Ive done some research and I suspect issues with my installation over the pinion as the cause

1)I didnt use toyota fluid

(mainly cos I didnt realise you had to until I opened the reservior, by which point it was too late) I used halfords power steering fluid instead.

There are 3 schools of thought on this issue: That it makes no difference, that you can use peugeot 307 fluid at a quarter of the price, or use toyota fluid

(£30+ a bottle).

I dont suspect this is the cause.

2)The rack guide also sets preload.

I did not realise this when I reinstalled and just did it up

'a suitably tight amount'.

I suspect the reason for the delay is this preload.

Unfortunately to adjust this I gotta remove the rack again.

3)I slightly overfilled the reservior as I was expecting 0.5L of fluid and it only took 0.3L

4)when i went lock to lock I did not leave it at full lock for 2-3 seconds as recommended in the manual, so it might not be bled fully.

I will address these 4 issues on friday and see what the deal is.

Only then can I accuse the pinion.
