23 replies to this topic

[minimikej]

Hi all,

I am now starting to think about hoarding parts for my 1965 Mk1 Hydrolastic saloon. Suspension is completely flat and I've no idea what condition the displacers are in. I would really like to get this saloon back to original and keep it hydro. So, some questions:

1. How do hydrolastic units typically fail? Is it the flexible pipe that degrades or do they usually fail internally?

2. Is there any way to check a second hand unit off the car? There's a lot of rusty old units on ebay that go for very high prices.

2. Has anybody had any success in repairing them? I came across this site for the ADO16 and there's some interesting stuff here: http://members.tripo...erica/id63.html

 

Cheers,

Mike

 

 

 

 

[Dan]

The real problem with displacers is that they are made from rubber. Rubber has a shelf life and nobody is making new ones. My personal opinion is that hydrolastic systems are unserviceable now due to the age of the rubber components.

[carbon]

Mike - good to hear you are looking to keep your hydrolastic suspension.

 

If the suspension is completely flat then I would suggest the first step would be to get it pumped up and see if there are any obvious leaks. It may not be the displacers, some of these seem to just keep on going without problem. Areas where I have experienced leaks are corrosion holes in the hydrolastic steel pipes running from front to back, and also with the 'top-up' adaptor connection on the rear subframe.

 

If the steel pipes are corroded best option here is to fit the ready-made kunifer pipes. If the displacers are faulty then you can get refurbished units from Minimail (see http://www.minimail.co.uk/parts/ )

[tiger99]

Sadly, I really think that you are on a complete loser here, at this point in time, and there is no point pouring good money after bad. You will not be able to get displacers with any useful amount of life remaining. That is sad, because it means that the era of hydrolastic Minis is almost over. I do like to see old things preserved, but sometimes it really can't be done.

 

The only thing that would make a difference would be if there were a sufficient number of hydrolastic Minis still left, and values were so high, that it became economic to tool up for the manufacture of displacers again. But I would emphasise that this would need to be done by a mainstream manufacturer of similar rubber things, not some back street shed in rural China. I would imagine that the cost would be upwards of £500 per displacer, if someone placed a bulk order for at least a few thousand. I can't say that it will never happen, but don't hold your breath.....

 

Meanwhile you can keep the cars running on dry suspension, and wait and hope for the situation to change.

[Daz1968]

My mk2 cooper is hydrolastic and I have collected a few spares over the years but agree they are a bit old now and finding good ones are not easy. The units themselves are very thick and unlikely to rust through. The pipes front to rear are available and fittings are not a problem. Weak point is where the hose connects to the unit itself I have heard of this being repaired but have never needed to go down this route. Hydrolastic when working is a superb system especially if the front shock absorber kit is fitted. I also acquired a correct hydrolastic pump for vacating and inflating my own suspension commonly called the Dalek back in the day. To change to dry would devalue the car and needs a change of subframes complete with radius arms and front upper arms so not an easy swap.

[Miss Piggy]

I had the same issue.- replaced the steel pipes with 3/8 copper tube (ac piping). One displacer had a failed flexible hose- I replaced it with a s/h unit. I understand that the hoses may be replaced.

 

Hydro ride I believe is superior to the dry- but use the competition bump stops.

[Gr4h4m]

I run hydro still. I have had one displacer fail. It was the hose. I have a few spare for a rainy day.

I run the comp bump stops and ream arb, it give a good ride and the the comp bump stops are some insurance against a displacer failing.

[minimikej]

Hmm, interesting, thanks all.

I did have hydrolastic on my first mini back in 1991 and that failed on a displacer where the hose meets the body. But in those days, you just went down the scrappy and took your pick.

Think I'll connect the compressor airline up and see what leaks out. As good a starting place as any I suppose :)

 

Cheers

Mike

[62S]

Ignore the naysayers and doom mongers, there is no need to bin off your hydro suspension just yet.

The original hydrolastic pipes tend to rust around the rear subframe area, especially on the corners.

The front displacers tend to fail more than back ones because when it rains, water can run down and sits in the top of the displacer and rots the connection to the hose. There used to be a company in the Blackpool area that could repair the hose connection if that was the problem.

Rear ones often look scabby and horrible because of where they live i.e. exposed to the elements but in my extensive hydrolastic experience they are much less likely to fail than better condition looking front ones. I certainly wouldn't change a rear displacer if it didn't leak even if the casing was not in its first flush of youth.

