Quote:
Originally Posted by SteveMX5
Hi This is my first post so please be gentle!
I am coming to the end of building the chassis for my MX5 based roadster using the Saturn (or NTS?) plans (with a few tweeks). Looking forward to the next stage which looks to be the suspension wishbones.
Maybe I need to go to specsavers but I cannot find any specs for the material used for the wishbones apart from the obvious dimensions. Do I need ERW or seamless and what wall thickness?
All help greatfully recieved
Steve
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Ive just started making my bones.... I went for 19mm and 25mm CDS, and its really expensive!!! Think its 3mm wall! The tube bushes are made from 33.7mm x 2.6mm ERW, but i think you can only get 2.5mm or 3mm in general. Its pretty cheap per length, but you dont need a full length obviously. I could only get 3mm wall, so i will be machining mine down just a touch to fit the bushes.
As far as i know, the book spec for the saturn/NTS wishbone adjusters is 25mm diameter mild steel bar stock, threaded to M18x2.5mm. This is a bugger of a job to do in my opinion! I drilled the holes in the lathe, then hand tapped the thread, took me 2 hours to do all 8!!!! If i was doing it again i would use M16x2.5, or M20x2.5, as M18 is a hard size of bolt to get!!! I have got some M18x2.5mm threaded rod, but the problem is its only 4.6 grade, but ive calculated that this should take more load than it will ever recieve. Only problem would be hitting a kerb or such like i guess!? M18 bolts seem to be hard to come by from local suppliers, and are expensive where i did find some!!
The front upper wishbone takes a 30mm diamater mild steel bar stock, threaded to M14x1.5 to suit the BMW drag link. Im sure at some point andy (saturn) said that 25mm round was used for this, but im sticking to book spec, to keep the angle the same.
One thing that isnt in the saturn guide, is the angle of the front upper wishbone jig, but im assuming its the book 78 deg! Maybe andy / nathan could verify this for you?
Hope this is of some help, best get back out to the garage and get my next wishbone made...