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Wide wheels rubbing your trailing arms? A solution!

17K views 142 replies 31 participants last post by  rand49er 
I'm in for a set of Stage 3 arms to clear these 19" Linea Corse wheels.

No hurry.

My car is sleeping under a cover with the bare minimum insurance on it.

I'd like to hang onto my stockers if that's okay.
 
Is the stress in tension during acceleration and compression during braking?

Killer, can you elaborate a bit on how that joint is fabbed? Is it just overlapped and welded?
 
Thanks, killer, for stepping up on this.

ctsv154's observation is a good one. It seems to me that the whole thing comes down to those two welds at the kink where forces of compression and tension get transmitted from one end of the arm to the other; that's where all the stresses are concentrated. Your weld looks pretty darn good, and without the ability to know what the forces are on the vehicle itself compared to the strength of the modified arm, this will be an exercise in empirical engineering. Who's first?
 
Well if I am not mistaken doesn't killer have them on his car? or did I misread something in this thread at some point
Yeah, my bad ... it's been a while. He did do some launches with his first set, didn't he.

Okay, then, who's second?
 
I'm honestly not sure which I'd choose to be stronger.

There's more of an offset (i.e. moment arm) with the original, and it's going to have one set of welds on the gusset in shear and the other either in compression (acceleration) or tension (braking). If the gusset had a longer welded edge where it's welded against the side of the arm, it would make it even stronger, but I'm not sure where the weakest point is.

In the second design, the offset appears to be less which helps reduce stresses. Each circumferential weld is seeing stesses in both compression and tension as that short portion between the two longer arm pieces is trying to straighten out (braking) or get crumpled (acceleration).

Certainly, weld quality is crucial. I can somewhat tell a good weld from a really rotten one, but I'm no expert. Killer's welds look pretty decent to me.
 
... If you guys really want gussets, I can put them on there of course. ...
I'm not sure if they're needed, BUT if you did put them on, maybe one on the outside flank extending from and supporting the short middle piece. Having said that, I could make two observations if you did: 1) that would strengthen one circumferential weld, but 2) it would concemtrate more stress in the one not gussetted. Gusseting the inner flank would defeat the purpose of trying to clear the wheel unless it was a really small gusset and then what would be the point?

Uh-h ... maybe forget the gussets.




Well good luck with the arms. I'll stop boogering up your thread. Just thought I'd voice my concerns. Hope for everybody's sake that they are indeed up to the task.
Your input is always welcome.
 
Pretty sure this is just seat-of-the-pants engineering like a lot of hotrodders.

Killer's welded arm is probably strong enough, just needs to be thoroughly tested.

Unless you have an hydraulic bender or a big-a$$ press to bend a steel bar with good repeatability then heat treat it, seems to me welding is the only way to do this. J-B Weld sure ain't gonna get it done.
 
Killer's arms would seem to be the only solution available. MAP arms are out of production and getting an exising set is very iffy. BMR arms have the same geometry as OEM, thus are of no help.

With significantly over $2k invested in my wheels/tires, so unless something unforeseen happens in the interim, I'm lining up to buy a set of killer's arms.

Killer, PM sent.
 
I called MAP a couple of weeks ago, and they seemed to indicate that there was some significant discontent (my words, not theirs) with their trailing arms when they were here trying to sell them, so they gave up trying to please CTS-V owners. I didn't follow any of those threads back then, so I do not know what the issues were.
 
Got the flex joints from ballistic and that stuff looks great, but I only received 2 sets of trailing arms from Cleveland pick a part instead of the 3 I was expecting. They slipped a set of toe rods in there instead like I wouldn't know the difference.

Anyways, I'm getting started on building the 2 sets I have today, finalizing the jigs, etc.
:food-snacking:
 
In the relatively few conversations I've had with Cleveland-Pic-a-Part, they've been very straightforward and frank with me. (I was considering buying a rear seat for my car, but shipping would've been too much, so I decided against it.)

Even so, sh!t happens. There are communication breakdowns in every line of work, and my impression is that C-P-A-P will fgure out how to make everything right.

This is blown up a bit more than it needs to be, IMHO.
 
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