mk1-forum.net

A friendly international forum for people interested in the tuning & modification of classic BMC vehicles
It is currently Fri Oct 20, 2017 2:33 am

All times are UTC [ DST ]




Post new topic Reply to topic  [ 91 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 10  Next
Author Message
PostPosted: Sat Aug 05, 2017 9:41 pm 
Offline

Joined: Thu Aug 03, 2017 9:15 pm
Posts: 20
Location: Eugene, Oregon USA
Thanks. I have seen a difference in the central tower but I haven't paid much attention yet. I will. I'm not sure it matters. It occurs to me that the steel cone bonded to the rubber donut is normally displaced upward by the weight of the car. That will always increase the clearance from the unloaded condition. Since the system uses an incompressible fluid under pressure to transfer the load to the donut it will never be any lower. I also noticed on one of the cross-section views above that a bushing on top of the tower is inserted into the fluid exit port not unlike the needle on a SU carburetor. However under loaded condition with the donut displaced the bushing may be clear of the exit port. I don't know the spring rate of the donut that would allow me to determine the deflection. But it just occurred to me that I can rig up something to measured the spring rate. I think I'll do it.

It seems odd to me that the only difference is the metering valve. This valve really only serves the purpose of an integral shock absorber rather than change the spring rate. But perhaps I'm missing something.

I have a document that lists 21A1872 and 21A1874 as equivalent to 21A2012 and 21A2014, including the 1 silver band and 2 silver bands respectively on the hose. The difference in part number may be related to a manufacture site or time frame or even a price change.

If you have a 21A2012 that you can spare, I'll be able to make full Cooper S sets. After I rebuild my 4, I'll have enough cores to build on additional set.

I just saw the "Spider" post. the comment on tower height makes sense to me. It's just a different stamping, perhaps something easier to fabricate without changing the performance of the device. That may also be the differentiation of the equivalent part numbers noted above. No functional difference, just a manufacturing change.

Niles


Top
 Profile  
 
PostPosted: Sun Aug 06, 2017 12:39 am 
Offline
User avatar

Joined: Thu Feb 05, 2015 9:40 am
Posts: 999
Hi Niles, excellent work on the displacers, if Tim cannot find his I have a spare front S displacer with a rotten hose that I can send you.

This is an Australian displacer, I am not sure if it was manufactured in Australia, Winabbey or Spider would most likely know, both post regularly on here or if there are any differences between Australian and UK parts.

I too looked at cutting through the crimp but came to the conclusion that fitting, for want of a better term, a banded displacer back into the front subframe would be very difficult because of the very limited clearance.

Do you have a picture of your solution please?


Top
 Profile  
 
PostPosted: Sun Aug 06, 2017 1:26 am 
Offline
User avatar

Joined: Thu Apr 18, 2013 1:45 am
Posts: 146
Location: Melbourne, Australia
There's some detailed discussion here. Also my post with the Oz engineering drawing, if that helps.

viewtopic.php?f=28&t=15392


Top
 Profile  
 
PostPosted: Sun Aug 06, 2017 1:45 am 
Offline
User avatar

Joined: Mon May 07, 2012 6:10 am
Posts: 2397
Location: Big Red, Australia
I'm pretty sure the 'springing' between Cooper S 'Stiff' types and mortal Mini ones were the same in terms of spring rate, however the differences between them being the Damping Rates, so what you've found in regards to the internal Damper Valves sound bang on to me.

If suitable Dampener Valves can be made, this would make it perfectly feasible to convert Mini Bags to Cooper S (and other ST) types.

Great project.

Any photos?


Top
 Profile  
 
PostPosted: Sun Aug 06, 2017 2:14 am 
Offline
User avatar

Joined: Mon May 07, 2012 6:10 am
Posts: 2397
Location: Big Red, Australia
smithyrc30 wrote:
This is an Australian displacer, I am not sure if it was manufactured in Australia, Winabbey or Spider would most likely know, both post regularly on here or if there are any differences between Australian and UK parts.


I can't categorically say with any certainty if our Displacers were exactly the same as those from the UK. At a guess, I'd say they were (I think we only had 2 types ??), Doug would probably be better able to respond to this one.

Ours did have an Aust Part Number, in which that revels that they were both Drawn Here and Manufactured locally (Some parts while manufactured here were done so from UK Drawings & Designs).


