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Post by dave1800 on Nov 18, 2014 6:13:16 GMT
After seeing photos of Tony's (Taiwan) failed displacer I came across an article in an Austin 3 Litre publication suggesting the rubber itself may be repaired. I can't copy the link as it is to a pdf file (anyone know how to?) but if you Google "May-June 2014 Austin 3 litre" it should appear.
An interesting article but I have no idea how effective it would be.
David
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Post by dave1800 on Nov 19, 2014 1:31:02 GMT
Peter raised an interesting point about the risks of introducing air (oxygen) in the hydrolastic system when it is opened resulting in corrosion and damage as seen in Tony's (Taiwan) displacer. Hydrolastic system corrosionI have tried to without success to find official guidance on whether the fluid should be renewed on a regular basis. Certainly we all know that failing to replace antifreeze in the radiator cooling (almost)sealed system can result in not just loss of potency of the ability to prevent the water from freezing but also severe damage to head gaskets and aluminium blocks and heads from electrolytic corrosion. This is not uncommon here in the tropics where it is referred to as summer coolant, maybe because there is no annual reminder in the form of snow and frost? It appears to me that the stresses on the hydrolastic fluid may be less severe than the cooling system and there are less interfaces for electrolytic corrosion. However, the high proportion of water in the system contains dissolved oxygen as is shown by fish. My search on the internet has suggested the hydrolastic fluid should be changed every 5 years or so but this appears to be published by organisations with a vested interest in selling the fluid, or their spiel being quoted by others. I thnk it would be helpful to get a definitive view on this. Maybe there is nothing that can be done to prevent the rubber hardening with age, I don't know. BMC must have published something, somewhere surely. Any ideas. David |
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Post by tony on Nov 19, 2014 8:55:11 GMT
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Post by dave1800 on Nov 19, 2014 9:59:13 GMT
Thanks Tony. I realise I should have set Firefox to open pdf in the browser and not Acrobat on the computer to get the url, thanks. I am not sure whether your 50% antifreeze / coolant 50% water is an issue or not. The 50% alcohol in the hydrolastic fluid was to prevent freezing in the UK (and other) winters and also to provide the correct viscosity. Your solution has a higher viscosity than pure water and a water /alcohol mix has a lower viscosity than pure water. Therefore when when one wheel hits a bump this would put more load on the displacer as the fluid would not run to the other displacer so fast. I recall there were different mixes of hydrolastic fluid available at one time with differrent viscosities that could be used to firm up the handling (minis I guess.) However, alcohol is known to attack rubber whereas coolant is compatible with the rubber hoses. There are a number of home made recipes on the internet but what effect these have on the displacers over time is impossible for me to determine. Please don't take the 5 years for replacing as anything other than words found on the internet. It may or may not be correct. As Peter pointed out it runs the risk of adding more oxygen from the air and new fluid which is needed for oxidation. regards David |
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Post by tony on Nov 20, 2014 5:12:38 GMT
Thanks David.
What if I use more water to reduce the viscosity, let me say 60~70 % water. I don't know if it will be fine or not. I agree with Tommy that postage could be the problem. Austin parts are not available here. There is just some snow on the top of our mountains so there is no need to worry about if we use antifreeze coolant or not.
Allow me to ask you a question, which is how long a displacer unit lasts in your country or Great Britain?
Regards
Tony
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Post by dave1800 on Nov 21, 2014 0:27:39 GMT
Tony I think it is impossible to give a response as to how long a hydrolastic until should last. I imagine there may be may units that have seriously deteriorated internally but other than gradual changes in the ride do not show symptoms. Many cars are still running on units 40+ years old. It would be interesting if the interor could be inspected with a fibre optic probe when fluid is changed or hoses repaired but this isn't going to happen to draw conclusons about the effects of differing fluids. There are a number of things that may affect the life of the rubber. I expect the ambient temperature may affect the rate of degradation, so your climate may be harsher than the UK. I do keep wondering about the hydrolastic fluid and the alcohol content. As previously mentioned the alcohol does attack the rubber and some aticles I have found suggest it may degrade its elasticity but others suggest it will slowly dissolve it. I just wonder if it is acting as a mild solvent if in fact this could in fact prevent the drying or cracking. No idea just a thought. If you are unable to import the hydrolastic fluid at a reasonable price it may be better to go back to a closer recipe and use equal parts of distilled water and alcohol. Note 50% coolant (ethylene glycol may have a viscosity > 3x times greater than water at 27C so will in my view place a heavy stress on the units. Coolant using propylene glycol is 3x more viscous than ethylene glycol. It is not clear which alcohol was used, maybe someone has a definitive recipe. Methyl alcohol has a viscosity 60% that of water, ethyl 10% higher and isopropyl 100% higher). You could then add a small percentage of coolant / antifreeze as the source of anticorrosion and leak detection but it would be a good idea to test the mix first to make sure there was no interaction. Hopefully someone here has a good understanding of the interactions and give you some better advice. Regards David Thanks David. What if I use more water to reduce the viscosity, let me say 60~70 % water. I don't know if it will be fine or not. I agree with Tommy that postage could be the problem. Austin parts are not available here. There is just some snow on the top of our mountains so there is no need to worry about if we use antifreeze coolant or not. Allow me to ask you a question, which is how long a displacer unit lasts in your country or Great Britain? Regards Tony |
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Post by Penguin45 on Nov 21, 2014 1:06:56 GMT
There may be a couple of things worth considering.
