Formatted for the SOL Morgan Web page by: John T. Blair (WA4OHZ)
This was an interesting discourse between Atwell Haines and Tony Souza. Atwell
was try to reduce the Morgan Front End Shudder on the Morgan mailing list. So
I've put it up to help others better understand the dampener blade's function.
Originally written: circa Aug. 2003
June 14, 2009 - Reformatted page
In my continuing quest to reduce (no, I didn't say eliminate) the Morgan
Front End Shudder AKA St Malvern's Dance, I found myself under the front
wings, adjusting the damper blades one more time.
This time I decided to totally remove the blocks and shims on the frame,
with the thought of cleaning and lubricating the blade sliding surfaces
(hadn't done that yet). Much to my surprise, I found that the blades could
rotate independent of the kingpin-hub assembly.
Is this normal?
My understanding of the damper blade system was that the damper plate
should be fixed relative to the hub somehow, so that the shims could
prevent rotation and resonance of the hub. Here I have both sides that will
rotate over several degrees (translates to more than 1/2 inch of movement
at the frame shims on one side, and 1/4" on the other). This is with the
weight of the car sitting on the wheels.
Digging deeper, I look at the Morgan Shop Manual and the Morgan Spares
and it seems that there is only a _hole_ for the kingpin in the damper
mounting plate. (Part # 21)
Have I found the cause of the "dance" on my car? Should I try to eliminate
this movement? If so, how?
To which Tony Souza replied to Atwell Haines front end shake:
Atwell, the damper blade bronze piece fits between the bottom of the spring
and the top of the hub assembly. The blade decouples the spring from the hub.
As the spring compresses and expands it tends to impart rotation to the hub,
With the damper blade in between rotation of the hub is prevented. The only
adjustment to the damper blade is to ensure that there's absolutely no motion
side to side at the chassis end. Only sliding in and out motion is
Do you have radial tires? Probably 16" bias belted tires. Are they balanced,
Even with good looking radial tires and all suspension surfaces fitting well,
some Morgan owners have found that the only cure to front end wblle was to
reverse the radial tires on their rims.
Return to the Index of Tech. articles