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MG MGF Technical - MGF Mk1 suspension
Once the suspension has started lowering what should be done. It was pumped up just over a year ago but now it is low again at some corners. Do the units need replacing if so how much might that cost. Any advice most welcome. Also there is a very slight yellow substance on the dip stick, the filler and expension tank are clean. Is this an early sign of HGF or just a little condensation (the car hasn't been used recently). Dave |
Dave |
You wouldn't expect significant reduction in height over a year. The suspension units are connected front to back so if the front and rear on one side are low that would suggst a leak on that side. If all fours corners are low then both sides must be leaking, unusual. The suspension units do age, the nitrogen gas in them leaks over the year, and this results in a reduction in the height of the car over 4-5 years. Once the nitrogen has gone the units are not as effective at absorbing shocks, new units will improve the ride but they cost around £160 per corner. The units themselves tend to fail catastropically not just leak though as the fluid is at a presure of around 400 PSI. A slight variation in height is normal between winter and summer as the fluid expands as the ambient temperature increases. |
Dave |
Are new Hydragas units available? I thought I had read that none were being made any more. |
Mike Howlett |
Its usually the fluid that leaks out past the seals, not the nitrogen because that is contained behind a thick rubber diaphragm. Fluid loss is normal if you live in an area with lots of speed bumps like me and it's something I've learned to live with. 6 monthly recharging has become the norm. Chris |
Chris |
Sounds like you need the suspension topped up like me. I live in Australia and since the melt down of MG, service work like this is nearly impossible to get done and the garages that are left are charging very high fees. We need the forums help that is the MG Car CLUB of South Australia we are making our own top up pump but we need help in purchasing the correct top op fluid, such as the description/specification, manufacture, order number etc. Have a nice day to all Eric Gray. |
E Gray |
Eric, There must be an old Mini ,1100 garage around somewhere, they should charge only a small amountand can do the job in a short space of time. I get my F pumped up once a year and for the $60 charge they will top it up or lower as many times as I go to them over the next twelve months. |
Andrew W Regens |
Brown & Gammons sell the units, as do MGOC - but they are approx £150 each as previously said. I replaced all four of mine with 'newer' units from the breakers yard for about £15 each. All four of mine had perished internally, they didn't visibly leak but the suspension kept dropping. Part of that was due to the fact that the internal seals separating the nitrogen from the fluid had gone, allowing the gas to mix with the fluid. After many top ups, the suspension became completely solid and every small bump in the road lead to a teeth jarring experience!! The units are connected front to back along the same side of the car - this should mean the levels should be equal but one low corner can indicate that the gas is going (or gone) in that particular sphere. If you bounce the car at that corner, the suspension should be noticibly stiffer. I needed such regular top ups that I bought my own pump. When I eventually plucked up the courage to replace them (spurred on by the sudden failure of one unit - fluid everywhere and car down to the bump stops on one side), the results were amazing!! Smooth ride, non of the harshness I'd associated with the car before. Cost me about £60 and well worth the money - The pump was a somewhat dearer though (but I had previously bought that). Now I can easily go 12 months without a top up - In fact, I tend to reduce the pressure in the summer (warmer weather) and increase it in the winter so that the ride height is the same all the year round - Tends to rise & fall with changes in temperature. In general hydragas units have a good reputation and have a long life span but there was apparently some with manufacturing defects which found there way on to the MGF and these seem to be prone to failure - Depends on the age of your car - The ones that I took off mine were in a poor state compared to the second hand units from a 'marginally' newer car. |
Mark Clayton |
Is there any type of conversion kit to convert hydrogas to coil-overs? Ollie |
ollie |
Mark, the symptoms you describe seem to match those of my F; the ride seems much harsher of late. I don't have any fluid leakage nor do I need to pump up frequently . Is there an "on-car" test to check if the spheres have failed or can it only be done off-car? Rgds, tony |
tony |
