Sorry, more trailing arm questions.
I got the pipe for my trailing arms okay (£1.85 per m for cold drawn seamless right enough) but I'm now wondering how to deal with fitting my rod ends to them (rod end one side, standard bush tube the other).

I figure I can either, make up threaded inserts and weld them in, or simply weld HT nuts straight on to the ends of the tube.
I know welded inserts seem to be the usual solution but is there any reason why I shouldn't just weld nuts on?

I can't see that there would be any difference strength wise, but I'm no expert so can anyone tell me a good reason why I shouldn't do it this way?

Cheers

Alex

dont just weld nuts on , youre asking just the weld to support the loadings .

its much better to use inserts - if you can find some hexagon bar and turn that down youve got something to hold with a spanner .

ideally you need bigger tube and taper the welded inserts down to the correct size for the nut .

Thanks for the drawing (and offer) Mark (I have a lathe so can do this as per your drawing)
I'm just not entirely convinced that this is any stronger than a welded nut though, but if you know differently feel free to tell me I am wrong and why?

I'm presuming that the arms only get tension and compression stresses, if so, why does a mild steel insert provide more strength than welding on a nut, both have the same amount of welded area surely, and the nut (while having less threaded area, will have stronger threads?

I'm probably just being lazy but I hate making more work than is neccessary to do the job

Cheers

Alex
PS
"Donated" what, the full axle or the inserts?
If you say axle I may have to change my opinion of Darren a touch

What do you need to hold it for? If it's welded on and the other end has a bolt through it it's not going to turn when you lock the joint thread. I ground a nut round and tapped it in on a bolt then welded it, took the bolt out and filed the end flat.

[Edited on 19/3/07 by Peteff]

not if you have left hand and right hand threads !!!

plus you need to hold the arm while you do the locking nut up .

welds are stronger in shear than in tension, thats why the best method is to use inserts, but without the shoulders like Mark's drawing, just leave enough of the insert protruding from the tube to take a weld. You shouldn't really ask welds to take loads in tension as a welded on nut would be.

No left hand thread on the standard bush tube

well theres no reason for hexagon bar then .!!!!

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Originally posted by Peteff
No left hand thread on the standard bush tube

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but without the shoulders like Mark's drawing

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If you wanted extra strength you could drill 4 small holes equidistant around the cirumference of the tube and plug weld the inner sleeve to the tube.

Cheers

Seabass is right to recommend rosette welding but I'd only use two as four just might raise stress-fracture issues.
Early F27's used nuts on the tube ends but there were cases of them pulling off - happened to a mate - so unless totally stuck go with inserts - seem to recall Rally design selling them for rose joints.
Cheers, Pewe

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Originally posted by SeaBass
If you wanted extra strength you could drill 4 small holes equidistant around the cirumference of the tube and plug weld the inner sleeve to the tube.

Cheers

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I'd only use two as four just might raise stress-fracture issues.

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The problem with plug welds is that you leave the space between the insert and tube open to corrosion....

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Originally posted by Angel Acevedo
The problem with plug welds is that you leave the space between the insert and tube open to corrosion....

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another reason i wouldnt use nuts is that they are rust proof, whatever process protects them from rusting will contaminate your weld, plus a nut isnt really long enough