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Re: Hydrolastic Again! but testing this time
Posted: Sun Jun 11, 2023 3:56 pm
by richardACS
Aussie Bill B wrote: ↑Sun Jun 11, 2023 12:32 pm
A couple of suggestions about the hydro system for what they're worth:
1. there is a list of many hydrolastic suspension units and their applications here on this site at:
https://mk1-performance-conversions.co. ... _units.pdf
Orange coloured markers or sleeves on the rear helper springs and struts indicate the upgraded versions of stronger springs and slightly longer struts introduced in UK in 1965. Colours on the displacers themselves indicate the vehicle they were intended for.
THANK YOU AUSSIE BILL FOR THE INFO ON THE ORANGE MARKED ITEMS, IMPOSSIBLE TO KNOW WHETHER MINE ARE ORIGINAL TO BUILD ALTHOUGH THE 1965 DATES MIGHT SUGEST THEY ARE....
2. These displacer units are surprisingly tough and long-lived. Most failures are at either end of the rubber hose due to age. There are repairs possible for failure at either end. Internal failure of mini displacers is very rare.
GOOD TO KNOW AND I'M HOPING THAT IN LINE WITH ALL THE FASTENERS AND BRACKETS, THE NEW ZEALAND LIFE MIGHT HAVE ALSO PRESERVED THE DISPLACER CONNECTIONS, I HAVE BEEN AMAZED BY HOW WELL (THE F&B'S) HAVE ALL CLEANED UP AFTER GENTLE MEDIA BLASTING (HAVE USED GLASS BEAD), HAVE NOT FOUND ANY RUST PITTING ON ANYTHING AND THATS 2 YEARS SHORT OF 60 YEARS! - I DON'T BELIEVE ANY UK CAR WOULD HAVE SURVIVED SO WELL.. IN FACT I HAVE A SET OF DISPLACERS FROM A 69 MK 2 S AND THEY ARE AWFUL - VERY RUSTY AND RUBBER HOSES DETERIORATING.
My suggestion is to not bother with setting up a testing rig; fit the displacers during the rebuild, pressurise the system and watch for leaks - usually fixed by tightening the fittings or the schrader valves in the rear.
IT IS INTERESTING TO NOTE THE VARIED EXPERIENCE, BUT I WOULD HATE TO REASSEMBLE THE ENTIRE SYSTEM ONY TO FIND IT WOULD HAVE TO BE DISASSSEMBLED. MY CONFIDENCE IN THE COMPONENTS IS GROWING EVEN TO THE REPLATING OF THE HYDRO METAL LINES BUT ONLY BECAUSE OF THE AFOREMENTIONED COMMENTS AND TO RETAIN OE ITEMS SEEMS TO WORK BETTER.
3. Don't flush the system with water as it MUST promote rusting of the internal valves. Steel parts will not rust while emersed in hydro fluid. A few pump-ups-and-drains will flush out the system if it's a worry.
GOOD ADVICE.....
Thank you for the
Re: Hydrolastic Again! but testing this time
Posted: Sun Jun 11, 2023 5:22 pm
by mab01uk
You might also find this long thread linked below of interest....
The future of Hydrolastic suspension:-
http://mk1-forum.net/viewtopic.php?f=5&t=14542
Section through a Mini Hydrolatic Unit - (Sectioning & Photo: Tim of Minimail)
Re: Hydrolastic Again! but testing this time
Posted: Sun Jun 11, 2023 7:21 pm
by Peter Laidler
I would say, in response to Aussie Bills last comment about flushing, is flush the things to death - until clean clear water comes out. You're only FLUSHING them! Once they're flushed as clean and clear as you can get them, evacuate AND FILL with hydrolastic fluid. If you are particularly worried about any remaining water content, just bleed a bit off and test it for its SG.
Imn my amateur way of looking at these things, I just flushed mine out with distilled water from Robert Dyass. But that is a far better option, once again, in my simple opinion, than leaving any remains of the pure sludge and sewage that's within the system - and even worse, still lurking in the Dalek tank
The major problem we seem to have here is that the strut end bag (the 'lastic' part of hydrolastic don't forget) de-laminates. While a new hose is a simple fix (see your local BobCat skid steer specialist. He can do it. Alas, a delaminated strut-end bag is the end of the road. Ain;t nuthin' gonna fix it.