According to the manual, the test is to de-pressurise the suspension and connect the hydragas pump directly to the suspect sphere and start to pressurise it. The pressure should go up quite quickly to around the 200psi mark (the nominal pressure of the gas) and then continue to rise more slowly (as the gas compresses). If the gas is gone, the pressure just rises rapidly, without any marked slow-down. I had the pump but couldn't get hold of a suitable connecter to attach directly to the sphere so couldn't try the test - In the end, I just replaced them. One simple test - I opened the rear boot and sat on the inner lip with my feet on the floor and then bounced up and down - The suspension hardly budged (perhaps moving about 1 or 2cm). Now with the newer units the suspension travel is like any other car. The only real give in the suspension before was provided by the tyres compressing - obviously when then sprang back the car bounced up in the air - I couldn't take speed bumps at anything more than a crawl, even then the car used to land heavily following by a wallowing series of up and down bounces as the tyres absorbed the shock. Now I can drive over them normally. |
Mark Clayton |
Hi Folks, Like Dave my F is dropping over time (mainly on the nearside). Also I’ve noticed the ride getting progressively choppier over the course of the last few years. I guess this means gas is being replaced by fluid, and I’d very much like to sort it out. Earlier in the thread a price of £160 per corner was suggested, is this for new replacement units, or second hand. What is the best source of new spheres and is this a representative price? I’m still considering the home made pump idea (grease gun etc) and wonder whose had experience of doing this. Cheers, Russ. |
Russ D Mellor |
Another thing... Can 2nd hand spheres only come from an F, or were the same spec used on different cars? Also which units did you use Mark, and how were you confident about condition etc? Thanks, Russ. |
Russ D Mellor |
Only from an MGF Notice two versions. MGF or MGF Trophy. details http://www.mgfcar.de/hydragas/compare.htm more stuff http://www.mgfcar.de/hydragas/index.htm |
Dieter |
Russ D if you actually READ the thread you will see the prices quoted are £150-£160 per corner for NEW and £15 per corner used - dont know how you could have picked it up any other way ???? |
Dick Pullar |
I used 2nd hand units (approx £15 each) from a breakers yard - I actually ending up buying 4 fronts & 2 rears as the scrap yard initially posted me 4 front units, not realising they were different from the rear ones. Interestingly I ended up using the front units all round - My reasoning behind this was that the fronts always looked cleaner and, I assume, don't take the same loads as the rears (plus it always seems to be rear ones that fail). Before I could put the front ones on the rear, I had to swap over the pisons from the rear units (as the displacement rate is different for the back, the flatter shaped pistons give a stiffer spring rate). I debated long and hard before doing this - although the dimensions of the rear units are different at the bottom, the rest of the measurements are identical (I assumed they would be identical internally and couldn't imagine Rover would go to the expense of having completely different units made), so I thought I'd give it a try. The only thing I couldn't understand was why the bottom section was narrower on the back ones.... until I tried installing them! I think the narrower bottom section of the rear units is to facilite removal & installation whilst the subframe is on the car, even then, it's really tight to get them in and out. The front units foul (on the wider bottom section) and won't locate (unless you gently pull the inner wing out slightly to get them in. I kept the rear units just in case handling was compromised, or the units were unsuitable in some other way... Anyway, 18 months down the line and they're fine... |
Mark Clayton |
Thanks Mark & Dieter, very useful. Local availability from a breaker is likely to be poor, but I’ll check it out and put it a search with specialist and national breakers. Is there any advantage in trying to secure units from a Trophy, I note some of the sizes on the Dr Moulton graph are different, but I’m not sure if this precludes fitting, or if there’s an advantage in going for the Trophy type? I must also bite the bullet and buy or build myself a suspension pump as well! I guess the system has to be depressurised first, will a home made pump (grease gun etc) allow this practically? I can check it out fully on other threads and the Rave CD, but other than the pump, are there other specialist tools required, and is this a practical non workshop based repair for a reasonably proficient home mechanic? Thanks again chaps, Russ. |
Russ D Mellor |
http://www.247spares.co.uk/mg-Mgf Russ, you may find the above link useful. Regards Tony |
Tony Harrison |
