athoirs
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| posted on 27/9/06 at 07:47 PM |
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Indy handling
Project over the winter is to improve the handling of my Indy for next years sprint and hillclimb season.
I have been doing a bit of research and studying Allan Staniforth’s RARCS book and one thing that jumps out at me firstly is that the Indy has near
parallel wishbones both front and rear.
Looking at Allan’s book what the effects of this are - “ Wheel angle in roll poor ( may be near equivalency with body roll angle)- makes me wonder if
there is room for improvement in this area. If you have a look at these posts it gives you some idea for the problem. Next step the string
computer?
(Please don’t say just buy the new Indy!)
http://www.locostbuilders.co.uk/viewthread.php?tid=27328&page=1
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Hellfire
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| posted on 27/9/06 at 07:55 PM |
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The front bones are parallel but not of equal length... kinda suggesting what you're reading does not exactly apply in the MK's case. The
rears IIRC are but are designed that way to improve the characteristics of the IRS.
Of course what I have said can and probably will be shot down 
Steve
[Edited on 27-9-06 by Hellfire]
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athoirs
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| posted on 27/9/06 at 08:03 PM |
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Hi Steve
This is talking about unequal wishbones as well. I am certainly no expert, but trying to understand how the car behaves the way it does
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alister667
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| posted on 28/9/06 at 12:21 AM |
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Something I found knocked about 3-4 seconds off my best lap at Kirkistown was moving down to 13" wheels. The reduction in gearing, (unsprung)
weight and ride height was great.
You'll need to check carefully if they'll clear your front calipers and guards etc.
Maybe you're running 13s already though
http://members.lycos.co.uk/alister667/
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carnut
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| posted on 28/9/06 at 09:48 PM |
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Just a point. Although the front wishbones look parrallel (in fact the tubes are) they dont act like their parrallel because of the angled fitment of
the top ball joint.
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athoirs
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| posted on 28/9/06 at 10:38 PM |
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I am going to try and take some measurements on the front and rear geometry and see if I can get some understanding of the standard set up.
I am running 14” yoko AR32’s at the moment but am changing to 13” ACB10’s (8” rear and 7” front) This will mean a big change to the car set up
anyway.
I was hoping some of the suspension experts on here might be able to explain if there were any advantages (or disadvantages!) to the parallel wishbone
design.
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athoirs
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| posted on 2/10/06 at 02:27 PM |
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Right been doing a bit of work on this today and by removing the springs from the shocks and fitting a jack under the car- fitting a laser vertically
onto the outside of the wheel and pointing it at the roof which I callibrated.
I found that the front wheels actually moved only about -1 degree over the whole suspension travel (droop upwards)which is at least the correct way!
However the rears went +2 deg camber change!
Anyway I am still investigating
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athoirs
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| posted on 4/10/06 at 07:33 PM |
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Little update..
Working on the rear of the car at the moment and the camber IS going positive ( in the order of 1.5 deg) The wishbones are set up parallel by MK.
(19mm between upper and lower wishbones.
Would any suspension experts like to comment on this. I would think you would like some neg camber as the wheel rises??
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DIY Si
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| posted on 4/10/06 at 07:38 PM |
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I seem to remember thses being discussed before, but basically to fix it, I think you need to move the upper wishbone mounts outwards by an inch or so
and then make some new wishbones to create the desired negative camber in roll. Basically a shorter top bone.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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