Moulton/BL hydragas units

[forddeliveryboy]

Has anyone with BL chod ever investigated recharging the hydragas unit pressures to original? - by the time they're 30 years old the pressure's down giving a less compliant ride. It's not exactly rocket science - but few seem to have investigated. The Aussies seem to be further down this path presumably because of their poor back roads and someone on ebayuk is doing it, but charging £400 if you supply him with the units, which appears to have the price based on the alternative than bearing much relation to the work.

 

Plenty of MGF owners seem to have been quoted over a grand for replacing flat units with coils (which don't sound to be brilliantly designed) and so then get rid of their car, since it's worth a few hundred. The HTH one is fine yet on smooth roads but struggles with less than perfect ones so I'd like to investigate the possibilites other than replacing with s/h ones.

[Mr_Bo11ox]

http://www.ebay.co.uk/itm/Hydragas-Unit-Re-Gasing-Service-High-Quality-Nitrogen-Sphere-Recharging-Testing-/351402600968

[forddeliveryboy]

Yes. that's him, tbf it includes postage and packing, but it's still £100 a corner. He mentions a small discount on doing whole sets at one go.

[philibusmo]

The nitrogen recharge as Bo1 posted is really only the tip of the iceburg as. Hydragas problems go. The real issue is that as the displacers on the BL stuff especially is getting very old, the diaphragms split and so far cannot be replaced.

 

This happened on the front of my Princess and caused a right kerfuffle trying to find a replacement as they are now rare and highly sought after with no guarantee of how long a replacement will last. At the moment, once we have run out of displacers, there will be no more and an alternative will have to be found, possibly a coil set up. Dunlop are not remanufacturing them and no diy method to replace the diaphragms has yet been found.

[forddeliveryboy]

Is it right to say (I'm a novice in these things, my only experience with gas springs is with Citroens) the lower the pressures they run, the more chance there is of damaging the diaphragm? Or does more movement mean more wear/chance of failure? Surely there are enough BL people around in the UK and Oz to make remanufacture by a man in a shed quite worthwhile? Aren't the joints crimped?

 

Here's the Aussie-can do/why the strewth would we want steel springs? attitude thread. http://www.mgexp.com/phorum/read.php?54,2776032

 

I seem to remember something vulgalour wrote mentioning the fact that AM had sorted a way of taking apart and putting back together these things, so presumably internal rubber should be replaceable. After all, anything's possible, it's just a matter of organising sufficient people to buy into it to make it cost effective.

[Asimo]

Just in case a picture helps.

 

 

If there is less gas in the unit,  when the car is on it's wheels  the volume of gas will be smaller, the pressure won't be much different. When the wheel deflects the pressure rises much more quickly if the amount of gas present is too small, ruining the ride. The lower diaphragm is then subject to more stress certainly. The bottom diaphragm is also vulnerable if the height is wrong, ie not enough liquid or if the droop stops are missing.

[philibusmo]

Here is the saga of my Princess when the suspension exploded. The next few pages include me desperately trying to get hold of a new displacer and Vulgalor explaining the solution found by Dr Moulton for changing out the diaphragms. If this could be put into practice along with the nitrogen recharging then there wouldn't be any issues with keeping BL chod on the road:

 

http://autoshite.com/topic/14673-1981-austin-princess-expletives-removed/page-26?do=findComment&comment=670334

[Squire_Dawson]

You should have more faith in the product. It is, after all, British designed and manufactured. They have already proven their longevity. I've not had a problem with any yet, touch wood, but there is always a solution should a problem occur.

[Richard]

Is it possible to adapt the system to take Citroën spheres?

[Mr_Bo11ox]

You should have more faith in the product. It is, after all, British designed and manufactured. They have already proven their longevity. I've not had a problem with any yet, touch wood, but there is always a solution should a problem occur.

 

Come on then professor_Dawson, what is the solution in this case?

[The Reverend Bluejeans]

The answer is most probably to forget about shagged out 30-40 year old displacers, and use the vast stocks of £20 MGF ones. There will be a way of adapting these, even if it means making up new pipes/adaptors. A Princess on coils is wrong.

[Bear]

Keep wondering if manufacture in China would be possible. Dunlop aren't interested in making them... someone with the right connections could probably persuade a domestic Chinese firm that the improved ride quality was worth part of the investment, too.

[Squire_Dawson]

Where there's a will there's a way. It was made by people so can therefore be dismantled, repaired and possibly be improved by people. Or do we not 'do' engineering anymore?

[The Reverend Bluejeans]

Princess Ambastardor displacer versus MGF unit. The 'Cess one is the single new one.

 

If they can be made to fit, you'd need to machine an extension tube as the MGF one looks like the operating rod is shorter - not beyond the wit of man.

 

The MGF units were very good and represented a big step forward over the previous versions. PRINCESS HANDLING PACK YO

[Mr_Bo11ox]

Would be well interesting to drive a wedge that had been fitted with a set of those. I wonder if the gas pressure would be ok with the increased weight of the wedge bodyshell??

[doobietoo]

TBF £100 is not a bad price seeing as they check the diaphragm and then have to drill a hole and weld a valve in then fill it with hydrogen re-test it and send it back. I am guessing no one else does it because it isn't worth trying to compete with that price. Even if there was demand for 10 units a week say at 2 a day which I doubt by the time you take expenses, insurance tax etc out of that its hardly a well paying or even a full time job probably more likely a bloke in a shed .....

[forddeliveryboy]

That's a fair point. I s'pose I'm just used to Citroën spheres, the prices and ease of fitting.The Moulton setup seems to maintain pressure much longer, on a par with the Mercedes spheres used on their estates.

 

If you could expect 6+ years from a set of recharged spheres, then £400 is probably acceptable. Bit of a bummer if a few months later the diaphragm goes.

[Taff]

MGF ones are in the region of £80 new. Used ones can be found for small change

[forddeliveryboy]

I'll get a pair of rears at that price - where from?

[Taff]

I'll get a pair of rears at that price - where from?

 

that was a quick flea gay search mate.

 

edit - my mistake. It was a knuckle for £80, cheapest new sphere I found was £135. sorry

[forddeliveryboy]

Ach! I was excited for a minute, there. As far as I know, new rears are almost unobtainium unless you start drawing nails from members of the MGOC. Hence looking into regassing.

 

Some have suggested Metro/100 fronts, but the MGF ones were upspecced with lower internal friction. If a pair of new Metro fronts were available for a song, I'd be tempted to try them - lack of damping can be corrected with changing the auxiliary ones.