ever88
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| posted on 23/7/07 at 04:12 PM |
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2nd dimension check please
I'm sorry to bore you and trouble you readers again but quite simply I'm stuck.
For something so fundamental I find the book is both brief and vague on the actual location of these front wishbone mounts.
when you look at the position of the LB & FU1 that the upper wishbone brackets weld to there must be a mistake I feel or perhaps my ignorance for
not seeing it.
I'm presuming that the brackets which hold the wishbones should be centrally placed of these members to give full support. But if you do assume
this then there is no way that the two brackets will locate on each if you look at the dimensions given in book.
This is very frustrating when you see many pictures of them clearly supported on each and there are so many successful builds on here but please refer
to my drawing I've put on Cad to see where I've gone wrong or if there is a common error that is rectified by DIY builders.
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big_wasa
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| posted on 23/7/07 at 04:20 PM |
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Best not to fit the Fu tubes untill you weld the brakets on. Then use a jig to set the position of all four brakets and the Fu tubes in one
go.
 
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big_wasa
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| posted on 23/7/07 at 04:22 PM |
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If you have welded them and dont want to cut them of, you could add a brace this is a pic of the first chassis I made.
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big_wasa
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| posted on 23/7/07 at 04:26 PM |
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If you center the bracket on the LB setup with book wishbones then you will end up with 2 deg of castor and the car wont self center.
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ever88
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| posted on 23/7/07 at 04:34 PM |
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I havent welded these members to the front yet but have just looked ahead and can see problems. I was advised to build and weld as you go due to the
presence of errors in the book.
I would like to centralise support brackets on these members so by welding brackets to members 1st as suggested and place the upper wishbone 22mm
further to rear of car off the wishbone central line of the lower wishbone as per drawing posted to me would all be OK?
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caber
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| posted on 23/7/07 at 04:38 PM |
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Yep them FU tubes sure FU everyone at some point in the build! I did as above and made a jig to hold the wishbone brackets where they should be and
used Aluminium "bushes" so that i could leave the 'bones in place as I welded the brackets and the FU tubes in. I was still not
entirely happy with the locations or the strength of the FU tube given the small interface area so I put additional braces between the back of the
bracket and the engine mount, these tubes are in the original Lotus 7 chassis so I thought they must do something as Colin Chapman hacksawed out
everything that was not under load in the original design!
If you have a scan through my photo archiove there are a couple of pictures called engine bay bracing or something like that which shows what I have
done to fit around my Pinto.
Caber
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Avoneer
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| posted on 23/7/07 at 04:40 PM |
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I changed the angle of the whole front square section (leant it further back and did the top and bottom of the front "square" in round) so
that the front upper U bracket would be dead central on a bar.
You have to be careful though as it affects your steering rack location!
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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mark chandler
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| posted on 23/7/07 at 04:58 PM |
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As above, make a jig to locate the brackets. When you make the wishbones you can discard the book and make you own bones to suit, if IRS rear then
they will need to extend out a couple of extra inches to match the rear track of a sierra axle.
Points to watch are:
* When viewed vertically the top ball joint should be around 22mm further back than the lower.
* Make sure the shock will fit in the jaws of the top bone (that's why some people use curves, although not good practice).
There is no need for then to be symetrical so you could if wanted make the lower ones handed to achieve the effect, just make sure its exactly the
same both sides.
Regards Mark
[Edited on 23/7/07 by mark chandler]
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big_wasa
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| posted on 23/7/07 at 05:02 PM |
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My current chassis I have welded the Fu tubes where they need to be and not where the book says. I have also given my wishbones 25mm offset (7 deg
castor) aswell as being 2" wider to match the rear track of the Capri axle I am using on the back.
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ever88
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| posted on 23/7/07 at 05:08 PM |
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I don't know what I would have done without your help here guys.
a special thanks to everyones comments here.
I've never written a book so I shouldn't be over critical of it but I truly believe a car is 9 tenths geometry for making it a pleasure to
drive and think this section in the book was perhaps a little rushed.
thank heavens for you guy's
all the best
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Mark Allanson
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| posted on 23/7/07 at 06:13 PM |
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Just a quick drawing of the brackets to go with my wishbone drawing. Makes it even easier.
 
Rescued attachment SideViewBrackets.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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Avoneer
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| posted on 23/7/07 at 10:10 PM |
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What's "SIDE ELIVATION" 
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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