Since I started this thread the car was off the road for a few months being repaired from an accident.
Now that is is back on the road I am noticing again the amount of steering wheel shake on bumps which
led to the initial posting. Now I realise that the source of the problem is a) lowering the car 1" but
b) not lowering the tie-rod junction at the hub. Then possibly made worse by c) the fact that I have
fitted roll centre adjuster to the control arm. So now I understand what is going on, the fix is simple
- lower the tie rod.
 The point of my original post was that if you are suffering steering wheel flicks over bumps,
you should fix it, because it can damage steering components (when both wheels hit simultaneously).
 
 Next I move to the rear suspension. I have done nothing to compensate for the 1" lowering yet.....
wondering if it requires tie-rod lowering to reduce toe change..??  with or without RCA ??
I'm getting the RCA anyway to reduce roll and help the SW20s meagre amount of camber.
 

Have you been in other Mr2 to discover if it’s something unique to your vehicle you need to look into further, like worn bushings, collapses spring, worn shocks, loosened link, steering aspect, worn engine mount, etc...

Had Mr2s with large rims (17-18), lowered by 1inch and more, without rca, highly maintained suspension/vehicle, high speed, and can’t relate to wheel shake/steering flicks that cause an OMG on bumps.

Engineered analysis of the suspension and modifications needs to be matched to the alignment centres settings they degree your suspension at as well as your driving style and other factors. Unfortunately not a simple post and solved IMO.

Hi Tony,
definitely unique to my car, actually unique is doubtful as many people would have suffered similarly when their geometry was misaligned. Anyway the problem and solution are clear. If you google "bump steer macpherson" you will get several sketches which make it clear, the arcs that the tie rod end and the control arm end "create" when the suspension shortens/lengthens, are no longer parallel. Perhaps lowering the car did it, or my rca on the control arm did it, or both. Either way the solution is to get the arcs parallel again.
  
 

After reading all this I'm not lowering my car, as it not a circuit car were I'm trying to get 10th of second faster. I'm also lucky I have a gen 3 setup as it already sit lower from the factory than a Gen2 would. With 17s on 635mm from ground to top of guard wheel arch.

Hi Hardtop,
 agreed. the only reason my car is down 1" is cause the shockies I got to replace the clapped originals, use Eibach springs which are shorter. If I had decent shockies with original length I wouldn't need to ask people to help me get out of the car when I park. 
cheers,
Nigel
 
 

I'm running Eibach Pro Kit springs without any of the issues that you've mentioned. My cars handling is brilliant....

Found the problem with the steering wheel twitching over bumps and it was my fault. When I installed Roll Centre Adjusters I neglected to install similar spacing to the tie rod ends. This weekend I removed the RCAs and took it for a drive and the twitching over bumps was gone. So I think I have misled people who probably presumed that the tie-rods were also spaced, as only a dope would do the control arms and not the tie-rods.  
 RCAs are really overkill for a road car, much more relevant for track use. I'm going through the exercise as the car is a project for my son (and I) to learn about cars.