Rubber being a natural, organic product has a small water content, which, over many years will leach out of the material. This will then harden and become less flexible. The constant flexing of the rubber can, just like in a metal, cause an equivalent of "work hardening". Eventually, the material can shear.
Obviously, if we were to drive around on perfect road surfaces all the time, the suspension would be gently flexed with the road's undulations. Bouncing the car over a speed bump at 40mph, or riding through an unexpected pot hole at speed will shock the system and induce the failure.
Hopefully, most of the time this will simply blow the connecting hose, which we know to be a straightforward fix. I suppose blowing the rubber top out of the displacer has to be a rare event, but as Neil Kidman's article shows is actually solvable.
The real problem which I have seen is where the metal casing of the displacer drum corrodes, and the thing breaks in two. There is a thread over on the Wolseley Forum concerning the 18/85 limo in Arizona which has been pimped in a rather ghastly manner where exactly this happened. I'll have a word with Nishka over there and see if I can pinch a couple of pictures.
As most of you know, I'm back at college doing the Restoration Course. I do have access to viscocity testing equipment, so it will be entirely practical to find out what the viscocity of Hyro fluid is. If anyone would care to outline the mix for alternatives, I can probably create small quantities for testing purposes as well. Only problem I can foresee is that we appear to have no knowledge of what the original viscocity might have been. If you know, tell me!
Snoopy11 on here has been running his car on hydraulic fluid and I do know that he's not entirely happy with the experience. Perhaps you could comment, Mark?
Chris.
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Post by dave1800 on Nov 21, 2014 6:09:14 GMT
Chris. If you are able to check the viscosities that would be very helpful. The data I found indicates that ethylene glycol varies in viscosity by a factor of nearly ten between 0C and 27C at 50:50 water whereas the ethanol & water only varies by a factor of around 3. Hope that helps (you probably know it already)!
regards
David
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Post by tony on Nov 21, 2014 7:28:37 GMT
I suddenly found this morning that there is a kind of hydrolastic fliud we use for Citroen and RR. It's called Total LHM PLUS. After searching its details, I realized it is NOT suitable or acceptable for Morris because of its Viscosity. Click the link below and read the file. www4.total.fr/middle-east/PDS/Auto/Total/LHM%20PLUS.pdflinkThe RR I work on has got two hydrolastic systems. There are two front accumulators and two rear accumulators. The spec of front is 62 bars ( 899 psi ) and the rear is about 16.5 bars ( 240 psi ). Thanks Chris for the more explanation of how a displacer unit works in English. This was what I meant. By the way, I have just seen displacer burst once and heard of it another time. And I think that it is beyond my ability to repair a burst displacer after reading Neil Kidman's article. Regards Tony |
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Post by dave1800 on Nov 21, 2014 10:56:05 GMT
As a bit of lateral thinking, I recall when the Austin Princess was being developed and road tested they were accompanied by a couple of Wolseley 6 cars that had been converted to hydragas spheres. Maybe there is a good stock of these somewhere?
Anyone ever seen anythijng on this? I guess the original article was in Motor/Autocar or similar around 1975.
David
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Post by snoopy11 on Nov 21, 2014 22:06:21 GMT
Snoopy11 on here has been running his car on hydraulic fluid and I do know that he's not entirely happy with the experience. Perhaps you could comment, Mark? I wouldn't really say not entirely happy. The only problem is that the ride is a little hard. Its great on smooth roads as the suspension is really stiffened up. I don't know how comfortable it would be on bad roads or what the long term effects are going to be. That said, it's been in there 18 months now without problems. I am thinking of going back to the hydrolastic fluid for the softer ride. |
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Post by dave1800 on Nov 22, 2014 4:01:28 GMT
I am curious as to why rear displacers seem to be far more liable to failure than the front. I believe the rear displacers in all bar the Utes are the same as the 1100/1300 front units. The rear displacers are smaller but the loading on them with the 1800 is quite a bit less than they are subjected to in the 1100/1300 based on vehicle weights and published distribution front /rear.
I have read that one way to reduce the risk to the rear is to carry a weight in the boot at all times. Firt thoughts are that this would be worse. Is this an urban myth or do you think it is advantageous to keep the suspension loaded in this way? Maybe laying the cars up for the winter and not subjecting the system to running conditions is not so good either?
Food for thought; any clever scientists out there?
David
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Post by foglaursen on Nov 22, 2014 8:12:30 GMT
As a bit of lateral thinking, I recall when the Austin Princess was being developed and road tested they were accompanied by a couple of Wolseley 6 cars that had been converted to hydragas spheres. Maybe there is a good stock of these somewhere? Anyone ever seen anythijng on this? I guess the original article was in Motor/Autocar or similar around 1975. David Hydrogas displacers are even more rare than Hydrolastic ones, so no solution there. Peter  |
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Post by snoopy11 on Nov 22, 2014 21:25:27 GMT
As a bit of lateral thinking, I recall when the Austin Princess was being developed and road tested they were accompanied by a couple of Wolseley 6 cars that had been converted to hydragas spheres. Maybe there is a good stock of these somewhere? Anyone ever seen anythijng on this? I guess the original article was in Motor/Autocar or similar around 1975. David Hydrogas displacers are even more rare than Hydrolastic ones, so no solution there. Peter As as a wild thought. If we are looking at retro fitting other components for suspension fixes why not consider air ride. Should be relatively simple as it can't back a lot different. |
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Post by dave1800 on Nov 23, 2014 4:40:15 GMT
Oh well that's a shame, thanks Peter I must have been reading old info on the net. That news won't please Andrew in NZ.
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