yellow
C-21A1705 Rally front or rear 1 yellow
21A1811 Rally front or rear 2 orange

C-21A1819 Race front 1 red
C-21A1821 Race rear 2 red
21A1872 Race front 1 blue
21A1874 Race rear 1 blue

These part numbers are form the Austin and Morris Mini Cooper and Cooper
'S' Mechanical Service Parts Catalog (AKD 3509) form 1965, so they
should be correct. It does include exact(?) body numbers for each of the
units but the list would be a lot longer...

Those numbers are for UK bags on UK cars...
We made hydro bags here at the Dunlop factory, Birkenhead Point.

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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.

I have a 8/70 S - ex NSW police.
1969/1970 Mk2 S would have 21A2012 displacers fitted to front (1 silver band on the hose near where it attaches to the interconnecting pipe to the rear). Rear displacers are stamped 21A2014 on the body of the displacer and might have 2 silver bands sprayed onto the hose near their end.
This spray-on band was not always visible in the period but is always visible on restored cars. The part number is stamped onto the body of the displacer but may need cleaning to read.
As best I can follow all the displacer evolution, each development meant a stiffer spring/or damping rate. Silver (and blue) were about the ultimate spring/damper rates for minis using hydrolastic suspension. For road cars, it is a very good system as I use it.

As for leaks, when you fit them and pump them up, they could leak slowly. You will see one side of the car slowly falling. The hydrolastic fluid will evaporate very quickly and you may not see it on the garage floor.
Most faults with hydrolastic displacers are at either end of the hose attached to the displacer or to the car and can be repaired by Pirtek etc.

Allen,

With all the responses provided I'm curious to know if you were you able to determine whether they're S bags or not?

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Jenk.

These are the bags I had on my Cooper 'S'



I am looking to get back into a Cooper 'S' or Clubman GT, so please let me know if there are any out their needing a new home.

This table is from the Australian displacer engineering drawing. YDO5 is Mini and YDO6 Cooper S.

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

There are a few very nice Cooper 'S' for sale , you just need a spare $40K or $50K

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1965 Morris 850
1966 Morris Mini Minor
1967 Morris Cooper 'S'
1977 Leyland LS

I believe my car still has 'S' bags fitted (at the front at least) and it was interesting to ride in your car several weeks back Bill. Every mini feels bit different and yours felt a little more firm than mine, I was wondering have you added shocks to the front?

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

My car and Lillee's both have front shocks. I have S front bags he has K. Both ride the same as far as I can tell by driving both.

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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.

Lots of info here. The 21A2012 and 21A2014 or whatever type you have is stamped into the metal with the year if the paint markings have faded or gone. Pics in link below.

viewtopic.php?f=2&t=84897

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

No front shocks added to the S. Does have competition bumpstops at rear, but they are cut down so suspension isn't riding on them. The displacers are all original.