Going back to the original question (in the hopes of preventing a war...)

After chatting to a mate, the only problem we could come up with regarding ERW is the chance of fatigue.

Due to the high levels of vibration the bones will experience, the greatest chance of causing problems during normal driving (excluding bricks, kerbs, other cars, etc...) will be from fatigue.

The weld in the ERW will act as a harder, more brittle area and as such will be slightly more susceptible to fatigue. Presumably this is more than made up for by the slightly larger tube thickness.

Thoughts? (The seeds of a new war have been sown, the facilitator sits back to watch the chaos...;) )

And yes, this discussion was held down the pub!

Before or after beer? :D

TK

It was suggested to me to use 4130 by a motorsport fabby but the trouble with that is you are then commited to 4130 welding rods + 4130 for any plate used +heat treatment after. It gets a bit overkill for a road smoker. I trust the book bones have proved durable so I will go with talon on this.

Bob

Must get the delivery driver to avoid and speed bumps just in case they break.

4130 is just cro-mo (stuff thay make bike frames from) so i dont see why you are tied to using 4130 rods (there is prob not a exact match in wire or rod anyway) you do have to take care not to over heat and harden it more like meny other metals.
you should have a look at some of the classic racers thay used hardend tubing and brazed everything together :rolleyes: so the tube wasnt over heated and hardend more.

i cant see why a roadster needs anything other than a mild steel tube realy and a seemless one is a better option if you can get it.
i got some for my roll bar back stays from a hyd hose co. and was fairly priced

Now someone has got to tell him hes been a twat for the last 30 years and in all that time he could have welded all those wishbones with an old coat hanger:o lol No he merely mentioned that is what they use and thats the way they do it and if I wanted some made he would do it but i think cds is more than good enough for my job. You will be seeing some of his work soon and there wont be anyone out there knocking his stuff. He knocked me up some collectors and its a shame to put them on the car. They would be more at home in a glass cupboard.

Bob

Bob

The advice you were given Re: 4130 tube was quite correct ;)

Here's a link to the science of it all :)

Heat treatment & 4130 tube

In my humble view, any CDS tube would be suited to the Roadster & would not explore other options unless I was into extreme motor sport :)

the point i was tring to make is that the filler has no effect on what you are welding its the heat you need to put it in that causes the problem hence the braze on old racers.
heat treating is a remidy to the effect of the heat on an already hard metal.
but there is more than one way to skin a cat
there are meny diffrent fillers (rods,wire whatever) in the welding world trust me i know i had to sell them over std mild stuff :rolleyes:
we dont need anything other than a good old mild steel tube for a wishbone and making it without a welded seem makes it better