Steering Angle/self Centre

[WallerZ]

Ok cheers for all the comments, I will be having a go this week after work and see how I get on. Please brace for a cry for help on Friday lol.

 

Cheers,

Zach

[Guest luke2152]

Zach - mine seems to have too many degrees of steering lock with the same rack so maybe need to come up with some kind of steering stop to reduce it. My rack is mounted further back then yours so might not be a direct comparison

Edited September 2, 2013 by luke2152

[Bob Tucker]

the usual way to reduce lock is to fit spacers inside the rack gaiters that stop the steering arms going too far into the rack .

They need to lock over the steering arms.

Bob

[WallerZ]

Well from a little play last night I seem to have reduced the problem, need to have a proper look both sides but it looked like my toe-in was too much. Will have to get it properly set/adjusted rather than done by eye and rough lines on the floor.

 

Self centring is still not happening though. I can't see how to adjust the castor angles at all as they seem to be fixed from the wishbone design...

[sj-bradley]

Do you need to add spacers on the top wishbone around the bushes?

 

You may be able to move the top wishbone backwards far enough for this to happen.

 

Simon.

[Guest luke2152]

Keep us posted on what you do because I'm going to need to get mine sorted too. I reckon raising the front ride height and lowering the rear would probably help too if only for the IVA

[WallerZ]

I've over inflated the tires, adjusted camber and toe (car now rolls easier - was fairly easy anyway) the wheels are now roughly in line with the rears. The castor is pretty much set by the wishbones and they can't move further back as they are already far back as they'll go. I've adjusted the suspension slightly, can't claim to be an expert but I think it's ok. Got my Dad round tonight to have a look at the passenger side as I can't see if from the drivers seat.

 

Would the ride height affect the problems that much? I can imagine it affects the settings somewhat but can't see if doing too much?

[Guest luke2152]

The ride height idea isn't a good solution but anything that lowers the back and raises the front will be increasing the castor. If it feels good but doesn't center enough for IVA I'd be tipping it back just for the test

[brumster]

Ultimately, Zach, given where you live you should get the car down to Chris at Centre Gravity. What he doesn't know about chassis setup isn't worth knowing, he can advise and tune as you want the car to be, and certainly tell you where it is now and what it needs to be to drive the way you want it. Not cheap, probably around the £200-250 for a full measurement and setup (depends on how easy the Zero is to adjust really) but a full setup by someone like this (rather than, say, Kwikfit!) is worth it.

[Guest mower man]

Ride hieght is very important and can have big effect on camber particularly , a slight amount of difference side tto side say1/4 " inch would not be significcant but 3/4 or over it will take effect and can also agravate bump steer probs but I think if orig poster sets thecar up to mazda spec he will not be far away unless gbs have alternate settings mowerman

[WallerZ]

Ok, so I believe the scrubbing issue is solved (would that be a problem on IVA?) Over-inflated tires, toe and camber improved from original set up from eye, ride height and suspension set(roughly).

 

Also, what sort of speed is the self centring tested at? I've been crawling and nothing but a little push of the accelerator will bring the steering round a bit. Obviously I can't test this fully due to space and not wanting to crash into anyone's parked car.

[sj-bradley]

I was told that the self centring just had to "start" it's self centring by my tester in order to pass. If the steering wheel wants to tighten up the curve instead, that would be a fail.

 

So long as your car "wants" to self centre, that should be ok.

 

(my opinion only)

Simon.

[Longboarder]

Usual comment from me about self centre. It's not about passing the IVA. Self centering is an essential element of car behaviour. It's like a gyro stabilisation unit for fast straightish roads and on corners provides the steering feel/feedback that tells you what the front end is doing. Absent self centre leaves the car like an early computer car game without force feedback.

I presume there is no design problem. There should be enough adjustment built in to correct manufacturing differences. If you get all the angles set accurately, camber, castor, KPI, and tracking, then it should be perfect and perform well.

And no you can't set them by eye or with a bit of string and a ruler. You are dealing with parts of a degree. We all still do this, think it's pretty good and most never get further but if the car is then set-up with the right equipment and an experienced operator it's transformed.

 

Nigel

 

One note. The lengths of the steering arms on the MX5 hub-carrier and the escort hub-carrier and the rack pitch on MX5 and Escort may differ giving quite different steering ratios and total wheel angle.

[Guest mower man]

Great post Nigel ,susp geo can be a night mare and as you say guesstimation is not good enough and the comment about steering arms and racks needs to be noted and understood .

Zach get intouch I have camber caster gauge and can poss borrow tracking equip .would you like a visit mowerman

[WallerZ]

Ok will do. I've started the IVA process by applying to VOSA, waiting for a handbrake from GBS plus a few other tasks left, so will probably give a shout out for a pre-IVA tire kicking session and a proper set up by those who can help with equipment etc all at the same time. So still a few weekends away yet