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MG MGF Technical - Ride Height Questions

Took my 97 VVC for a service last week and asked then to test the suspension as the ride is very hard.

They told me it was 160 psi and that the correct band is 160-170 psi. Therefore no adjustment required!

I since read the threads about ride height and promptly measured mine at 340mm all round. Even allowing 7 mm for cold weather and a few mm for inaccuracies. I still think this is way short of the 368mm it should be. So here are my questions

1. Should I promptly have it pumped up to 368mm, irrespective of the PSI reading?

2. Wll this make the ride less hard (my brittle bones are being rattled to bits)?

3. Have I measured correctly ie:- from centre of hubs to bottom of the plastic on the wheel arch - as this is about 3mm lower than the metal of the wheel arch.

A few other comments

- I don't know if tyre wear is uneven as I have not had the car long and the tyres are new.

- When I was at the dealers, I quickly measured their secondhand MGF cars on the forecourt and they seemed about the same hieght as mine!

- The headlights also seemed badly adjusted ie:- on dip, they might as well not be on - heavens knows how it passed it recent MOT! Is this possibly due to the ride height being wrong?

Thanks in advance for any replies.
John Bleazard

Test NM
John Bleazard

John, your hydragas is clearly a little on the low side (about the same height as my car actually, but I wanted it that way!). Having said that, one must note that it is cold at the moment, and the MGF suspension will be alot lower now than it will be during ther peak of summer. Therefore, pumping up the suspension now may result in a car looking embarrisingly like a LandRover!!!

Raising the suspension will improve the ride (if only so the car no long bumps along on its bump stops!!!). It is entirely up to you what you do next.

Regarding headlamps, the dipped beam isn't the best- depends on what you were used to before- but perhaps shouldn't be as bad as you describe. Therefore check the beam patterns against a wall to see if the alignment really is radically out, and adjust them (or have them adjusted) accordingly.
Another possibility is that the head lamp lenses have become too dirty- what colour are the dipped beam lenses? Might require replacement.

Rob Bell


hydragas pressure is worth a measure on one hand but there are other terms also to be mentioned.

Its also a case of tolerances of the setup of your cars individual suspension.
For example if the washers between the hydragas piston and the ball joint got lost or changed at any time then the ride hight gets also 'wrong'.

The pressure indicator at the official hydra gas pump is also not that great precision and tolerance varies surely from pump to pump.

More important is the more or less constant ride hight with the below stated tolerance all over the year, cause this has influence on the front tracking (Toe IN is important)

If the ride hight varies +10mm to -10mm in relation to the hight where the tracking got adjusted, then its OK.

Strange term, I know, cause how remembers the hight of the car at the date when the tracking was adjusted.
Unfortunately its never drawn to the tracking measurement result sheets.

PS. notice the hight change if it gets warm ouside :) and check the front tyres inner side for uneven wear from time to time.
Dieter Koennecke

I think your dealer confuses right height and hydragas pressure.
Right height should be 168 mm (hence his 160-170 assertion) when the pressure should be around the 360-400 psi mark. But as said Dieter, they usually don't check the pressure, they adjust the hydragas pressure according to ride height.

>>Fabrice Right, I won't take any notice of the pressure, but I still think it should be 368mm as the wheel has a radius of about 200mm.

>>Dieter A bit technical for me, but I will make a point of noticing the height the next time I have my tracking checked, and keep a good check on tyre wear - I'll add it to the other 10 or so daily/weekly checks that I seem to need to do.

>>Rob Once I've sorted out my ride height I look further into the lights - the list never ends.
John Bleazard

I'm sorry for the spelling failures above... Enhences confusion.

Anyway, guess you are on the wrong way regarding the hight measure. (comment to what Fabrice mentioned).
Its independent of the tyre diameter, cause measured gets the center of the wheel (= axle) to the upper metal lead of the wheel arch.
See also Robs Website for a better description. Or also this one

Dieter Koennecke

Sorry, i wrote complete crap in my last post.
Ride height should be 368 mm, not 168 !!!

I'm thinking of fitting a set of lowering knuckles from 'Moss'. They lower the car by 30mm without disturbing the hydrogas system at all (apparently). Anybody out there tried them?
Rob Marsh

I think you do need to de-pressurise the hydra-gas system to fit the knuckles, hmm or was that bump stops. Anyone? :-s

A few people on this board have them I believe. Knuckles that is, well not just knuckles but lowering knuckles! :)
Paul Lathwell

bump stop, my godness, I forgot to write about that silly parts.

Yes, Paul, both mods need to depressure. But only the knuckel change needs vacuum pumping to get the old out and the new in.

Back to the bump stops. IMO one of the most cinfusing parts.
I ever (mostly) beleaved in what MG mentioned or better said advised to do. Now as I saw the parts in last week and compared them with the standard parts... I only shaked my old head.

IMO its wrong what they say.
Bump stops should be installed if 16' rims get to the car.
Phaaa !!! This silly 'holders' for the front hydragas units are only enhenced by a strong sheet metal welded to the lower area.
Comes to work only if the upper wishbone lifts dramatic. In that case (IMO) the wishbone meets this holder for the HG unit.
Nothing more.

See the pictures of my 'under construction HEF-MG96 upgrade site far below. (click the pictures to enlarge)


The comparison shows a dent in the old holder where the upper wishbone hit the holder. This happened cause the ride hight was far to low. Nothing to do with 16' rims so far or the danger of tyre damadges if a Unit gets blown.

IMO they are required for lowered MGF instead of the advised installation 'if 16' rims'.

Any other thoughts ??

Dieter Koennecke

This thread was discussed between 01/02/2001 and 08/02/2001

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