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SPL Parts rod end failure

Motorsport Wheel Alignment Fundamentals

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Not really an alignment question, but the components are featured in the course so it seems like an appropriate place, if any, to ask. I recall that you experienced a rod end failure on one of the SPL Parts front lower control arms; it was mentioned on a webinar preshow. It was also mentioned that you were assisting SPL, in their efforts diagnosing the cause of the failure. Did SPL reach a verdict on why the failure occurred?

Hi Daniel, yes we did suffer a rod end failure on two sets of our front LCAs from SPL Parts. One was a proper failure where the rod broke. We then inspected the other car which showed severe bending in the rod ends. SPL have upgraded to a chromoly rod end and we're tentatively testing that at the moment. So far so good but it's very early days. The issue as I see it is that the arm design is relying on the bolt through the LCA to the caster arm being tight enough that the arm doesn't pivot around the rod eye. I'd prefer to see a proper triangulated design where this simply isn't a possibility.

Hello Andre, I see what you're saying. So this is likely an issue isolated to the 86/BRZ lower control arms, due to their design (as well as affecting similarly designed arms), rather than a rod end issue that affects the entire SPL range?

Hi Dan,

Following up on what Andre said, it's more about the design SPL have gone with. Using rod ends like in this way is not ideal in that they are subject high bending stresses, which is not a great way to use a rod end due to the stress concentrations you get at the threads.

This is why the've uprated them, to try get around the stress concentration being an issue.