And just as Richard says, you're testing them OFF the car so that you don't encounter a leaky when it's ON the bloody car!. Those simple fill-with-air-or-water tests at low pressure WILL tell you. Ex physics teacher hat on now....... Remember your physics lessons from school, that under load or pressure, gas and air ALWAYS find the route of least resistance
Just my totally amateur, simplistic and oft repeated take on things
Re: Hydrolastic Again! but testing this time
Posted: Sun Jun 11, 2023 7:34 pm
by Spider
I gotta say, I do like Andrew's method of off car testing. Easy way to see if there's going to be any leak issues prior to fitting.
I fitted a bag not too long ago that while it looked very good, it leaked at the crimped hose connector when fitted up.
While the hoses can be replaced, many shops who have the crimpers can get their tooling deep enough in to the displacer to do them. A simple screw press / clamp can be made at home to depress the displacer to the position as shown in the centre of Martin's previous post, then take it to the Hydraulic Hose man like that, so he can get his tooling on your bag
Re: Hydrolastic Again! but testing this time
Posted: Mon Jun 12, 2023 8:32 am
by richardACS
mab01uk wrote: ↑Sun Jun 11, 2023 5:22 pm
You might also find this long thread linked below of interest....
The future of Hydrolastic suspension:-
http://mk1-forum.net/viewtopic.php?f=5&t=14542
Section through a Mini Hydrolatic Unit - (Sectioning & Photo: Tim of Minimail)
That's a very interesting link that gets to the nub, I wonder what became of the (US) engineer's work on his displacer - it all went quiet it seems...
As an aside, I find it amazing how well the rubber to metal adhesion has lasted without separating! that must have been some kind of adhesive.
One of the oft repeated comments mention that the performance of new displacers soon dropped off - I wonder what this means? as the comments do not include the symptons - I can only assume it means the car become less taut and more bouncy would that be a fair statement?
And if so I seem to recall that some owners used to add a conventional shock absorber to the front suspension to create further control on the front to rear motion - I wonder whether others have fitted this combination of wet dry and what their view is. I have always intended to go this route...
Re: Hydrolastic Again! but testing this time
Posted: Mon Jun 12, 2023 9:54 am
by Peter Laidler
Ah, back to the various diagrams and schematics of the workings of the system as shown above and elsewhere in the published world. Don't even get me started on the so called technical description within the various workshop manuals. Each one seemingly copied from another - and so on.
For example. If you've got an hour to spend inbetween watching the grass grow, take a look at the cross sectioned illustration above and compare it with the workshop manual......... Then try to compare the two - with the technical description that seems to defy logic. Someone suggested that the wording and illustrations were there to hide what actually went in internally. Certainly today, there's probably nothing going on except the free flow of fluid between the chambers, courtesy of the rusted out valving
The sectioned unit does effectively show the laminated expanding diaphragm at the strut end - the 'lastic' part of the displacer. Pliable and flexible with the rubber layers sandwiching layers of canvas and nylon multi-hatched cords for strength...... a bit like a Dunlop radial ply tyre!
During that earlier discussion between us, (thoughtfully mentioned by Mab, above), on and off the forum and on email, we seemed to agree that the only true way to see exactly what is happening inside a hydro unit was to radially separate one, in a lathe, by cutting along the rolled joint that separates the top sleeve from the bottom.
That's a good idea from mechanical maestro Spider Chris to use a screw press from the diaphragm end to move the hose nozzle outwards, in order to allow common hydraulic kit to re-hose the units. Here we have found that the compact BOB-CAT loader service agents, servicing Bob Cats with recessed hoses can re-hose. But maybe better to let your heart rule your wallet and utilise our own Mini suppliers/repairers for this
I'm sure that in the near future you'll settle on an acceptable answer to your quest Richard
Re: Hydrolastic Again! but testing this time
Posted: Mon Jun 12, 2023 11:33 am
by Aussie Bill B
Again, for what it's worth.... ignore the rambling comments.
Just fit the displacers, pump up and see what happens. Then you know what you're up against.
I fitted a full set of silver displacers to a 1966 S about 5 years ago. The used displacers were sitting in a box for maybe 20 years - not flushed, just corked off - and all 4 went to full pressure (minor leaks were from lose terminals). Still working well on the car now.
After 50 + years of owning minis with hydrolastic, my opinion is the displacers are better filled with fluid and working in a car than lying about.
