Suspension Losing Pressure

Hi,

My MGF has started to lose pressure and sag on its drivers side.
I have pumped to up to spec several times but after a few days it drops.
I have checked for leaks and try as I might , I cannot find any. I have checked all unions for tightness also the schrader.
Odd thing is , it seems more affected by time than use , as I recently completed a 300+ mile drive without much of a drop.
I have pumped it up around 5 times so far so I expect that if the suspension unit diaphragms are damaged the upper chamber would now have been well filled.
I'd really appreciate any useful info on this.

Kindest regards.

Just keep pumping. You will soon find the leak. Really, this is not the right answer. If the car is constantlly dropping, there is a leak either into the sphere or out of the sphere. Try dislodging the plastic cover on the knuckle strut and see if there is any moisture. Is one corner hard when you bounce it? If it is then the sphere is flat and continually pumping it up will only do further damage.

Yep, if you had an internal leak in the sphere, the suspension would just end up rock hard on that corner.

The system is at circa 450 psi so if there is a leak, it really should show itself fairly quickly once pumped up to circa 450psi. If the car is stored in a dry garage, it should show itself on the garage floor (although the fluid does dry fairly quickly). It could be losing fluid at the pipe junctions, pipe to spheres, Schrader valves, or the rubber membrane in the spheres.

PS: In my experience, the pipe connections should never be over-torqued and indeed there is no need as the seals (like aircon seals) are very good. The valves within the Schrader casings (same type as in bicycle wheels) can be replaced (just purchase the tool which is a couple of quid off eBay or a bicycle shop) - sometimes they just need to be tightened.

Minimax, thanks for the swift reply.
I thought Id ask as Im no expert on these and thought there might be something I'm overlooking that I did nt know about.
The fluid/pressure is obviously going somewhere and as it has been pumped several times, it must be leaking outside the circuit.
Pity they did nt use coil springs and wishbones...

David, thank you for the reply.
What you said makes sense.

Julian,
There is no hard standing at my home , I ll put some dry cardboard underneath to see if I can locate a drip. Each time I pump it to circa 450lbs and when it sags it drops to around 200.
Thanks for the heads up on the tightening of the unions.
I 'll persevere and thanks again to you all.

Heretic! The hydragas suspension is one of the best bits of an MGF. Set up properly, the car corners flat and nimbly while at the same time being comfortable to drive all day long- Think Dieppe to Bordeaux on Routes Nationales. There aren't many sports cars that can do that without beating you up in the process. Now. Remove each wheel in turn on the saggy side and find the rod that connects the upper link to the sphere. You will find a plastic dust excluder that simply pulls free from the bottom of the sphere.pull it free and look at it with a decent torch. The likelihood is that there will be moisture there at one end.(Hint: do the back one first!)

Sorry for the delay in replying.
Heretic?? Probably! They certainly do corner flat.
I removed the sphere and noticed some congealed antifreeze and dampness. So now need to source a decent one. Are the front ones easily modified to fit the rear? They seem to be easier to find.
I also noticed excess play in the knuckle joint and bought a new Lucas one, which was £££. To my surprise the new one had almost as much lateral play as the old joint! Is this normal?
Noticed the pipe join from the rear sphere to the mid section very corroded too, so would like to replace.
Has anyone on here got a sphere and pipe for sale please?

Having cut some buggerd spheres open to see what’s inside the only difference I could see is the conical alloy piece in the bottom
(I’m told some blokes like conical things in the bottom……each to his own ) :omg: :bust:
Can’t remember which is which, but one is longer than the other.
Interestingly the Trophy model spheres have a different part # and use the same part front and rear……. I wouldn’t be surprised if the only difference between the normal spheres and Trophy spheres was the cones.

To remove this you’ll need to have the sphere off the car.
Apply air pressure to the fluid port, this will push the diaphragm down, once it’s all the way down ( with to pressure still applied)
Take a firm grip of the cone and twist it out of the rubber retaining ring of the diaphragm.
To fit the replacement push it into the rubber retaining ring of the diaphragm, release the air pressure, I then apply vacuum to the fluid port to make sure the rubber retaining ring of the diaphragm has a good grip of the cone.

Cobber wrote:

Interestingly the Trophy model spheres have a different part # and use the same part front and rear……. I wouldn’t be surprised if the only difference between the normal spheres and Trophy spheres was the cones.
.

The Trophy spheres do have different part numbers front and back.

In addition, the pipe interconnects/pipe assemblies left and right are different from the standard MGF (from memory there is a constrictor in the Trophy version).

https://hahsltd.co.uk/ these guys are the experts on Hydrolastic/ Hydrogas suspension, they came out and fitted new (refurbished) spheres to my F two years ago and haven't touched it since, the ride and handling is superb

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