trueblue
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| posted on 10/1/05 at 05:24 PM |
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Book chassis/Sierra uprights/Wishbone Mods
Scene:
Standard Chassis,Sierra Uprights/Adaptor.
What changes to Wishbone design to accomodate these components?
Any thoughts apppreciated.
Trueblue
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GaryM
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| posted on 10/1/05 at 06:11 PM |
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Wishbone Changes
Hi Trueblue
I've just reached the stage where i'm mounting my wishbones and am toying with a practical solution to ensuring I get sufficient castor
AND have the wishbone brackets not unacceptably overhanging the chassis tubes.
My chassis and wishbones are to the book dimensions (Lolocost bushes and bush eyes) and i've used slightly oversized brackets to mount the lower
wishbone (to give some fine castor adjustment via shims).
The best castor reading I can achieive is 2.7 degrees (measured with an inclinometre). I could squeeze some more if I wanted to increase the wishbones
bracket overhangs and gusset them, but it just doesn't feel right somehow (i'm no engineer).
So the only solution left to me is to get some modified wishbones made up (probably top) with a greater offset built in (like Mark Allisons). I live
locally to you and have had some trouble finding someone qualified to weld them up for me for a reasonable cost (best so far is £75 per wishbone) so
i'd be interested in hearing from you should you decide to take this route.
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Surrey Dave
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| posted on 10/1/05 at 06:29 PM |
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Wouldn't it be possible to use MK wishbones?
I thought that the MK chassis was the same width ,but possibly an inch taller, if so I dont seehow that inch above the mounting point of the wishbones
would effect anything.
As regards caster angle its probably best not to fit tubes FU1 FU2 untill you can measure the caster angle. As a lot of us had to cut them out and
start again..........
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James
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| posted on 10/1/05 at 11:05 PM |
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Trueblue,
You need to find out definitively if the Sierra track is the same as Cortina.
When I first started I was told it was not the same. (That the Cotina was +4" and the Sierra +7" ) Since then I've read it is the
same so who knows! 
If the Sierra/Cortina track is the same then you're fine with the above plan- ie. Cortina rear axle, and MK Indy (Sierra track) front
wishbones.
If the Cortina is narrower than the Sierra then this will end up with you having a wider front track than rear. And God only knows what the
handling consequences of this would be! 
All the best,
James
[Edited on 10/1/05 by James]
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ned
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| posted on 11/1/05 at 10:31 AM |
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i've seen many chassis where the brackets overhang the tubes on fu1+2 so overhanging with properly gusetted brackets shouldn't be an
issue, or move fu1+2 further back to suit?!
Ned.
beware, I've got yellow skin
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trueblue
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| posted on 11/1/05 at 01:31 PM |
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Book Chassis/sierra uprights/wishbone mods
Thanks for the info ; its obviously time for more research. Looking at an MK chassis would help to get a baseline for those dimensions; cue camera!
Sierra / Cortina Track again measurement time without the spacers.
Im not putting in the FU1/2 uprights until i have finalised what wishbones i will eventually use.
Enough thinking for one day wheres the aspirin.
Regards
Trueblue.
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James
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| posted on 11/1/05 at 02:21 PM |
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What a lot of effort for 20quids worth of saleable, heavy, ugly, Sierra upright!
James
[Edited on 11/1/05 by James]
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Mark18
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| posted on 11/1/05 at 03:11 PM |
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quote:
Originally posted by James
Trueblue,
You need to find out definitively if the Sierra track is the same as Cortina.
When I first started I was told it was not the same. (That the Cotina was +4" and the Sierra +7" ) Since then I've read it is the
same so who knows!
If the Sierra/Cortina track is the same then you're fine with the above plan- ie. Cortina rear axle, and MK Indy (Sierra track) front
wishbones.
If the Cortina is narrower than the Sierra then this will end up with you having a wider front track than rear. And God only knows what the
handling consequences of this would be!
All the best,
James
[Edited on 10/1/05 by James]
This is exactly what Caterham are doing with their new 7. Seen pictures of it in Autocar, and the new IRS system looks like it uses a sierra diff of
all things!
Mark
"I don't know what I may seem to the world. But as to myself I seem to have been only like a boy playing on the seashore and diverting myself
now and then finding a smoother pebble or a prettier shell than the ordinary, whilst the great ocean of truth lay all undiscovered before me." -
Isaac Newton
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