alister667
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| posted on 9/10/04 at 05:50 PM |
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Indy Set-up Advice
I got talking to Bill Adair about set up of my Indy and I'm going to pass on what I've found out.
Just to put it into perspective Bill has been racing cars for the guts of 25 years, has raced westfileds and is the Ireland agent for MK. I'm
no expert and I'm merely relaying what he told me, also I'm jusyt starting to do this stuff to my own Indy.
First off is toe in / toe out. First get your car onto flat surface and point the front wheels straight ahead. Attach a couple of straight pieces of
wood (any material woill do as long as they're straight) to the front wheels pointing out front - I used bungy cords seemed to work OK. Make
sure the wood isn't being fouled by the front cycle wings or your fancy sticky-out alloy spokes!
I measure two points on the sticks (measured from the centre of the wheels) one 60cm out and one 120cm out. Measure the differnce in the widths of
the sticks at these two points. If they're the same you're wheels are both pointing straight ahead niether toe in or toe out. If the
120cm point is narrower you're toeing in. Bill recommends a small amount of toe-in on an Indy. I sat down and did a bit ot trig and reckon
that if the 120cm point is 10mm narrower than the 60cm point that's about 0.5 degrees toe in.
For castor Bill reckons if your castor is the same on both sides it's a big help. This can be checked by turning your wheels full lock to one
side then hanging a plumb line down from the top of the wheel and seeing how much it overhangs thebottom of the wheel. Do the same on the other side
and I guess you can adjust your mushroom insert to get them to match. I'm setting my castor basically to maximum, but I'm going to get
both sides to match (they're about 3mm different at the mo).
Bump steer - this is one Bill told me about he reckons is veryt important. One of the big advantages is of an Indy is that the steering rack is
shortened to reduce bump steer, however Bill reckons that if you take the bottom bolt of the coil-over and use a jack to move the car up and down
(simulating full suspension travel) you can see if the car toes-in or out (using the stick method from above) if it is then shim the steering rack
with a washer and try again. Ideally you should be able to get the suspension to travel without changing the toe-in or out of the car at all.
According to Bill this greatly improves the car's handling and stability. On his hillclimb Westfield he had had had to shim the rack by 10mm to
get it right, but when it did he reckoned it was worth 2000 quids worth spent on the engine!! I guess it's all to do with geting the ball
joints at the end of the rack to line up exactly with the suspension brackets.
Corner weights. Bill reckoned getting a sturdy set of bathroom scales and 3 pieces of wood exactly the same height as the scales then setting the car
up on these and rotating the scales round each wheel taking note of the weights (with you sitting in the seat of course). You then adjust the spring
platform on the diagonallt opposite wheel (increase ride height to throw more weight onto the opposite wheel). Repeat until all 4 wheels are weighing
the same, or as close as you can get them.
Now he never mentioned any way of measuring or setting up the camber of the front wheels - anyone got an easy way of doing that? I can't think
of anything without removing the cycle wings!
I hope this might be of interest to some of you and I'm interested to hear if anyone has any improvments in any of these ideas - or spotted any
mistakes!
Cheers
Ali
http://members.lycos.co.uk/alister667/
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Mark Allanson
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| posted on 9/10/04 at 07:30 PM |
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All good stuff, you can do the camber using a spirit level vertically and measuring the distance between the lower and upper rims and doing the
trig.
I will stick to my own system though!
 
Rescued attachment HunterSystem.jpg
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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GeoffT
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| posted on 9/10/04 at 07:55 PM |
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Ali,
10mm of toe in over 60cms (about the width of a wheel) sounds an awful lot, I'd be inclined to recheck your trig on that!
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zetec
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| posted on 9/10/04 at 08:07 PM |
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I also found the tyre presure made a big difference. Mine are about 18PSI, suspect BEC might run as low as 16PSI.
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Jim
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| posted on 9/10/04 at 08:36 PM |
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On the corner weighting front, i did the corners before I took my car to elvington track Day. It seemed to Handle good. better than before. You
have to be patient as it takes forever. Small adjustment to springs make sjob easier. My car is set to zero toe, roughly equal castor and one degree
negative all round.
For another opinion ask hellfire as i treated him to some laps at elvington.
I think it handles the track well.
Tyre pressures are around 15 psi. Indy Blade by the way
Cheers
Jim
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Peteff
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| posted on 9/10/04 at 09:44 PM |
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Castor adjustment
The 10mm toe in will be for both wheels, 5mm each I should imagine, that's about what I set my locost to at a metre out. I used Dexion bolted to
the wheel studs with the wheels removed. If you do remove the cycle guards you can turn it upwards to do the camber with it. If you have the Sierra
uprights with the offset centre adaptor you have a little bit of castor adjustment but it alters the camber at the same time so you will have to
adjust the top balljoint thread again.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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alister667
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| posted on 9/10/04 at 09:53 PM |
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quote:
Originally posted by G.Tyler
Ali,
10mm of toe in over 60cms (about the width of a wheel) sounds an awful lot, I'd be inclined to recheck your trig on that!
I know what you mean, I got the answer - I was expecting about 2-5mm maybe, I did recheck the working out - it seems to be OK. I have it on paper out
in the garage, I'll scan it in so you folks can run your eye over it.
The degree I'm referring to is the angle between straight ahead and the angle of the wheel. Both my wheels are about 0.5 degrees inside
straight ahead by my calculations.
Cheers
Ali
http://members.lycos.co.uk/alister667/
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Wadders
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| posted on 9/10/04 at 11:53 PM |
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Hi Alistair,
i know nothing about suspension setup, (on cars at least), but to reinforce your point, i took mine to Paul at Playskool.
http://www.plays-kool.co.uk/ and for not a lot of money he transformed the handling of my car, experience is invaluable,and unless your
totally skint, don't even waste time trying to set a car up at home with bathroom scales, bits of wood and string, believe me it ain't
worth the frustration and dissapointment, bung a few quid to a pro, and then enjoy the ride.
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GeoffT
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| posted on 10/10/04 at 07:10 AM |
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quote:
Originally posted by alister667
The degree I'm referring to is the angle between straight ahead and the angle of the wheel. Both my wheels are about 0.5 degrees inside
straight ahead by my calculations.
Ali
That's a good point, does 0.5 degree toe mean overall between both wheels, or each wheel and the centreline? Maybe someone more
knowledgable than me (not difficult...) can clarify!
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Hellfire
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| posted on 11/10/04 at 11:26 AM |
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Yeah,
I can certainly verify that the car handled well with that setup. Next job for ours.......................... corner weights. quote:
Originally
posted by Jim
On the corner weighting front, i did the corners before I took my car to elvington track Day. It seemed to Handle good. better than before. You
have to be patient as it takes forever. Small adjustment to springs make sjob easier. My car is set to zero toe, roughly equal castor and one degree
negative all round.
For another opinion ask hellfire as i treated him to some laps at elvington.
I think it handles the track well.
Tyre pressures are around 15 psi. Indy Blade by the way
Cheers
Jim
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