Miata SPL CAMBER ARMS Review & Issue
 

I purchased SPL camber arms, rear upper control arms, in July 2016. I primarily use the car for drifting (road courses, parking lots), and SCCA Track Nights. At my ride height I wanted to run less camber, and from word of mouth and reading online SPL looked like a reliable and trusted brand.

SPL originally required drilling out one of the mounts to pass their bolt through (pictured in instructions)
https://cimg9.ibsrv.net/gimg/www.mia...faac092906.png

I wanted to avoid that and purchased an extra kit that was being sold by the same vendor to help with that. The kit used grade 12.9 threaded rod instead of the hex key bolt. So I gave it a shot.

https://cimg8.ibsrv.net/gimg/www.mia...fa66129253.png

I ran the car at track days, and drift events for about a year and half with that setup. This season I noticed play/slop in the rear wheels when the wheels were pushed and pulled at the top, I thought the camber arms lock screw had come loose. Upon inspection, the lock screw was set, and the collars were tight, so I removed the arms to find this.

https://cimg9.ibsrv.net/gimg/www.mia...78365904fd.jpg


https://cimg1.ibsrv.net/gimg/www.mia...d3bf78abdf.jpg
https://cimg3.ibsrv.net/gimg/www.mia...7ea0d98b23.jpg

https://cimg5.ibsrv.net/gimg/www.mia...995db92886.jpg
(supposed to be smooth inside)

So I called SPL regarding my issue, and to see what my options were. I asked if they sell replacement bushings since my current aluminum bushings were damaged from the bolts allowing all that movement, and if they sold rods that were only threaded at the ends that I could run.. The engineer I spoke with was very nice and we spoke about other ideas like maybe they could make the bushings from stainless or a similarly hard material vs aluminum. He asked me to send him photos of the damage, and we ended the call. I sent him those photos.

SPL responded to my email and asked what bolts I had used, so I sent them the link to the kit I used. They responded that the kit was responsible for my issue.

I asked to purchase replacement parts since I need to get the car ready for an event in the next couple weeks.This is the current product they are selling, which is an updated product from the original hex bolt included in 2016.

https://cimg5.ibsrv.net/gimg/www.mia...2ef9a7a0fa.png
https://cimg9.ibsrv.net/gimg/www.mia...91ca29535d.png

The current product on offer includes blue grade 12.9 threaded rods.

SPL said the threaded rod is not where the issue came from, so I will see how their product fares this season, and will be updating this as the season goes on. I should be receiving the replacement parts in the next few days. If the issue happens again, I will have new bushings made, stainless or titanium.

We are seeing potential issues in the S1 cars with the OEM upper control arm not controlling the top half of the spindle adequately. This arm would exacerbate that issue substantially. Hard, hard pass on this product.

An issue that would be exacerbated substantially with these arms.

The short answer is that the arm in the photo is a piece of junk. Throw it away and put stock arms back on the car.

The longer answer is that the job of the control arms is to control the motion of the wheel, by locating the upright (to which the hub and thus the wheel are attached) relative to the chassis. To do this, the control arms need to be stiff, and to only move in the way that they are intended to move. The control arm is designed to rotate vertically, to allow the suspension to move up and down. It is not designed to rotate horizontally (at least not very much), because that would allow the top of the control arm to move forwards and backwards, which would have strange effects on the camber and toe of the wheel.

Stock arms have two inboard mounting points for a reason, this is a big part of what delivers the necessary stiffness to resist rotation in the horizontal plane. Replacing those two inboard mounting points with a single mounting point (like the arm in the photo) will substantially reduce the stiffness in this plane. There is no reason to do this, it's hugely compromised from its intended purpose.

--Ian

Can anyone point out any logic behind spending $340 for this single-attachment garbage when V8R offers a properly designed upper control arm with the same camber adjustment properties for less money?

https://v8roadsters.com/product/rear...-control-arms/

One attachment point is more lighter, bro. Race car.

