#31
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You don't need to apologise, Johno, this is clearly on-topic. From your photo it does look like the wheel axis is a bit further to the front than the kingpin axis, and I assume Andy left the caster angle the same as in the Sierra-based wishbones.
Actually, it's easy to test-self centering in the stage you are in, just put it on the wheels, turn the wheel to the lock, and push the chassis a couple of feet and back. My steering wheel stays where it was on the stroke forward and unwinds a bit when pulled back.
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Albert Haynes Roadster FAQ | Haynes Builder Locations Gallery, build thread in Lithuanian / via Google Translate. |
#32
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Johno, robo posted an amazing link about suspension geometry a while back:
http://www.haynes.co.uk/forums/showthread.php?t=7371
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Albert Haynes Roadster FAQ | Haynes Builder Locations Gallery, build thread in Lithuanian / via Google Translate. |
#33
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Hi Alga good site,
Still trying to get my head round it all (too much info ). I'm going to remake my top wishbones soon and need to readup on this before I fab them. But I actually found out what "bump steer was this weeend". I fitted my new wishbones and moved them throughout their travel with the shock on and noticed the wheel moved in and out...LOL Johno |
#34
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Dont panic the steering rack has to centralised mm perfect before you can run that check.
Edit ,another usefull site http://www.optimumg.com/OptimumGWebS...me3_legacy.htm Bob
__________________
When The Results Disagree With The Theory: Believe The Results And Invent A New Theory If I had two brains I,d still be a halfwit The cave http://s1116.photobucket.com/user/my...deshow/mancave The build http://www.haynes.co.uk/forums/showthread.php?t=12669 Last edited by robo : 18th September 2012 at 08:41 AM. |
#35
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Quote:
After a bit of work on CAD, i came up with this rough figure. I assumed a vertical distance of 200.5mm between ball joints (according to this drawing) and a slight divergence between the upper and lower wishbones towards their outer ends (ball joint ends). According to my calculations, by offseting the wishbone chassis mount by 2.5mm you increase caster by 0.7deg and by making a new wishbone with 10mm more offset you get 2.8deg of caster! For 5mm offset wishbone you will gain 1.4deg Original setup: 5.73deg 2.5mm offset chassis mount: 6.43deg new wishbone with 5mm more offset: 7.14deg new wishbone with 10mm more offset: 8.54deg |
#36
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Reading a geometry article by Nigel Dean handed out by Track Developments at a Kit Car show he recommends 3 to 3.5 deg for a 7, 5 to 7 degrees for a Cobra
How much are you guys looking for ultimately? |
#37
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Self-centering is a safety and stability feature.
If you don't get any sufficient self-centering effect with 5.5deg then you have to go for more. I think that the best solution would be a new top wishbone with 10mm more offset and rose jointed so you will be able to fine-tune the caster angle according to your specific needs. I will seriously think of making a pair for my car as soon as i finish building it. Maybe earlier than that.. |
#38
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Quote:
bob
__________________
When The Results Disagree With The Theory: Believe The Results And Invent A New Theory If I had two brains I,d still be a halfwit The cave http://s1116.photobucket.com/user/my...deshow/mancave The build http://www.haynes.co.uk/forums/showthread.php?t=12669 |
#39
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you may as well ditch the sierra upright and go for some light cortina rep front uprights and redo the whole lot in one go
you cant polish a turd and rolling it in glitter is messy |
#40
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A first mock-up:
Last edited by DRCorsa : 18th September 2012 at 07:47 PM. |
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