I went the whole hog and bought a pump with vacuum facility - Some just do pressure only - Either way, the pump comes with a schraeder low loss connector which attaches the pump (via a length of hose, also supplied) to the hydragas connection points on the car. The valve allows you to connect up, then turn a small lever to depress the pin and allow the fluid to be released into the chamber of the pump or for you to add more fluid into the car. The vacuum facility allows you to completely draw all the air out of a depressurised suspension before re-filling (just makes sure you get no air bubbles in the fluid) and is also useful for drawing a vacuum and drawing the pistons up into the spheres if you are trying to get at the pins underneath. Trophy units may have a lower gas pressure (not sure) which would give a stiffer ride and they definitely have shorter pistons at the bottom which gives a lower looking car without the need for lowering pins. Other than that, they are the same fit. B&G sell the trophy ones as a set (new). Tony, you beat me to it! I was going to recommend the same site - It's where I bought mine from - You simply add your details and a series of breakers text you or ring you with quotes if they stock the part you want. I replaced all mine outside on the drive, so definitely a DIY job as long as you have the right tools (namely the pump). Once the system is depressurised, it's a 'fairly' straight forward job to remove the units (just 4 10mm nuts/bolts holding each one in & the connector to undo). The front ones are easy to access from under the wheelarch, the rears a little more involved due to the space resriction - Need to unbolt the ECU on one side & the expansion tank on the other to work on the units from above (not as scary as it sounds, you just need to unbolt them and move to one side, not disconnect completely) You also need to access them from the wheelarch too. I asked lots of questions on here first and panicked a little about tackling it but was plesantly surprised that it was easier than I had anticipated. Dieter's site was very useful as he had pictures of a rear unit he had changed |
Mark Clayton |
Thanks guys, very useful. I've registered for the 2nd hand spheres and have checked the cost of pumps. The vacumn one looks the business, but is £325 on eBay, even the non vacumn is £200. It would be great to hire a vacumn one for the weekend, but I'm not aware of anyone who does that. I may try the local owners club to see if anyone has one I can borrow. Given the extent of the job, I may even consider new spheres. It would be a shame to go to all the trouble and find they were duff. Until then I may have a go at the home made grease gun pump. Where I've lost some height on the NS, I'm sure rectifying that would help a bit, thanks again. Cheers, Russ. |
Russ D Mellor |
On the same topic, is it possible to convert the suspension (hydragas) on a MGF Mk I to the later model TF suspension ? Is there an aftermarket modification kit available ? I'm somewhat concerned about the reliability and parts availablity for the hydragas system in the future. Thanks. |
Wim Vergauwen |
I'd also be interested on the conversion option, would a new sub-frame be required? |
Leigh |
Swapping the subframes is the way to convert, laborious in the extreme but secondhand ones are not particularly expensive; another option is to take your car and probably a lot less money overall to someone like TechSpeed and they'll make your Hydragas suspension just as good, if not better. Without disembowelling your car, too, which is always preferable. The people probably best to talk to about converting to the TF setup are Vehicle Handling Solutions, the guys there were about as close as it gets to the development of the F and TF chassis and have applied their knowledge quite convincingly - their sprint TF is consistently fast & well behaved and seems to turn up, win, turn up, win, turn up, win etc etc. Whichever option you choose, book a track day for before and one for after, then you'll get to see what size grin you have after each. As I recall, most of the Fs I couldn't keep up with on track had TechSpeed stickers... a particular red MGF with aforementioned TechSpeed sticker (and a DVA sticker too) overtook me at Donington despite being technically on fire at the time, so that just shows how good they can make your F ;o) |
bandit |
Totally agree about having the TF suspension as improved by VHS 'Comfort' dampers. (They make it a bit harder than Hydragas, so goodness knows what a standard TF's like!) The only thing is the cost - a bomb to get it done with new parts, a little bit less with used as it's mostly labour and a pig of a job (ask Mike Satur who did my F). You'd have to be pretty handy to do it yourself. But the results round Silverstone were excellent. Ta very much again to MS & VHS! |
Mike Cunningham |
Mike, I've always preferred the looks of the F to the TF, but that aside the things that's put me off getting a TF is the way they handle. Any that I've driven on anything other than a VERY smooth road jump and bounce about all over the place (my ZR is the same). Mike Satur "sorted" my F's suspension a few years ago, lowering it, fitting poly bushes and adjustable shockers and I can honestly say that it's 100 times better than any of the TFs that I've had the misforture to drive (performance and comfort). Remember MGR didn't change to springs because they were better it's just that they weren't prepared to pay the going rate for the hydragas units to continue to be made. |
