Restrictor for hydrolastic pipes

[Aussie Bill B]

Does anyone have information about restrictor washers that were used to increase the damping rate of hydrolastic suspension systems mostly for racing setups?

They were domed washers with a small centre hole, fitted at the end of the hydro flexible hose where it screwed into the mounting union.
A part number is 8G98 but I can't find any information about dimensions and where they were fitted.

[Peter Laidler]

It is said, certainly around these parts (Abingdon....) that ST had the 'adaptor', between the front hydro pipe to the front-to-rear pipe sleeved down to 3mm to act as a valve to restrict the flow of fluid between the F and R hydro unit. It could (questionably ?) work because any restriction is effectively a valve of sorts.

Having made a study of hydrolastic, I'm a bit sceptical about that 'valve' idea. Mind you, I'm a bit sceptical about the whole of hydrolastic. Why would you use an in-line valve or restrictor when you've already got a restrictor or valve built into the hydro unit - identified by the coloured bands that are said to indicate hardness or solidness - of what.

Don't get me going about it Bill. A frill if not a total fraud Bill! Judging from the systems I've stripped and had apart in the past 15 years (admittedly, not as many as most others I expect) the amount of rusty clag, crap, sewage and rusty shite that is drained from them them, then any notion that the internal valves are still working - or even present - is farcical.

And while we're talking of restrictors in the adaptors......... When you take them off a well used car, they are virtually rusted solid inside. I turned up a couple of new ones last month (in stainless...) to replace two from my pal Clever Trevors 998 because when I eventually ran the 5mm drill through them, to clear them they were totally eaten away.

Just my take on things. Pete the Pom

[trevorhp]

FYI both of my Vita cars have restrictor valves fitted between the front and rear Hudro units...in the form of domestic gate valves, not unlike the ones fitted to any standard domestic water or heating circuit.
I was told by the only likely authority on this setup (Norman Grimshaw r.i.p) that they were used to lock off the rear units to prevent the back end of the car sitting down under acceleration and cornering.
I'm certain they were not legally allowed but nevertheless they are fitted and were apparently used in 1968 ETCC events.
Crude but effective, they were attached under the bonnet to the ends of the cut hydro rubber tubes.

I am certain I have a picture of this setup somewhere or I have seen it on the net.
Currently mine are stored away during the renovation process.

Don't know if this helps, but just adding info to the thread.

I agree with Peter, unlikely that washers would be effective over time.
I wonder where the part number came from?
THP

[Aussie Bill B]

Thanks for those replies.
I am aware of Peter's predilections on the hydro suspension topic and I appreciate his research into the operating parts in the system. Thanks for your memory of the sleeved unions as a method of constricting the flow rate. Seems like an attempt at achieving the same result.
As I have 3 hydro minis, and all working well, I feel the system should continue functioning to the best of its ability while I can maintain it.

From "trevorhp", thanks for your information.
I was first told about these restrictors by a suspension specialist in Sydney whose business was one of the main sources for factory and private competitors in the heyday of mini racing.
I cannot remember where I found the part number. Just recorded in my notes. But see the reference in the Leyland Special Tuning booklet included here. Not sure if this listing made them 'legal'.
Were they dished washers with a small centre hole?
Where were they fitted to the hydro line? eg both ends where the flex hose screws to the union?

[swindrum]

My only hydro cars have been MG1100's and they have had the restrictors on the front pipe union. For that application they are brass domed washers with a small hole.
My current MG was missing one, so I made one by peening a Canadian dime into a dome shape and drilling the appropriate sized hole in it. That was in 2005, and it is holding up fine...

Not sure if that helps...

[Dearg1275]

This from mk1 1100 microfiche.

81632B7E-0165-4F03-88A3-DAF3759E6AD2.jpeg

D2E21F62-49AC-438D-A29F-9ACB4EC3F4E6.jpeg

31G98 was a “washer choke” fitted to all mk1 1100s.

D

[Ronnie]

Thanks for those replies.
I am aware of Peter's predilections on the hydro suspension topic and I appreciate his research into the operating parts in the system. Thanks for your memory of the sleeved unions as a method of constricting the flow rate. Seems like an attempt at achieving the same result.
As I have 3 hydro minis, and all working well, I feel the system should continue functioning to the best of its ability while I can maintain it.

From "trevorhp", thanks for your information.
I was first told about these restrictors by a suspension specialist in Sydney whose business was one of the main sources for factory and private competitors in the heyday of mini racing.
I cannot remember where I found the part number. Just recorded in my notes. But see the reference in the Leyland Special Tuning booklet included here. Not sure if this listing made them 'legal'.
Were they dished washers with a small centre hole?
Where were they fitted to the hydro line? eg both ends where the flex hose screws to the union?

It just shows how bad the UK ST information was, My folder (all models) purchased 71/72 has nothing like that in at all, and when compared to Ford (Escort) and GM (Chevette) competition literature, were not really fit for purpose!

[LuisM]

Have found these restrictor washers in a 1300 Vanden Plas princess.
I believe also Metro challenge cars had the hydro units working independently, having the front/rear pipes removed.

Cheers
Luís

[mgcm1598]

Re Metros, these were Hydragas and were never connected front to rear. Fronts were individual units and rears were connected side to side. From memory, pre-facelift cars (up to about 1984ish) had front dampers but I think these were deleted on later cars (MG and Turbo might have kept them?). I think Metro Challenge cars had turrets welded in to take rear dampers and probably a rear ARB too.

[davidmuir]

Contact these people:- "Hydragas and Hydrolastic Service Ltd"..........they'll surely know !

[Aussie Bill B]

My thanks to "Dearg1275" for the image and correct part number.
Using that, I have managed to find images and sale items on ebay now, if a bit expensive for what they are.
After "swindrum's" experience of making one from a Canadian dime, I'm prepared to go DIY, although we are short on Canadian dimes in Australia. I wonder how big a bitcoin is.....
Thanks for all contributions. Interesting little rabbit-hole. And a way to help improve hydro suspension.

[Nevsmini]

The Works CCC cars also had valves taken from the Churchill hydro pumps fitted in the Engine bay. They pumped the cars up turned of the valves and pumped the rears up harder. With the higher pressure front and rear they machined the trumped down in the hydro bag to correct the hide height.