Because they aren't "SPL".

There weren't many options, that I knew of, for adjustable arms back when I bought the SPL arms. I was looking to pull camber out of the car at my ride height, stock arms were maxed out.

I like those v8r arms, I'll look into that option. Thanks.

IMHO the best way to change the camber adjustment range in the rear (certainly the cheapest) is to use offset delrin bushings with stock arms. I know SadFab makes them for the front, don't know that I've seen them for the rear although I can't imagine it would be any harder to make them.

--Ian

But then you're still left with the stock arms.

And they aren't ricer enough?

--Ian

The V8R rear uppers put an eccentric on the wheel side at the top of the hub. Makes its super simple

They're weak, floppy, and feel bad. The difference is not subtle driven back to back.

The stock arm itself is fine, it's not flexing enough for your uncalibrated ass to feel. All flex is in the bushings which can be addressed.

Just an update, we've ran ~2 hours combined at a track day, 7 hours of an enduro, and another 6 the next day with no issues so far. I'm not saying they're perfect or ideal, but I thought I'd report. Again I'm not really sure what I'm looking for though.

For perspective, our average fast lap times are equal with a typical Spec Miata qualifying lap (1:59), our fastest was .7 seconds under SM record (1:57.333), according to a quick google search.

These arms are like the equivalent of removing both front wheels and suspension from the car and replacing with a single front wheel. It might work ok for a little while tooling around to the shops and a couple jaunts, but it's going to fail spectacularly and is the very opposite of what's needed for an SLA suspension. There is literally zero fore-aft support to a design that was conceived to require essentially no movement in that plane. The fact that the "manufacturer" has not pulled these from sale is simply astounding to me...

You're looking for catastrophic failure, dude. The OEM arm limits rotational movement of the spindle by limiting fore-aft movement of the top half of the spindle. The OEM arm is a dogbone design which will not deflect substantially in the fore-aft direction. You have taken the OEM arm, which does this job with arguably marginal effectiveness, and replaced it with an arm which is not in any way designed to do the same job. The spindle is free to rotate fore/aft with absolutely no restriction aside from what is offered by the lower control arm and the RLCAO bolt. Every time you are on throttle, the axle twists the hub, the hub twists the tire, the tire twists against the ground and tries to roll itself forward, and that rotational force applies an enormous twisting force on the RLCAO bolt, the lower control arm, and the lower spindle attachment points. Those parts were never designed to endure such a twisting force.

These arms are fucking awful and anyone with even a modicum of knowledge of mechanical system design can see that. The fact that you continue to champion these is really odd to me.

^ which is exactly the concern I expressed in the Greta build thread, but more eloquently and with more detail. What is the purpose of this part?

I don't even know what the purpose is. I have never experienced an issue with inadequate camber settings in the back of the car. I think the adjusters in Rover are set dead center of their range for 2.5deg. I know Spec Miatas want more, but they are weird and with proper spring rate they shouldn't need as much camber.

These are so bad in so many ways, basically.

I've tried to get rid of them, I don't own the car.

The only advantage of these arms is to be able to easily make camber adjustment without affecting toe. Of course that advantage is not worth the issues these introduce.

I think we can all agree getting rid of the compliance in the upper arm is a good thing but doing that without introducing bind is tough since the knickle will be located at a different point front to rear depending on what toe setting you're running. This is the reason I built my custom adjustable A-arms for the rear, no bind and little to no compliance and I get the ability to adjust camber without even pulling a wheel.

https://cimg6.ibsrv.net/gimg/www.mia...80e2f979b1.jpg

I have some poly bushed rear uppers I'll throw you for free if you pay for shipping, in great shape.

FWIW sadfab will offset any bushing you desire.

