Custom Make Suspension Arms

[Proximity Motorsport]

Hey,

Im currently in the progress of building a r32 gts-t with a rb25/30 and while im waiting around I've been thinking of a few ideas. I have a r33 rear cradle spare so I'm going to machine up some offset bushes to fit it into the r32 gts-t.

Im considering making some custom rear traction rods, and toe rods. They look simple enough. Im just asking if anyone has some aftermarket arms laying around, for a r33/s14/s15 if you could please get some photos of the arms with a ruler beside it, or if you could please measure up the lenghs of everything and post it pretty please

I have found these rose joints on ebay for cheap. They have a female thread, and the usual arms you buy have male but I think the female would be a better way to go. I can get LH and RH threaded ones. Im also after a size of the thread on these, as the largest I can find is 14mm

http://cgi.ebay.com.au/M14-Female-RH-Rose-...=item587dd0cfbb

Also if someone could tell me which threads are LH and RH.

Thanks a million for any help, and discussion is welcomed

[Proximity Motorsport]

anyone?

[doo doo]

Just out of curiosity, why do you think a female thread is better? Is there a supplier for race quality spherical rod ends in mackay?

[Proximity Motorsport]

Well.. I was just thinking, if I have 25mm OD tube, with 3mm wall thickness, I could tap the internal bore out to M20x1.5 or M22x2.5 and get a 20mm/22mm male rose joint to suit.

But if I used a female rose joint I could machine a 1" thread on the outside of the tube and use a 1" (25.4mm) female rose joint

Just a thought anyways.. and as for Mackay having a dealership I will try calling SKF bearing supplies before I buy anything, they sell rosejoints, I will just have to enquire if they're suitable for automotive

[scotty nm35]

I used stainless rose joints for some swaybar linkages, they lasted a while but the weather eventually got to them. Is this for a track car? If not, they will need protection. Notice the ebay ones you posted have a rubber contact seal.

[doo doo]

My view on threads is that machined threads are quite a bad design- they are weak as they act as a stress raiser. Rolled threads (ie, male rose joints) are much stronger as the metal (usually heat treated) is compressed and the groove is not a sharp cut. In a suspension application that you want to not have fail this is somewhere I would only use quality rolled threads in this application. I would make an exception if the part was lathe cut on a large diameter (larger than any available die) with enough thread engagement to spread the load, and with the design of the part putting the thread outside the main load-bearing diameter.

Also if you use 4130, 4140 or 4340 they are harder steels and much more notch sensitive, you need to take even more care to eliminate stress raisers from the design.

I've heard mostly that stainless on teflon lined bearings are best for auto application- also heard that with the teflon ones it's preferable not to use rubber seals. I think you'll find that most race car series rod ends are imperial in measurement. Here's a (place down the road from me) website- www.sesgroup.com.au - there's a list of what sort of load rating each size has. (the race car series are stainless on teflon, and male threaded)

Edited July 10, 2010 by doo doo

[bigmikespec]

But if I used a female rose joint I could machine a 1" thread on the outside of the tube and use a 1" (25.4mm) female rose joint

That is a horrible idea, stick to what works. With a 1" thread you wont have much wall thickness left on your tube (if it is 3mm) also the ball joint will be huge.

[Risking]

To start with of from an engineering point of view you have to ask about design and rod ends you probably shouldn't be playing around with it.

Don't buy cheap rod ends!!!!! Use ONLY good quality teflon/stainless end at least. Teflon/4130 end are available as well.

They can be bought metric but imperial are easier to source and more widely used

3/4unf MALE joints are what you should be using for any lower control arm and 5/8 unf for most other things.

Do not ever cut a thread into a control arm and screw the rod end into it directly. Biggest no no of all. Machine up a sleeve that is a neat interferance fit into the tube and leave a step atleast half the length of your rod end length. Drill and tap the thread into your sleeve then weld the sleeve into the control arm. Allows a far greater wall thickness of the threaded section and a smaller wall thickness tube to be used For the arm.

For the outters don't use rose joint ends. Use spherical bearings and machine up a sleeve with a circlip groove to retain them. Spericals in a sleeve are far stronger for a single application ( you have two inners and one outter on a lower arm for example) and it allows the arms end to penetrate into the sleeve ad be welded far better

I use 1inch 4130 for pretty much everything except front lower arms.

[T04GTR]

yeah, id stick to imperial. far easier.

[doo doo]

To start with of from an engineering point of view you have to ask about design and rod ends you probably shouldn't be playing around with it.

Don't buy cheap rod ends!!!!! Use ONLY good quality teflon/stainless end at least. Teflon/4130 end are available as well.

They can be bought metric but imperial are easier to source and more widely used

3/4unf MALE joints are what you should be using for any lower control arm and 5/8 unf for most other things.

Do not ever cut a thread into a control arm and screw the rod end into it directly. Biggest no no of all. Machine up a sleeve that is a neat interferance fit into the tube and leave a step atleast half the length of your rod end length. Drill and tap the thread into your sleeve then weld the sleeve into the control arm. Allows a far greater wall thickness of the threaded section and a smaller wall thickness tube to be used For the arm.

For the outters don't use rose joint ends. Use spherical bearings and machine up a sleeve with a circlip groove to retain them. Spericals in a sleeve are far stronger for a single application ( you have two inners and one outter on a lower arm for example) and it allows the arms end to penetrate into the sleeve ad be welded far better

I use 1inch 4130 for pretty much everything except front lower arms.

I would also add don't forget to fishmouth the tube where the sleeve is welded in so you don't get a heat affected zone all in one tension/compression plane. If 4130 is welded stress relieving would be beneficial, even for 3mm thick tube IMO (plus using 4130 filler rod or oxweld #32 rod)