hydragas sphere

[PerS]

Hi,

I am in the process of doing something about my hard front damping.
What for me could be an easy start is to change the spheres to newer ones.
Would spheres from a 97 MGF suit?

PerS

[Hans Efde]

That's the reason why I changed to springs. These spheres get older and the nitrogen in them gets depleted. You can have them filled with fluid to get the correct height again, but the fluid is just for damping. The nitrogen is the springy bit that has to take up the bump. You can not refill the nitrogen unless you modify the spheres by putting a schroeder valve in the head. Here's a link:
http://www.aronline.co.uk/blogs/2011/08 ... i-spheres/
Else you have to do the impossible, find 2 new ones.

[PerS]

Thanks Hans,

The modification with a valve on top of the sphere is quite interesting. Even if it makes practical sense to change the spheres to a more robust system, I think
there can be qualities of a well executed hydragas suspension that could be worth some extra effort.
Main question still is though, will the spheres of a MGF fit?

PerS

[ACourtney]

Hi Pers,

The MGF spheres will fit physically, but they are set up for a mid-engined car, i.e. light front end, heavier rear. The spring rate is set by the gas volume (as Hans said, you lose gas over time so the spring rate gets stiffer) and the damping is integrated within the hydragas units, so it is unlikely that MGF units will be ideal for your Midas. Furthermore, they are designed to be linked front to rear so you would need to fit isolator valves if you want to run them separately and that will stiffen them further as all the fluid will then be retained within the unit rather than flowing between units.

The nitrogen valve mod, on Hans' link is quite easy to do and well established. I have done it myself, so it can't be that hard! Metro racers first dreamed it up as it gave them the ability to tune the spring rates as well as the damping. I recall seeing cars fitted with a pressure gauge at each corner and the serious racers kept a bottle of nitrogen with them. You need a Schroeder valve for each hydragas unit and the brass fitting. I get the valves from Rover 100/Metros in scrapyards - let the pressure out before attempting to unscrew them first though. The brass adaptor is a standard pipe fitting from a plumbing supplier. On the front units you will need to fit the valve off centre to clear the Midas body. The brass adaptor can be soldered in place with plumbers solder. Make sure that you have cleaned the surface back to bare steel first and use a flux, making sure that none goes inside the unit. Also, I used a wet rag around the flange of the top section to make sure that the rubber diaphragm did not get hot. Finally, I used some plumbers ptfe tape when fitting the valve into the brass boss.

Alternatively, if you are a fan of Hydragas, fit a complete set from a Rover 100 including link pipes. I run this set up on my Excelsior and cannot speak highly enough of the ride and handling that you can achieve. I shall be straightlining the chicanes at Castle Combe again tomorrow to prove it!

I do have some new, old-stock, hydragas units in stock, but they are not cheap at £125 each, plus you would have carraige to Sweden on top.

Alistair

[PerS]

Hi Alistair,

I hope you had a nice run at Castle Combe today!

That´s good news that the spheres of a MGF are of the same shape.

If you calculate the weight/pressure that is put on the front of a MGF, 45% of 1060kg(=477kg) it would equal a weight balance of 65% for a Gold at 735kg(=477,5kg) I therefore do not think it will have to handle more weight in a Midas Gold compared to in a MGF.
It´s great that you can refill with Nitrogen.
This should make it easier to choose the handling characteristics you are looking for in your Midas.

I´ll keep your converted spheres in mind.

Thanks again Alistair.

Per

[b1zbaz]

I will have some of them converted spheres please can we organise it for stoneleigh next year please