Topic

Hi- Are the knuckles under hydragas spheres supposed to be tight like a ball joint? I’m replacing the hydragas spheres with re-gassed units from HAHSLTD.co.uk. Took out the old spheres and was surprised at how floppy the knuckles were. If they were ball joints, I’d assume they were bad, but since these are in compression perhaps it doesn’t matter as much? They also have plastic parts inside which makes me think they aren’t supposed to be tight. A new set is very expensive.

Thanks, John

Are you referring to the cast alloy bit that’s on the bottom of the sphere?
With no hydraulic pressure in the sphere that will always move a bit as it’s secured to the lower diaphragm by a ridge and lip arrangement

Hi Cobber,

This the part I’m referring to:

https://rimmerbros.com/Item--i-RGG001219EVA

Thanks,

John

As a matter of fact this part can be removed from the diaphragm by inflating the diaphragm with compressed air via the fluid port
(With the sphere removed from the car of course) Once inflated you can twist the alloy cone shaped piece out from the lip formed in the diaphragm.
Refitting is just reverse the procedure.
The reason that someone might do this is that the only difference between front and rear spheres is this alloy cone, and they may need to convert a front sphere to a rear sphere, as rears are almost impossible to find now and the Trophy models spheres are totally unavailable so standard sphere can be converted by using the alloy cones from the Trophy spheres in the standard ones.

So even if your old spheres are totally buggered and unable to be regassed……Remove and save these before you throw the old spheres in the bin! Especially if they are Trophy or standard rear spheres!

N.B. Trophy spheres, are the same pard front and rear.

Hi- My concern is not the cone. I’m talking about this thing… there seems to be a great deal of play/looseness to it.

Good morning John & welcome. Something doesn’t hang together there. The nylon inserts age, become brittle & are adept at failing if you try & strip the joint down. There was a spell when f owners replaced the standard foot for the lower design as used on the 160 & much hair was pulled out during that phase.
I have & intend to fit shortly a full set of 160 suspension arms which are inaccessible behind an immobile car, I hope that this will change either later today or tomorrow in which case I’ll inspect the foot hold & give you a definitive reply.
M

Yeah that bit should not be sloppy, they’re easily damaged with rough handling, once fitted they seem to hold together well enough until wear and tear sets in.
I’d be inclined to take the opportunity to replace them whist the opportunity is present.

I’ve not forgotten about checking the roller foot. As I said the car is still immobile but that’ll change shortly, providing I can sneak out unnoticed from being pleasant to some visitors.
Fortunately they are aware of my preference for talking to my dog & the inanimate objects in my collection; the definitive answer will be later.
M

Ok, the definitive answer. The four roller feet on the lowering set I’ll be fitting when the rain stops & I can get the car out & under the tent so I can get all around it without ending up in A&E; they all feel like ball joints. So again Cobb’s was correct, get them changed whilst it in pieces.
M

I bought four new MG Rover OEM knuckles. I’ve attached a video showing they have the identical play the old ones have! They absolutely have a great deal of slop, even when brand new.

This can make some sense.. If this were a ball joint, there would be a spring pushing up from underneath. On these cars, the spring is above, pressing down. In addition they are under compression because the hydragas sphere is constantly pressing down.

Since I figured I already paid for them, and returning them to the UK is prohibitively expensive, I decided to install them anyway. Guess what? They don’t fit. The combined thickness of the bottom steel pad and the nylon cup is larger than the hole. I broke a new one trying to shove it in there before I measured they are physically larger. Said screw it, and put the old one back in.

Further I contacted Dawn Kennedy at Hydrolastic and Hydragas Service who regassed the spheres for me and asked “ Question about knuckle joint under displacer. These have lots of slop. If is was a suspension ball joint I’d say it’s got to be replaced. Is the same true for these knuckles?”. Her reply was “ Knuckle joints don’t need to be replaced unless they are broken, they don’t wear like ball joints.”

I don’t doubt the aftermarket lowering style feel nice and tight, but after spending the dough on OEMs I can say they are not worth it.

Vid: https://youtube.com/shorts/t3jI4gZ2sKo?si=szkwQ_JAptQks4CU

I apologise if I’ve been in some way instrumental, in the predicament you find yourself in. I stand by my report of “a ball joint feel “ to my set of rollers & short of stripping them down I’ll not find out what mechanism is involved.
However I will study the ones that I’ll be removing & if you wish me to send a report please indicate via a PM & we’ll take it from there.
M

No concern Airportable. I would have bought them anyway. Just leaving the conclusion for the next guy!