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MG MGF Technical - Suspension spheres

I am racing an MGF here down-under. The car was originally built as one of the cars sent to Japan for the MGF series there in 1995. I acquired it last year and have completed 11 race meetings in it to date. Over this summer I have built a new engine for it and would like to now start some suspension tuning. I have read how the moulton spheres work and have made adjustable pins for the connection between the suspension arm and the bottom of the sphere. I understand that "harder" spheres were (are) available in order to stiffen the suspension. Does anybody know if that is true and are they still available in the UK?
Any suggestions regarding improvements in the handling/traction area would be helpful.
Regards........David Mottram
David Mottram

David,

Before Roy Forde, now at TechSpeed, retired from MGR, he was involved with the MGF cup cars that went to Japan. You may want to try to contact him directly - I will email you some contact details.

Dave
Dave


Hi David,
I assume You will get loads of answers regarding this from various people doing racing / club-racing with the "F" ... Not knowing what original dampers there are on the Japanese MGF-series cars an upgrade to fully adjustable dampers is well worth the money.
On my "F" also used for slalom and club-racing I use adjustable Konis (low setting front / hard at the rear )to give the preferable more neutral handling (slightly towards oversteer) when doing slalom events.
Also a "homebrew" nipple job = no interaction (or heavily restricted one)between front and rear spheres is a nice alteration.Also more solid bushes are desperatly needed, even so in the sway-bars to really get away with the rubber band feeling. But this is probably done from the beginning on Your car ? Anyway - if You are going for stiffer shocks check that there are reinforcements made at the rear upper mounts. Slightly sloppy spot-welding here canīt take the extra load .
As said - others will fill in with more info and possibly links!

BR, Carl.
Carl Blom

My car is already fitted with adjustable dampers all round and the various suspension bushes have been replaced with material with less compliance and the body/chassis has been extensively re-inforced by Techspeed when they built the car. Basically it was built to a good standard by Techspeed before going to Japan. I intend seperating the operation of the front and rear hydraulic spheres as suggested. My real need is for a stiffer suspension, not just stiffer dampers. I can lower the car by dropping the fluid pressure but that does not stiffen the car's suspension. My understanding is that the "race" spheres have a lower initial nitrogen pressure which makes them stiffer due to there being less suspension medium.
David Mottram

dont lower it by removing the fluid mate. thats no good.
you need to cut some of the suspension parts down then pump the fluid back in at a higher pressure. lower and stiffer.

yeah the stiffer hydro units are available (from me ;) or MG Sport and Racing.
they also do some high pressure valves.

Drew
Drew Spalding

>I can lower the car by dropping the fluid pressure but that does not stiffen the car's suspension. My understanding is that the "race" spheres have a lower initial nitrogen pressure which makes them stiffer due to there being less suspension medium.


Hi,
you mentioned you read about the hydragas units. Is my website and the following links common for you ?
http://www.mgfcar.de/cut_unit/index.htm
http://www.mgfcar.de/hydragas/hydragas.htm

On first hand the cup cars front to rear connection got cut and all four are working as seperate springs. That's what Carl did as well to his MGF.

The lower initial pressure in the upper sphere can be made adjustable by some more DIY works. Though, finding the 'right' pressure for this stiffener units is another question. At last a formula for calculating can be found with some experiments.

The units have a 'working range' up and down by design. I assume this is app. +-5mm (could be up to +-10mm ?). The resulting work range of the individual found balance between upper pressure, lower pressure, car weight (load). This all is quite similar to the spring rate of standard coil springs.
Non linear though. Don't forget to add washers between the unit ally piston and the upper arm roll bearing to balance the relations between prewssure consumption (upper/lower) and suspension height.

You need to drill a hole to the upper sphere and release the nitrogen.
Then you need to assemble another valve to the upper nitrogen sphere. The material is 2 mm sheet metal, so a small M5 thread and affiliated joint and pipe and valve should be no problem. Tyre valve for example as used for the fluid.

Voila, now you can pump the upper with nitrogene or pressed air to any pressure you like and the lower as usual with the hydragas fluid.

May be an option. Would be great to hearing from you how you get on.
Welcome by email as well. NOSPAM_mgf@mgcc.de

Hope this makes sense. I'm sorry for the may be funny sounding 'German-English'.

Regards
Dieter
Dieter K.

You have an interesting car there David! I am not fully up on the specs of the Jap-spec MGF Cup car, but I believe that they ran on non-standard hydragas spheres in any case?

Depressurising the spheres is counterproductive, insofar as the depressurisation actually drops the spring and damper rates: the spheres will be softer.

There are alternative units. Here in the UK, the MGCC prohibits most modifications to the cars (to keep costs down), but does allow the fitment of stiffer MGF Trophy 160 SE spec hydragas spheres. These are significantly stiffer than standard, and use shorter knuckles as standard. These should not be too costly or difficult to source - order through your local MG dealer.

I am sure that more details will be forthcomming from Techspeed if you contact them directly as Dave suggests.
Rob Bell

This thread was discussed between 05/01/2003 and 06/01/2003

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