I have had either dry or wet minis for the past 44 years so I can understand why some Hydrolastic suspension Mini owners are having problems. I have a Suzi mini which I have converted to fully independent on all 4 corners. Each corner has a standard mini shock absorber and standard bump stops front and rear. There are no helper springs at all on the rear. In my opinion and others who have either dry or wet minis all say that my set up is far superior to either standard wet or dry minis. There is no nose lift under fierce acceleration, the ride is smoother and there is minimal body roll. I've had this set up for 5 years now with no problems what so ever. I am fortunate to have an original BMC Hydro pump which enables me to set the pressure at each corner to give the optimum ride height with the Mini K bags.I run 275 psi front and 180 at the back. I thought this post might be of interest to some

I've seen this mod to hydro cars a couple of times now (often billed as "rally pack suspension"), and I still can't understand how it's an improvement.

Fluid doesn't compress, so by sealing each corner you're effectively solidifying the suspension to the point that the only movement is in the tyre, or possibly expansion of the hydro bag.

Unless there's air in the system acting as a spring, it can't be an improvement, can it?

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Simon

The adventures of an owner builder in the Tallarook Ranges

Mishy, does that have any sort of overflow bottle, or does the bags terminate pretty much at each bag outlet?

Other than that, I've blasted back my old bags over here, many have the part number 21A1477 cast into the top rubber moulding around the base of the hose, these are bonded very differently from the other bags to the outer steel case. On the rear subframe versions of these bags, there are extra part numbers stamped onto the outer case 21A1804. I wonder if the addition of the rear valve and T-piece makes the difference in the bags and hence the part numbers?

Also, what does it mean (for the earlier bags) if the only number stamped into the side is C61 or 23?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Welcome Dennis....and yes, quite interesting....some comments on how she handles would be appreciated....and isn't the Suzi engine/gearbox combo slightly lighter than the original?? thats got to give better handling as well......good to see you on Ausmini..Cheers, Mick

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"Show me the Mini!"

Hydros are not like a hydraulic cylinder.
Hydro displacers are actually a rubber cone, with a hydo `bladder' and valving inside. As such, if you block the fluid flow front to rear, or separate them as Mishy has, they still act somewhat as a rubber cone.
You can watch this effect if you bounce on the front of the car, the hoses flex as the top of the displacer moves up and down.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I'd agree with DrMini, I understand the BMC Hydrolastic system needing displacement - typically front to rear. A sealed unit has no such displacement, independant or not.
To my mind its like a Citroen Hydropneumatic system running on flat spheres, it defeates the intended purpose as there is no give other than the give in the rubber of the units on a Hydrolastic system, or the flow of high pressure fluid from within the Hydrpneumatic system.

One question I'm inclined to ask is "Why reinvent the wheel?"

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YDO005 1965 stock standard MORRIS MINI DELUXE

I always wondered how you set it up Dennis - lower pressure at the back is obviously a must.... have you ever had a bag burst or fail with it set up this way?

remember a blue van when you were at Wakefield a few years ago? that was me.

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The displacement of fluid front to rear is not your suspension, it is just there to improve the ride.
When you hit a bump with hydro you are not pushing all that fluid from the front to the rear, you are deflecting the rubber spring and pushing a little fluid to the rear.
A Citroen Hydropneumatic system with flat spheres is like hydrolastic without the rubber springs.

Removing the interconnection does not alter the spring rate, it gives better control of pitch. Good for a competition car but lousy over speed humps.

So once reduced to a modified version of a rubber doughnut suspension, is there much difference between the rides of either?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I'm a little surprised as to how much interest there has been to my post. I'm not a hydraulics engineer, however I can see where some of you are coming from.Perhaps theoretically what I have done should'nt work but it does. As i said previously I'm very satisified as to the ride comfort and how it handles. The car has had this set up for 5 years with absolutely no problems whatsoever. My driving is mainly on the" highway" if that's the right term for the Prince's Highway in my part of the world. The only thing we don't have is speed humps.

Aaah... Thanks, excellent description, it's much clearer now. I had wondered how well it would work, having to shift hydraulic fluid at high frequency to the rear of the car.

Still not going to do it to mine, though

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Simon

The adventures of an owner builder in the Tallarook Ranges

Someone please correct me if I'm wrong, but don"t the early 90's Lotus Elise use
a Mini Metro front subframe in the rear & independant hydrolastic suspension
They seem to go around corners 'almost' as well as a Mini

Blue

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Keep shiny side up

Mishy, how did you go about putting a valve in each bag? I would guess that you just remove all the interconnecting pipes and then put a valve in the end of the hose on each displacer? Sounds like an interesting thing to try out, but I would want to have easy access to a hydro pump first.

Realistically though the conversion sounds like having rubber cone suspension with hydraulic hi-los.

wasnt that an early 90's nissan?

The MGF uses a type of hydragas, with fluid and nitrogen, the lower the nitrogen pressure, the harder the suspention, as there is more fluid at a lower pressuee.

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