[Dan]

  Its not failure that I'd really be concerned with, people know where and how they fail and for most issues where parts aren't available there are workarounds.  My own issue with the system is just about the performance of it.  Old rubber dries up and hardens, the displacers don't perform how they are meant to.  They will end up as rigid and useless as old cone springs.  There are people out there who will tell you that solid, collapsed old cone springs are fine to keep using.  They have slowly got used to them as the springs have hardened up in their cars over time and forget how good a Mini should feel with working springs.  It doesn't make these people right, new springs are simply better than old ones.  My argument is that the old displacers are exactly the same.  Nobody can tell you that they have a fresh car to compare their current car with because all displacers are decades old.  

[62S]

The problem with rubber cones is that they compress over time and whilst hydrolastic may to some extent suffer the same problem, it is the displacement of the fluid that gives the suspension. Have you ever heard of a hydro Mini owner complain that suspension is too hard?

 

Even now people are buying competition bump stops or shock absorber kits to stiffen them up.

[Captain Mainwaring]

Hi all,

I am now starting to think about hoarding parts for my 1965 Mk1 Hydrolastic saloon. Suspension is completely flat and I've no idea what condition the displacers are in. I would really like to get this saloon back to original and keep it hydro. So, some questions:

1. How do hydrolastic units typically fail? Is it the flexible pipe that degrades or do they usually fail internally?

2. Is there any way to check a second hand unit off the car? There's a lot of rusty old units on ebay that go for very high prices.

2. Has anybody had any success in repairing them? I came across this site for the ADO16 and there's some interesting stuff here: http://members.tripo...erica/id63.html

 

Cheers,

Mike

 

 

 

 

 

I have 4 brand new units that have been properly stored - for what it's worth, they can be reconditioned - the ADO16 guys know how to do it - it's mostly the flexi joint with the body that fails.

 

PM me, I'll be back in the UK around may/june

Edited by Captain Mainwaring, 10 April 2014 - 02:36 AM.

[Captain Mainwaring]

The problem with rubber cones is that they compress over time and whilst hydrolastic may to some extent suffer the same problem, it is the displacement of the fluid that gives the suspension. Have you ever heard of a hydro Mini owner complain that suspension is too hard?

 

Even now people are buying competition bump stops or shock absorber kits to stiffen them up.

 

 

This - they don't collapse and go hard the same way cones do.

It's a shame that such a system by it's nature has a finite shelf life that is shorter, much shorter than say coil springs, because it is a great system when working well.

[tiger99]

Yes, as a couple of people have said, the springing medium is RUBBER, not HYDRAULIC FLUID (actually mostly water in this case), as someone has incorrectly said, which is incompressible and only provides damping and fore and aft coupling. When the rubber is hard, as it will be, there is basically no springing, and the stresses on the rest of the car are increased. Once they get above the fatigue threshold in some part or other, you are well on the way to a structural failure. It may be the top arm, which may fracture near the knuckle joint, or maybe the subframe or bulkhead structure, or the welds between side members and front cross member of the rear subframe, or maybe somewhere else altogether, depending on the overall condition of the car.

 

But any car, or any sort, will break due to fatigue fracture after a while, if the suspension is too hard. Some, not Minis, and often much more expensive, have been known to break when there is nothing wrong with the suspension, due to ignorance on the part of the designer, who allowed the peak repetitive load on some part or other to be above the fatigue threshold. Some, apparently, were made in Bavaria, which was inexcusable on any car, especially an expensive one, in an age when computing facilities of which Issigonis could not even have imagined had become commonplace, and should have detected such gross errors. Issigonis got rid of all that once and for all by thrashing the Orange Box prototypes for indecent miles on horrendous surfaces, which led to the solid mounted subframes being introduced. Then someone reintroduced fatigue problems along with the abominable rubber mounted front subframe, but I digress....

 

Actually the amount of rubber in the spring in the displacer is fairly similar to that in the dry suspension cone, which should not be surprising, as you need a certain volume of rubber to do a certain amount of work. Less rubber, same amount of road roughness, and it will overheat. And, it is more or less in the form of a cone, so it acts in shear, rather than compression, same as the cones.

[Vipernoir]

Will the fluid not dissipate heat from the rubber and prevent overheating ?

 

I'm a big fan of hydro, and haven't yet found a car that has displayed the same sort of cone-fatigue that dry cars suffer from.