Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) 65 Plus 4 right front intermittent wheel wobble

A couple weeks ago I got caught in a rainstorm. I went through a parking lot puddle and suddenly the steering felt like the right front wheel was wobbling violently. I slowed down, and the wobble went away. It happened again last week on a dry road last week. I have her on my lift, and I can't find anything obviously wrong or broken. The right front strut #28 does have a slight bend, while the left strut is straight.



What should I be looking for?

Ah, the famous St Malvern's dance, has more potential causes, cures and opinions than parts to build a Morgan

Cue lot's of conflicting discussion...

So what CooperMan is referring to is the propensity of Morgan's to get a bit unsorted and violently shake - mainly at the scuttle, as the resonance propagates through the chassis.

Cooperman is also correct that the causes, and solutions are an ENDLESS, point of discussion...you could write a book...

My advice to you is to enjoy the car - if you feel it shaking again, slow down and stop...then head off again on your merry way. With that said, it seems like a bent strut could set up the conditions to start The Dance...try replacing it first before anything.

It is scary when it happens though...

#22 & #23...
The damper blade and a pair of damper shims on either side of the damper blade.
Best to grease the king pin, top and bottom first.
The loosen the bolts holding the damper shims. Use you finger to get grease into the upper/lower and sides of the damper blade.
Use a dab from the grease gun or a bit of chain saw oil.
Gently hold the damper shims, #23, against thedamper blade, #22, while re-tightening the bolts holding straps: #26's together.

BTW. Check the back brace #28 is tight, along with the crosshead brace #34.
I had snapped #28 before and had a very scary 'Malvern Dance'. Replaced with stainless steel from Linda & Larry.

Ron Davis
R9644
CanTab #1,
First FI +8 in USA

Fully agree with Rob. First stop the damper blades.

Clean as far as possible then grease kingpins (which should be done every 1000 miles max) and damper blades as a start.

Check for play in wheel bearings and kingpins/bushes. Check for play in steering linkages.

Was it a simple puddle or was it a violent drop into a pot-hole?
I am thinking simple things like:
Loss of a balance weight
Damage to rim
Broken cords in the tyre
All of those could be ruled out by temporarily replacing a wheel with the spare.
Rod #28 has already been mentioned and I recently found that mine was loose at the bottom of the kingpin, though it mainly produced clunking noises when braking.
I have twice suffered broken diagonal tie rods (#34) but it didnt produce any noticeable effects.
Failing all this, I would go for the damper blades as they are most vulnerable at the bottom.

Yep, I'm with Ron too!

Damper blade friction is the first call for me as well, especially as you described wetting it and then it all went wrong.... water lubricated it perhaps or at any rate changed to friction element. The blades wear more than you may expect as do the friction areas mainly on the top clamping piece. you may find that the left side had been replaced at some time and the increased friction from the left as opposed to the right side is greater and a little wear has freed the right hand side to being effectively frictionless! A new set of blades and shims for both sides would be a good starting point. Of course a good check of all steering and suspension parts is also required! Plus hub security/adjustment too.

Your bottom cross head support bar you say is bent, Depending on the degree of bend it could slightly shorten the distance it is designed to hold at and this could alter the caster angle on that side, granted only very slightly but perhaps with poor friction blades it could at certain speeds induce a wobble. Think of a supper market trolley with a wobbly wheel yet there is no obvious damage. The steering geometry is not something akin to being made in NASA on a Morgan and if the support bar was structurally sound I would probably remove it and straighten it and at the same time see if the bend was caused by some form of impact causing the crosshead to push back against it. I can't or won't suggest exactly what you should do as I can't see the car and don't know your level of skill or knowledge but know this, your car was fine and this has just started so it looks like it can be sorted out!

Yes there are a myriad of possible problems and probably the cause will be a combination of issues. Steering box, track rod end/s, trackin, tyres maybe something lose! If you find an obvious problem then that's great but there will be an other issue that in combination has caused this to happen so don't stop checking when you've found the blindingly obvious, go through it all carefully. Don't stress just try and enjoy the process. The Morgan is a simple car and to some extent that is why these issues occur.

For me, diagnosis is 90% of most mechanical problems

It may have nothing to do with your suspension. The Malvern Dance (easy to check) develops at the vibration point of your wheel which changes with overall wheel diameter. That does not change much through the years, though the MMC, like all other cars in the developed world now, uses much less air and more metal. Figure the logic result of that aesthetic chccie.For example, best I can figure the Dance, happens at 55-60 mph with 15" wheels. It disappears, after you allow the vibration to stop, at speeds below that point. That does not sound like what you experienced.

On the other hand, ALL sorts of things occur when you suddenly plunge heated brakes discs into cold water.

1. disc cans instantly. warp. MMC discs look thick but are delicate.

2. it can contaminate the pads

3. The old pads do not vent water well. You can actually be squeezing a coating o or pocket of water rather than your discs directly for a short period..

The effect of this stuff will be is exactly as you describe. The front end becomes uncontrollable. REALLY scary, right up there with the Dance. My doubt comes from its disappearance and return after a week..though the front may damaged to the point where it expresses its symptoms only when the discs heat to a certain point. This is common. You see it if ever you try to skim Morgan discs rather than replacing them. They seem fine again until you drive for a few minutes..then your brake foot starts pulsing again.

In any event, it is all easy to check and fix. Here is a action . One can never be too concerned about brakes, especially the fronts. In the following order;

1. Check your setup for the Malvern Dance. (why not?...it is on this diagnostic route anyway). Jack the front and have someone try to wobble the wheels gripping the top and bottom of the tyres while you watch for movement at the bottom bush. There should be none or near none.

2. Check for discs warping This can be done with wheels off and a pointer (a pencil will do) aimed 90 degrees near the front discs. As you slowly spin the wheel, does the distance between the disc and the pointer vary? .

3. Remove the pads, clean them and switch them with those from the other side. The cleaning could even cure the issue and if not, the wobble will move from one wheel to the other.

4. The bent strut could have been caused by an impact. In any event, straighten it. A hammer or a table vice (man's best friend aside from small needle nose pliers) will do.

gmg

Thank you all. I'll get some time in the shop next week to apply this wisdom.