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Post by alonei on Jul 14, 2015 0:17:11 GMT
Hi Guys Does anybody knows if I can perform a pressure test for the units with the wheel assy off? I mean only the displacer unit is installed?
Cheers guys and thanks Al
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Post by Penguin45 on Jul 14, 2015 23:23:51 GMT
The only access to the hydro system is through the Schraeder fill valve, providing that the system is on the car. You can therefore pressurise the system, but without wheels and the weight of the car on the system I don't think you'll learn much. The book indicates about 230psi is about right, but it doesn't follow that the ride height will be correct.
The pump I am using at the moment has a high quality pressure gauge, which I *think* is reasonably accurate. Snoopy and I have both used it recently to inflate or level up our cars. The Austin seems to like about 245psi on one side and 240psi on the other. Snoopy's car is at 230psi on one side and 245psi on the other. Not quite sure what that's about, but the car sits level with the correct ride height.
Trying to pump up the system without the suspension assemblies in place strikes me as a recipe for disaster. The suspension units meet bump stops which restrict movement. Without them, I suspect that the displacers could keep on moving out due to the rubber stretching and without the stops to backload the travel on the rods, you may never see 230psi before something goes bang!
I think that makes sense...
Chris.
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Post by alonei on Jul 15, 2015 4:17:36 GMT
Sure is...
Thanks mate
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Post by dave1800 on Jul 15, 2015 11:55:50 GMT
That's an interesting observation. I believe that the service notes initially suggested setting the pressures but then this was changed to adjusting the ride height at the front. I guess we have probably all seen cars that appear correct at the front but have sagged at the rear. Never sure whether this is incorrect evacuation of air or possibly Slipflex bushes distorting with age for example. Whatever the cause of the rear sag it must surely affect the ride height measurement at the front? I recall years ago being informed by a BL employee that there were different grades of hydrolastic units, some being softer than others, but have never been able to find any reference to support this. I guess the outstanding question is whether the correct way is to have equal pressures on both sides of the car or to focus on ensuring the ride height is consistent. Maybe Alexander can enlghten us on the implications of what looks to me as though it may equate to inconsistent spring rates on a conventionally sprung vehicle? David The pump I am using at the moment has a high quality pressure gauge, which I *think* is reasonably accurate. Snoopy and I have both used it recently to inflate or level up our cars. The Austin seems to like about 245psi on one side and 240psi on the other. Snoopy's car is at 230psi on one side and 245psi on the other. Not quite sure what that's about, but the car sits level with the correct ride height. Chris. |
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