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...