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Straightening Subframe Leg
scootz - 13/12/17 at 11:39 AM

Seems that one of my subframe legs was pinched off-square after welding.

It's only a few degrees, but it knocks the end-point of the diagonal that I plan to attach to it way off.

I could proceed with it 'off-square' and just attach the wishbone mounts in such a way that they square up the geometry, but it'll be visibly noticeable and therefore bug me forever!

So any hints and tips to recover the situation? It's 2" OD 1.65mm T45 steel.

I'm running low on tube, so I'm favouring mechanical straightening. I'd just crack-on (no pun intended) if it was mild, but I've never worked with T45 and have no idea how it would respond to the forces required to straighten it.









owelly - 13/12/17 at 11:50 AM

IFAIK, tempered tube can be cold bent without and adverse effects. Clamp and push...!!


nick205 - 13/12/17 at 01:11 PM

Do you have any round bar that would be a snug fit inside the tube?

Might be easier to try and pull it square rather than risk crushing the tube by applying a force to the outside of it.


motorcycle_mayhem - 13/12/17 at 02:23 PM

I've never worked with 2" OD, but quite a lot of 1" T45 (manganese) has found it's way into things.
If this was a recalcitrant piece of 1" I'd simply heat the tube opposite the join that has shrunk and nudge it gently, no drama, it's not wildly out from what I can see.

As for 2" tube... ?


scootz - 13/12/17 at 03:23 PM

Thanks guys.

Encouraged to read that you’re all suggesting things that I was already thinking of myself... I just didn’t want to charge-in and screw it up.


Angel Acevedo - 14/12/17 at 12:41 AM

If you are doing tig, run the torch a couple of runs on the outside of the pipe...
Distortion will pull a mm or two at the end of the pipe..
You may not like the look of two beads leading to nowhere...


Theshed - 14/12/17 at 10:03 AM

I agree with the above but you do not actually have to lay a weld. Just get the opposite side red hot.


scootz - 14/12/17 at 12:34 PM

Thanks guys - some food for thought there. I was going to try and pull it cold, but I'm now leaning towards the idea of heating the joint first.


nick205 - 15/12/17 at 09:33 AM

quote:
Originally posted by Theshed
I agree with the above but you do not actually have to lay a weld. Just get the opposite side red hot.



Had the same thought myself - if you have a gas torch then applying heat to the opposite side of the joint may be enough to make it pull straight. You may lend some force as described above to help it straight and the for it to stay straight while it cools down.