Any reason why not?

Was thinking about using bright bar or silver steel bar to make my trailing arms (maybe 16mm dia?), I reckon I can drill at least 4" in either side, so weight wise it won't be much more than cds tube (if at all) and it's cheaper

Any thoughts, daft, pointless, complete overkill, or just use erw and get on with it?
While I can't come up with a good reason not to, that usually means I have missed something obvious, so does anyone feel like pointing out the error of my ways to me?

Cheers

Alex
BTW
one end will be rosejointed so it would save making up inserts if nothing else

Hi Alex,

Any good engineering tool suppliers can supply drills in long series (5xD even 10xD), so, if you go this route you could drill all the way through.

Remember, all the best driveshafts get gun drilled!

ATB

John

[Edited on 15/3/07 by jroberts]

Just use erw and be done with it!

David

Or just use 3/4" ERW tube.

Yup, fair point, but my lathe might be the limiting factor there John, lets just say it was at the back of the Q when the long beds were getting handed out

Although I am glad to see no one has any points against to make.

Still not sure why solid bar is cheaper than tube though, more work in making tube I suppose!

No one else done this before? Why don't I believe that

Cheers

Alex
PS
I know drive shafts are generally (always?) hollow, but I don't think I've ever seen a reason why though?

PPS
LOL...you just had to didn't you FM

Andy too!

[Edited on 15/3/07 by ecosse]

Anyway I thought ERW was a no no for trailing arms, not up to the job?

And while we are on the subject (well i am anyway ) does a sierra rear with dedion put more stress on the trailing arms than a live axle or less?

Go on you know you want to tell me

quote:

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Originally posted by ecosse
PS
I know drive shafts are generally (always?) hollow, but I don't think I've ever seen a reason why though?

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Mine, and all the GTS (along with several other manufacturers) trailing arms are all ERW, more than man enough for the job. Would go for no thinner than 16g if i were making them, perhaps 14g if you are worried at all.

David

quote:

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Originally posted by flak monkey

That do you?

Dave

[Edited on 15/3/07 by flak monkey]

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quote]Originally posted by ecosse
Any reason why not?

Was thinking about using bright bar or silver steel bar to make my trailing arms (maybe 16mm dia?), I reckon I can drill at least 4" in either side, so weight wise it won't be much more than cds tube (if at all) and it's cheaper

Any thoughts

I've done mine in solid 1" bar (each one nearly 1 meter long...) and i'm considering re-doing with seamless tube. I'm told tube is actually less likely to bend. don't know really.

seen some racing cars use aluminium tube for trailing arms. interesting.

Interesting, if I use a female rose joint I could use thinner bar nice 1 Gazza, that might just be the way to go, some 1/2 bar machined down for 1/2 unf rose joint.

1" bar a meter long must a be a fair weight although as not on a seven (pickup?) possibly of no consequence?

Cheers guys

Alex

trailing links

thats them in orange/white/unpainted. they are heavy, but for suspension i'd prefer to over do it, than have it all fall apart. like you say though, very heavy so i'll probably re-do them with seamless tube, threaded 5/8" inserts from rally design and 5/8" rose joints. got 1/2" on there, which i'm not happy with. using 5/8" up front you see

here's what i'm doing

Not sure I'd use as thin as 1/2" though, you still need to stop it flexing under compression. Mine are seamless Hydrolic pipe.

Don't use silver steel it will harden when you weld it, and may lead to cracking.
My choice would be to buy some cds tube from a local hydraulics company. It is available in various diameters and wall thicknesses.

Mal

Exactly as Mal says, just buy some 3/4" steel hydraulic tubing, cheap enough (certainly cheaper than bar!!!! )

ERW will be fine for trailing arms though.

It might harden if you weld it, but why would he be welding it?

trailing arms should not be subject to any (or very little) bending loads anyway. If they are subject to bending they must be binding.

You should be more concerned with the buckling load which is also dependant on the 2nd moment of area of the links rather than the cross sectional area which is basically what was eluded to above with the bending comment.

Watch out just basing material selection on strength though, how rigid the material is, is also a factor. link are no good if they move and flex under the load even if they don't break! This is apparent in structures that use chromoly tubes for example, it is strong but the rigidity doesn't increase that much so the tube will take the load but it will deflect more than a heavier thicker tube.

All the above is only in my opinion and should only be taken as that ... please check it out for yourself before taking any of it as fact LoL

Who said anything about cross sectional area and bending? . I answered a question about driveshafts which was slightly off topic, but still a valid question. And thats all about second moment of areas (moment of inertia if you like) which comes into all buckling strength, beam stiffness and torsion calculations.

