I have noticed on some pictures of other people's builds that they have used 1" square ERW tube for the rear suspension arms. 'The book' et al suggests using round tube for the same. My understanding is that round is stronger than square tube. Is using square not a bit risky for such a highly loaded are?

JB

Easier/quicker to make in square tube.......as only have to hit the sides with a sander to get the profile right......If you use Oval it gets even easier.

Square tube is not weaker than round, just heavier for the same amout of strength. And it is significantly easier to work with. No extra risk as long as the builder dosen't undersize it. In other words, if the builder is going to use 1 inch round tube he would also most likely be fine with 1 inch square tube, or they could go to 1.25 inch square tubing to get an even stronger member.

Eric B

1.25" square isn't a good idea as it places the sides of the arm to close to te ends of the bush eye. With 25mm square the ends can be cut quite easily and accurately with a decent bi-metal hole saw

Thanks guys. As I bought plenty extra 1" box then I may as well go with that. I am all for easier

JB

If using square, cut a length that will allow you to get all 4 arms out of..then mark it out at 12" ctrs....drill these centres with hole saw to match bush tube.....lot of farting about though.
I would opt to use the bush tube as a template to scribe the trailing arm ends then buzz them with a sander with a flap disc as easy to control....and quick and accurate providing you mark them out right.

If you go the holesaw route everything needs to be clamped down as holesaws move all over the place and if it grips the job....umm.

Use a pillar drill with the drive belts slackened off ....not ideal but saves a smack in the face as the drive belts will slip rather than want to keep driving if drill bit of holesaw grips......use plenty of suds or even wd40 at a push.

I scribe the arc that needs to be cut out, get it close as I can with an angle grinder and then use a die grinder to finish off. Not the quickest way but I have the tools around me.

I'd rather use a holesaw but decent bimetal saws are quite expensive, and cheap ones...well lets just say they are good for about 1/2 a hole.

If you live closer I'd loan you mine -- Bosch hole saws seem last forever (well almost)

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Originally posted by britishtrident
If you live closer I'd loan you mine -- Bosch hole saws seem last forever (well almost)

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