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  #1  
Old 31st March 2011, 10:24 AM
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Talonmotorsport Talonmotorsport is offline
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Don't forget that the face of the rear upright is determined by the bottom rail of the suspension cage, the bottom wishbone and the rear upright it's self. If all these things are even 0.5-1mm out any where the worse case you could end up being 3mm out very easily. With the best will in the world the rear suspension is made from fabricated parts welded together not CNC made and assembled production components.
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  #2  
Old 31st March 2011, 10:35 AM
trick-kit trick-kit is offline
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Quote:
Originally Posted by Talonmotorsport View Post
Don't forget that the face of the rear upright is determined by the bottom rail of the suspension cage, the bottom wishbone and the rear upright it's self. If all these things are even 0.5-1mm out any where the worse case you could end up being 3mm out very easily. With the best will in the world the rear suspension is made from fabricated parts welded together not CNC made and assembled production components.
It's called accumalative error, if you start with the basics, each item will have a tolerence on dimensions, then if it is a welded component, each weld will have a tolerence too, once you start to add fabricated items together then all these tolerances can quickly become a problem if not kept in check.

I appreciate that this is a home built car, so keep the tolerances in the real world, it would be impossible to work to 0.1mm for example.

The way round it would be to have a jig for the suspension pick up points front and rear firmly screwed to the table and make sure that these are in alignment, then build the chassis around these. After all, the purpose of the chassis is to join the important parts (suspension etc) together.
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Old 31st March 2011, 10:53 AM
Ashtonr Ashtonr is offline
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Thanks Guys, is the track width the same front and back ? guess I need to put all the front and rear suspension back on and check its all paralel, I never did this before I used the book jigs at the front and offerred up the wishbones at the back.
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  #4  
Old 31st March 2011, 10:56 AM
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Originally Posted by Ashtonr View Post
Thanks Guys, is the track width the same front and back ? guess I need to put all the front and rear suspension back on and check its all paralel, I never did this before I used the book jigs at the front and offerred up the wishbones at the back.
Yes front to back, not easy to measure on your own though. If you take a measurement from the rearmost front bracket to one on the rear do exactly the same on the other side. If its on wheels measure centre of wheel to centre of wheel...it MUST be the same CASTOR MUST be the same angle also or weirdness will set in.
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Old 31st March 2011, 10:57 AM
fabbyglass
 
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Doesn't just apply to track cars it's a MUST for road use unless you like hedges
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Old 31st March 2011, 06:42 PM
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james3004 james3004 is offline
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I think I'm going to uses washers/ shims on the rear hubs to correct mine
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  #7  
Old 31st March 2011, 07:50 PM
ayjay ayjay is offline
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Puts me in mind of a Renault back in late 70s or early 80s .It was the Renault.5 Ithink. One of the rear wheels was about an inch forward of the other to accomodate some strange suspension idea. They made a selling point of it --Quirky/cute French "flair" or something like that( they were crap anyway ).
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  #8  
Old 31st March 2011, 10:56 AM
mopple mopple is offline
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My solution will be an adjustable rear suspension. Based on Rorty plans and suited to Roadster. I think that my car will be on wheels on summer. Then I can share my experience. Adde also a picture of 3D model.
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