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MG MGF Technical - softer ride

Hi all
i would like some help please
here is my problem when driveing my 97 mgf on all roads that are a bit uneven i can feal every bump in the road though the rear end .
when i go over a small hole or train tracks it sounds and feales like the struts and everthig are hiting bottom i have replaced the struts and new rubers on them the struts were second hand off a car that had done 30000k mine has done 120000k and it is still the same the hydragas system is ok hight is good .I have two cars same year when i drive my wifes over the same roads hers is ok.
i am at a loss what to do
any ideas please
thanks Andrew
AR Cayzer

Maybe the spheres are holding the gas or the bushes?.
Andrew W Regens

what do you mean buy spheres
how do they work
AR Cayzer

I have a very harsh ride (but the suspension is set to the correct height) - A few months ago one of my rear hydragas units blew and I replaced it with one from the salvage yard - What a difference! That particular corner is much softer. I assume the gas must have leaked out leaving me with little or no suspension. I've since bought a unit for the other side, just got to get round to fitting it!!
Mark Clayton

if my hydragas units were broken or leaked i would think it would not be the correct hight
i thought the softness only comes from the struts
is that not correct
AR Cayzer

The unit is made up of two spheres - the top one contains pressurised gas, the bottom has the water based green fluid in it and they are separated by a rubber diaphram. When the suspension is compressed the fluid displaces the diaphram and compresses the gas, which then absorbs the shock and 'springs' back into shape - Acting like a coil spring. The damper is used in the normal way to dampen the spring effect.

The most obvious leak is a fluid leak but you could have a unit which loses it's charge of gas over time. The suspension would sink a bit but the annual top up of fluid would bring the height back (but the volume lost by the escape of gas would be taken up with fluid) so that everything looks normal. However, the top and bottom spheres would effectively be full of fluid (which does not comptess), hence the hard ride. A gas leak would not be as obvious as a fluid leak as the fall in height would stop once all the gas has gone. Also, it's probably a gradual thing, unlike a fluid leak.

When travelling over speed bumps, the rear end of my car used to come down with a teeth jarring thud and the only thing to absorb the shock was the tyres. I didn't know any better and just assumed it was normal, until I changed the unit! Now, that side of the car acts normally but the other side is still solid (which is an odd sensation).
Mark Clayton

mark you had the same problem as me so that is good news for me now it is looking better to get it fixed
ok so without takeing them off can you check if there is in fact gas still in them
and did you change them your self?
i guess i would need to change both ?
how long did it take ?
how much did it cost ?
should i do front as well ?
were did you get them from
thanks Andrew
AR Cayzer

Maybe look at second hand say from a trophy, talk to Victoria at the MGF Centre.
Andrew W Regens

I got my units second hand from a salvage yard - It cost me about 60 pounds for the four. They were off a fairly new model car (newer than mine anyway). New units are 150 pounds approx. I did do it myself but I have a hydragas pump (with vacuum) which I bought off ebay, so it was easy to drain down the system, replace the unit and re-charge the system again. I suppose it took me about 4 hours but that was because I was feeling my way a bit as it was the first time I'd tackled anything like this. It was fairly straight forward though. I've only put the one unit on at the moment (because it failed completely and lost fluid so I had to do it) but I think I might replace all four eventually (certainly the other back one).

According to the workshop manual, you can test each unit to see if the nitrogen charge is still okay. You do have to drain off the system on the side you want to test and have a hydragas pump to peform the test. Basically, you connect the pump directly to the unit you want to test and start to fill it with fluid. The pressure of the fluid should rise rapidly up to about 240psi (which is the nominal pressure of the nitrogen in the top sphere) and then rise more slowly after that (as the compressing nitrogen pushes back against the diaphram). If the pressure continues to rise rapidly past the 240psi mark, then the gas has gone. I might just do this test before replacing all the units but I need to get an adaptor to connect directly to the spheres.

The manual also says that a loss of gas can be indicated if the suspension is unusually lower on one corner of the car (this was the case on my car just before the unit let go of it's fluid).

Also, because the units are connected front to back, the fluid is displaced from one end of the car to the other as one corner of the suspension compresses, effectively using the gas in both the front and back units to absorb the shock - Even if only one unit has lost gas (say on the back), it might mean that the front unit appears stiffer too? I don't know?
Mark Clayton

I think the boys at Link in Mitcham can help as they deal with the old Mini's as well as F's.
Andrew W Regens

ok update for those who would like to know and a bit more help please
well after much fun and games i now find it is not my hydragas that is the problem i just need new not second hand shocks the pair i have just put on are no better than the old pair so i am going to get 4 new gas shocks here is my question
has anybody tryed gaz type shocks or koni they both have types in australia made for mgfs i think made in the uk
i can set the type of ride i like with out taking them off the car
or are there any other types you can recomend
thanks Andrew
AR Cayzer

Phill Stafford fitted Spax but had problems in the end went to Pedders who sorted out his problems at a far cheaper cost and with agreat improvement. If you have old copys of Wheel Spin his number should be in it, give him a call.
Andrew W Regens

This thread was discussed between 16/09/2007 and 21/09/2007

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