paulmw
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| posted on 18/4/08 at 05:59 PM |
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Steering Rack & Self Centering
After numerous attempts to get the Indy to self centre my last hopes are to add some springs to the rack. MK engineering made up some spacers to
restrict the turning circle. I pressume the springs go between the spacers and the ball joint thingy:
Also how big do the springs need to be and how do you get the ball joint thing off the steering rack (I have tried and its on bloody tight)
 
Rescued attachment DSCN0034.JPG
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tegwin
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| posted on 18/4/08 at 06:08 PM |
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If its a kit built car....IE made on someone elses jigs with their recomended parts, there is no reason why it wont self center without springs....
I would be wanting to know why it doesnt work properly before i go bodging some springs on it!
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jacko
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| posted on 18/4/08 at 06:10 PM |
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If i remember right you use old valve springs off a ford pinto engine .
you will not need spacers if you fit springs
my car past sva without springs so yours should too
i just had toe out as much as pos but not looking daft and had 30 ps pressure in the front tyres
Jacko
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Bob C
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| posted on 18/4/08 at 06:13 PM |
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Paul
if you put valve springs on, you will need the lock limiters turning down or you'll have insufficient lock left when the spring coils bind.
If you decide to proceed with this, let me know when you have your springs & I'll turn down your spacers for you.
The steering doesn't have to snap back for SVA - just have a "tendency". What they are keen to avoid is steering which instead has a
tendency to steer MORE...
Bob
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Mr Whippy
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| posted on 18/4/08 at 06:51 PM |
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how light is the steering when the wheels are off the ground?? should be easy to turn with your finger.
If it’s a new rack try adding a card shim under the pretensioner cover on the rack (the one that does not have the steering shaft come though it) to
loosen it off.
I notice the scratches where you've been trying to remove that balljoint cover, sure there is not a steel pin going through the side?? or is
that one even in one piece and designed to be removed.
[Edited on 18/4/08 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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nitram38
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| posted on 18/4/08 at 07:38 PM |
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MK still doing the "bodge"?
Why can't they just supply the correct top wishbone?
It beats me how nobody has been injured by this sort of quick fix 
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KJK
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| posted on 18/4/08 at 08:31 PM |
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self centering
took my mates indy for sva monday and failed on self centering, spoke to mk and they said put springs in but i would rather ad some caster has anyone
modified or made new wishbones and if so is it just a case of shortening the rear and lengthening front of the top wishbone so that it moves the top
balljoint backwards?
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graememk
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| posted on 18/4/08 at 09:44 PM |
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mine didnt self center as there was 2x uj's in the steering and it was to stiff, the indy should need to have this bodge in it but it will make
a big differance to the self centering for sva but i wouldnt leave them in to be honest.
i sorted out mu stiffness, 30psi and 2degs toe out, passed no probs
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D Beddows
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| posted on 18/4/08 at 09:48 PM |
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In all seriousness here......why, when you guys have usually given MK 4 figure amounts of your hard earned cash for this stuff, do you still put up
with 'quirks' like this??? after all MK Indys have suffered from the same 'quirks' for g*d knows how many years now - and
it's nothing to do with how you've built the car...!!!!
[Edited on 18/4/08 by D Beddows]
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graememk
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| posted on 18/4/08 at 09:56 PM |
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because at the end of the day its a kit car not a £20k caterham, they arnt perfect.
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David Jenkins
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| posted on 18/4/08 at 10:02 PM |
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It's been said many times before - there's no excuse.
It really isn't a difficult problem to fix - all they need to do is to modify their jig by moving one fixing point by a few millimeters.
I took advice and modified my jig before making my top wishbones. I have positive self-centring and I'm sure it's a safer car.
[Edited on 18/4/08 by David Jenkins]
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D Beddows
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| posted on 18/4/08 at 10:07 PM |
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But no other 7alike has quite the same issues with self centering, so that would lead you to the conclusion that either MK builders are usually more
rubbish than builders of other 7alike cars (and I don't believe that for a second) or MK should be selling you better stuff..... that's
just my opinion obviously and all I'm saying is that if what you've bought doesn't work or fit properly you shouldn't just
accept it and then bodge up the car because you're told 'they're all like that mate' because actually they're not....
[Edited on 18/4/08 by D Beddows]
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mangogrooveworkshop
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| posted on 18/4/08 at 10:38 PM |
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First of all the steering rod and mounting should turn freely. The top bones are wrong...plain and simple....calvinix modded redeyes bones and the
worked a treat.
I'm a bit busy at the mo but it is number one on the list of thing to make it handle correctly. It makes for a much better drive and safer as
its predictable in its tracking. Bump steer is something else that should be covered later. As nitram says how long before this bodge of flat tyres
and stupid amounts of toe out gets a guy hurt.
