The main thing is that the threads are loaded in tension and compression with very, very little bending. Loaded that way, pretty much any threaded steel rod in that size range will live forever with the loads coming through there.
I'm not sure what you are saying here. Are you saying that the threaded rod that failed on Honey badger must have had a manufacturing defect? What are the loads on that steel rod?
No, I'm saying if you load something like that in bending (which in the FTBR, Steeda, UPR designs, they are), it's going to fatigue at the threads. Threads become big stress risers when loaded in bending or shear. This is far from the first failure of this type of adjustable camber arm that I've seen. Most have been UPR but I've seen the others too.
I went out and looked at the SPC parts. The "rubber" is a 45mm diameter ring bushing about 1/8" thick between the arm and the steel core. Less play than OEM, could be similar to poly, hard to know.
I might be imagining it, but it seems like your motor rips from 5500-redline much faster than a stock one. You can definitely tell a difference in the rate at which the revs build from 4500-5500 and from 5500+ in the video. Extra shifts cost time, but that looks really promising for overall speed. And it sounds amazing. Count me as very curious to see what lap times look like on fresh tires. Of course there is one other, bigger variable - you, and your extra Miata seat time. Driving slow cars makes you faster, and I guarantee that's going on here too.
Always a bonus!
I'm more mystified why the designer thought it needed such a ridiculous range of adjustment.
Hmmm... thinking back on it, when I first bought the BMR parts in 2019, I looked at the various designs and I liked BMR's because the adjusting screw was dead in-line with the bushing at the far end. The only bending moment on it would be from flex of the billet aluminum bar, which is likely "not much". The real moment in the design is on the assembly that goes from the knuckle to the spherical bearing. It's a big stainless piece with the same bolt through it as Ford uses, so presumably it's strong enough.
I think a 4.11 gear would fix the shifting issue. Keep third usable and just barely top 5th on the back straight--especially with the taller Pirellis. But not sure it's 100% needed, my shifts have gotten fairly good and there's still room for improvement. With super grippy tires and the mellow-er power deliver, I might be able to put the power down in 2nd more easily.
I designed a set of subframe slot lockouts with 0.1 degrees of camber change from piece to piece to use with the OEM UCA. Basically a flat plate with an island that fills the slot with a hole through for the UCA mounting bolt. Then I got the BMR's instead. I'm still thinking about making them, although if I install the SPC's I don't need them. The BMR's are great for adjusting (which is torture because it's cross-linked to toe so you have to adjust both together) but they get noisy pretty quickly. The noise doesn't bother me, but noise = wear and that does.
Mine are silent when they're greased. When they start to squeak, it's time for more grease.
Got my SPC replacement camber arms today. Pretty nice piece of hardware with some really nice design elements. The adjustment approach is particularly nice. I like how it locks out the OEM slot on the rear subframe, so there’s no movement capable there. And then on the knuckle, instead of a bolt, it uses a sleeve, so it shouldn’t move when you tighten the bolt down. Nice strong hardware too.
They do seem a bit physically bigger than OEM (arm for scale since I didn’t have the internet's ultra-precise banana). Does anyone have any OEM pieces they can measure? Curious about size and weight.
Thanks @JAJ for the recommendation.
I’ll post some more info when I go to install them
