Nash
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| posted on 5/6/09 at 06:42 PM |
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Self Centreing Steering
Someone mentioned to me that SCS (self centreing steering) is a bu**er to sort for the IVA on the Indy. Is this an urban myth or is it an issue? If so
what can be done to sort it?
Thanks..........Neil
It's What You Do Next That Counts.
Build It, Buy It, Drive It:
Southern Kit Car Club
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mistergrumpy
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| posted on 5/6/09 at 06:48 PM |
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I believe it is a problem. I'm really not trying to fob you off but if you do a search under self centreing you'll find loads and loads.
Fixes generally involve overinflating the tyres and toeing out a lot. In the Indy's case putting springs in the rack has been mentioned a lot
but I'm not sure if I'd try that.
You could buy some of Wozchers front bones with adjustable camber that would also sort it. You'd have to do a search on his name and check the
spelling too.
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matt_claydon
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| posted on 5/6/09 at 07:04 PM |
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I simply can't understand why after 5+ years of knowing about this problem, MK still haven't moved the top wishbones back to make the
front suspension work properly. It's frankley staggering as it's hardly a major redesign!
To sort self-centring properly there are two easy solutions:
Move the upper wishbone mounting brackets back on the chassis to give the correct amount of caster; or
Buy a set of wishbones from Wozsher (on here) which have the correct caster built in and are also adjustable for both caster and camber.
People on here will tell you to:
Pump the tyres up
Let the tyres down
Put on loads of toe-out
And even to put valve springs in the rack!!!
These are all bodges. Do it once and do it properly, you will be glad you did.
[Edited on 6/6/09 by matt_claydon]
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hellbent345
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| posted on 5/6/09 at 07:05 PM |
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don't know about specifically the indy, but there has been a lot of mention of many sevens having issues with self centering, and what most
people say, including myself, is the only proper way to fix it is to get new top wishbones/adapt your own wishbones or chassis mounts, so that the
wishbone can be moved backward, increasing, what is known to me as, the caster angle.
The way to do this is either making your chassis mounts wider (i dont recommend that) respositioning them back, or by cutting off the bushes/bush
tubes on the wishbones and welding on threaded tubes to take rose joints. (or by buy a set of wozsher's wishbones) Or you could make another set
of wishbones with the right positioning (no adjustment)
It can be fudged for the test with other methods but i think the aforementioned way is the best/most elegant etc etc
[Edited on 5/6/09 by hellbent345]
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David Jenkins
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| posted on 5/6/09 at 07:12 PM |
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One thing to check before you go much further - make sure that the steering can move VERY easily. The best way to check is to raise the front wheels
off the ground and try to push each wheel to the left and right. It shouldn't take much effort.
If there are any sticky or tight joints then any natural tendency to self-centre will be lost.
If the steering is reasonably mobile and the car still won't self-centre, then you will need to think about moving the top pivot point back a
bit.
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ReMan
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| posted on 5/6/09 at 07:42 PM |
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quote:
Originally posted by matt_claydon
I simply can't understand why after 5+ years of knowing about this problem, MK still haven't moved the top wishbones back to make the
front suspension work properly. It's frankley staggering as it's hardly a major redesign!
Same reason as side and back panels don't join neatly I guess
(awaits flame!)
[Edited on 5/6/09 by ReMan]
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Daddylonglegs
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| posted on 5/6/09 at 09:02 PM |
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Although I'm not building an MK, I am in the throws of sorting the suspension and steering. I have made my own wishbones and they should give me
about 7 degrees if I did my maths right. I have got a little room for movement forwards and backwards within the constraints of the brackets.
What is the best way to check for self-centreing (bear in mind I have no power yet  )
JB
It looks like the Midget is winning at the moment......
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Hellfire
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| posted on 5/6/09 at 09:09 PM |
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Best way to check for self centreing is to actually drive it, although making sure everything is correct beforehand will help to achieve it.
The standard MK top wishbones do actually have the required set-back to achieve 5 degrees of castor and the bodywork is being/has been modified to
give a less noticeable join between side and rear panel. 
Phil
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ReMan
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| posted on 5/6/09 at 09:58 PM |
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In my experience a new/ recon rack will be quite tight on the rack and also have very tight outer arm balljoints.
This coupled with a minimal castor and a light (BEC) engine do not help centreing.
Good news on the side panels
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austin man
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| posted on 5/6/09 at 11:42 PM |
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The mention of 1" is worrying as this amount over a small distance would probabl give a castor angle of 10 to 12 degrees.
I havent seen a problem with the indy passing sva due to self centering.
Easy fix to give a degree or two of adjustment would be to trim the top and bottom wishbone (bush tubes) by a few millimetres then shim out using
washers or see the wishbones that Hellfire made
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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BenTyreman
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| posted on 6/6/09 at 12:17 AM |
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We have measured the castor on the Indy wishbones and have found them to be approx. 5 deg. With 18 psi in the tyres and 1mm toe-out the self-centring
is very positive coming out of corners. The self-centring force is strong all the way to about a quarter-turn from straight ahead.
What we found to be most important was to completely back-off the rack preload and set it up properly. Previously you could hardly move the rack at
all by hand.
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