Once again heavier thicker tubes do not necessarily increase stiffness! They increase the tensile strength of a member.

The advantages of using CrMo tube over mild steel is that it has a much higher strength, so will yeild at a much higher force. There is absolutely no stiffness variation across any of the steels, regardless of what alloy you care to mention.

David

[Edited on 16/3/07 by flak monkey]

As per other post, would this stuff, ASTM A106 grade B, cold drawn seamless do the job?
Trailing arms and panhard?
Okay trailing arms seem less important than the panhard but I can get this stuff for a couple of quid a meter so the trailing arms would get a dose of it as well

Cheers

Alex

[Edited on 16/3/07 by ecosse]

CDS is the standard seamless tube. Will be perfectly ok.

David

At last, a local supplier at a good price and with the right stuff, I was begining to think it was not possible
Thanks David (and everyone else too ) much appreciated

Cheers

Alex

quote:

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Originally posted by flak monkey
Who said anything about cross sectional area and bending? . I answered a question about driveshafts which was slightly off topic, but still a valid question. And thats all about second moment of areas (moment of inertia if you like) which comes into all buckling strength, beam stiffness and torsion calculations.

Once again heavier thicker tubes do not necessarily increase stiffness! They increase the tensile strength of a member.

The advantages of using CrMo tube over mild steel is that it has a much higher strength, so will yeild at a much higher force. There is absolutely no stiffness variation across any of the steels, regardless of what alloy you care to mention.

David

[Edited on 16/3/07 by flak monkey]

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OK i think I know what you are trying to say. But using a stronger material in a structure of any kind doesnt increase its stiffness, only the load it can take to failure.

By reducing I you are reducing the bending/torsional STIFFNESS of the beam regardless of what material you use, whether its stronger or not. The strength of the material you are using doesnt enter into the equation at all until you want to calculate the buckling load.

There is a distinct difference between stiffness and strength.

In short if you want a stiff structure, then you need to use beams with a high second moment of area/polar moment of inertia. The effect of the strength of these beams has no effect on the overall stiffness of the structure. If you want a strong struture as well you also need to use something like CrMo steel which has a higher yeild point.

Another point, reducing the second moment of area doesnt necessarily reduce weight. Quite the contrary infact. You can increase the stiffness of a chassis, and reduce its weight by choosing the right beam sections to use.

David

[Edited on 16/3/07 by flak monkey]

Alex did you try Hydrasun at Cambuslang . They have seamless hydraulic........was reasonable when I bought from them.

Alex

quote:

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Originally posted by gazza285
No twisting moments are applied through to a trailing arm. Strictly compression and tension my friend.

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quote:

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Originally posted by flak monkey
OK i think I know what you are trying to say. But using a stronger material in a structure of any kind doesnt increase its stiffness, only the load it can take to failure.

By reducing I you are reducing the bending/torsional STIFFNESS of the beam regardless of what material you use, whether its stronger or not. The strength of the material you are using doesnt enter into the equation at all until you want to calculate the buckling load.

There is a distinct difference between stiffness and strength.

In short if you want a stiff structure, then you need to use beams with a high second moment of area/polar moment of inertia. The effect of the strength of these beams has no effect on the overall stiffness of the structure. If you want a strong struture as well you also need to use something like CrMo steel which has a higher yeild point.

Another point, reducing the second moment of area doesnt necessarily reduce weight. Quite the contrary infact. You can increase the stiffness of a chassis, and reduce its weight by choosing the right beam sections to use.

David

[Edited on 16/3/07 by flak monkey]

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quote:

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Originally posted by Alex B
Alex did you try Hydrasun at Cambuslang . They have seamless hydraulic........was reasonable when I bought from them.

Alex

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metal supermarket in govan, basically right across from Ibrox, is good for getting stock. not as cheap as £2 per meter though bought some seamless tube yesterday and it was £15 for 3 meters.

they are good though, they'll cut anything for you, say for instance you wanted 5cm of tube, you can buy 5cm, you don't have to buy it by the meter.

why the hell is it snowing outside?!

[Edited on 18/3/07 by blakep82]

quote:

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Originally posted by blakep82
metal supermarket in govan, basically right across from Ibrox, is good for getting stock. not as cheap as £2 per meter though bought some seamless tube yesterday and it was £15 for 3 meters.

they are good though, they'll cut anything for you, say for instance you wanted 5cm of tube, you can buy 5cm, you don't have to buy it by the meter.

why the hell is it snowing outside?!

[Edited on 18/3/07 by blakep82]

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