hi could any one tell me if the steel used to make the wish bones has to be seamless thanks

I saw this asked a while ago, and iirc it was only for aesthetic reasons

Yes, purely aesthetic - you look really ugly with bits of engine sticking out of your skull

Use seamless, there is a really good reason why its more expensive

the better you design your bones, the further you can push it with weight saving. Using seamless would let you go further down the path of lightness.

quote:

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Originally posted by Mark Allanson
Yes, purely aesthetic - you look really ugly with bits of engine sticking out of your skull

LOL

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Mark Allanson - 28/8/06 at 09:29 PM

quote:

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Originally posted by JoelP
the better you design your bones, the further you can push it with weight saving. Using seamless would let you go further down the path of lightness.

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You really have to get the design right, I have seen pictures tonight of lower wishbones with totally insupported balljoint mounts, and the reinforcing plate at 90° to the support tubes.

The owner of these wishbones will die if the SVA doesn't pick up the design 'flaw'

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Mark Allanson - 28/8/06 at 09:40 PM

...I have added the 'optional' safety bits in yellow
Rescued attachment kitcar004.jpg

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zetec7 - 28/8/06 at 11:50 PM

I used seamless, DOM (drawn-over-mandrel) 25 mm (1" tubing for the lower bones. Didn't add any weight, really, but is very strong. The steel plate to support the ball joint is 3/16" thick, and the plate under the shock is 1/8" (and curved down to the bottom of the tube, then welded), It's pretty bling at the moment, but it's to be powder-coated black to match the rest of the bits....
Rescued attachment lower bone.jpg

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britishtrident - 29/8/06 at 06:41 AM

To be honest I would advise buying in the wishbones as I and many on the list have experienced they are a pain in the neck to jig up and weld just for a car set.

This topic has been covered many many times if you do a search you will find the threads.

Essentially points for the lower wishbone
(1) DON'T use the book lower wishbone design -- it is seriously flawed.
(2) Use a design more like the GTS or MAC or latter MK pattern, which avoid the stress raisers and high local bending stresses inherent in the book design. Make sure the damper mounting point plate is in line with tube centre lines.
(3) Go up in tube wall thickness and diameter --- in addition to adding bending strengt and stiffness this makes using seamless no problem. But with seamless align the seam so is is in horizontal plane.


Upper wishbone design is much less critical as the stress levels are much lower.

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leto - 29/8/06 at 06:53 AM

quote:

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Originally posted by welshboy
hi could any one tell me if the steel used to make the wish bones has to be seamless thanks

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No, it don't.
Seamless is better only as long as you don't weld it. The moment you put the torch to it most of the advantages go up in smoke. So DOM is good for pub talk, but really a waste of money.
Steel grade and design are the important parts, get them right and you will have no trouble.

Cheers!

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JB - 29/8/06 at 03:04 PM

Dom is actually seamed tube. It is welded then formed in the way CDS is. Dom has a more consistent wall thickness so is preferential to CDS for applications such as propshafts. Look carefully and you will see the seam.

I tried DOM on my wishbones but due to having to flatten the ends slightly to get more surface area to weld in the spherical joint housing, it split.

I would always use CDS for my wishbones. The quality is consistent, it welds very nicely, it will bend rarther than snap.

Anything "better" such as 4130 or T45 needs a stress relieve.

There are certain parts of a car that you never want to fail, suspension, steering and brakes are those. Design and build these parts the best you can.

John

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britishtrident - 30/8/06 at 06:45 AM

This the way it should be done (a GTS bone frome an earlier post by FlakMonkey)

Important points to note

(1) Uses Maxi ball joint
(2) Plate is in line with neutral axis of tubes not just welded on the top surface as it is in the book design.
(3) Ends of plate are nicely radiused

(2) & (3) are vital as they removed a really nasty stress concentration that occurs in the book design that has caused more than a few builders to encounter bent or broken wishbones.
Rescued attachment lowerwishbone.jpg

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britishtrident - 30/8/06 at 06:58 AM

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Rescued attachment lower.jpeg

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britishtrident - 30/8/06 at 07:04 AM

Picture from NickGs original post that started the long running thread on wishbone failure.

Probably not the world best made whishbone to start with but it illustrates the point of failure of book design very well.
Rescued attachment Nicks.jpeg

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britishtrident - 30/8/06 at 07:10 AM

one of 907 bones - as always you can tel by the nice welds ---we are not worthy

Note the plate is in line with neutral axis and very nicely radiused to reduce stress concentrations.
Rescued attachment w-bones.jpeg

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JB - 30/8/06 at 06:47 PM

Good illustrations and a good point about the gusset on the neutral axis, something I had not considered.

John

Ps Now checking my wishbones!

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welshboy - 30/8/06 at 08:01 PM

thanks very much everyone for your help maybe i will just buy them thanks again

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