Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Double Wishbone IFS for Classic Morgan's

All suspension design is a compromise. Sorry; should have defined my terms more precisely. My understanding is that Morgan suspension offers the benefits of minimal track change together with constant camber angle and low unsprung weight. Wishbone suspension offers the choice between relatively consistent camber angles but with greater track change (equal wishbones) or more consistent track with variable camber angles (unequal wishbones); all at the expense of higher unsprung weight. The compromise being of course the ubiquitous Mc Pherson strut which is half Morgan, half wishbone. The argument is however largely theoretical. We know that in the real world a well set up wishbone suspension together with modern tires is probably going to work better than the Morgan. But I suspect Morgan owners don’t live in the real world and probably don’t want to.

What I was trying to do was analyze why Morgan design didn’t work as well as more conventional suspension systems and came to the conclusion that the main difference was the effect of the variable frictional resistance in response to the lateral loads to which the suspension is subjected. The only fix for this being a much better lubrication system. I hadn’t considered the torsional effects of the dampers; which when you think about it isn’t brilliant but since the system has a certain amount of damping inbuilt into it anyway the dampers don’t have nearly as much work to do as on wishbone suspension and I am sure that running the dampers at a lower rate is helpful.

However the real point is that there are issues with Morgan suspension, which Morgan should have fixed years ago. We all know the lubrication issue is critical, but as I have tried to demonstrate it isn’t purely an issue of durability. The lubrication is an essential part of how and why the suspension works. It shouldn’t have to be up to enthusiasts to devise ingenious fixes to fundamental design problems when fairly simple solutions exist. The message to the factory is simple. Get on and design and independent pressurized lubrication system that doesn’t leak. Then at least we all know the suspension is working as well as it is theoretically capable and everybody can get on with enjoying the car.

We seem to have hijacked this thread from its original topic. Given that both the wishbone and the rising rate springs are of great interest perhaps we should ask if Simon can split this into two threads?

OK, that makes good sense, how? I am new to this.. PJB

Sorry if I appear to have muddied the water. All I wanted to do was to see if their was any enthusiasm for a debate about how you might re design Morgan suspension to overcome some of its inhierant problems...

No need to applogise, also no enthusiam that I can see (just kidding!) PJB

Guys, Fascinating debate/ education keep it coming.

Oh I don't know if it is possible but I suspect it is. Simmon would certainly know. Other option is to just simply start a new thread or pick up an old one like http://www.talkmorgan.com/ubbthreads.php/topics/118504/Comfort_suspension#Post118504

The silence is deafening... O.K, if, perish the thought, you had to replace Morgan suspension with anything why assume that clunky wishbones are the only way forward? When the obvious alternative is the Mc Pherson strut. The geometry/ unsprung weight is as near to Morgan as your going to get and purists could argue that it was a rational historical development of Morgan’s design, which it is.

The conversion ought to be relatively simple. The suspension sub frame stays more or less as is except that the bottom tube gets cut off near the chassis and the inboard joint for the radius arm welded in. The top tube probably needs an additional diagonal brace to give it more stiffness. The diagonal stay bar for the bottom radius arm bolts onto the chassis wherever. Snag is its not really a DIY conversion because I doubt whether there is an off the peg strut that would be exactly right for the job. However there should be something fairly close that a manufacturer might be persuaded to adapt. What’s needed is a small beefy strut with a solid round bar welded on the bottom, which would fit into an existing Morgan stub axel, minus the bush tube. Probably secured with a wedged cotter pin .The bottom ball joint just screws into the end of this.

Its tried and tested so you know it’s going to work and the critical angles can be easily tweaked experimentally by varying the length of the radius arm and stay bar to find what works best for the car. And it’s even got a grease nipple on the lower ball joint so we still have something to do. Just a shame it’s not more exotic and peculiar.

Sounds interesting Raf 1 - do you have the facilities to carry out the experiment?? Perhaps Peter Mulberry might be interested as he apparently has had a lot of input to the "librands" alternative suspension that is now being marketed

Sorry Peter, I wish it was simple to split threads but it isn't. I'd end up butchering it and loosing too many posts. The software will allow me to break a thread at a certain point but not allow me to pick and choose which replies to apply to each new thread.

My suggestion is to either keep this one as is - I view most topics on TM as a logical progression rather than one topic that stays rigid - or start a new one and simply cut and paste the posts you want to have in the new topic (I can help with this if you wanted).

Hope that helps?