Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Steering diagnosis please.

I'm sure when I describe my steering issue, people will know exactly what I mean and will be able to tell me if it's fixable.
When I go around a bend in the road at speed there's a juddery feeling in the steering wheel, almost like the wheels want to go left and right really quickly. Is this the malvern dance I've heard people talk about? Would fitting brake reaction bars solve it? Thanks.

BRB would certainly help any Morgan, it could be you need new dampers.

I would also show it to a specialist workshop, it could also sound that the toe-in is not correct.

St Malverns Dance is a wobble that usually occurs at around 50 mph even in a straight line.
I recognise what you have experienced, as I am sure many others have on occasion. You can throw money at it with BRBS, shockers, etc but personally I think it is a Morgan “thing”. The relatively firm suspension meeting usually, a bumpy corner or one with poor camber and maybe too much throttle at the wrong moment, can easily upset balance.
It is worth checking the basics but if the tracking is incorrect, you should see it as uneven tyre wear. Too much toe-in will wear the outers of the tyres whereas too much toe-out, will scrub the inners.

Check the obvious first . Tyre pressures , tracking and grease the front end. Do you have power steering? If you do pull the fuse and see what that doex.

My car suffers a bit of “bump steer” I wonder if that is what Leroy describes.

As Deejay describes, St. Malvern's dance is a meduim-frequent rythmic wheel wobble that is transfered to the steering wheel, resembling what you sometimes can see at a wheel on a shopping cart. Most often in a straight line, around 80 km/h. A steering damper might help, but you are lucky if it totally eliminates it. BRBs will not affect this, but it will make the front end calmer and give a more stable feel, strongly recommended - easy and cheap. But it will not solve the problem.
Bump steer is when road wheel movement due to uneven road conditions is transfered to the steering wheel. This is pronounced on a Roadster S1, due to the tie rod geometry specific to that model. But it is dependant on the road, should not be present if the tarmac is slick and even, and it should not be a rythmic wobble. A steering damper is a good remedy for this, but again, lucky if it disappears.
As others have said, check the easy and obvious before you turn to more advanced surgery.
Are your wheels balanced? King pins OK? Wheel bearings worn or not? What about your damper blades? Road wheel alignment?
You might also check out the effect of fitting steering bearings,of which I have no personal experience.

As Robbie said above.......

Roadsters of that era had Devol bushes and steering damper blades. The track rod angles were compromised leading to bump steer. The first owner of my Roadster was so unhappy with the steering feel that he had some quite direct exchanges with MMC, because he thought it was dangerous. The outcome was that before I took over, the stub axles were replaced with bronze bushes, and this levelled up the track rods, thereby improving steering feel. Now my Roadster track rods are almost level, and the track rod ends are below the steering arms.

A 2004 Roadster will more than likely have had a kingpin change, so may not still be to original spec.

What puzzles me is that the S1 Roadster continued most of the Plus 8 specification. Mine even has front springs marked Plus 8, and yet I've never heard a Plus 8 owner of the 2000 era complain about bump steer. Maybe the steering rack was moved.

Is there any play in the steering system. I.e can you move the steering wheel with no reaction at the road wheels when you're stationary.

If there is play, that will allow the wheels to move slightly and set up a vibration which would feed back to the steering wheel.

Check the chassis to steering rack clamp bolts, the steering rack drop plate bolts (and the plate itself to make sure its not cracking) and also the steering rack drop plate to track rod bolts.

Could also be play in the steering rack itself which, in most cases, can be adjusted.

If there is play in the steering, work your way back up the column to check the u joints and splines are all ok.

Thanks for the ideas and possible remedies. The tyre inflation is good, and no evidence of uneven tyre wear. The next time I'm out, I'll pay attention to the road surface as it could have been bump steer. It never happens in a straight line, so I just need to fine a nice newly laid road with a fast bend. I think the king pins have been changed as it has 2 grease nipples, and someone pointed out that the devol bush set up only had one.