Upper control arm dilemna
 

Alright guys. Tried searching all over the internet and can't find an answer. Here's my situation:

Finished installing a set of Feal 441's on my MSM today. Ran into an issue with the lower locking collar coming into contact with the nb2 upper control arms when I initially installed them. As such, I sourced a set of NB1 upper arms per the service bulletin on Goodwin's forums - https://www.mazdatalkforum.com/viewtopic.php?f=9&t=3337&p=20334&hilit=control+arm #p20334 . Fitment is good now and no more issues there.

Finished buttoning everything up today but one small thing isn't sitting well with me. The hole for the cotter pin in the ball joint bolt on the NB1 upper arms is now being covered by the nut itself, although the bolt fully engages the nut with 2-3 extra threads with the NB1 arms. This means I can't run a cotter pin. I compared the NB1 arm and the NB2 arm, and the bolt on the NB2 arm is slightly longer. Also, the hole for the cotter pin on the nb2 arm sits a good bit lower. I quickly threw the nb2 arm back in and with the nut tightened, i can slide the cotter pin back in.

I ended up assembling the NB1 upper control arm without the cotter pin, and just used a dab of loctite blue to keep vibrations from causing the bolt to back out. This isn't sitting well with me and my OCD however. Worth it to disassemble and re-check and perhaps run a locking nut (nut with a nylon insert to prevent it from backing out) or should the loctite blue be good enough? Appreciate the help on this n00bish post. Thanks.

Those are NA arms, they have shorter ball joints. Super Miata sells replacement ball joints for NB's, I suggest you go that route or go back to the NB2 arms and just man up and take a grinder to them.

The thought of them being NA arms crossed my mind, although they were advertised as coming off an NB, complete with pics of the donor car. Went this route since griding the nb2 arms is tough given that I live in an apartment.

Otherwise, assuming I have full engagement of the nut and then some with some loctite, is there really a safety concern?

I have a NB1 and used NA replacement ball joints in the control arms I fabricated (check link in my sig) I was able to get half of a cotter pin through the hole on mine. You can also drill a hole in the spindle and use safety wire to lock the nut as well. Is it "safe" without a mechanical locking means? meh.......it's a mission critical nut and without it you die, or at least really tear up the car. No one is going to tell you it's fine.....you just have to weight the risks yourself.

Yep. That answers my question. Death is not the preferred outcome here. A bit odd of an issue given that they were advertised as NB1 arms, but i did notice they were from a very early NB1 (listing had the door jam tag for the donor car and it was an 1/98 build date). Doubt that has much to do with it, but it was an interesting observation.

Looks like I'll be grinding the nb2 arms down and re-doing it. Oh well.

Another option I just thought of that may work. Using a castle nut on the bolt, which should expose the hole and allow me to get the cotter pin through. Suspecting that may work and am going to give that a shot.

Uhh... Were you not using a castle nut to begin with? Because that's what you're supposed to use on any ball joint that uses a cotter pin.

My MSM had a standard flange nut like the image below with the cotter pin "under" it to presumably pin the nut and preventing it from backing out. Struck me as a little odd since every ball joint/tie rod i've serviced has used a castle nut as you mentioned, but I remembered that I saw this setup on an NC once as well. Given how the cotter pin lined up right under the end of the nut, i assumed it was OEM. Now I'm curious if it was something the previous owner did?
https://cimg4.ibsrv.net/gimg/www.mia...4d58b7aa35.jpg

Definitely something someone did.

Thanks for confirming. Welp. This car is the gift that keeps on giving. It struck me as a little odd since it wasn't a nylon locking nut or a friction nut like you see on OE replacement stuff these days, but didn't think much else of it since the pin lined up right under like you'd expect it to.

I'm going to put the car back up on jackstands in the coming days and just go over all the critical hardware. Can't really trust it at this point :(

Picked up a set of castle nuts from a local junkyard's NB2 and that did the trick. Just enough room to get the cotter pin in.

Just for my peace of mind, let's assume they're NA ball joints (even though they were sold as coming from an NB), any inherent safety concern running them assuming the cotter pin goes in and everything is torqued down to spec? Only thing I can find is the difference in shank length, but otherwise they seem the same.

If you can get the whole cotter pin in place they are NB arms. But even then no there is no safety concern with NA arms as long as some sort of nut safety (tm) is used. Gotta keep your nuts safe.

Words to live by.

NA UBJ stud/knuckle is 5mm shorter than NB. To my knowledge, the only UBJ with longer stud is ours https://supermiata.com/SuperMiata-Upper-Ball-Joint.aspx
Fits all 90-05. Comes with a spacer for the NA knuckle.

We prefer the NB2 FUCA for it's additional rigidity and just clearance them.

Thanks Emilio. I threw the NB1 arms in last weekend, but buggered the threads on one of them when I pulled it back out to swap the ball joint boots. One of the ball joints is also sort of questionable so not going to chance it. Going to clearance the NB2 arms this weekend.

I'm assuming a die grinder and some carbide bits should be enough to do the trick?

That's what I used. Putting them back on this weekend to test and hopefully confirm clearance.

What version/spring rates did you go with? Been hifhlh considering those when the time comes.

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9k front 6k rear Swift Springs. It'll see some track time eventually, but it's primarily going to be a street car.

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Yep. Die grinder did the trick for me. Found some nice carbide bits on amazon that worked well.

Just buttoned everything up a little while ago and took it for a short drive around the block up to 30mph. Some slight metallic rubbing noises, but looks like its just corrosion on the brakes from having the car sit outside.

Ah. Thank you. Let me know how you like them, and what ride height you are running. I had 12k/8k on my Ohlins "race" DFVs from Goodwin and loved the stiffness. I'm actually thinking of going higher if I get the 441s...like 15/10.