Topic
Hydragas service 6 years 8 months ago #179391
We've discussed at great length what to do about prolonging the suspension life of the F. I made it a resolution this year to do something about mine and I finally have.
As I guess all the F owners know, the MGF has a Hydragas suspension with displacers connected side to side acting on double wishbones all round and backed-up with special dampers that have very little compression resistance but more on the rebound. The MGF was the last car designed to use Hydragas (it was dropped for reasons of economy on the replacement TF) which was developed by Dr Alex Moulton with Dunlop. The ride height drops a bit over time so the ‘hydra’ side of the suspension (basically a water & antifreeze mix) can be pumped-up using a special tool. However, the reason for the drop is normally a reduction in the ‘gas’ side of the displacer as the nitrogen gradually disappears via the rubber membrane. The ride, considered exceptional when new, becomes progressively harder. When the cars were built this wasn’t seen as a problem as the life expectancy of the MGF and the displacers was around 15 years. Production ended in early 2002 so all MGFs still existing have passed their use by date but of course many are still providing excellent service.
The stock of new displacers disappeared off the shelves several years ago and even they will have suffered from some gas depletion. Suplex came up with a spring in a can replacement with matching dampers (now marketed by X-Part) but this kit has had very mixed reviews (I'm being polite) and is not cheap at £850 plus fitting. There is an Australian made spring replacement but with shipping included to the UK it’s almost twice the cost of ‘Suplex’ and finally Mike Satur is developing a spring kit solution but this will cost around £1100! But there is another answer.
Ian & Dawn Kennedy are offering a re-gassing service (ie replacing the nitrogen). This involves welding special valves in to the gas chamber then filling with nitrogen to the original pressure. The units are quite small and it would be easy to damage the rubber membrane, also the clearance for the valve in the front displacers when fitted is very tight. Ian, who is a City & Guilds qualified Pressure Vessel welder has found a reliable solution to all these challenges. He can supply units outright, or re-gas customers’ units or even a full service where you leave the car with him and he removes, re-gasses, re-fits the displacers then does a pump-up. I went down the last route and took the car to Telford where Ian started work at lunch time on one day to complete it by mid-morning the following day (it’s an advantage to leave the car overnight to do a final check that the ride height is still correct). All of this cost £480 and I am very pleased with the results – a very well damped and compliant ride (still firm but I'm on 16 inch wheels with low profile rubber). The displacers are well built and Ian reckons the rubber membranes should last another 15 years provided you’ve not left it so late that they have been contacting the rivet in the top of the displacer (the rivet closes the original charging point).
More details at http://www.hydragasandhydrolasticservice.com/
I’m very happy to have kept the car on Hydragas as it is a unique feature of the MGF and no other sports car in the world has had this system or sadly will ever have it in the future.
Here are some photos of the work in progress.
Richard
As I guess all the F owners know, the MGF has a Hydragas suspension with displacers connected side to side acting on double wishbones all round and backed-up with special dampers that have very little compression resistance but more on the rebound. The MGF was the last car designed to use Hydragas (it was dropped for reasons of economy on the replacement TF) which was developed by Dr Alex Moulton with Dunlop. The ride height drops a bit over time so the ‘hydra’ side of the suspension (basically a water & antifreeze mix) can be pumped-up using a special tool. However, the reason for the drop is normally a reduction in the ‘gas’ side of the displacer as the nitrogen gradually disappears via the rubber membrane. The ride, considered exceptional when new, becomes progressively harder. When the cars were built this wasn’t seen as a problem as the life expectancy of the MGF and the displacers was around 15 years. Production ended in early 2002 so all MGFs still existing have passed their use by date but of course many are still providing excellent service.
The stock of new displacers disappeared off the shelves several years ago and even they will have suffered from some gas depletion. Suplex came up with a spring in a can replacement with matching dampers (now marketed by X-Part) but this kit has had very mixed reviews (I'm being polite) and is not cheap at £850 plus fitting. There is an Australian made spring replacement but with shipping included to the UK it’s almost twice the cost of ‘Suplex’ and finally Mike Satur is developing a spring kit solution but this will cost around £1100! But there is another answer.
Ian & Dawn Kennedy are offering a re-gassing service (ie replacing the nitrogen). This involves welding special valves in to the gas chamber then filling with nitrogen to the original pressure. The units are quite small and it would be easy to damage the rubber membrane, also the clearance for the valve in the front displacers when fitted is very tight. Ian, who is a City & Guilds qualified Pressure Vessel welder has found a reliable solution to all these challenges. He can supply units outright, or re-gas customers’ units or even a full service where you leave the car with him and he removes, re-gasses, re-fits the displacers then does a pump-up. I went down the last route and took the car to Telford where Ian started work at lunch time on one day to complete it by mid-morning the following day (it’s an advantage to leave the car overnight to do a final check that the ride height is still correct). All of this cost £480 and I am very pleased with the results – a very well damped and compliant ride (still firm but I'm on 16 inch wheels with low profile rubber). The displacers are well built and Ian reckons the rubber membranes should last another 15 years provided you’ve not left it so late that they have been contacting the rivet in the top of the displacer (the rivet closes the original charging point).
More details at http://www.hydragasandhydrolasticservice.com/
I’m very happy to have kept the car on Hydragas as it is a unique feature of the MGF and no other sports car in the world has had this system or sadly will ever have it in the future.
Here are some photos of the work in progress.
Richard
1.8i Mk2 Solar Red, 16 inch square spoke wheels, MGFMania hood with zip-in glass rear window, DRLs, Kmaps ECU, Pipercross panel air filter, MGOC Supersports back box & some cockpit bling
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