Please don't throw the pinion away as it may be able to be resolved.

So I finally installed this pinion today.  Not many people seem to have given feed back so I will.
 
I was in pretty much the same boat as WIDEMR i.e. I had a 'rev A' rack and my QR pinion was missing a bearing sleeve.  The pinion bearing in the rev A rack is only slightly bigger than the pinion teeth outer diameter - not enough fit a strong sleeve.  So I tracked down a rack assembly from after September 1993 ('rev B') which runs a larger bearing, then got a bearing sleeve from BSC (p/n: PI121608), then had the pinion machined down from 19.7 to 19.06mm and pressed the sleeve on.  That bearing sleeve fit perfectly into the rack so I was finally ready to test it out.
 
First problem I had was the power steering acting up.  Same sort of symptoms as Marty and others had with a damaged seal - i.e. steering pulls to one side and tends to steer away from centre.  Even though the PS was odd, the steering ratio definitely felt like it should have been that way from factory - much livelier.
 
Then I disconnected the power steering pump, having read that it doesn't do much over 30kph.  That's BS - the steering was still heavy at 90kph but had no extra road feel.  I wouldn't recommend disconnecting the PS but iyou could live with it. Manual racks might work better, not having to pump steering fluid around.
 
The main issue I had was that the steering had a really wide dead band of about 4 degrees - it was great mid corner but sucked when changing direction.  I did adjust the rack preload but there really was no happy place - either the rack was very loose, or it was tight, notchy and still with loose spots.  It's possible that this issue is due to me machining the pinion down from 19.7 to 19.06.  If any else has had these pinions fitted without introducing slack into the system I'd be interested to know.  I still don't understand how you can add a tooth without changing the pinion diameter or rack...
 
On a side note, Marty was very helpful in getting dimensions and other info to get the pinion in the car. Glad to have at least tried it but will refit the old rack tomorrow : /

 

 

I also can not understand how this could possibly work correctly. Thanks for posting your findings MC.  Most informative.  I feel very sorry for Marty who organized this whole damned thing and Im sure acted in good faith.
I doubt your machining of the pinion has created any of those symptoms you describe . (Loose on centre. Notchy and binding elsewhere.)  It is pretty much as I would have expected unfortunately.
If anyone else has fitted this quick ratio pinion I would be most interested in an in depth appraisal of your experience.  Something along the lines of MCs would be great.  Thanks.
 

MC
I still don't understand how you can add a tooth without changing the pinion diameter or rack...

Simply, you cannot do this properly. To introduce another tooth into the pinion while maintaining the pinion diameter and center distances means your changing the tooth shape/pitch to one that does not match the rack, hence why your getting all the slop now.
 
If your looking at adjusting the steering ratio, I would look at a steering quickener box that is fitted into the non-collapsible section of the steering column.

 
These are regularly used in rally and speedway where they need quick steering movements and good feedback.

While I am as mystified by this just as much as the rest of you. I must add that this pinion is a rhd version of the lhd US quick pinion that I had purchased from the US group by. I had the UK manufacturer make the helical thread in the opposite direction so it would work for us rhd owners.
 
So I ask myself, why are there no complaints about the US lhd version ?
 
If we forget for a moment about the power steering (electohydraulic) for a moment; the pinion fits the rack mechanically correct and also reduces the number of turns it takes lock to lock just like it is supposed to. So why does the power steering behave oddly when activated ?
 
I am wondering if the power steering ECU is somehow malfunctioning due to the new ratio ?
 
Anybody want to throw in some thoughts or ideas to get this working ?
 
 

I'm not studied up on the SW20 PS system. But if it has some kind of position sensor that is on the column side that then references against the rack side, the shift in ratio will definitely cause issues.

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?

Marty J
 
I am wondering if the power steering ECU is somehow malfunctioning due to the new ratio ?
 

That's funny this has just come up, I was reading this thread the other day about issues the US guys were having with the VMAX quick ration pinion on the earlier model EHPS equipped cars...
 
http://www.mr2oc.com/showthread.php?t=436121
 
 

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