David Clelland |
Hi all I've recently bought a 97 MGF from a neighbour - have been admiring it on and off for a while then she put it up for sale. However, when she had it MOT'd recently it failed because the Hydragas unit needed pumping up - she had that done, but I think it must be overdone, as the ride height looks very high, and there's very litle movement, especially at the rear. The ride is very firm, but as this is my first sportscar, difficult for me to judge. Can anyone advise a novice about this? Better still (as I'm not into car DIY) can anyone recommend somwhere in north London to look at / sort this? Thanks Chris London N10 |
CW Faux |
Chris it's dead easy to check the ride height of an MGF. Park up on a level piece of ground and let the car settle for a little while to let the suspension fluid cool down to ambient temperature (you can bounce on the front and rear and roll it forward and back about 1m as well to even out the suspension front and back). For an MGF with standard suspension, the ride height should be 368mm +/- 10mm measured vertically from the centre of the front wheel to the underside of the front wheel arch. This measurement is correct at 17°C and you allow 0.6mm of a difference up or down from 17°C (suspension is slightly higher when the temp is warmer). You only need to measure the two front wheels since the hydragas setup is connected front to back on both sides of the car. If it's too high, have a look at this page from Rob Bell's site - http://www.mgf.ultimatemg.com/group2/DIY/suspension/howto_lower.htm |
David Clelland |
David, I find that with the VHS Bilsteins there's not a huge difference in ride quality, a little firmer, but it was never exactly soft before. There's a pitching movement that's noticeable at first, but I'm only aware of it now if I'm looking for it. I think the bounce frequency is a bit higher, but it's no more awkward over the dreadful speed humps along Auchingramont Road in Hamilton. Conversely it was extremely happy at Silverstone, especially the fast corners. Round the never-ending Brooklands it was definitely understeering, but nowhere else. I agree the ship was spoiled for the hap'th of tar with the factory dampers, but I accept VHS's Alan Philips' explanation of the underlying technical improvements to the geometry. Plus there are no longer any Hydragas units to settle or leak! I'm not expecting to have to do anything more to the underside during my lifetime.. Just leaves interesting things like cool air intakes and/or TF135 cams..... |
Mike Cunningham |
Evening guys, My car's really firm (boneshaker) when driving, not really been out much until recently but really now getting on my nerves (and my fillings). Hadn't been out in it much after having bits of the front sub-frame replaced, and initially anticipated a duff hydragas unit (or rather all 4 having lost their nitrogen). However, has dawned on me that I only noticed this after the repair, and wonder if the hydragas has been overpressurised if this could cause it? Or do I need new hydragas units? Cheers! |
Leigh |
Hi Leigh, My understanding is that suspension is set on height, rather than pressure, so I doubt this is the case, (i.e. if it was over pressurised, it would be too high). I suspect you have a similar problem to me, in that over time the gas in the spheres has been replaced by fluid and the ride is less compliant. I'm looking at eventually replacing spheres, for which there is a bunch of info in this thread. Cheers, Russ. |
Russ D Mellor |
Hi Russ, > (i.e. if it was over pressurised, it would be too high). I think it is, will double-check tomorrow but currently I have no problems with speed bumps which I used to before the repair. If it is too high (i.e. 395 or so), would this result in a much firmer ride? |
Leigh Reid |
Evening all Firstly, thanks to David C for prompt reply. I ended up taking the car to an mg specialist, RW Services, who found that the suspension was higher one side than the other, but recommended trying a slightly lower height than standard - 360 mm, which seems to make the car look better without changing the feel. They reckon after a test drive that my MGF rides similarly to others - but I still feel that it is too hard. Like mark C, I sat on the boot and there seems to be mnimal movement. I have to take speedhumps at 10mph or less. I'm finding I can't drive faster than about 55mph on the average B road because of the ride. Is this normal? Grateful for any feedback on this. Chris, London N10 |
CW Faux |
