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AdgeC

Steering Self Centering

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AdgeC

Just thought I'd pass on my experience of the self centering check at my recent IVA on my Sport 250. It was an aspect of the test that I was concerned about, mainly because unless you have acces to a large area to check it, you're in the lap of the gods.

My test consisted of driving the car round in circles, taking your hands off the wheel, and seeing what happens! Simple and logical really if you think about it. So car was driven round in circles, take hands off the wheel, and happily the wheel span smoothly back towards the straight ahead position, every time, result!!

Having read various threads on self centering, I concluded there's no magic formula to get it right.

The front set up I opted for was: 1deg negative camber, and ~1/4deg toe out (if my trigonometry is correct!), ride height set quite high initially (my sump is very low!), I'm sure it will settle. Tyre press. 23psi. Bear in mind this was done in the garage with rudimentary equipment.

Not claiming this is "the set up", but it worked for me, so thought I'd pass it on, might help somebody hopefully.

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Archibald Meatpants

I thought caster was the main thing that affected self centering?

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Thrustyjust

I have my car set up as a road car and did try different things for self centreing for IVA. To be honest, I feel that the combination of a new steering rack, steering column and knuckle joints will make more issues than geometry . If you are building a car, then , what I did was stripped out the column and greased with graphite grease. Made sure it spun nice and free. I kept the short shaft knuckle near the rack as straight as possible, but also I exercised the knuckles and oiled them to free them up. After assembly , I also ran from lock to lock to free the rack up. You also have track end joints that free up. So, perhaps, a bit of time exercising will go a long way to help self centre. I find that the steering has freed further from use now, so although I had a road based track set up, it wasnt 'massively' different from the pre-IVA Stringtech TM , that I set up.

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DamperMan

I think the challenge some builders have is with all the new parts everything's a bit stiff.   I fitted a replacement escort quick rack the end of last year and it was stiff and it didn't self centre nicely...

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AdgeC

Mechanical stiction in the steering was my concern when assembling. As well as the bushes in the column, I've got two further support bushes on intermediate shafts, and three UJ's linking it all together. Plus of course the rack itself, and track rod end joints. All in all I'm happy the way it self centres.

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Thrustyjust
1 minute ago, AdgeC said:

Mechanical stiction in the steering was my concern when assembling. As well as the bushes in the column, I've got two further support bushes on intermediate shafts, and three UJ's linking it all together. Plus of course the rack itself, and track rod end joints. All in all I'm happy the way it self centres.

Wait until you get some miles on it Adge, I enjoy letting the wheel slip in the hands as it straightens out of junctions etc. Dont tell the wife ( ex driving instructor !!) :d

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AdgeC
1 minute ago, Thrustyjust said:

Wait until you get some miles on it Adge, I enjoy letting the wheel slip in the hands as it straightens out of junctions etc. Dont tell the wife ( ex driving instructor !!) :d

I'm looking forward to getting some miles on it :t-up:. Not long now!

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stephenh

Caster angle is very relevant to self centering, but on most Westfields it is the one thing that isn't adjustable.

The common view seems to be that having a bit more air in the tyres helps (say 22 or 24 psi). Personally on my XI I found that toe in made it more likely to self centre. I now have zero toe, and it makes the steering very light, and not much self centering.:(

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Martin Rice (Sparkymart) - Cornwall AO

Is this any good  this is how Matt Seabrook set mine up for fast road (I believe he use to race Westfields)20160923_221053.thumb.jpg.4ad30e7fc62c46f2be65eb1b1c4c6f83.jpg

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AdgeC

Interesting. On the front, is "- 'toe" toe out? Mind you 11mins (I assume it's minutes?) is pretty small.

On the rear is the 20mins (+ ' ve) also toe out?

Amazes me that small setup changes can make a difference to handling, not disbelieving, I'm sure the experts know what they are doing. Will be interesting to get mine set up properly when I've got some miles under my belt, and everything settled in.

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AdamR

-ve toe is out, +ve toe is in.

I would personally run more toe in at the rear (double that) because of how the Westfield suspension design works, and more camber unless the car only ever sees a pootle on a sunny Sunday afternoon, but that is a good baseline.

Alignment makes a HUGE difference. It's probably the best 'upgrade' for any car that hasn't had it done.

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Archibald Meatpants

100% agree. Adam is a magician. 

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Archibald Meatpants

Side note - how often do you recommend reviewing it Adam? Presumably it doesn't change unless you have a bump?

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AdamR

Ha, thanks Russ...

And yes, there's nothing to move, so no need unless you have a bump.

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CraigHew

My memory is getting a bit hazy, is the "thrust angle" (shown at the bottom of the printout image above) a good indicator of how straight your chassis is?

With 0 being perfectly straight.

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