I'm building a recumbent trike and I need a universal joint for the steering arm. Car steering joints are a bit big but I've just seen a 3/8" socket set joint which looks ideal. Normal ones are stainless but impact driver ones aren't. Is the steel used in these weldable? If so, I've got the solution!

hmm, is it a proper universal joint? or one of those nasty things with a rectangular block in the middle?
if its got the rectanular block in the middle, i wouldn't use that for steering at all. regardless what it is on.
they seem to be able to twist up easily (ie, bend 2 different ways at once), on any socket set that i've used

Use a decent quality UJ, you can get them anywhere:

http://www.motionco.co.uk/universal-joints-c-45.html

And that's just one place!!

I know what you mean. Snap-On Tools 3/8 Drive Impact Universal Joint | eBay is what I saw. Is there a better alternative?

[Edited on 13-12-2011 by smart51]

that one looks alright actually!
i was thinking this type

which as you can see it bent over, and is able to bend towards you too.

as for whether they can be welded, i'm not sure. i expect they probably can. i've got impact sockets here, and they feel like some kind of steel... of course thats not very scientific, but get a cheap impact socket off ebay and try maybe?

Try car Builders solutions Budget Gear Linkage Universal Joint
Ref. Code: UJG23

Socket set UJ's are not designed for the negligiable backlash required in a steering joint. A proper UJ will have ball or needle rollers in the joints, one designed for sockets will have a plain steel/steel bearing surface. Absolutely not suitable for a road going vehicle IMO.

AFAIK the Snap On one in the link is actually a pseudo CV joint, very similar to the design used for driveshafts in model RC cars. These have even more slop in them than the UJ ones.

[Edited on 13/12/11 by MikeRJ]

Proper steering UJs are needle roller with seals to keep the grease in and water and dirt out --- they are made that way for good reasons.

The Toyota MR2 one is fairly small, it's one of the few bits of donor running gear I don't use so I just bin them, may have one lying about here somewhere if you want a pic of one let me know & I'll try & find one - it has splines at each end, but as it's forged steel can't see any reason why you couldn't weld it with care not to overheat the bearing section - not sure what the IVA would have to say about it tho'

Thanks Russbost, that would be great.

As it is a pedal trike there is no IVA. All up weight of 12.5kg plus rider means that ultimate strength is not the highest priority.

I'd agree with the above thinking that it's not the best thing to use, but yes they can be welded in most cases.
I keep broken tools to make special one-off tools out of, like a the good end from a broken spanner welded to a broken socket to make a crows foot style spanner for somewhere with limited access & I've cut/bent/welded a fair few spanners to suit an awkward job! If they can stand the torque from loosening a bolt at 50lb/ft then steering a push-iron should be no bother.

I've welded car steering joints a few times too, no problems there either.

Recumbent trike? Sounds awesome, I'd like to see the finished article please

I'll have a look tomorrow, can't promise I've got one, but I think I have.

Sorry, I've searched high & low, but can't find one - suspect they went out with the last scrap load

On reflection, I think it might be a bit chunky & heavy for what you want, hadn't realised we were talking about a man powered vehicle originally! From memory they are around 100 - 125mm long & I would guess around 30mm dia.

Thanks for looking Russ. Yes, they do sound a bit big. Ideally I'd like 17mm diameter and 40mm length.