Chris, As you said above, I think that you have to remember that's a sports car that you have and you've got to expect the suspension to be a lot harder than your normal family hatchback or saloon. However, after having said that I really can't complain about the ride or handling on my MGF and it's been lowered and has adjustable shockers fitted (set about the middle number of clicks). Also, I have been known to go a little faster than 55mph on B roads (ask Leigh Reid). I've travelled all over Britain and the Continent in my car and I can honestly say that it's one of the most comfortable cars that I've ever owned. Could I suggest that you find someone close to home that has a similar car so that you can try and compare the ride quality. If you don't know anyone try the F Register at http://www.mgfregister.org/forum |
David Clelland |
I have to agree with David having the same setup, speeds that I can travel B roads on are far greater than posted. As you become more used to the F you will be amazed at how well the vehicle handles, perhaps do a track day as I did, to give you an idea how the car goes in a safe environment. Yes the ride is firmer than say a Renault Laguna but on par with Golf R32. |
Andrew W Regens |
One of the few things that many critics agreed on as far as the *F* was concerned was the good comfort levels of the Hydragas Suspension system - far superior to the later *TF* system - ask Alan Dunlop! And as the others have said it is a 'sports car' and if it is soft suspension you want then stick to 'normal' cars. Our little *F* spends a lot of time 'at rest' these days but I still find after many, many years (Note Dick Pullar no numbers) when we do take her out she is still great fun and we can still spend hours driving her and not feel fatigued! |
Ted Newman |
Thanks, all No, I don't want soft suspension, I'm just trying to find out if mine is abnormally hard. The car handles great on smooth surfaces. Chris |
CW Faux |
You need to take a bit of care running the car lower than standard, as it can lead to excessive tyre wear. It's a feature of the original design that it's very sensitive to wheel alignment. When the cars were new, the factory set the alignment to be correct for the standard ride height. The problems arose when the cars were delivered to the showroom, the Hydragas units hadn't settled to their final ride height, so the cars looked rather jacked up. Some dealers de-pressured the system to get the right height, so when the units settled they were then too low, and the tyres wore out rather rapidly. Having said that, I had my new TF suspension aligned at mid-height and promptly dropped the front Bilsteins a notch! Tyres are OK, but it's the back that's most at risk, and the TF geometry was designed to get rid of the extreme sensitivity. Hope I've not mis-quoted the VHS guys on this! |
Mike Cunningham |
I would confirm DC has done more than 55 on B roads if it were legal but it's not so I won't! Checked the ride height of mine tonight, it was 370mm, so I guess it's the gas in the spheres that's the problem, though surprised all hydragas units have failed at the same time. |
Leigh |
Ted I notice you're in London' if you are willing, contact me and perhaps you could have a drive in my F and see what you think? cwfaux@gmail.com Cheers Chris |
CW Faux |
Mike, As far as I know the MGF were delivered to the dealers with the suspension high so that they didn't have any problems getting them on and off the transporter. It was part of the PDC that the dealer had to set them to the correct height. On the Trophy model a standard exhaust was fitted to the car and the dealers were given a Trophy exhaust to fit before delivering to the customer - only way they could get the car through the drive-by noise regulations. |
David Clelland |
One thing I was told by someone who specialises in hydragas suspension systems was if you run on too low a pressure (i.e. lower the ride height by lowering the fluid pressure) is that you run the risk of damaging the spheres by rupturing the diaphram which divides the nitrogen & the hydrolastic fluid, causing the two to mix (and then allowing the gas to escape when you top up the system). How true that is I have no idea... ... but judging by the number of dings in my sills & the bent towing points on my front subframe, I assume that my car spent a fair bit of it's life riding very low to the ground - and my spheres were definitely shot... whether this proves the point or not, I can't say but in my case replacement solved the issue of a harsh ride. |
Mark Clayton |
Similar to what Mark says, my F has definitely taken a battering over time. When I bought her 5 years ago she was running at circa 320, with tow hitches beaten virtually flat. It looked great but would not clear the most innocuous speed bumps and would regularly rebound off the bump stops if driven hard on uneven roads. I have since the set her circa 20 mm higher but I think the damage is done, I intend to sacrifice a little of the aesthetic and set her higher on the next pump, but think the NS spheres are shot and should be replaced when I can. Before I bought the car we took out an MX5, but the ride quality did not compare to the F on our local roads. Now with knackered spheres, I’d suggest the ride was worse than a conventional coil spring set up. BTW, anything close to or higher than a standard ride height makes the F look ridiculous, PRAISE THE LOWERED! Cheers, Russ. |
