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Hi quick question again I know what most people are using in their hydraulastic suspension but what my question is is there an actual Factory type of fluid that should be used from the factory when it was installed originally installed.

BLACKJACKф wrote: ↑Sat Apr 22, 2023 2:10 am Hi quick question again I know what most people are using in their hydraulastic suspension but what my question is is there an actual Factory type of fluid that should be used from the factory when it was installed originally installed.

This thread might be helpful if you’re planning on making up your own…:

http://mk1-forum.net/viewtopic.php?t=13954

If not, I believe ready made stuff can be purchased still from parts suppliers.

Hope this helps!

There were several versions of the fluid used across the BMC range of hydrolastic vehicles (Mini, 1100, 1800), and even different formula mixes for the Mini depending on geographic location (hot to freezing) and application (road, racing).

The specification in the BMC Australia Standards manual covers five pages so a bit big to be posted here. It gives the precise ingredient mix for the various applications. Some tweaking of the mix was done at times to eliminate squeaking, for example.

On the basis that you can't compress a liquid you could use plain water - or better still, distilled or de-ionised water! Which is 90% of what hydro fluid is. Together with some antifreeze and anti corrosion mixture thown in for good measure. But even then, the pipes rust through and the front bulkhhead adaptor* corrodes internally and prevents virtually ANY transfer of fluid front to rear.

As a matter of probably little interest, when I restored my car in the mid 80's, starting with all new pipes and displacers, I used silicon brake fluid throughout and never looked back until an overhaul 8 years or so ago.

More importantly, and I don't want to treach my grandma to suck eggs here, when you need to inflate the system, make sure that you FULLY evacuate the system THEN FLUSH IT THROUGH to get rid if the residual crap then flush the cabinet tank and system so that only new fluid is pumped into the car hydro system instead of the usual shite that is usually in the tank

You have probably guessed my opinion of the hydro system from an engineers perspective.

*(Catmint make a stainless steel versions of this now. The best improvement in hydro since it was invented)

Also lots of good info in this long running thread linked below.

The future of Hydrolastic suspension:-
http://mk1-forum.net/viewtopic.php?t=14542

It's still available from the usual sources

http://www.minispares.com/product/Class ... o%20search

Good to read that thread again, so thanks Martin. Certainly some good input from Spider Chris, Geroch and that absolute hydro maestro, NilesEH plus others. I remember having long off-forum PM's with Chris and Niles back in the day. But we really haven't got any further. Except......

To look after what you have got, keep the fluid new and clean and if the steel casings are looking dog eared and corroded, to gently soda (?) blast, paint and wrap in that smelly, sticky DENSO tape stuff. Especially so when it comes to the front hydro units..... Drill a 1/4" dia vent hole through the top of the displacer, JUST clear of the diaphragm (the 'lastic part of hydrolastic) so that crap and water CANNOT collect in the sizeable bowl to eventually rust out the steel crimp that locks the hose to the unit. And as a secondary measure, wrap those crimps in DENSO tape too.

The best advice to those with hydro cars is not be scared of hydrolastic

Can one fill the pipes with vinegar - let it stand overnight - to clean the inside of the pipes?
They are disconnected from the displacers at the moment.

Arctic Circle wrote: ↑Sat Apr 22, 2023 8:00 pm Can one fill the pipes with vinegar - let it stand overnight - to clean the inside of the pipes?
They are disconnected from the displacers at the moment.

Good question - about to address this myself - will welcome thoughts/tips/experience....

Yep, a good question with an alternative answer. Some time ago someone suggested using a long length of the spiral springy curtain rail wiry stuff (cheap per yard at any local haberdashery shop). Open up the first inch or so and start sending it down the hydro pipe. Alternatively, set it rotating slowly in a battery drill. Being springy and able to spin/rotate, it will find its own way through the bends in the pipe. Do it from both ends and watch how it descales and clears the crap out of the pipes.

Not done it myself but clearly you\ll be able to do it in situ too. Flush pipes out and there it is.

Don't foorget that by using readily available bits from any hydraulics supplier you can pressurise your pipes to water mains pressure if you need to test them

From memory… I ended washing out / shaking the displacer once full and emptying, did this for at least 1hr on each displacer until the water ran clear out of the units. I used a spare connector (one off the rear subframe) and adapted this to take the he hose pipe to aid cleaning. Once cleaned I tested each unit over night on the hose pipe.
Once tested I ended up putting some brake pipe down mine to straighten the run pipes and let it drain upside down into a container. Once drainer, cleaned, painted and red rubber greased the rubber parts.

I am a bit unsure about using a curtain wire to clean the line. If it gets stuck inside the line during the process you get a serious problem.. I used vinegar and gravel in the petrol tank/s for cleaning and rust removal, was fitted in/on a cement mixer, the steel was like new after a few hours.

Found that Grass Strimmer the "Nylon Strimmer Strand " stuff of the thicker type is ideal to clear through blocked tubing

all brilliant ideas for sure. Colonel Mustard has the idea though. Just look after what you've got. I think that you're being a tad OVER cautious Arctic Circle. If the twizzly curtain hanger wire gets stuck, you pull it out and it unwinds, getting narrower until it frees itself. As a result of this idea several years ago I use the same method to clean my kitchen sink, shower and bath plug holes. Great stuff for finding its own war around U bents etc etc

While I think about it, there was a suggestion to let the hydro units dry inside (don't ask me how as I don't remember) and then puur some of that latex rubber solution inside so that it collects and hopefully seals the bottom strut end. My son and his cyclists pals use it to seal their road and track/cross country bike tyres. I did try it with a dodgy unit and pumped it up with air to 70psi and left it dangling for many days and the pressure held up. But ain't used it on the car - yet!

Arctic Circle wrote: ↑Sun Apr 23, 2023 1:35 pm I am a bit unsure about using a curtain wire to clean the line. If it gets stuck inside the line during the process you get a serious problem.. I used vinegar and gravel in the petrol tank/s for cleaning and rust removal, was fitted in/on a cement mixer, the steel was like new after a few hours.

what a neat idea! (with regard to the fuel tank)

Arctic Circle wrote: ↑Sat Apr 22, 2023 8:00 pm Can one fill the pipes with vinegar - let it stand overnight - to clean the inside of the pipes?
They are disconnected from the displacers at the moment.

I cannot see what functional benefit there could possibly be pouring a corrosive material into a steel pipe that is already showing signs of corrosion. All it can do is make it "look" cleaner while at the same time bringing the pipe that bit closer to failure. Replacing a blown hydro pipe is not a quick or easy job!

While the repro pipes do have some issues regarding shape, they are in most cases, probably a better bet than used pipes of unknown integrity.

For a "perfect" replacement set that could rot just like the originals, it would be possible to make your own using something like this.

https://www.ebay.co.uk/itm/373997622976 ... %3A2047675