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MG MGF Technical - MG F, suspension coils ?

To the many MGF BBS experts,
I often read many debatable contributions about the MGF suspension. As you people probably imagine, when you have to live away from the UK hydragas suspension is very difficult to service, a real pain indeed.
The question: Have anyone managed to replace the hydragas units for coils in the F?. Can be done?. If so, how?. Does it work?.
Contribution to the subject will be most welcome.
Rob Brown

Come on chaps. No one at all?
I really need your help on this subject mates.
Rob Brown

Hi Rob.
As nobody else is brave enough, I'll have a go.
I suspect it could be done, after all MG managed it on the TF, but IMO the cost to do such a convertion would outweigh the cost of the vehicle.
You only need to look at a TF to see the amount of work required, the suspension mountings need relocating and strenthening considerably, as the hydragas mounting points are not upto the job, its not just a matter of removing the hydragas unit and replacing it with a spring and damper.
Steve White

Essentially, Steve is absolutely spot on. Nothing is impossible, but the number of changes that need to be made to the location of the suspension hardpoints, purchase of new parts, etc etc make the conversion prohibitively expensive. The more economical answer in this case would be to buy a TF... :o(
Rob Bell

...or buy the complete subframes from a crashed TF and fit them to your F.

Ralph
Ralph

Not that simple Ralph (when is it ever?).

The upper mounts for the dampers are in completely different places on the F compared to the TF. This fact alone means much more hastle and fabrication.

An example of this is shown on these pix of the front bonnet area sent to me by Roger Parker - see http://www.mgf.ultimatemg.com/TFvMGF_susp.jpg

As I say - not impossible, but a lot more involved than it would first appear.
Rob Bell

I had the chance to look at couple of the TF damper/coil units a few weeks back and they have a very large ring/plate that I would guess locates on the underside of the body and distributes the load. So maybe (this is just a guess after all) not too much strengthening of the body would be required, just a couple of plates welded on?
The rest of the damper/coil module is similar in length and mounting points as the dampers on the F so might not require new subframes etc. Thou you require the subframes if you wanted to use new rear geometry. Not to easy to tell how the car would handle on the springs but with F suspension?
R Baker

>> and mounting points as the dampers on the F <<

Unfortunately not Richard - see the above linked image as an example: coil over damper unit appears through inner wing inboard and rearward to the original damper mount. Point taken about local body strengthening though: it the plates are just localised, then this opens up more possibilities.
Also you are right about the rear subframe: TF and F subframes are, in fact, very similar. In fact, if you were to weld on the central fulcrum point for the lower TF suspension arms, and bolted on the TF's trailing arm, then you'd pretty much have converted the F subframe to TF spec. Then all you'd need to do is weld on the TF's coil over suspension turret to the subframe above where the hydragas unit would mount on the F - and the job would be a good 'un.

Front subframes are also very similar - although the TF's is triangulated - and persumably has the coil over turrets too...

Looking forward to being proven wrong on the expense issue though...
Rob Bell

Sorry a bit of confusion on the mounting points. Was referring to the position on the upper arm, not the body. Could do better as my English teacher used to say! Will see if the TF dampers are still around and try and get some pics!

R Baker

Agreed - the front suspension is the same in terms of upper and lower arm location and length (especially judging by the static geometry settings of camber/ king pin inclination), and similarly the rear upper arms seem to be same as the F as well.

Look forward to seeing those pix Richard :o)
Rob Bell

Hi all,
surely the mounting support of the Hydra-gas system has to be just as ridgid (not) as the upper pick-up points on the TF!
F or TF, these 4 points have to cope with the car-load and additional abuse when driven on bad roads.
So if one can get a suitable spring-ratio together with decent shocks + some reinforcements IMO it can be done. The main problem is probably to get springs that fits into the low build-height of the original system on the F.
More and more modern cars get these ball-shaped rather short springs so maybee there are already suitable ones somewhere...
Another thought : Wonder how the F would perform with something similar to the old Mini Hydrolastic pure rubber system ? Emptying the fluid and re-fill with silicone rubber ;o)
BR, Carl.
Carl Blom

Deviating a little from the thread, however with the cold weather I appreciate that the Hydragas units will fall (ideal gas law etc) the problem is one cold morning last week the ride height looked pretty low and at full lock the drivers side front wheel was rubbing on the inner skirting. Is this common problem or have I a leaky piston. In summer the ride height seemed high.

thanks
Simon B

>> surely the mounting support of the Hydra-gas system has to be just as ridgid (not) as the upper pick-up points on the TF! <<

True. See the pix of the rear TF suspension on Dieter's site. Notice how the coil over's turret is effectively welded on top of the hydragas sphere mounting point on the subframe. I guess this could be replicated...
Rob Bell

Simon, you are only likely to have a problem if the ride height is different on one side compared to the other - otherwise, as you rightly say, it is most probable that you are seeing the 'seasonal' ride height change ;o)

Wheel still shouldn't rub on the liner though - may need some subtle 'realignment' with a hot air gun to reprofile the liner.
Rob Bell

