bushes / rose joints
timf - 27/6/03 at 07:37 AM
Any one got any ideas as to how to make adjustable pu bushes along the lines on a rose joint and still retain some strength
James - 27/6/03 at 10:11 AM
Have you seen the top-rear wishbone on the MKIndy?
It uses a PU bush outer tube welded to a threaded bar- this then screws into a threaded tube on the wishbone- just like the front-top with the transit
BJ.
You could do something similar- have the wishbone arms a little shorter and weld an internally threaded bar inside the end of the wishbone. (As the
rose-joint guys do). You PU bush outer tube is welded to a threaded 'rod' which can then be screwed in the end of the wishbone.
Bear in mind the finer the thread the more fine adjustment you'll be able to get.
I guess there are some strength issues with this- the weld between the bush tube and the threaded bar needs to be bloody good!!!
You could of course cheat to make the bush tube/threaded bar part. You could do this by getting a transit ball joint, removing the BJ bits of it (so
all you've got is a cast thread with a ring at the end). Then machine the ring large enough to fit your bush tube inside and weld all around it-
it'll be nice and strong then and at the same time you won't have a single weld holding the tube to the bar! 
Hope that makes sense!
Cheers,
James
timf - 27/6/03 at 11:37 AM
I thought about the bolt welded to the bush tube approch but then thought that welding it will cause the thread to soften and loose the high tesile
properties.
the cost of the ball joint option including the maching work would outweigh the cost of proper rosejoints
maybe rorty may have an idea ?
stephen_gusterson - 27/6/03 at 12:30 PM
I posted an idea a few months ago that solves this problem - with a sketch - if you can find it.
You dont weld the bolt on.
Get your bush tube, and fold a bit of steel into a 'saddle' wide enougth to fit over the dia of the tube - basically a C shape.
Drill a hole for the bolt in the 'C' bit in the vertical wall of the C and insert bolt so head is inside the saddle.
then push up agains the tube, so bolt head is against it and the tube, and weld the saddle sides to the tube.
My idea was to weld the bolt head inside the saddle to prevent the head rotating - which prob wouldnt upset the tensile strength of the thread if you
keep it relatively cool.
Rortie also posted stuff on commercially available stud-on-a-tube joints.
atb
steve
[Edited on 27/6/03 by stephen_gusterson]
James - 27/6/03 at 03:54 PM
quote:
Originally posted by timf
I thought about the bolt welded to the bush tube approch but then thought that welding it will cause the thread to soften and loose the high tesile
properties.
If it's good enough for MK...
quote:
the cost of the ball joint option including the maching work would outweigh the cost of proper rosejoints
A pair of BJs from Lolo is only £7.
It's then gonna take about 20mins with a grinder to get them apart (it's two cuts with a stainless 1mm disc!) and then a bit of time with a
lathe or mill.
A couple of hours maybe?
Strong enough Rose joints are up to about £20 each aren't they? Correct me if I'm wrong...
quote:
maybe rorty may have an idea ?
Probably...
Cheers,
James
MikeRJ - 27/6/03 at 06:42 PM
quote:
Originally posted by James
A pair of BJs from Lolo is only £7.
That sounds like a good deal, where do I find this Lolo woman?
Anyway, back out of the gutter...The main problem I can see with replacing a rose joint with an "adjustable" PU bush like this is that as
soon as you start adjusting one side of your wishones to change e.g. castor angle, the bush will forever be working at an angle to it's mounting
bolt. Probably not a problem for small angles, but I'm not sure if this is an ideal situation.
Irrespective, if you need adjustability, would it not be simpler/stronger to effectievly chop a section out of one side of the wishbone and fit
threaded bushes into each end (idealy with opposite handed threads) and then use a length of threaded bar to connect them? You'd obviously have
to size everything up properly to retain enough strength, perhaps using larger diamter tubing on that side to take large diameter threaded bar..
Rorty - 28/6/03 at 02:57 AM
If you can find the thread Stephen Gusterton mentions, I attached a pic of some welded adjustable bushes to one of my posts there. They're quite
simple to make, and so long as your material selection is correct, they'll be plenty strong enough.
Use 1/2" UNF bolts or machine screws (Grade 8) for the thread, as that designation will afford the finest adjustment, and best tensile
strength.
Use ColdFront paste (available from Frost Auto Restoration) to protect the thread from excessive heat build up.
Use CDS or CDW tube for the bush tube to be welded.
TIG welding would be the best, but if you're competent with a MIG, then that would be fine too.
If you're after angled adjustable bushes, don't exceed 8 degrees.
Actually, the pic's in my Photos.
[Edited on 28/6/03 by Rorty]