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 Post subject: Displacer - volumes
PostPosted: Fri Feb 08, 2019 1:37 pm 
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Location: Sth of Ipswich in the Scenic Rim
Has anyone else measured the volumes of their displacers when they were cleaning them?
My 69 Cooper S had a 21A 1477 on the left hand front, a 21A2012 on the right hand front and both rears were 21A2014.

When I cleaned them out I noticed that the 1477 did not take as much fluid as the 2012 and the 2014's.
The 21A1477 was 225ml
The 21A2012 was 290ml
The 21A2014 were in the range of 270 to 280ml.

I also have a 21A2008 and it only took 175ml.


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 Post subject: Re: Displacer - volumes
PostPosted: Sat Feb 09, 2019 10:15 am 
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848cc
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I have never measured the volumes all I do is make sure they are the same numbers both sides I have CS numbers at the back and the front displacers have the same part numbers but not CS they work OK.When I got the system evacuated and pumped up the technician knew how much fluid to fill the system both sides.
Allen


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 Post subject: Re: Displacer - volumes
PostPosted: Sat Feb 09, 2019 12:36 pm 
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848cc
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Location: Sth of Ipswich in the Scenic Rim
When I noticed the difference in amounts of fluid to fill each displacer to the top of the connecting hose, I wondered if the 'S' displacers had a larger volume than standard displacers.

In my parts manual, it says the replacement displacer for both deluxe and Cooper S (Code 6 & 7) have a part number 21A1477. I wonder if 21A2012 and 21A2014 were only available during manufacture with replacement displacers only available as 21A1477.

I have a spare 21A2014 but not another 21A2012 to have matching displacers on the front. I always thought my car rode nice and firm, so I am inclined to put back what was already on the car.


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 Post subject: Re: Displacer - volumes
PostPosted: Sat Feb 09, 2019 2:49 pm 
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998cc
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Joined: Sat Feb 09, 2013 5:44 pm
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Location: Camden
The code "21A1477" is cast into the rubber around the hose connection on every displacer I have seen for both Deluxe and S models for front or rear. 21A1477 may have been the part number for the first displacers.
All the displacers you have should have 21A1477 on the rubber.
Later displacers usually had their part number stamped onto the metal barrel, along with paint codes.
I have never measured the volume of a displacer as I have never been able to empty or refill one satisfactorily. I'm not sure there is any point.
The accepted wisdom is to have matching displacers on the same axle. However, if it seems to work well for you, then OK.
21A2012 and 21A2014 were the stiffest settings and used for later Mk1, all Mk2 and GTs. 21A2008 was late Deluxe, mini K & clubman with hydro.
When pumping up the system, the amount of fluid is not measured and the pressure not important, within limits - the aim is to get ride height the same for both sides at the front (cannot set rear height independent of the front).


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 Post subject: Re: Displacer - volumes
PostPosted: Sat Feb 09, 2019 4:40 pm 
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848cc
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Location: Sth of Ipswich in the Scenic Rim
The displacer that was on my left hand front is stamped 227 21A1477 N74 on the side of the steel casing.

Regards Fritzie


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 Post subject: Re: Displacer - volumes
PostPosted: Sat Feb 09, 2019 5:14 pm 
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998cc
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Location: Camden
Fritzie wrote:
The displacer that was on my left hand front is stamped 227 21A1477 N74 on the side of the steel casing.

Regards Fritzie


Thanks for the reply.
It is very interesting that those numbers are stamped on the case. The only references I have to 21A1477 lists it as the original displacer for minis; and also for early Cooper (not "S") for Front & Rear (in UK). They were made in about 1964.

Does the rubber part also have the 21A1477 cast in?

The last 3 letters/digits (N74) are usually digits only, indicating month/year of manufacture. But 1974 is too late for hydro - as it ceased in 1971.

Are the stamped numbers clear to read? Just a thought that the only numbers remotely similar to 21A1477 and possibly able to be misread are 21A1872 or 21A1874.


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 Post subject: Re: Displacer - volumes
PostPosted: Sat Feb 09, 2019 7:31 pm 
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848cc
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Location: Sth of Ipswich in the Scenic Rim
I have just rechecked the stamped number. I am sure that is 1477. The 4 and the 7's are definitely the same as the stamps in the N74.
Is it possible that displacers were still being made in 1974 as replacement parts? I have an BMC parts manual that shows on Page H.11 and Page K.5 that displacer replacement parts for both Mini Deluxe and Cooper S were Part No. 21A1477.
As in all my other displacers, 21A1477 is marked on the rubber component.