Rob (Brown)
my advice is to buy a hydragas pump and a workshop manual this way you will have sufficient to be able to have the suspension worked on or serviced. Far cheaper than trying to fit springs etc.
It would be possible to convert the standard subframes to springs but IMO that would be a retrograde step.
Mike.
mike

Thank you chaps. Not very encouraging indeed. Things are hard away from the UK owning a MG with leaking hydragas units and no spares. And if the part would be available no one who knows how to replace it.
Have anybody tested the feasability of hydragas units filled with silicon rubber? Just to put the car back on the road, no racing performance required.
Rob
Rob Brown

Rob, you do come across some reports of hydragas failure on these boards - but it is fairly infrequent: usually the things last for a very long time indeed. As for filling the sphere with silicone... er... I don't think it'd work, but if it were a last resort, then I guess it might be worth a shot.
Rob Bell

Have managed to hold of the front and rear coil/damper units from a TF. Anyone got a website I can mail the pics to so they can be shared out?
R Baker

Or even an email address so that someone can show them?
R Baker

you're welcome

mgf at mgcc dot de
Dieter K.

Love to see the pix too Richard :o) robert dot bell at ucl dot ac dot uk - cheers :o)
Rob Bell


Have anyone put Richard Bakerīs pics in a website? If so, address please?
Rob

-Have managed to hold of the front and rear coil/damper units from a TF. Anyone got a website I can mail the pics to so they can be shared out?-
Rob Brown

Just digging out digi camera now, so give me an hour or so.
Would have done it earlier but crisis at work....as usual.
R Baker

Your guys should have mail, well I haven't had a delivery failure yet anyway!
R Baker

Got them, thanks Richard.

Now posted:
http://www.mgcars.org.uk/carclub/mgfregister/temp/TF_suspension/PIC00002.jpg
http://www.mgcars.org.uk/carclub/mgfregister/temp/TF_suspension/PIC00003.jpg
http://www.mgcars.org.uk/carclub/mgfregister/temp/TF_suspension/PIC00004.jpg
http://www.mgcars.org.uk/carclub/mgfregister/temp/TF_suspension/PIC00005.jpg
http://www.mgcars.org.uk/carclub/mgfregister/temp/TF_suspension/PIC00006.jpg
http://www.mgcars.org.uk/carclub/mgfregister/temp/TF_suspension/PIC00007.jpg
http://www.mgcars.org.uk/carclub/mgfregister/temp/TF_suspension/PIC00008.jpg
http://www.mgcars.org.uk/carclub/mgfregister/temp/TF_suspension/PIC00010.jpg

I'm sort something more elegant later...
Rob Bell

Thanks for the pics Richard and Rob. Nice indeed.
Would you believe it could be possible to replace the original F dampers with these FTīs?
Rob Brown

Hmm - possibly, yes: might be worth checking the lengths. One down side though - and something you need to bear in mind is that the TF dampers are tuned for TF suspension (different rear geometry, coil springs etc) - so the dampers may not work all that well on the MGF...
Rob Bell

Rob, I am sorry to be late to this interesting thread. Hydragas units failure is quite frequent in my experience. I donīt know if this would help but I saw somewhere -the BBS?- a few pics that show that a suport for a coil had been adapted into the place of the hydragas unit. I have those pics -I could send them to you- but no mention of where they came from or if that modification worked.
Ian Millar

Ian,
I think Rob is still in HK ?
Drop pix to mgf_at_mgcc.de please.
We silly internet MGF petrol heads work together and I'll forward to Rob in any way.

Cheers
Dieter
Dieter K.

Hello Rob,
Why would you want to replace the hydragas units on your car !. These units are far more efficient than convensional coil & wishbone systems and the reason for their demise on the MGF and coil on the TF is purely a cost exercise and the fact that the f is now very predominant in the club racing scene. coil springs make for a simpler and quicker way of adjusting suspension settings for racing purposes, I would suggest keeping with the hydragas and getting a hydragas pump , cost around Ģ250-00 uk pounds,( i can give you the address of a supplier) however the conversion you talk about is not impossible but the cost is considerable and will not improve the handling or the ride of your car.
If you need more info on converting then please do not hesitate in contacting me.
Robert.
R J Hemphill

"From Chris Sheppard: Further to the thread regarding replacing Hydragas units with coils, I was wondering what will happen when, in years to come, you have a unit failure, but the things are no longer available. Won't the spring issue need to be solved."

Robert, as you can see I am not alone with my hydra trouble. I love this car and it is not that I want to replace the hydragas units on my car just for the adventure! It is that I need to do it or otherwise abandon the car! Not even possible to sell in the actual condition.
If you have the conversion know-how please share with us.
Rob
Rob Brown

Just got back to the UK.

>>Hydragas units failure is quite frequent in my experience.<<

That's interesting that you say that Ian. Perhaps warm climates are a feature in these system failures?


>> I donīt know if this would help but I saw somewhere -the BBS?- a few pics that show that a suport for a coil had been adapted into the place of the hydragas unit. I have those pics -I could send them to you- but no mention of where they came from or if that modification worked. <<

Interesting - yes, definitely interested in those pictures...
Rob Bell

This thread was discussed between 22/11/2003 and 10/12/2003

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