Seamless tubing for the triangles?
tug - 10/6/11 at 12:10 PM
Hey,
I was reading "build your own sport car on a budget" by Chris Gibs, which is far from flawless..Coming to the suspension chapter I realized
he asks to use seamless tubing for the triangles. Is it really necessary? Because I would have to custom order it and it is pretty expensive(as I have
to by 6m bar) compared to lower quality steel.
Here is what I am doing (not locost):
The 50x50 3mm steel support aren't finished, still need to cut them in a pretty shape, any tips?
cheers
-Tug
[Edited on 10-6-11 by tug]
loggyboy - 10/6/11 at 12:21 PM
Each of those wishbones will be taking about 150kg of static weight and several more hundered kilos of imposed loads, do you really want to scrimp on
the really important bits?
[Edited on 10/6/11 by loggyboy]
CaptainJosh - 10/6/11 at 12:28 PM
quote:
Originally posted by loggyboy
Each of those wishbones will be taking about 150kg of static weight and several more hundered kilos of imposed loads, do you really want to scrimp on
the really important bits?
[Edited on 10/6/11 by loggyboy]
He speaks the truth
Doctor Derek Doctors - 10/6/11 at 12:30 PM
quote:
Originally posted by loggyboy
Each of those wishbones will be taking about 150kg of static weight and several more hundered kilos of imposed loads, do you really want to scrimp on
the really important bits?
[Edited on 10/6/11 by loggyboy]
I agree, seamless isn't really that expensive, even on eBay 2.8m is only £20(ish plus P&P, the price comes down considerably if you buy one
long piece.
Alan B - 10/6/11 at 01:37 PM
Guys,
I think he's refering to the square tube for the brackets, which of course does not need to be seamless.
Alan
Trollyjack - 10/6/11 at 02:39 PM
I got mine from local Hydrolic hose repairer Mend a Hose or Pirtec
They sold me it by the metre
MikeCapon - 10/6/11 at 02:49 PM
quote:
Originally posted by Alan B
Guys,
I think he's refering to the square tube for the brackets, which of course does not need to be seamless.
Alan
No Alan, he means the wishbones. "Triangle" is french for wishbone.
And another vote for using CDS from me. If he lived a bit closer I've got some nice 20X2 CDS in my barn...
ETA I've just seen the "copper inserts". If the wishbones are really going on solid bushings the fixings better be perfectly aligned
or the bones will eventually break whether made from CDS or anything else..
[Edited on 10/6/11 by MikeCapon]
Alan B - 11/6/11 at 02:29 PM
quote:
Originally posted by MikeCapon
quote:
Originally posted by Alan B
Guys,
I think he's refering to the square tube for the brackets, which of course does not need to be seamless.
Alan
No Alan, he means the wishbones. "Triangle" is french for wishbone.
Makes sense I guess..I was just looking at his arrow (fleche?)
indykid - 11/6/11 at 02:46 PM
The loads on the upper wishbone are far less significant than the lower.
Having said that, the oval section MK use for their wishbones is ERW isn't it? They survive...
The copper inserts are more likely to cause failure than using ERW tube, though make sure your welding's up to scratch. Your tacks are messy and
look quite badly aimed. Were you using a mask or was that eyes shut and hope?
tug - 11/6/11 at 03:34 PM
Alright, I'll go buy some seamless tube. And yes it was for the wishbones.
For the brackets, I didn't use seamless, but I'm cutting out the weld part.
About the copper inserts, I won't have a lot of room for mistakes. Is it bad? lots of vibrations?
indykid - 11/6/11 at 03:46 PM
quote:
Originally posted by tug
About the copper inserts, I won't have a lot of room for mistakes. Is it bad? lots of vibrations?
There's no compensation for misalignment unlike a rod end or polyurethane bush.
If it's not in perfect alignment, it will generate massive stresses as the wishbone articulates and no doubt break the wishbone or bracket in a
short space of time
Neville Jones - 12/6/11 at 09:18 AM
quote:
Originally posted by Trollyjack
I got mine from local Hydrolic hose repairer Mend a Hose or Pirtec
They sold me it by the metre
AAArgh!!!! The stuff they use in hydraulics may be seamless, but it's annealed within an inch of its life, is very soft so that it can be bent
easily.
Not the best choice a man can make, and only slightly better than the erw seamed stuff. The erw melts like butter compared to the proper cdw, or
better still, DOM, which is stronger.
Cheers,
Nev. 
indykid - 12/6/11 at 11:40 AM
quote:
Originally posted by Neville Jones
Not the best choice a man can make, and only slightly better than the erw seamed stuff. The erw melts like butter compared to the proper cdw, or
better still, DOM, which is stronger.
But DOM has a seam...
Neville Jones - 13/6/11 at 10:59 AM
quote:
But DOM has a seam...
Not quite so, if you fully understand its production process.
Welded, fully annealed, heated to negate the HAZ, normalized, then Drawn Over a Mandrel, to size the OD and ID very accurately.
The annealing and normalizing, together with the mandrel drawing, produces a tube better than cds in many respects, and is effectively, seamless. You
can hone the inner walls, and run pistons and seals on them, as is done in its application for hydraulic cylinders.(Not pressure tubes, though it can
be used as such.) The metal melt analysis is also much better than cds, being tougher and stronger.
Oddly enough, DOM is the preferred tube of the aus CAMS, and by the USA SCCA and other USA sanctioning bodies for roll cages, and is passed by the
FIA. ( MSA seem to think they are better than the others, and spec cds. FIA approval is overriding.)
I've used DOM for roll cages in the past under FIA approval, and will again. Use it constantly and solely for wishbones, as it is not far off
Chrome moly in properties, but much more user friendly.
Cheers,
Nev.