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Post by dave1800 on Jul 1, 2013 0:11:22 GMT
I met an Austin 1300 owner yesterday at my local classic car garage here in Thailand. He was having his car's suspension blown up and I noticed they were using an ethylene glycol summer coolant ie antifreeze 50% mix with water in the absence of the correct fluid. He had owned the car for 24 years and confirmed this was what had been used to top all this time without any problems.
Any views or known suitable alternatives?
Regards
David
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Post by Penguin45 on Jul 1, 2013 0:37:40 GMT
Technically, you could just fill it with water! Alcohol and antifreeze both have a low freezing point; the latter has rust inhibitors as well, so why not?
Chris.
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Post by indianajones on Jul 1, 2013 6:00:07 GMT
From an engineering point of view (very limited at this stage of my career, mind you) water, for most practical purposes is virtually incompressible. As Chris has said, the addition of anti-freeze and other chemicals like it are to reduce rusting within the pipes.
-Andrew
PS I just finished a Hydraulics paper lol (I hope I passed!)
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Post by dave1800 on Jul 1, 2013 7:49:52 GMT
You'll be feeling all pumped up then (groan). Thank Andrew and Chris. I guess the ethylene glycol /water mix is pretty good as it contains a rust inhibitor and is compatible with rubber. Only missing the fluorescein to help find any leaks. regards David -Andrew PS I just finished a Hydraulics paper lol (I hope I passed!) |
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Post by tommydp on Jul 1, 2013 14:15:07 GMT
I've heard of many people using antifreeze in Norway too, instead of Hydrolastic fluid.
I 've also used it on an 1800, when I was a student and couldn't afford the proper fluid. The original fluid was extremely expensive here and hard to find..
The situation is better today, as we have a Mini specialist in south of Norway which offers Hydrolastic fluid from Morris lubricants. Still quite expensive though...
I think there was a recipe for alternative fluid on the Australian crab page once..
regards, Tommy
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Post by threelitre on Jul 1, 2013 14:48:43 GMT
I actually hope that no hydraulic fluid can be considered compressible during its normal working conditions... If there wasn't heat and rust, brakes would work very well with water too....
On Hydrolastic viscosity is important too, as it defines the damping. The original fluid seems very 'watery' to me. Using an oil like engine oil (if it were compatible with the rubber!), would lead to much stronger damping characteristics, due to being less 'thin' than water.
When water is in liquid state, the nice thing is the low spread of viscosity versus temperature. As Dr. Moulton thought typical Hydraulic oils (like used in Hydropneumatic or standard shock absorbers) had too much variation with temperature, he looked at something similar to water in this respect.
Regards,
Alexander
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Post by dave1800 on Jul 3, 2013 11:29:53 GMT
Thanks guys. Interesting to read (Tommy) that you have experience of ethylene glycol working fine and Alexander I didn't know the formula changed, I always assumed that the Mk11 firmness was down to suspension changes.
Regards
David
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Post by threelitre on Jul 4, 2013 7:56:48 GMT
Dave, you must have misread my comment or it was badly worded on my behalf. The fluid did not change - at least I am not aware of this. The reason this kind of fluid is used as it is, is based on a) being kind to rubber and b) the viscosity being more or less constant between freezing point and boiling point.
The major difference in the Mk2 is the rubber bonded bearings in the rear trailing arm. Introduced to reduce bounciness by inserting a certain amount of added friction/damping.
Regards,
Alexander
PS: Has anyone a good explanation why Hydro-fluid containers should not be stored under freezing temperatures? I fail to find one.
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Post by dave1800 on Jul 12, 2013 4:10:19 GMT
Sorry Alexander I missed your posting. Yes I was aware that the Metalastik bearings in Mk11/111 cars act as a sort of friction damper, I believe that this follows a similar principle in the use of leather dampers before hydraulic ones were introduced. Having researched this a bit more I find that in fact there have been a number of hydrolastic fluids over the years from BMC/BL in an attempt from what I can gather to modify the viscosity. Here is an article from the public area of Tony Cripps' Australia website, just follow the link to hydrolastic fluid HEREHowever I now have another related question as I have found owners of hydrolastic cars here, sadly not yet a working Landcrab. As you can imagine no one here has a proper pump and they don't seem to understand the need for evacuating the system after disconnecting a unit with the result that the couple of Austin 1300s I have found seem to ride strangely (bouncing excessively) and nose down. In the absence of a vacuum pump has anyone any experience of whether it is possible to simply fill the system and then bleed it later? I seem to recall the local garage back home just bouncing the car, leaving it half an hour, bouncing it again and topping it up / bleeding any air. Unfortunately I didn't take much notice at the time as I never contemplated having to do it myself. In theory as long as you ensure the top up valves are kept at the highest point it should work, but my question is DOES IT? Thanks David Dave, you must have misread my comment or it was badly worded on my behalf. The fluid did not change - at least I am not aware of this. The reason this kind of fluid is used as it is, is based on a) being kind to rubber and b) the viscosity being more or less constant between freezing point and boiling point. The major difference in the Mk2 is the rubber bonded bearings in the rear trailing arm. Introduced to reduce bounciness by inserting a certain amount of added friction/damping. Regards, Alexander PS: Has anyone a good explanation why Hydro-fluid containers should not be stored under freezing temperatures? I fail to find one. |
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Post by threelitre on Jul 12, 2013 9:12:12 GMT
Bleeding may work - depending on what has been changed.... The problem however is, that the valves are not at the highest point and that the rear displacers are not standing and can trap air inside them. I once encountered a rear brake cylinder with broken bleed nipple. Since I had not choice than re-using this one with new seals, I adapted the fitting routine to the missing bleeding point: I filled the slave cylinder with fluid before putting it back to the car and bled the brake hose/pipe by leaving it slightly loose. Something similar may be working in case of a partial repair in a Hydrolastic system.
