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Author: Subject: Steering rack ratio influence on self centering?

posted on 16/10/22 at 10:42 PM Reply With Quote
Steering rack ratio influence on self centering?

Hope here to find the answer.
I wonder what if any influence on self centering steering wheel has a ratio on steering rack?
Assuimg all other equal including caster.
Have to choose between 2.5 and 3.5 old Escort steering rack for my road Westfield. 2.5 is tempting but if this affect self centering worse 3.5 would be fine.
Currently just finished to build and register a road Westfield bolted some cheap used 3.5 rack.
Dont like the almost lack of self centering the wheel. Joints seems ok. Caster is fixed as there are bushed wishbones and Cortina upright. So after some readings I blame the rack .
Just dont know if it has some mechnical failure as it is used and old . Assume it has.
So want to change to some new one but not sure if 2.5 or 3.5 ratio to choose. Ignoring driving experiences which is better in terms of self centering? Does the ratio have an impact on this subjects at all?
What are Your experiences?

[Edited on 16/10/22 by Andrzejsr]

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posted on 17/10/22 at 10:43 AM Reply With Quote
There will be a bit more frictional resistance and inertia from the higher gearing, but it shouldn't make much of a difference.
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posted on 17/10/22 at 12:20 PM Reply With Quote
I would have to agree, rack ratio should have a negligble impact on self centering at least in the difference between 3,5 and 2,5.
If the rack has a problem that prevents this then it would be stiff to steer aswell?
If it was a self built car I would say its a caster/SAI issue but since you say its a Westfield kit then the simple answer is to just get whatever rack Westfield uses in their cars.

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David Jenkins

posted on 17/10/22 at 02:13 PM Reply With Quote
My car had various steering ratios in its time, from 2.4 to standard (3.5?). The fastest rack was the most fun to drive, but I found it tiring on the wrists - at slower speeds you have less leverage to overcome the self-centring forces*, and you will experience greater kick-back when one of the front wheels hits a pothole. I found the best compromise ratio was one of the middle ones: I can't remember the exact ratio I had, but I think it was 2.7 or 2.8. I had a fairly small steering wheel as well, which didn't help - I did wonder whether a fast rack and a slightly larger wheel would have made everything work better/easier.

That steering rack failed eventually, so I replaced it with a standard one. I found that excellent for general day-to-day driving, which was all that I was doing anyway.

* My car had the mod to give extra self-centring (more caster angle), which worked, but it did make for heavier steering at slow speed.

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posted on 17/10/22 at 02:26 PM Reply With Quote
Yes its fixed caster angle, in fact I was on aligment service to measure, but as it if Westfield with fixed brackets, cortina (i think it is cortina ) upright with bushed wishbones, I have no impact on caster as I assume . Measured 5'14 on one side and 5'55 on other. I assume its is ok as read that for westfield between 5 and 6 deg is ok.

Steering rack is suspected as it was a used cheap one just for start (was changing RHD to LHD chasis elements) and I have read that such racks can suffer with drag and not lively self centering. So if I am about to buy new anyway, so can choose among 2,5 and 3,5. Would like 2,5 for driving experience hands on steering wheel etc, and if it is not worse and even slightly better in terms of self centerig the better !

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