I had a similar problem to this whilst going straight over a level crossing. I eventually found the cause of the trouble wear in the steering box. Particularly in where straight ahead would be . At each end of the lock where it gets far less use the wear was minimal but in the centre quite a lot making it difficult to adjust correctly. Either correct in the centre and tight on both locks or vice versa.
My cure was to wash out all the oil and grease put it back together with valve grinding paste between the geared wheel and worm, tightened up the adjusting screw until it was ok in the centre (most worn part) then turned the steering wheel from lock to lock until it all became even and reasonably free. Dismantled again and thoroughly washed out to get rid of any traces of grinding paste then re assembled and filled with grease. No further problems.

John Mason

Location: Nottinghamshire

Thanks Tony Press and a few of the chaps who attended the Derby and Notts Group meet at the John Thompson a couple of weeks ago.

Following your suggestions, the root cause of the problem was a slightly loose ball joint connecting the radius to the chassis.

I have the later spring loaded type and have now tightened the nut and secured with a locknut.

Just out of interest, how tight should this be? I guess that over tightening will increase the wear on the brass cups? (although they are well greased).

Hopefully no more steering wobbles!

Matt

Location: Derbyshire