Replacement SPL parts came in. They are claiming their blue threaded rod is the solution....
https://cimg7.ibsrv.net/gimg/www.mia...f52fad95e2.jpg

https://cimg0.ibsrv.net/gimg/www.mia...f48658857d.jpg

Or, you know, a rod that isnt threaded in the center - you know, because magical metallurgical properties of the blue coating isn't actually going to prevent the threads from digging into the sleeve it sits in.

He's dealing with a bunch of morons. They're going to continue to provide moronic solutions.

If they were any smarter, they'd not have designed this thing so terrible to begin with.

Yeahhhhh that's not going to work.

Stop attacking a color idiots. It just designates a different metal, you two are the first humans I've heard of who can tell apart two different mild steels from their...smell? The way they look at you?

You're trolling at this point, right?

#BLUELIVESMATTER

:facepalm:

I spoke with SPL this morning and they have agreed to issue me a refund for the replacement parts I purchased (blue threaded rod and aluminum bushings). They also mentioned my car is the only car that's had this issue.

:rofl::rofl::rofl::rofl:


Serious question: are they owned by BEGi/Bell Performance Tuning/Stephanie?

:rofl::rofl::rofl:

Stephanie's Precision Lathing?

I would throw those arms in the garbage and run away. The ONE arm in a Miata suspension system that needs to be more robust than the factory arm is the rear upper due to twisting force. The ONE arm I changed immediately when I added the LFX was to put in a V8R tubular rear upper arm because it solves exactly that issue - the camber adjustment is just an extra perk, the primary reason for replacing that arm is to minimize twisting. That SPL arm is far, far, far worse than a factory arm in that crucial department. I wouldn't run it on a bone stock car.

But what about if its got a blue boltttttttt????

Pretty sure that solves all it’s problems rightttt???

:D

Oh, the bolt is blue? Never mind, carry on. Mods can you delete my post, we've got a blue bolt here problem solved.

Never mind the magic blue stuff. If you're gonna use/reuse nyloc nuts instead of castle nuts, keep an eye on the prevailing torque. Not sure I'd trust my life to nyloc.

Serious question, why the threads cut down on the one end of the blue bolt?

Presumably to use as wrench flats to get approximately equal thread engagement on both sides.

​​​​​​SPL recommends 50 ft/lb for their nyloc nuts.

Prevailing torque is the resistance of the fastener to being run down prior to it clamping, AKA the nylon on the nyloc binding on the thread of the bolt. If you end up chewing up the nylon and then reusing the nut, you won't have a locking feature any more.

As bad of an idea as the nylock nuts are, that ranks down at about 5th or 6th place for "bad ideas" that went into those arms.

How many bad ideas?
#ALLOFTHEM

Thank you, that makes a lot of sense. Maybe the only part of this that does. :giggle:

Here I am chuckling like an idiot at work because of the blue threaded rod picture. This whole thread kinda feels like trolling to me.

#BLUEBOLTSMATTER

Thread from the dead update. Same issue as before, this time using the blue threaded rod...I guess the color of the threaded rod didn't matter.


This is after maybe 10 events on the car, the car is not street driven anymore. So in total, maybe only a dozen or so hours of track time on the replacement parts they sent me the first time. SPL is now sending me more blue bolts and aluminum bushings. The engineer I spoke with at SPL (really nice guy btw) is/has been pushing for a new arm design, they no longer sell this upper control arm on their site, but it's still being sold on other sites.


The video below is the driver side rear, the passenger side has less play (obviously), but has also failed again.




TLDR
The arms are trash, the design is trash, mt.net was correct. I'll be buying new upper control arms this winter.

New threaded rod and aluminum bushings from SPL have arrived, swapping parts. Unfortunately the arms I wanted to buy are on back order so I have to run these for a few more months.

Attachment 229254


Collection of failed SPL parts, I have 2 more bushings to add to this line up.

Attachment 229255

The journey is complete, finally ponied up and bought better arms. Pacomotorsports arms with Energy poly bushings.

Attachment 229253


SPL junk in the trash...

https://imgur.com/K2RT6Bw


https://imgur.com/EJQdLOa