Regards Fritzie


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 Post subject: Re: Displacer - volumes
PostPosted: Sat Feb 09, 2019 8:43 pm 
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998cc
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Location: Camden
I can't add much more. Attached is a page from Leyland ST for 1275GT and Cooper S showing most of the displacers for most minis and I don't think just Cooper and S. For instance it lists 21A2008 which was the Deluxe/K displacer.


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 Post subject: Re: Displacer - volumes
PostPosted: Sun Feb 10, 2019 10:23 am 
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Bill B wrote:
I can't add much more. Attached is a page from Leyland ST for 1275GT and Cooper S showing most of the displacers for most minis and I don't think just Cooper and S. For instance it lists 21A2008 which was the Deluxe/K displacer.


interesting! that's the first time I've seen an actual measurement for the restrictor - 0.025"

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 Post subject: Re: Displacer - volumes
PostPosted: Sun Feb 10, 2019 10:41 am 
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998cc
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Joined: Wed Sep 30, 2015 9:38 am
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Location: Brandy Hill, NSW
Is the restrictor placed in the bags or the connecting tube?


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 Post subject: Re: Displacer - volumes
PostPosted: Sun Feb 10, 2019 11:20 am 
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848cc
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Joined: Sun Mar 16, 2014 11:01 am
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Location: TOWNSVILLE NQ
When pumping up the system, the amount of fluid is not measured and the pressure not important, within limits - the aim is to get ride height the same for both sides at the front (cannot set rear height independent of the front).[/quote]

I tend to disagree with "pressure is not important". Standard ride height for a CS is 12 1/4" with a pressure of about 295 psi max. If you don't come within those parameters ie. pressure is too high.
You will need to fit spacers to the strut foot.


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 Post subject: Re: Displacer - volumes
PostPosted: Sun Feb 10, 2019 12:57 pm 
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998cc
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Location: Camden
Stibbsy wrote:
When pumping up the system, the amount of fluid is not measured and the pressure not important, within limits - the aim is to get ride height the same for both sides at the front (cannot set rear height independent of the front).


I tend to disagree with "pressure is not important". Standard ride height for a CS is 12 1/4" with a pressure of about 295 psi max. If you don't come within those parameters ie. pressure is too high.
You will need to fit spacers to the strut foot.[/quote]

When I said pressure was not important, I added 'within limits'. What Stibbsy has said on here are exactly the 'limits' I had in mind.
Since Fritzie's original post seemed to be concerned about having displacers with differing volumes, I was trying to get to the more relevant measurements when they are on a car - like ride height.
Measuring displacer volumes is a bit like comparing the volume of party balloons - you don't expect them to be identical so long as they all blow up and hold air.


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 Post subject: Re: Displacer - volumes
PostPosted: Sun Feb 10, 2019 2:50 pm 
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848cc
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Location: Sth of Ipswich in the Scenic Rim
Attached are photos of the 227 21A1477 N74 displacer.

I have cut away most of the rubber that had rust behind it. Is the rubber on this displacer, typical of how the rubber on a Cooper S displacer goes further up the sides?

I was going to get a new rubber hose fitted, but feel that the ferrel into the rubber may be too rusted.


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 Post subject: Re: Displacer - volumes
PostPosted: Sun Feb 10, 2019 3:54 pm 
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998cc
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Joined: Sat Feb 09, 2013 5:44 pm
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Location: Camden
Fritzie,
Thanks for the photos - not that I didn't believe you! Now we are waiting for someone else with more information.
Re the displacer condition:
I don't think the slight peeling of rubber from around the barrel is much of an issue. Bad rusting might be treated by cutting back the rubber and using fishoil as I don't think it is detrimental to rubber.

The hose end might be a future fail. The rubber loses its elasticity and can pop off the displacer even if the ferrule is OK.
Has happened to one of mine which I have had repaired by Pirtek. See photo.
The ferrule and hose is removed leaving a short stubby spout in the displacer. Pirtek and others have a small threaded joiner that can grip the spout and leave a threaded end to attach to a new hot with suitable unions.
Purists are not happy that the original hose pattern is not available.


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