Talk Morgan Forums Community The Malvern Arms The pros and cons of sliding pillar suspension.

With the Sliding Pillar system camber only remains the same if there is no body roll. So as soon as you enter a corner camber becomes directly related to body roll in part due to the fact that with this design geometrically the roll centre is below road level.

Hence the need for negative camber sub frames in race cars to try and keep the loaded wheel as upright as possible and hence more tyre contact.
In the era when it was designed I believe the advantage was that suspension loads were taken out by fixed chassis members rather than moving ones (wishbones) and this a strong design with the roads as they were.Things have moved on somewhat in suspension design of course, but the anachronism rather goes with the car doesn't it?!
Cheers

A simple McPherson strut might be easier to engineer by lifting the ends of the upper cross tubes, and pivoting the lower arm on a shortened lower tube. Then you could build in negative camber on bump. That might even be lighter than a double wishbone set up. The limitation though is the limited travel.
There would have to be reaction arms from the outer ends of the lower arm, and since there's limited scope forwards, they would have to come back in the same alignment as the lower brace tubes are now, but bushed.
That is almost a shed solution.............

I'm very happy with the standard set up although steering bearings do offer a big improvement over damper blades without taking too much away from the traditional design..........

PMSL Missed that one Colin.
Wasn't a member at the time - had probably given up with some other BS long before the suspension one!!

Something I wrote on TM some time ago and updated slightly:

Apart from the impact of track rod lengths on bump steer on a Morgan, one of the main limitations of the sliding pillar design is on cornering. The side forces generated in cornering tends to lock up the suspension and this is compounded by the stub axle flexing as well. Bumps encountered shock the stub axle up the pillar but the main spring cannot overcome the stiction to return the stub axle.

This trait is less of a handicap on a smooth race circuit than it is on the public highway. In any event, most sane people will not be generating the same side forces experienced on a track when driving on the public highway.

Another compromise with the Morgan suspension setup concerns roll centres. At the front with zero camber the front roll centre is at ground level; with negative camber it lies below the ground. At the rear, without panhard rod, the roll centre lies on the leaf springs; with panhard rod or anti-tramp bars, it lies slightly lower. In effect this means that under hard cornering, the rear inside wheel will lift although it's probably limited by the outside stub axle locking up due to the side forces.

A few years ago, David Rutherford was experimenting with a double wishbone front subframe for a Morgan that would replace the existing sliding pillar subframe. Although I saw the setup in the workshop, I have no knowledge of how it drove. Peter Mulberry and Librands have refined the setup further and are marketing it.

So in summary, a Morgan's sliding pillar suspension is an early 20th century solution to an early 20th century problem. Any improvement since then is probably as much due to advances in tyre and damper technology.

It's crude, harsh and inelegant it works after a fashion and is part of the Morgan cars character! Enjoy it!

'roads as they were' - will suit roads as they are, then!
http://www.bbc.co.uk/news/uk-29358202
Gerry.

Good point!

I have asked just this general question before now and the replies could be paraphrased as " we are buying an old design but with modern components and modern reliability. We arent looking for modern technology or we would have bought a Boxter".

In a way, the three wheeler is an even mre extreme example of this approach. Its a modern re-creation of a vehicle that only ever existed because of the peculiarities of UK vehicle licencing laws. But you pays your money and makes your choice, dont you?

I am not sure that the Mini, the modern Beetle and the Fiat 600 are examples of a philisophy that would work well with Morgan. You could argue that Morgan tried this with the Aero and all say that the Aero wasnt a great financial success.

Hi, If you take the front suspension off a Morgan you will find it is pretty heavy, one would think it is pretty rigid and stable, but as David points out is prone to stiction as cornering and braking forces cause it to twist and bend albeit very slightly enough to impair upward and downward travel of the hub when most needed. Brake reaction bars help to alleviate this.

If you have a look at say a caterham front setup and various similar designs they could be accommodated into a Morgan design. However the chassis of a Morgan is quite a flexible thing and most cars with more modern suspension have a pretty stiff chassis or integral body/chassis. So it would be interesting to hear how a Morgan drives/feels with a wishbone setup such as the Mulfab setup?

I have discussed the issue of suspension and chassis flex with an acknowledged expert in the field. I voiced the opinion that an improved and more supple suspension system would put less stress on the chassis and cause less deformation. He was in agreement with that statement.

I have always believed that a re-engineered Morgan chassis, something like this chassis for the TR6, would be a viable proposition.

http://www.britishv8.org/articles/fastcars-tr6-frame.htm

Has anyone considered buying a Hawke kit car, the front especially looks like a classic Morgan however it has ford cortina underpinnings.