Series 3 Fitting Castor Correction Plates with Parabolics

My S3 Lightweight has Parabolics fitted, and the steering wanders constantly. I've renewed all the ball joints and the idler, and there's no slack in the steering box, so I assume the problem is that the Parabolics alter the castor angle adversely, and there's very little castor to self-centre the steering. I have Castor Correction Plates to fit, which I hope will solve the problem. How to do that is the question? If I just slacken off the nuts on the U bolts will the axle lift far enough to slide the correction plate inbetween axle and spring, and then tighten everything up, or will a more comprehensive dismantling be needed? (I have long reach shocks to fit at the same time, but that should be straightforward).

I did this on my 2a but it was a long time ago. However I think you should support the chassis on axle stands and remove wheels to reduce the weight and get working room and then slacken the U bolts [ both sides ] while jacking the axle to a point where you can slip the plate over the location pin. Some jigging may be needed to get the pins to relocate in the axle so make sure your chassis is well supported.

What tyres do you have fitted and is the toe-in correct? Is the steering relay in good order?

A properly manufactured set of parabolic spring wont alter the castor angle. I know some parabolic springs give some "lift" but as long as its the same at the front and rear then the castor remains the same.

Do you have a steering damper on by any chance and is it gas one ?

check your toe in before you fit castor altering shims- and remember which way you want to alter them-positive or negative.

Mine did whats yours is doing.....turned out to be a very very stiff steering relay.