If your running a Ron Sutton subframe and control arms, you want to read this

[sccacuda]

st an FYI for anyone running a Ron Sutton Race Technology sub frame or control arms. People are already aware of the failures on his two piece, curved design. If you have the one piece lower design, it can (will) fail as well. Here you can see the crack in the arm. This is on a low 3K pound car, 315's, and maybe has done 30-35 AutoX events, a few track days, and under 10 thousand street miles. If that's not scary enough, the front lower control arm mount is also a failure point. This high load attachment is mounted in a cantilever arrangement with only one and a half sides welded/supported at the bottom, below the load path. Here are a few pics of one that tore off, and a few pics of the other side, stress cracked, and about to tear off. I'm not posting this to call out Ron Sutton as a hack parts designer and fabricator, although it does make for a happy coincidence, but to let you guys running this stuff know you need to make some changes in the design if you want it to be safe.

[c4racer2]

What car is that for - or is it a universal design?

[Sleeper68]

Wow. I am sorry you have to deal with this. That is a very bad failure. I hope the failure was not catastrophic and happened at low speed. Something similar happened to me with inferior lower control arms so I know how it feels. Also I'm glad you're putting it out here so others are aware. Can't say I am surprised coming from RSRT though unfortunately.

[stab6902]

That's a bummer. Thank you for taking the time to share for the benefit of others.

[dontlifttoshift]

I was driving the car at the CAM Challenge when the LCA mount tore off the frame. Thankfully it was uneventful as the car just washed way wide of my line and there was plenty of runoff. Zero damage to the car.

That bracket is completely unsupported where the load is. Under breaking the LCA is pulling on it and in cornering it is pushing on it and it was constantly bending.

[Mark@lateral-dynamics]

But hey, the LCA bolt is in double shear! Sorry, had to. I shouldn't have, but had to.

That is scary setup. The LCA mount is obviously very wrong, but it's not clear what the failure mode was on the LCA, do you have other pictures from a larger view?

And, I have to ask, what are you planning on replacing it with?

[dontlifttoshift]

Not my car. As far as I know, there are no plans to replace it. It will be repaired and properly supported and then it should live forever.

The LCA itself failed quite awhile back and I didn't see it broken, nor did I pay much attention to it last weekend. Just guessing, insufficient beam strength coupled with some cool windows cut in to look fast along with coilover and sway bar loads hitting the LCA at essentially the same point.


Maybe add "universal front clip" to the LD product page....... right after 2nd gen Camaro gets listed. ;)

[Mark@lateral-dynamics]

Maybe add "universal front clip" to the LD product page....... right after 2nd gen Camaro gets listed. ;)

Roger that!

Cheers.

[sccacuda]

But hey, the LCA bolt is in double shear! Sorry, had to. I shouldn't have, but had to.

That is scary setup. The LCA mount is obviously very wrong, but it's not clear what the failure mode was on the LCA, do you have other pictures from a larger view?

And, I have to ask, what are you planning on replacing it with?

I have this same crap on my car. Here are a few pics of the LCA layout, curious on your thoughts..

[mikedc]

It looks like those lightening holes are just too aggressive. The LCA walls are all swiss-cheesed in the area where the sway bar link is pushing & pulling on it.

The subframe mounts for the LCA . . . the bolts are double-shear, but the whole bracket is only attached to the rest of the subframe in single-shear.



Next thing that jumps out at me in the pics . . . the coilover's lower mounting brackets (on the LCA) look kinda thin for what they are. Notice the sway bar brackets a few inches away appear thicker. I dunno if that will cause a problem or not.

[Mark@lateral-dynamics]

Thanks for the additional pics. I agree, it just looks like there isn't enough material in the load paths for the stressed component connections. Also, it you look at the crack on the LCA in the first set of pic's, it looks pretty clear that it originated from a poor weld-mate, in the window area that the sway bar mount pokes through. Looks like it started on the top surface with a small crack, and then repetition probably created the vertical failure that you can see in the sanded pictures.

Actual shock mount on the LCA in itself isn't scary, this is clearly an off shelf stock car bracket that you can buy anywhere. But what does concern me is that there is likely no direct load path reinforcement UNDER it to tie into the second plate - but there is the two vertical sections on each side of the control arm to help, but if one section of a component is prone to failure, I immediately skeptically assume that there are further design flaws, not just on this piece but on any.

Really sorry for the folks that ran into these issues but commend the folks for bringing the information to the table so others can learn from it and hopefully address prior to bad episodes.

Out of curiosity on the CUDA, I assume that the install of the front frame required hacking the original frame structure out of the car? We really want to, and at some point most likely will, adapt our front setup building blocks to the Mopar crowd. Love those cars but not nearly as many options for suspension out there.

[protour_chevelle]

Also, it you look at the crack on the LCA in the first set of pic's, it looks pretty clear that it originated from a poor weld-mate, in the window area that the sway bar mount pokes through. Looks like it started on the top surface with a small crack, and then repetition probably created the vertical failure that you can see in the sanded pictures.

This. Looking closely It looks like material is bend to form it and not welded entirely creating a pocket/joint that can flex until failure.

The control arms wouldn't be an issue with the windows removed, sway bar pocket welded entirely around and a gusset of sorts under the shock mount or a slightly better thought out shock mount.

[sccacuda]

Out of curiosity on the CUDA, I assume that the install of the front frame required hacking the original frame structure out of the car?

Just a little bit of hacking...

[Mark@lateral-dynamics]

Just a little bit of hacking...

Oh my! One suggestion would be to find a good local circle track fabrication shop. RS pretty much just used what was available in that market, which there is a LOT, and you can almost certainly improve on the design deficiencies. I.e. make a set of tubular LCA's, address the pickup points, etc. Way too much work into it now to start from scratch. It puzzles me how RS always boasted about how much successful RACE experience he had, real race cars take TONS of abuse and break as a result. There's like no lessons learned on so much of his stuff.

Best of luck - Mark is outta this one.