my friend has just finished building his westfield, and has it fully ready for its SVA.

the thing it failed on, is it doesn’t self correct, i.e. keeps steering round corner rather than straightening up. as far as I know it has a modified (by Westfield) escort mk2 steering rack in it.

What causes the self correct, is it the amount of toe in/out, or something in the steering rack.

Please help, cos if we fix it before weds we can get it retested taxed and plated in time for le mans next week

Many thanks

R

 

Castor is used for self centering.

 

it was all set up to the manual specs by a guy (richard?) at power engineering, just doesnt seem to self centre at all

 

it's something to do with the angle of the front struts, they need to lean back ever so slightly and inwards just a little to give you self centering

then again, i could be hopelessly worng

i'm sure soeone will be along to tell you what you need to do to make it right soon enough but if it's using the escort rack, if it also using the escort front hub assembly?
it might be down to the positioning of the lower arms or soemthing

 

http://www.ozebiz.com.au/racetech/theory/align.html

 

Give Troy at Northampton Motorsport a ring, he races a Westfield along with several of their customers and they do 4 wheel suspension alignment so he will be able to tell you exactly what you need to do to put castor into the front end to get your self correcting.

01604 766624

 

If he is using sierra front knuckles/hubs, then tell him to invest in some eliptical musrooms for the top of the hub - the hole is off center and you can adjust the caster with them.

Also, if using an adjustable balljoint arm for the top wishbone, he can adjust the camber aswell - thus giving you the abaility to adjust the steering self correction to the required amount

 

Front castor, thats what makes cars self centre, or not.

Positive castor gives it more self centering, drift cars often have 7degrees or more, no idea what the average car has tho, but a good bit less!

 

.....just as i said...castor

 

cheers guys, as usual passionford helps again

now he's gotta try fix it before weds

 

Less castor is better for low speed turn-in but affects stability, more ifs better for high speed.

 

May be it is a simple as a stiff steering column or stiff interconnecting column shaft

 

the steering is still quite light aparently, but he will be investigating, and greasing what he can tonight i guess

 

right now i'm confused

which castor is better for self correcting, having the top of wheel move back or forward.

there are washers that you can move apparently, but were unsure which way, some people say more or less, some say positive and negative

i need it in laymans terms

 

gingeRS what do you actually need self correcting for? Most rally cars I have driven have very little self-centering effect.


You need to move top of the knuckle to the back or bottom of it forward to get more centering effect.

 

next time you go shopping take the time to examine the trolley castors

 

I recently got trolley with completly fooked geometry. Couldn't make it go straight.

 

As part os the SVA test the car must be observed to have 'some' self centering effect and the car currently has none. its the only thing stopping it from passing, and westfield have stated its not a problem with the rack itself.

 

So you need temporarly to make some moge castor as described above.

 

Ask Rick, hes the expert on Rear castor

 

thats oil or suger

thing is though, there are so many otehr things that it can affect if it's wrong it could end up being more dangerous ith it self centreing that it not, you've got to think about ackermans steering principle as well as the angle the wheel will go through when it's turns if you offset the strut too much which could lead to much less stability going round a corner

if there is a known setting for this with the parts that are fitted then it would be better to get it set up based on that and then tweak it to suit his purposes, at least it won't be too far from factory settings so a bit of spannering can get it back ot basics again

it's either been set up to run at a specific requirement by the person who's set it up or it's been set up based on incorrect settings, i can't see soemone deliberatly misaligning the susnepsion