Path: utzoo!utgpu!alliant.com!UUCP Reply-To: british-cars@alliant.com Errors-To: british-cars-request@alliant.com Sender: british-cars-request@alliant.com Return-Path: Date: Fri, 9 Feb 90 19:18:00 EST From: sfisher@abingdon.wpd.sgi.com (Scott Fisher) Message-ID: <9002100018.AA14333@abingdon.wpd.sgi.com> To: british-cars@alliant.com Subject: Re: 1100's, New British Roadster? Newsgroups: list.british-cars Distribution: ut Approved: devnull@gpu.utcs.toronto.edu Ok, can anyone clue me in as to what a hydroelastic suspension is? Since no one else has leaped to the fore, I'll give it a shot. The HydroLastic suspension was part of Alec Issigonis' design of the original Mini, and was a brilliant piece of work by most standards of measurement. The simple definition was that it used rubber cones and metal pins to provide the springing action. One of the advantages of such a system is that rubber compresses at a progressive rate, meaning that it got stiffer the farther you squeezed it. This meant that the cars effectively had soft springing if you hit a little bump, and firm springing if you had it rolled over on its doorhandles. There were two types of HydroLastic suspension, called wet and dry. The dry kind is the simplest, and is preferred by Mini racers in general because of its simplicity, light weight, and familiar feedback. In the dry system, the suspension is mounted with a parabolic, machined metal pin that is in constant contact with a truncated rubber cone. As the suspension compresses, the pin goes farther into the rubber cone (and because of the curvature of the pin, it encounters more of the surface of the cone, which also acts as a progressive spring). There is one such cone/pin pair at each wheel, all of which are independently suspended from the floorpan. Another feature of such a system is that you can adjust the suspension's stiffness simply by adjusting the ride height, due to the nature of the rubber cones. This makes the Minis an ideal vehicle for situations like road rallies, where they need to skitter lightly across broken surfaces but they also need to dig in on high-speed sections. The wet system is a modification of the dry type (and it's here where the Hydro part comes into play). In the wet systems, the cones are hollow and filled with hydraulic fluid. There are tubes connecting the various cones together (I think it was done diagonally but I can't recall); the idea here was that compression at one corner caused the hydraulic fluid to increase the ride height at another corner (and it's the exact algorithm I can't recall). The effect was to have a vehicle that rode almost flat on almost any road -- much the way active suspension works today. The problems with the wet suspension for competition are its weight -- not much altogether, but significant on a car the size of a Mini -- and the fact that it gave such odd feedback to drivers accustomed to body roll and movements. It also didn't "feel" sporty -- drivers of the early Sixties were used to cars that rattled and bumped and in general behaved like, well, like old British sports cars. (Imagine a time when a 1963 MGB was state of the art... yeah, such as 1935 :-) I have never had a satisfactory answer about why the HydroLastic suspension isn't in wider use today. One answer, I suspect, is that it doesn't provide much in the way of suspension travel, and that it doesn't work well on heavy cars -- the Austin America, I think, was the largest vehicle to use it. For the rest, I suspect a healthy dose of NIH ("not invented here" -- I still find people who presume this means National Institute of Health) -- that and possibly a licensing issue.