Over the winter, I wanted to make some suspension updates.
Bushings
The Big change was the bushings. I started out with rubber bushings that were stiffer than stock. They were OK, I guess. But I just did’t like the way they worked. They just seemed to bind all the time. You had to push the arms up and down to get them to move. From past experience, I knew that a light weight car works better with rod ends and spherical bearings.
With rubber or poly bushings, when you hit a bump it would transmit that movement into the chassis, causing the entire car to move instead of just the tire. The ride is slightly harsher, but not nearly as much as you would think.
I replaced all the bushings with Spherical Bearings. I wrote an entire page on that, because it was kinda involved. Be sure and read through that.
Front Lower Arms
I bought these front lower arms a couple of years ago from someone on the V8 Miata board. I had already installed my stock
arms, so I put these on the shelf. Now was a good time to install them. They fit really well, and are lighter than the stock arms. It would be really easy to adjust them for some pretty radical camber.
SEE UPDATE BELOW!
Springs
It was clear that the spring rates were not high enough. The bump stop were jammed up into the top of the shock hats. I tried raising the ride height up more than I really wanted it, and cutting the bump stop in half. But I was still down on the bump stops. When that happens, you’r not really using the suspension any more, and it all becomes solid.
So, I went to a higher rate all around. I added 50# to each corner.
Ride Height
There’s been a lot of talk about ride height on the Facebook page. Finally, some Miata experts have been taking a close look at the Exocet, and making some recommendations.
I set the front at 5.5″. Because of how the rear subframe mounts in the Exocet frame, it was recommended that the rear be a little bit lower. That actually sets the Miata subframes pretty square. I set the rear ride height at 5.25″
Alignment
After installing the new bushings, I needed to do a new alignment. I used a lot of the data I gathered from the last two seasons to set the new alignment specs. You need to keep in mind that there is very little body roll in the Exocet. You don’t need a lot camber, front or rear. 2 years ago, I started out with the recommended race settings for a Miata. Based on tire temps, and gradually decreased those radical camber settings. As I did that, the tire temps looked better and better, and lap times got faster and faster.
Front: Camber -1.25* Caster 5*, Toe out 1/32″ Rear: Camber -1*, Toe in 1/32″
With the new springs and bushings, we’ll see how these settings actually work.
While I was at it, I replaced all the concentric bolts with the updated version, and used the new Paco Motorsports eccentric locks. Why? Because it made me feel warm and fuzzy inside. 🙂
Corner Weight
Now that all this is done, the final step is setting corner weight. There are lots of articles on the web on how to do that, so I won’t go in to a lot of details here. Essentially, I wanted to adjust the corner weights to get them as even as possible. The weights are with a full tank of fuel, and me in the drivers seat.
Did it work? 4/16/18
We spent the week end at the track, Pueblo Motorsports Park. We left the house Friday night with a little bit of snow and a howling wind.
Saturday was cold a windy, but the sun was out all day. Track temp never got above 60*, and I never got tire temps above 100*. Not nearly warm enough for the Hoosier R6 to work well. It’s very hard to get enough heat in the tires because the car is so light. But we still managed to post some fast times; down in the 1:42 – 1:43 range. For this track, that’s pretty good.
Sunday was much better. Air temp in the 60’s, and track temps got up to 100* by the end of the day. Despite that, we posted some very fast times. out of 150 cars at the track that day, there were only 4-5 that ran faster. And those cars cost 4-5 times what my little Exocet did. We’re talking about highly modified Corvettes, Porsche RS 3’s, etc. I can keep up with C7 Z06 in the hands of a very good driver.
BUT… the new suspension is AWESOME! The car worked better than it ever has. Tire temps got to 140-150*. And my lap time came within 1 second of my personal best at that track! Yesterday I managed a 1:41.5. My personal best here is a 1:40.6, and that was on a hot day with a sticky track.
Was the new suspension expensive? Yes. Was it hard work? No, not really. Was worth it? OH, YES! 
We also managed to lose another fender. I’m telling you, these fenders are a real PITA.
Also, let me put in a plug for NASA, National Auto Sports Association. If you want to go racing and have a good safe time, this is the way to do it. Look for your regional association, sign up, and hit the track a few times. It’s a boat load of fun in a safe environment. The first few times you’re out you’ll get an instructor in the seat next to you, and nothing will make you faster and safer than that.
5/21/18
We raced at La Junta Raceway last week end. The track there looks pretty simple – mostly flat, and only 7 turns. But it’s a lot more difficult than it looks. The biggest issue is that it’s an old track, and kinda rough. There’s some “washboard” sections, some new sections, and a few holes here and there. The south end of the track goes across an old taxiway, so it transitions from asphalt to concrete, and back to asphalt. And there’s a big bump there that can really upset the car.
The new suspension is absolutely amazing. It’s not a smooth ride like a BMW, it’s a little bit harsh at triple digits. But the suspension works so well it’s almost scary. Well, OK, not almost. It was scary sometimes. 🙂 The car is so fast, I managed to scare myself, thinking it wouldn’t hold. But it did!
I ran turn 1 and 2 at about 120-125mph. I backed off the throttle a little bit for the big bump before 3. But I didn’t brake until after the bump. And the car took it! Couldn’t believe it at first. But it did, lap after lap.
When I could get traction, I was running 55-56 second laps. That’s Viper and Z06 territory.
If you really want you car to handle, the spherical bearings are answer. It allows the suspension to actually work, and not transmit all that motion to the chassis.
UPDATE 10/18
As said above, I replaced the front lower control arms with some parts from V8R. That turned out to be a huge mistake.
The ball joint isn’t really a ball joint. It’s a King Pin.
The end of the King Pin fits into the center of this rounded captured bearing. The gold colored cap goes on the end. And a small bolt retains the cap. The entire weight of the car is held up by that one small bolt.
Unfortunately, that one bolt is probably not as strong as it needs to be.
And this is what happens when it fails at speed.
Fortunately, this happened at the slowest corner on the track, So I was probably only going about 50-60mph. 30 seconds prior to that, I was moving along at 135mph, and then braking hard for turn 1. If it had failed then…….
So, both of these arms went in to the trash. Along with a few other damaged parts. I’ll be going back to the stock Miata arms, with Moog ball joints.