Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Front end shake - Malvern Dance?

Taffmog, a serious question - what is the difference between "Morgan Shimmy" and what is known as "St Malvern's Dance"?
I know what shimmy is as that is well known within the automotive industry and what the mode(s) of vibration are on a Morgan and how to control them etc, but I have always assumed that this is what is also colloquially known as 'St Malvern's Dance", hence the question. Best regards PJB.

Violent shimmy??

I think it is just a humorous reference. St Vitus' Dance (or Sydenham's Chorea) is a symptom - jerky movements - associated with Rheumatic Fever, which is caused by streptococcal infection and damages heart valves etc but in this case is affecting part of the brain.

So St Malvern's dance is presumably just the Morgan community's term for steering shimmy. It seems to happen quite a lot though! I had steering shimmy once on my Discovery while towing a heavy boat and braking at speed downhill, despite it having a steering damper - perhaps it was St Lode's dance?

Lack of pre-load on front err, can't think of the word now...
Something that had to be corrected during the rebuild of my 90 as it could occasionally give a good shake at the front...

Cheers,

Has anybody noticed if and how much fitting of 'break reaction bars' affects the shimmy? In my mind the flexible Morgan frame could be a weak point in this context and that the geometry of the reaction bars should restrict flexing in the front end. (pardon my English... )

Richard Thorne serviced my car & it was nearly undriveable.
The causes:-
1. They adjusted the damper blades and they were so loose they moved easily. Fix those first.
2. Tyre presuure. 1&2 fixed 95%
3. My wires were tired. 15 years of English potholes didn't help. I repalced them & it all went away.
Good luck

Thomas,
That was one of the things fitted where I first took my 4/4 - but they didn't notice a crack in chassis leg, nor did they spot where the chassis had got rather thin. Several months later my MoT man spotted the crack and welded things up, but less than a year later, the 'dance' was back again.

It's how I ended up with 3 cars as I couldn't trust the Mog for a while, until it went to New Elms to be sorted and they did a great job of making it all strong and shake-free again.
Now I just need to go back to two cars

Interesting Graham - I had a constant and quite severe shake on my -99 4/4 when I picked it up outside London a few years ago. Had to stay under 60mph all the way to northern Sweden...
Finally it turned out to be the tyres. But it got me thinking - I could feel that the whole front end was flexing and that could eventually cause a crack in the frame if there is a weak spot somewhere. My frame has the triangular reinforcements and I have full confident in it still
I'll stick to this one (1) for now

Thanks for all your great advice. I have been away this past week and will look for loose bolts and examine the damper blades this weekend. I'll look for too much oil as well.
It happened once before, but less since I wasn't going too fast the first time. My mechanic did change one of the king pins and I haven't had it occur until now, 2 years and 1200 miles later.

If you have over heat the brake discs this could cause the discs to worp and cause the symptoms. I did this to a 911