Russ Mellor |
Mark - my F is running very low 305mm at the front. I'm just 5 miles out-side Chester any chance of getting together to pump the old girl up? |
Steve Ratledge |
Anyone had a go at refurbishing a hydragas unit? With them no longer being made, this might be a worthwhile exercise? |
Leigh |
Well done Ted your finally listening !!! |
Dick Pullar |
Dick - have you never heard of 'irony' :-) |
Ted Newman |
Steve, No problem - I'm about the same distance outside Chester too - Drop me a line: markclayton60@btinternet.com |
Mark Clayton |
Yes Ive heard of irony have you ever heard of a razor ? |
Dick Pullar |
I think that you can get refurbished Metro units. Do you think that the same people do ones for the MGF? |
David Clelland |
<have you ever heard of a razor ? > Ah yes ... the cutting edge technology that the Hydragas Suspension is !! |
Ted Newman |
Hi Ted how you doin? I am pleased to say that in the next month I will be taking the plunge and buying an MGF, looking out for a quality bargain in this period of buyers market :-) Just to comment on the hydragas as I have a lot of experience with these units racing Metros. The rears of metros were slightly different to the front in their construction. Inside the rear ones was a liquid damper type arrangement that acted like an external shocker, where as the fronts did not need this facility as they had a pukka external shock absorber fitted. When the gas escaped the suspension unit would become solid with only non compressable liquid inside. On the later Rover 100 cars the units were connected for and aft, ie front left to rear left. Then for example if the front unit lost its gas the front would drop and go very firm. When someone then tried to pump up that side the rear would become very high due to the excess pressure introduced in an effort to raise the front. So you would have a car with a low front and high backside. Generally then if the whole side was low it would be either both unit faulty or more likely loss of liquid. Finally in answer to Leigh it is impossible to repair these units although we did modify a few to help with suspension settings. :-) dont tell anyone!! |
Bob (robert) Midget Turbo |
> I think that you can get refurbished Metro units. Do you think that the same people do ones for the MGF? Hopefully otherwise we'll all be stuffed in a few years! I read an interesting post in the archives from a guy in Australia that could set the nitrogen pressure on his hydragas units, that to me suggests it may be possible to attempt a refurb surely? |
Leigh |
To adjust the nitrogen pressure is a straightforward modification, however if gas has leaked from the rubber sphere that means the sphere is leaking and would require replacing, that to me is impracticle for a number of reasons. |
Bob (robert) Midget Turbo |
As the present Hydra-gas sphere is a "one piece unit" that bolts on to the chassie why not replace it with a similare bolt on unit with normal springs? The original "dampers" has of course to be changed for real items with the correct bounce and re-bounce rate. This without giving structural damage to the turrets as can happend even now with too hard adjusted exchange shocks. To me this is something for the aftermarket boy´s to develop so we can get rid of the worries for the future use of our MGF´s. Small suitable almost ball-shaped springs are on the market for other light vehicles. The final unit could probably be a very close look-alike to the original one ! Height adjustment now done by spannes instead of high pressure fluid... / Carl. |
Carl Blom |
Hi Bob I am doing fine! And you? Welcome to the *F* world and I am sure an old MG hand like you will have no problems with the car and its wonderful K Series engine - it such a sweet running motor even given it's love of upsetting one or two people by letting off steam! Oh and as a BTW (just to upset D.Pullar) 12 and a quarter years ours has been looking after us and it still puts great big smiles on our faces! Just completed a 2000 mile trip to Scotland and back and we are now putting the final touches to our trip to Berlin in August when we join in the MG Rally there - that normally puts another 4000 miles on the clock as we visit Karin's relatives whilst out there. And just to keep the posting in line with the thread - with the two of us in the car and luggage for a months trip (boot full, bonnet full and the space behind Karin's seat full) the suspension is perfect! And BTW #2 We do know that the bonnet is the 'crumple zone' so its full of soft items only. |
Ted Newman |
Hi all, and thanks for all the help to a novice F'er. Having now sorted a few things out like track rod ends etc., and running at 360 mm (within tolerance) things are loking pretty good. I'm now reasonably happy with ride and handling,altghough potholes and similar are still scary. Chris |
CW Faux |
This thread was discussed between 16/04/2008 and 11/06/2008
MG MGF Technical index
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