Learning how to tune suspension. Kindergarten level.
 

Hey guys, so I just did my first autocross last weekend with the semi-almost-kinda-finished car. I have a ton to learn about how the car drives and feels as well as navigating and learning courses better. I would like to learn more about each part of the car that I have assembled, and this thread is about my suspension.

Current setup: Tokico Illumina, FM springs, Jackson Racing solid adjustable front and rear sway bars with FM endlinks, R1R 225/45/15 on 15x9 6UL. Nothing in the way of chassis stiffening other than a roll bar.

I realize my first mistake last weekend was I probably should have unhooked my rear sway bar - the car was a bit tail happy on the course which was basically two long slaloms and one fast curve. I also should have taken my hard top off to lower the gravity of the car a bit. I had my shocks on setting '5' on all four corners and both sway bars were in the middle/moderate setting. I had just also gotten an alignment with FM specs.

My question is, what are the things I should look at in my suspension settings with my setup? I really don't yet understand how everything I have assembled ties together. Just want a better understanding on what having a proper suspension setup really means. Party on.

The best tip I can give you for dialing in a set up is to have good fresh tires. You can't set a car up on old hard tires, unless of course, you are never planning to run on new fresh sticky tires.

The rest is trial and error. Sway bar settings, shock settings, tire pressure, alignment including rake and toe, etc. All of these things can affect how the car feels and you don't always need to make broad changes in order to get the car to what you want it to do.

And also, everything needs to be in good working order. If bushings and sway bars are binding or you are always on the bump stops, a multitude of changes may have no affect on an issue you may be having.

Tires are pretty good, maybe 1200 street miles with one autocross on them. With my motor swap i also replaced every bushing in one go, that $5 tool did a hell of a job!

Over the next few Autocrosses I'll try different settings and see what works and what doesn't. I probably could have lowered my tire pressure a bit too seeing as my wear line didn't touch the mark. So lots of trial and error it is! And maybe another set of tires after these bite it lol. Thanks for the input :party:

Well, if you're happy with your setup, that's great. However it's an incredibly basic setup with very little adjustment. I guess I'd start by checking for sway bar bind and preload. Disconnect both end links and make sure the bar swivels easily. If it doesn't, try greasing the bushing. If that doesn't work, you'll have to shave the bushing which is a REALLY common thing on RB bars, not sure about JR. And unless you have an NB (don't know?), I don't like the FM end links due to the bushings. If they're not banned by class, I'd grab some 949 end links and throw one on. Adjust so when the car is on a level surface the sway bar is level. Then install the other one and adjust for no preload. You'll feel as you move the adjuster there's one setting where you're not jacking the bar up, or trying to pull it down. Do the same for both bars, put the front at full stiff and the rear at full soft and see if you're still tail happy.

Other than that, you're really out of options. You can't lower the car AFAIK, or corner weight it. I guess go a little softer on the rears, or stiffer on the fronts, usually you don't set Miata shocks to even all the way around. And with 225 R1Rs and 15x9s, once you get good you're going to blow your suspension to pieces. Especially on a track (if you ever plan on that), you'll find you have a pretty big lack of spring and dampening.

I'm not familiar with that tire but I would assume it's similar to other super 200's just without the ultimate grip. So a rather stiff sidewall and a good sized wheel with a light car in the miata likely means mid 20's for pressure. Tire roll over is not a good indicator for pressures. A pyrometer and a stopwatch are.

Also, tire pressure is a decent tuning aid once you have established a baseline pressure. On less sticky surfaces I like to run a pound or two less pressure all around. Or if the car is loose, drop rear pressure and vice versa if tight.

Thanks Curly! I understand it's basic, I went off of recommendations for a decent street setup, but I guess probably not an amazing performance setup. You've made me realize that I think I forgot to grease my bar bushings. What about the bushings on the FM links do you not like? Lastly, in what way will the suspension get blown to pieces? Should I just plan for Xidas soon? lol

.

Not necessarily true. Better heat dissipation is tire compound dependent. Section width helps with this, but tire compound is the main factor here.

A wider tire will be faster than a skinnier one. A 245 r7 (for example) on one hot lap will be faster than a 205. Plain and simple. More mechanical grip.

I think Curly is referring to the fact that your tire/wheel combo can generate a lot of grip and your coilover setup will be struggling to support the cornering loads once you progress in skill.

First thing I suggest is a notebook or some form of data tracking to keep tabs on your setup, lap times, and notes after each session. I support getting adjustable endlinks. This is because you can zero out static swaybar loads which I have seen throw off cornerweights. To do this you need to park on a level surface, install the links, and adjust the lengths until the heim joints can "easily" rotate. It should be pretty clear when the swaybar is no longer statically loaded.

