ecosse
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| posted on 19/3/07 at 11:24 AM |
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Trailing arms & inserts question
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
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Volvorsport
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| posted on 19/3/07 at 12:20 PM |
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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 .
www.dbsmotorsport.co.uk
getting dirty under a bus
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ecosse
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| posted on 19/3/07 at 01:04 PM |
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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  
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Peteff
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| posted on 19/3/07 at 01:26 PM |
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hexagon bar and turn that down youve got something to hold with a spanner
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]
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Volvorsport
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| posted on 19/3/07 at 01:29 PM |
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not if you have left hand and right hand threads !!!
plus you need to hold the arm while you do the locking nut up .
www.dbsmotorsport.co.uk
getting dirty under a bus
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hughjinjin
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| posted on 19/3/07 at 01:34 PM |
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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.
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Peteff
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| posted on 19/3/07 at 01:52 PM |
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(rod end one side, standard bush tube the other
No left hand thread on the standard bush tube
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Volvorsport
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| posted on 19/3/07 at 02:03 PM |
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well theres no reason for hexagon bar then .!!!!
www.dbsmotorsport.co.uk
getting dirty under a bus
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ecosse
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| posted on 19/3/07 at 02:12 PM |
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quote:
Originally posted by Peteff
No left hand thread on the standard bush tube
Yep, as Pete says, I'm only fitting rosejoints to one end of the trailing arms.
quote:
but without the shoulders like Mark's drawing
Just a straight insert without the "top hat" type end?
I never knew that about a weld (better in shear) but doing it that way certainly sounds like it has an advantage over a butt weld
I'll go and start turning then
Thanks again everyone
Cheers
Alex
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SeaBass
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| posted on 19/3/07 at 02:42 PM |
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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
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pewe
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| posted on 19/3/07 at 04:56 PM |
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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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ecosse
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| posted on 19/3/07 at 05:59 PM |
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quote:
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
quote:
I'd only use two as four just might raise stress-fracture issues.
Good idea, thanks guys
Cheers
Alex
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Angel Acevedo
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| posted on 20/3/07 at 10:50 PM |
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The problem with plug welds is that you leave the space between the insert and tube open to corrosion....
Beware of what you wish.. for it may come true....
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SeaBass
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| posted on 21/3/07 at 08:47 PM |
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quote:
Originally posted by Angel Acevedo
The problem with plug welds is that you leave the space between the insert and tube open to corrosion....
That's why you would weld round the joint as well. Note my use of the words 'extra strength'...
Cheers
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JoelP
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| posted on 21/3/07 at 08:55 PM |
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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
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