Not so worried about the PS, happy to believe it's a damaged seal at the moment. I don't think it's a smart system, the ecu just turns the pump on and off to save power when you're driving straight? No sensors at all on the rack.

If the pinion ran smooth I'd be ok with loosing the power assist.

Knightrous is right. For normal involute gearing (constant velocity ratio, no sliding contact at the tweth) Pinion diameter = Modulus (tooth size) x Number of teeth. I can still imagine there is a tooth profile that allows extra teeth on the same diameter without introducing slop but would introduce sliding contact and oscillating velocity ratio, but what I have isn't that.

It could easily be bad machining work - they stuffed enough easy things that I'd honestly be surprised if they could correctly machine a helical gear profile. Aside from missing the bearing sleeve entirely, the dowel hole in the end of the shaft was not even aligned through the centre, meaning I had to cut the dowel short.

It could also still be that reducing the OD by 0.65mm was *part* of the problem. Doesn't sound like much but it's probably a 10% reduction in tooth height, which could easily create slack points, depending on how much spare tooth there was in the original profile.

To clarify, my rack is not just loose on centre, it goes loose-tight-loose-tight... The centring problem was PS related.

So at the moment I'm inclined to think there's some combination of:
- 'improper' gear profile because PCD ≠ M x N
- unbelievably **** manufacturing quality - it's not like this is even the first one they made
- my reduction of the OD, which was required to use the pinion at all

I would also like to know the answer to Marty's question - why was there so much good feedback from the US?

FYI - How to improve an MR2 Turbo’s steering | Project Toyota MR2 Turbo | Toyota MR2 Turbo | Project Car Updates | Grassroots Motorsports