Mark showed me what he did to Patricks car and it wasn't anything more difficult than re jigging the top bone to give more castor.
As well as that check your rack as most are stiff from lying around for a few years. 
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nitram38
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| posted on 19/4/08 at 02:46 AM |
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It is an easy production fix for MK so why go to all the effort to get around it?
If I built my first production kit, I would have ironed this out, but perhaps that is just me.
It is not as if it is difficult to alter, so why not just do it?
At least you could high light it as one of your benefits.
It is just amazing that even though it is cheaper than a catering van, why should their customers be driving cars which in my opinion are not safe at
speed?
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rusty nuts
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| posted on 19/4/08 at 08:30 AM |
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This is typical of the sort of problem that the SVA test was introduced to overcome . People may moan about having to have the test but at least
modern kit cars don't have the sort of reputation they had a few years ago? I'm not having a go at MK or any other manufacturer but I
feel that known problems should be rectified at source
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procomp
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| posted on 19/4/08 at 09:10 AM |
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Hi as said many times above just modify the top wishbones so that you have 5deg of Castor instead of the 1-3 deg that comes as std on both the Indy
and the spec R. It should also be pointed out that fitting valve springs or any other sort of springs on the rack is not MOT or SVA compliant.
And for a manufacturer to actually suggest it as opposed to sorting the problem out which would take them no longer than an afternoons work with the
jigs for the top wishbones is ludicrous. 
Cheers Matt
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David Jenkins
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| posted on 19/4/08 at 06:00 PM |
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That's the annoying part - a professional fabrication company like that could modify the jig in 1/2 hour at the most.
They might even open up a market for people who want to buy new 'bones to improve their handling!
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Hellfire
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| posted on 19/4/08 at 06:29 PM |
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I'm sure that if it was just a case of half an hours work re-making a jig, then MK would have done that a long time ago. Surely, there must be
other factors to take into consideration?
I'm not sure what degree of castor the Indy has but know that the Spec R Indy has 6.51 degrees of castor. (Which is the chassis the OP has)
It just so happens we are in the process of making some new top bones for our Indy. If there is no self centring with 6.51 degrees of castor, how much
do we need to achieve self centring? If anybody actually has a definitive answer to this (for Sierra uprights), let us know and we'll get the
top wishbones fabricated and report back with our findings.
Phil
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Bob C
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| posted on 19/4/08 at 07:27 PM |
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As I see it there are 2 components to self centring.
1) static - combination of KPI and scrub radius means turning the wheel from straight on actually lifts the front of the car
2) dynamic - caster or trail effect.
With the old cortina uprights [1] was quite important, but I don't know how sierra kit + adjustable mushroom inserts would affect it.
[2] is the part that "remake the top wishbones" would affect. Again the sierra factor brings in the adjustable mushroom insert effect
which alters trail.
All that BS really means is that cortina experience doesn't really help sierra users.
I used mx5 uprights on my 7 - these have zero scrub radius so [1] is negligible and even though I doubled the (incorrect) 'book' caster
(to the 'correct' 5.5 degreees) I pretty much scraped a SVA pass with extra toe out. If I were doing it again I'd go up another 50%
to 8degrees on mine - again no help to the sierra user I'm afraid.
Bob
[Edited on 19/4/08 by Bob C]
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procomp
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| posted on 19/4/08 at 07:30 PM |
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Hi it is simply a question of modding the top arms. I have done it to many over the years. And the spec R car may have been designed with 6.5 degs of
Castor but what is turning up on the cars is nothing like 6.5 degs. The one i have measured only had 3 deg one side and 1.5 the other. The fact that
they cant get the two sides any where near the same is worrying enough. The one that raced in the 750mc kits Admittedly by eye but certainly had less
than 5 degs on it. And the most i have ever measured on any of the Indy's over the years has been 4 degs. I think that was on OX's car 18
months ago or so.
Either way there is no excuses for selling a product that dose not do the job it is designed to do. And recommending customers to add valve springs to
bodge it past SVA is absolutely disgusting.
It has to be asked if the original desighn is supposed to have 5 on the Indy and 6.5 on the spec r. Do the people who designed it actually know how to
measure Castor. And why do the chassis that are sold have such a big discrepancy from one side to the other. Are the jigs being used correctly.
As to how much Castor is required for self centering with a sierra upright well a genuine 5 degs works fine. And it can be taken all the way up to 8
degs depending on the weight of the car. But the steering gets a little tiring on longer journeys but is good for circuit usage.
Cheers Matt
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Hellfire
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| posted on 19/4/08 at 07:56 PM |
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I see what you're saying although I doubt whether MK would actually recommend using valve springs as a fix for self-centring at SVA.
How many degrees would you suggest for a 500kg vehicle and how do we go about measuring it? Anybody got a diagram which shows the points to
measure?
Phil
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