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MG MGF Technical - hydro gas suspension

had my suspension pumped up last sept at main dealer ,
however within a week or two they had all dropped back down ,so far that the off side front tyre catches the fender housing. took back to dealer and they checked for leakes ect , but found nothing ,replaced the valves on each unit and re pumped them up. same has happened again , i dont want to take back to dealer and have them tell me they same old sh*t , is there anything that it could be other than a leak ? are all the units seperate or would one leak affect all?
guy

a hydragas leak would effect one side (both tyres) If you have a failing sphere then only one courner will be effected, in this case it is a new sphere.
Will Munns

Guy,

On a standard MGF the fluid systems are linked as follows:

* front left linked to rear left
* front right linked to rear right.

In other words a fluid leak in any one system should affect one side of the car - both front and back.

However, each Hydrogas sphere can fail and leak gas. These are all independent and one failed sphere would only it's individual wheel.

HTH

Dave

Dave

OK, Will types faster and uses less words!
Dave

Just as info for "guy", if you own a Trophy Above "linkage" ain't correct. imho

T

I thought Trophy hydragas still linked, but restricted, so less flow front to back
Chris

Yes, still linked on a Trophy AFAIK Chris,

Dave
Dave

Just to confirm what's been said above:

At each wheel there is a pair of spheres arranged one on top of the other. The top sphere contains Nitrogen and the bottom Sphere contains an alcahol based fluid (similar to antifreeze). There is an internal rubber membrane between each sphere and the bottom spheres, as has been mentioned above, are linked front to rear.

If a fluid sphere has failed the car will drop on one side only (as the spheres are linked).

If a nitrogen sphere has failed the car will drop on one corner only (as the spheres are independant).

Note, the suspension is not linked accross the car, this means that the two sides are completely independant of one another.

This makes your circumstances very odd. You say that the whole car has dropped? The Hydragas spheres are pretty robust and failures are pretty rare, but they can go, indeed there was a spate of them a couple of years back, this was traced to a faulty batch from the manufacturers (Dunlop IIRC). The chances of there being two independant Hydragas failures at the same time one one F must be astronomical, but the symptoms you are describing point to just this conclusion.

If it was me, i would check for leaks elsewhere first. The valves used for adjusting the pressure in the fluid spheres look and behave exactly like tyre valves, this is a potential leak point, as is any of the joints int he hoses that link the spheres. The pipework is pretty easy to find, open the front bonnet and remove the shroud panel, full step-by-step instructions to do this can be found here:

>> http://www.sfforever.co.uk/viewgallerypicture.asp?id=8-12-161-162-163-164-165-166-167-168-169-170-171-172&queryon=19 <<

Click the 'next picture' button until you get to the end. The last picture shows the Hydragas valves, check for leaks. The fluid is a luminous green colour so it should be pretty easy to spot.

If they appear sound, follow the pipes to the spheres in the front wheel arches, checking the joints on the way. The pipes then travel from the front spheres, down under the floor pan and along to the rear wheel arches, again check for leaks.

Other than this, i don't know what to suggest. If the spheres HAVE gone, then they need replacing, this is not cheap and is a job for your dealership (argue with them that they were 'not fit for purpose' if necessary, with a bit of luck they will either stump up the cash or at least contribute).

Good luck

SF



Scarlet Fever

Trophy linkage,
When I had my suspension leaking it affected one side only the same as any other 'F', so what are you trying to say T,Lux, ?
Mike, M2 VJN, 2001,TY,Trophy
Mike

Chris (and everybody else except me) is correct :
"Moreover, pitch control has been augmented by the installation of a restrictor valve in the Hydragas interconnecting pipe, limiting the movement of fluid from the front to the rear sphere under braking."

Sorry for the confusion, always do read my -> IMHO warning ;) Thanks to clear this up.
T

Don't forget that the hydrogas unit can be tested for loss of the nitrogen cell which will have the same effect as fluid loss.
Mike.
Mike

If it was fluid loss you would be able to see the fluid under the car. A test with a pump as Mike suggests is what is needed.
Spyros Papageorghiou

Most likely cause of this mystery is poor technique.

What may have happened is someone at the dealership pumped the suspension up.

Then realised they'd over done it, and dropped the suspension back down to where it should be: 368mm.

Only they didn't allow the suspension to settle - which means that when you collected the car, 5 minutes after they'd finished fiddling with it, it looked fine. But left to settle over night, the suspension settled down to its correct height - centimeters below what it should be...

Probably nothing to worry about - get the suspension reset (don't forget the tracking!!!) - but DO be concerned if this problem recurrs.

HTH
Rob Bell

This thread was discussed between 10/07/2003 and 11/07/2003

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