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MG MGF Technical - Hydragas fluid

Just wondering, and apologies if a daft question, but does anyone know if there's a type of Hydragas fluid that has been made to be more temperature resistant i.e. doesn't expand and contract! (as much)

The warm weather seems to lift my car a fair bit and I'd quite like it to stay where it was (and where it was tracked etc!)

Chris, it isn't the fluid expanding that causes the problem. It is the nitrogen gas in the hydragas sphere that is at fault.

And all gases expand with heat.
Rob Bell

Thanks Rob,

So is there any cure to this? Are Trophy type spheres more susceptible than standard ones?

Do I just get my 'F converted to springs (and slim the wallet somewhat!)

Almost feel I need a thermometer to see how my cars going to handle!


There is no cure Chris.

The effect can be reduced by lowering the car using knuckles - but never removed.

Fitting springs - by fitting TF suspension - is possible, but you'd need very deep pockets, as the rear subframe would need changing, and the body of the car extensively modified to accept the new damper positions and more robust mounts.

Your two options, therefore, are to:
1. lower the car with knuckles, and fit new dampers - which will noticably improve the handling anyway - I've taken the Tech-speed route
2. Trade your MGF in for a TF.
Rob Bell

I've had the car lowered Rob, and I love it so much. Just this one problem perplexes me!It's not extreme, but irritating.

For me, option 2 is a non-starter. I am however, looking very closely at an Elise 135R. Can't help thinking though that I may lose the suspension problem and end up with others!

Think I'll take up a different hobby, stamp collecting can't be this much trouble! ;)

>>Think I'll take up a different hobby, stamp collecting can't be this much trouble! ;) <<

Ah well, you say that now, but wait until you start hankering after penny blacks... ;o) ;o)

BTW, how have you lowered your car?

An Elise 135? Always fancied a 160 Sport myself...
Rob Bell

iv'e done option 1 and pleased :) even though still costs few pennies, Dave T6 DCM.
DC Morris


I'm surprised that you have so much variation on ride height with lowering knuckles. Since my own '98 VVC has had the TechSpeed lowering package I have noticed little fluctuation from Winter to Summer. The car sits typically around 330mm.

Can there be another factor coming into play?

>Can there be another factor coming into play?

Yes. Air bubbles within the fluid system side. (Not right evacuated before filling)

Can easy be heard if you open the bonnet and bounce the car at the front. (silent ambient conditions required)
Knackering flow noise at the HG Displacer pipes indicate this fault.
Dieter K.

During Alan Dunlop and my little jont to Le Mans and Silverstone we couldn't help notice how high our suspensions were and how badly the cars were handling due to the warm weather. Neither cars have lowering knuckles and normally I can get about three fingers between the tyre and the wheel arch. However, during the trip I could get my whole fist in the same space. It must be murder for anyone who lives in a country where there is a big difference in temperatures between the seasons. I feel a trip to Mr Satur coming on to have the knuckles changed.
David Clelland

This thread was discussed on 25/06/2003

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