Board logo

Ball joints
bumpy - 9/8/13 at 09:59 AM

Hi

I'm trying to construct some tie bars and would like to use ball joints rather than Rose joints.

I need an M16 female, stud-located ball joint as in the picture. Can anyone recommend where I can get these. The only place I have found wants about £50 each for them.

Thanks

designer - 9/8/13 at 10:14 AM

Can't help you will the supply, but it's generally recommended that you never use a female joint on suspension.

britishtrident - 9/8/13 at 10:36 AM

That style is called Male-Female
You will find it in 5/8" UNF easily enough UNF is a better choice than standard metric. McGill Motorsports have these at a reasonable price.

However I would sugest using a male-male or standard male rod end would be a lot more suitable as although you describe it as a tie-rod it will have to take compressive loads.

phelpsa - 9/8/13 at 10:52 AM

quote:
Originally posted by designer
Can't help you will the supply, but it's generally recommended that you never use a female joint on suspension.


??

bumpy - 9/8/13 at 11:05 AM

Thanks so far guys.

I arrived at the selection of a the ball joint by choosing it over a Rose joint (female). This female Rose joint seems to be the default joint when ARB are replaced by tie bars.

The M16 thread is dictated by the thread required for the fitting on the Sierra lower control arm.

MikeRJ - 9/8/13 at 11:27 AM

Could you not use a standard female rod end with a bolt and spacer?

bumpy - 9/8/13 at 11:35 AM

quote:
Originally posted by MikeRJ
Could you not use a standard female rod end with a bolt and spacer?


I could, but I felt that the ball joint will give me more degrees of freedom for alignment. To hold a rod end a bolt which passes through a bracket becomes quite directional, and means the bracket that holds it will need to be more precisely aligned.

bumpy - 10/8/13 at 10:00 AM

quote:
Originally posted by britishtrident
That style is called Male-Female
You will find it in 5/8" UNF easily enough UNF is a better choice than standard metric. McGill Motorsports have these at a reasonable price.

However I would sugest using a male-male or standard male rod end would be a lot more suitable as although you describe it as a tie-rod it will have to take compressive loads.


I take your point about the compressive loads, but if I was to use a male/male how do I then link to my tie-rod which is also obviously male.?

britishtrident - 10/8/13 at 09:12 PM

Using the crystal ball if your are doing a RH 2B conversion the ground is fairly well trodden ,, Dave Andrews has drawings on his web pages.


The normal way to make an adjustable tie bar for M16 or 5/8" is use 22m inside dia tube and weld threaded insert into the ends.

McGill sell the inserts ready made for a very fair price so you don't need expensive M16 or 5/8" taps and dies.

bumpy - 11/8/13 at 08:36 AM

quote:
Originally posted by designer
Can't help you will the supply, but it's generally recommended that you never use a female joint on suspension.


Why is this?

I cant find anything on Google, so is it just an old wife's tale.

britishtrident - 11/8/13 at 09:26 AM

A couple reasons;

Any suspension radius rod even if designed to work as a tie (i.e. in tension) at some point will have to act as a strut (i.e. take compressive loads).

Because they have different structural properties under tension and compression long rods under compression are a called "struts" and when under tension are called "ties".

This difference in structural properties can be seen in house hold item like a drinking straw or a strand of uncooked spaghetti, from which we can see a long slender strut is prone to a form of buckling called "Euler Buckling". To resist Euler Buckling we need to design the strut to be as resistant to bending as possible.

Image from Wikipedia commons



If we make our strut out of 25mm o.d. tube with threaded inserts welded to ends to take male rod ends it will have considerably higher resistance to bending than a 16mm dia. solid bar and will also be lighter.

Another reason is connected with fatigue and fracture toughness; a thread cut with a die into a random piece of 16mm steel will have a lot less resistance to fracture than that formed by rolling a thread into the high grade alloy steel rose joints are made from.

[Edited on 11/8/13 by britishtrident]

bumpy - 11/8/13 at 10:27 AM

Thanks, thats a brilliant explanation and makes it much clearer.

I very much appreciate your taking the trouble.

bumpy - 11/8/13 at 10:52 AM

If we make our strut out of 25mm o.d. tube with threaded inserts welded to ends to take male rod ends it will have considerably higher resistance to bending than a 16mm dia. solid bar and will also be lighter.

OK, for a bit of detail. My application is to replace the Sierra ARB on a JBA Falcon, so it will take both stretching but more importantly compression when pot holes are ecountered.

1. With a 25mm o.d. steel tube what wall thickness would you recommend?

2. I will use a 16mm threaded rod up front to keep all the fittings and nut standard into the lower control arm. Is it necessary to use a 16mm threaded rod into the Rose joint at the rear. This part does seem a bit of over engineering.

[Edited on 11/8/13 by bumpy]

britishtrident - 11/8/13 at 11:44 AM

McGill Motorsport on ebay sell both the threaded bungs and matching tubing. istr they do both 1" OD and 1" ID