When reading the bit about Hydrolastic fluid on Tony Cripp's website, it seems that the lubricant was introduced not to change the viscosity, but to reduce possible noises - making the viscosity more temperature dependant should be seen as a trade-off that was the unwanted part of the compromise.
Regards,
Alexander
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Post by dave1800 on Jul 12, 2013 10:09:22 GMT
Thanks Alexander.
The article suggests "Part No HYL3478 is recommended for the
Austin 1800. According to Norm Prescott’s service sheet, the higher concentration of lubricant (such as in HYL3478) results in a firmer ride, especially in cold conditions."
On reading it again I think you are correct the primary reason for the change was to improve lubrication and the desirable? firmer ride was a consequence. Not sure how using ethylene glycol Summer Coolant / Antifreeze affects the ride.
I can see that trapping air in the rear displacers is an issue because of the way they rest so I think your idea of filling them first and bleeding by leaving the connector loose sounds a feasible solution, thanks.
Regards
David
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Post by threelitre on Jul 12, 2013 11:18:36 GMT
The viscosity of (mono-)ethylene glycol looks like it is 16 times the one of water (based on a quick google-search), so changing the fluid for pure glycol antifreeze will result in a noticeable change in the suspension. The spring rates will be the same, but the damping will be changed, both internally and for the interconnection. Water and Ethanol are very similar. Moulton's reason for a watery solution was that it is less temperature dependant than Hydrolic oils or other liquids available at the time. I have a paper some where at home were Moulton shows the results of measuring damping coefficients over temperature and compared to oil based dampers the influence was rather low.
Regards,
Alexander
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Post by dave1800 on Jul 12, 2013 12:12:56 GMT
Alexander That is a huge difference in viscosity if used undiluted but I am not sure how that would translate into firmer damping - would it be rock hard? I recall somewhere that rally cars had a valve in the interconnecting pipe that ran inside the vehicle that allowed the interconnection to be turned off (or reduced?), maybe a reader here has experience? There is no chance here of experiencing temperatures sufficient to freeze a water alcohol solution here based on my experience. It may fall close to zero for a few hours at the tops of the mountains giving a slight air frost but elsewhere 12C is the lowest I have encountered. The key issue I think would be to prevent corrosion by adding just sufficient ethylene glycol to a water alcohol mixture. As far as I am aware the ethylene glycol is compatible with the rubber and readily available. Any idea of the percentage required to prevent corrosion of the metal pipes? The mixture percentages used in the cooling system is geared to protecting down to a certain temperature (and raising the boiing point) so not sure if this is a good indicator of corrosion effectiveness. It could be argued that the cars, especially Mk1 vehicles would benefit from a little more damping. Regards David The viscosity of (mono-)ethylene glycol looks like it is 16 times the one of water (based on a quick google-search), so changing the fluid for pure glycol antifreeze will result in a noticeable change in the suspension. The spring rates will be the same, but the damping will be changed, both internally and for the interconnection. Water and Ethanol are very similar. Moulton's reason for a watery solution was that it is less temperature dependant than Hydrolic oils or other liquids available at the time. I have a paper some where at home were Moulton shows the results of measuring damping coefficients over temperature and compared to oil based dampers the influence was rather low. Regards, Alexander |
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Post by threelitre on Jul 12, 2013 15:31:33 GMT
Dave,
it will surely not be rock hard - the pipe's diameter is quite large. Flow will be reduced, but how much I cannot say of the top of my head. As it should be used diluted in a similar mixture as in an engine's cooling system (1 in 3? or 1 in 2 for frosty winters), the influence of a 'sensible' mixture will obviously not be a lot.
The valve in the interconnection pipe can effectivly be used to add more damping to the interconnection - but this is only solving a little part of the problem: A stronger damping of the bounce springing of the wheels would be a better solution, as this will be hardly affected by closing the valve to a part or even completly. The rally cars used additional dampers for this, at one end is sufficient if some of the interconnection is left open. 3 Litre and Hydragas had the right solution by separating bounce damping from the interconnection.
Regards,
Alexander
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Post by dave1800 on Jul 13, 2013 3:04:37 GMT
Hi Alexander I'm aware of the use of auxiliary schock absorbers on the front or both ends on rally cars. Nick posted a photo the the front shock absorbers fitted to his car HERE which would I believe dampen the bounce. Maybe they are actually a good long term investment to save the displacers from shock? Unfortunately I cannot see any way of fitting them without making changes to the bodywork. I am intrigued when you say that the 3 Litre overcame the bounce. Was this through the self levelling arrangement at the rear. I thought hydragas spheres simply replaced the hydrolastic displacers (eg Maxi), is there something fundamentally different between using rubber and compressed gas as a spring I wonder ? Regards David Dave, it will surely not be rock hard - the pipe's diameter is quite large. Flow will be reduced, but how much I cannot say of the top of my head. As it should be used diluted in a similar mixture as in an engine's cooling system (1 in 3? or 1 in 2 for frosty winters), the influence of a 'sensible' mixture will obviously not be a lot. The valve in the interconnection pipe can effectivly be used to add more damping to the interconnection - but this is only solving a little part of the problem: A stronger damping of the bounce springing of the wheels would be a better solution, as this will be hardly affected by closing the valve to a part or even completly. The rally cars used additional dampers for this, at one end is sufficient if some of the interconnection is left open. 3 Litre and Hydragas had the right solution by separating bounce damping from the interconnection. Regards, Alexander |
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