Trailing arm suspension + Rod ends

[boyracer]

This is a two question thread, so probably means I'll get neither answered

I'm looking for some photos or descriptive text at a pinch on how the BMW E30 group A rear arms were made for the rear suspension. I've seen some partial pics on a website, but wanted a better idea of how it all goes. I'm looking at replicating something similar for a Datsun/Nissan eventually. Probably the bit that intrigues me most is the way they did the adjustment, as seen in the links within this page here

The second question kinda relates to the first, but I've seen it elsewhere as well. Why lay the rod end flat ? Why not stand it up ? Does it simply come down to the easiest way to get the bolt into it ?
Seen a lot of suspension designs go this way though and wondered why. To me it seems as though if the rod end is standing upright you get a greater range of movement and still retain the full strength of the end rather than pulling thru the eye at an angle. But obviously I'm missing something.

Any help much appreciated

[MIdsm]

http://e30m3performance.com/tech_art..._arm/index.htm

http://e30m3performance.com/tech_art...tech/index.htm

[phoenix]

Originally Posted by boyracer

Why lay the rod end flat ? Why not stand it up ? Does it simply come down to the easiest way to get the bolt into it ?
Seen a lot of suspension designs go this way though and wondered why. To me it seems as though if the rod end is standing upright you get a greater range of movement and still retain the full strength of the end rather than pulling thru the eye at an angle. But obviously I'm missing something.

The reason is that mounting is this way is that it ensures suspension movement up and down causes the ball to rotate within the housing, rather than the possibility of the rotation being the whole rod end rotating around the through bolt. The interface between the bore on the ball and the bolt is not designed to carry the rotational movement and would wear rapidly, there being no lubrication.

[brown dog]

On the E30 M3's, the earlier cars had the rod end standing up. the later cars reverted to the rod end laying on its side. This was done to enable adjustment of the rear roll centre, by changing the out the spacers above and below the rod end for ones of different length. Of course this would alter camber as well, but could be corrected on the M3 by the adjustment on the end of the trailing arm.
All rod ends wear on race cars and must be replaced periodically, and I have seen and worked on several different trailing arm setups, with the outer rod end mounted vertically, and horizontally, and both seem to work okay.

[boyracer]

I actually posted a link to that E30mperformance site, but it doesn't seem to have worked ? Oh well.
Cheers guys, that's the kinda answer I was after.

"The interface between the bore on the ball and the bolt is not designed to carry the rotational movement and would wear rapidly, there being no lubrication."

Wouldn't have seen that as an issue with it clamped up tight, but I can see the potential for it to all go pear shaped.

"with the outer rod end mounted vertically, and horizontally, and both seem to work okay"

Seems like it's down to personal choice. I'll have a look and see what suits this cross member. Early stages yet. So much to stuff with, so few hours after work

Edit: Just noticed the quote about the lateral movement of the rod end, which I had considered. yet they didn't bother with it in the later designs. Would love to know exactly how that rod end height adjuster thingo works.