Top
 Profile  
 
PostPosted: Sun Aug 06, 2017 4:13 pm 
Offline

Joined: Thu Aug 03, 2017 9:15 pm
Posts: 20
Location: Eugene, Oregon USA
I agree on the spring rates being the same for standard Mini and Cooper S applications. All the displacers I looked at have the 21A1477 part number molded into the face of the donut.
The comment on clearance to fit a banded displacer is absolutely correct. There is none. I tried a number of configurations and techniques to get a banded displacer into the subframe without altering the subframe and finally came to the conclusion that the modified device could be no larger in diameter than the original. This is especially true in the front subframe. The assembly retainer is just that. I have placed it in the subframe many times without difficulty. I didn't want to have to reconfigure the standard subframes.

The dampening valve is a rather simple affair. It can easily be recreated with the original rubber bits or recreated entirely with rubber of the same durometer. That may not be important either because the dampening rate is a function of the opening of the valve. Anything restricted to the same opening should provide the same rate. It just occurred to me that if the function of the metering valve is strictly dampening, perhaps it could be removed altogether and replaced with conventional telescoping shock absorbers. I believe there are kits available to add shock absorbers to Cooper S models that have been converted to coil springs. I’m not sure how that would affect the intent and performance of the front to rear fluid displacement.

In any case, the comment about converting standard hydrolastic to Cooper S specification seems to be correct. All the internal bits are the same. The only difference seems to be adjustment of the valve opening. Cooper S displacers can be created from any displacer with the 21A1477 spring unit once the dampening settings are known.

I have a picture of the retaining ring, but I not proficient in posting things: I don't know how to place an image in this text. I tried to attach it in the dialog box below, but I'm not sure it is successful. If anyone can provide guidance, I'll add images to my nest posting. sorry.

If anyone has a known part number displacer, send me an email and I will make arrangements to get it here for analysis.


Top
 Profile  
 
PostPosted: Sun Aug 06, 2017 7:09 pm 
Offline

Joined: Thu Jun 02, 2016 2:45 pm
Posts: 140
Spider wrote:
Sensational research, effort & work nileseh

timell wrote:
Another difference between S displacers and standard is the distance from the steel 'crown' to the top of the rubber doughnut spring (21A1477)...in S's it is about 30mm and on standards appears to be about 40mm. Have your dissections shown a specific reason for this?
Tim


Wonderful of you Tim to donate a Hydro Bag to the cause.

In regards to the difference in height, when I went through a number of Hydro Bags here a few years back, I found that height difference related to whether it was an early or late type of Bag, not if it was Cooper S.


More than happy to do it, if it helps prolong their availability for our use Spider......should be able to dig it out by Wed hopefully Niles, just hope the part no is still legible.
Regarding the Doughnut height Spider, I wonder if that may be specific to Aussie displacers; the 5 I have date from 66 to 71, and are all from S's with the doughnut recessed by 30mm. I also have 8 standard 21A2008's of various dates, all with the doughnuts at 40mm..another Moulton mystery?


Top
 Profile  
 
PostPosted: Sun Aug 06, 2017 8:12 pm 
Offline

Joined: Thu Aug 03, 2017 9:15 pm
Posts: 20
Location: Eugene, Oregon USA
Thanks. If the part number is not legible (I'm not entirely sure all of them were even marked with a part number, but I have seen some with the part number stenciled on the barrel) the banding on the hose is also indicative: 1 silver band is 21A2012, 2 silver bands is 21A2014.


Top
 Profile  
 
PostPosted: Sun Aug 06, 2017 8:44 pm 
Offline
User avatar

Joined: Sun Oct 07, 2012 8:28 pm
Posts: 104
Location: Lugano, Switzerland
Very interesting... If you send me photos by mail, I public on the forum. hb9fez(et)gmail.com


Top
 Profile  
 
PostPosted: Sun Aug 06, 2017 11:22 pm 
Offline
User avatar

Joined: Thu Jun 24, 2010 7:08 pm
Posts: 2743
nileseh wrote:
I have a picture of the retaining ring, but I not proficient in posting things: I don't know how to place an image in this text. I tried to attach it in the dialog box below, but I'm not sure it is successful. If anyone can provide guidance, I'll add images to my nest posting. sorry.


Great work and research on the mysteries of Hydrolastic! 8-)

For adding pictures as attachments see Forum help here:-
viewtopic.php?f=33&t=10177

Better still register free with 'Imgur' below to host them, then simply drag your chosen photos over to upload them to your new Imgur account and then copy/paste the image link code for each photo into your post on the Mk1 forum to share the images.
http://imgur.com/


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 91 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 10  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 13 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
Localized by Maël Soucaze © 2010 phpBB.fr