Only make one change at a time and record how it affected the handling. Look into your rear toe settings to see how toe in/out my help with settling the rear and preventing oversteer.

"How to make your car handle" by Fred Puhn is a dated but good resource.

Thanks guys! I appreciate the feedback. As a noob this is going to take time to learn but I'm gonna keep at it. After this thread I realized i have a couple more thousand dollars to spend to really tease out what the car is capable of, but that's probably over the next year. I'm in SSM because i think my built motor swap. It'll be turboed soon as well, so that'll be fun. I'm gonna check out those books.

Looks like the future holds: 275s and 11" wheels, Xidas or comparable, BBK, is lexan easy to work into a big spoiler? I'm having a ton of fun so far and have to learn how to drive this car. I wish more events were closer so i can try more. Getting 4 or 5 runs every few weeks isn't enough 😩 I ain't about that street recklessness

I would move my F sway bar to the full stiff setting (inner hole), and R to full soft (outer hole) -- that's how I had my JR sway bars setup.

then it comes down to tuning the damping on the shocks and tire pressures. Keep the rears adjusted a bit softer than the fronts if it's over-steering still too much, and same with tire pressures. increase the pressure on the front tires so they would lose traction first.

A slightly oversimplified explanation of shock tuning is to think of your shocks as a tuning aid for transitional situations. When you first turn in the shocks will influence the balance while sways and springs will dictate mid corner and exit balance.

This isn't always the case, and their are a ton of other variables but I betcha once you get the car balanced like you want with the sways you can get the car to either push or be loose on turn in with your limited shock adjustability.

pretty much exactly what I was suggesting.

Yeah sorry wasn't trying to repeat, guess I was trying to point out the concept of breaking up a turn into sections and where each piece of suspension plays a role.

i was suggesting we are either both smart or dumb, together.

Thanks guys, the explanations given so far are really helping me understan how the suspension ties together. My rear was entirely too stiff last time so that's going to be first change. What are the pros and cons of disconnecting the sway bar versus having it on the softest setting [edit: why would i buy a new bar if I'm just gonna have it disconnected]. I didn't notice understeer as much as the ass end trying to outrun the front.

What's what's the point of buying a sway bar if all you're going to do is disconnect it the whole point was improved performance. You might however be better off going back to the stock rear bar...

I realized that was dumb as soon as I posted it. I'll try the soft setting on the JR bar and compare to the OEM bar. What was your experience with comparing the two, Scott?

I went stock rear with tiens, and front JR on stiff.

That reminds me to ask while we're on it even though I can search. Teins seem to be pretty popular. Is there a tier list of performance shocks and coilovers? After this thread I realize I am limited by my Illuminas because they are pretty basic and not height adjustable (how much difference does this make anyway?).

i love the illumina/FM combo. I recommend that still as the best DD setup.

I don't recommend tiens.

It really is a nice DD setup with my limited experience. I'm curious about a good AX setup. I realize I can throw money at it and get Xidas but I'm just nowhere near good enough to get a lot out of that quite yet, or so that's my understanding. I'll do some reading, this is another deep rabbit hole I know I'm getting into. It's gonna take a lot and a long time to get remotely competitive in SSM, but I wanna start honing in on a ball park setup for the next year or so. Holla holla spend dolla y'all.

To get to the pointy end of a class like that you need to jump from below 400lb/in spring rates and long soft bump stops to 700/350 - 1000-550 lb/in range and invest in shocks that will control those rates.

This is where you'll find a lot of opinions, exida's are a proven commodity. Afco's are also an option, but no shock will be worth the money without the proper valving. In fact even lowly old Bilstein's with the right valving can kick some butt.

(Personal opinion alert) I've looked at the valving of hard s and MSM Bilstein's and calculated the critical dampening % and the low speed numbers look pretty decent up to 800/450 range. The high speed numbers are a little soft, so they won't be as good on rough tracks. A revalve by someone who knows what they're doing and I betcha they would be darn close to the high end stuff without adjustability. I'm running stock hard s shocks with 800/450 rates and the car does pretty darn good.

"Pointy end" I like that haha. So you introduced me to a new term, valving. A google search later and my understanding is that valving is the size of the hole that allows the fluid to travel through (damping?) on compression and rebound, so the two parts of the assembly are the spring and the shock(?)... I'm figuring spring is for rebound and the shock itself controls the amount and rate of compression... am I right so far?

Shocks are a deep rabbit hole that most people see as a black art because they don't have access to a shock dyno to be able to tune them. I can try till I'm blue in the face to explain it but this site does a much better job.

Autocross to Win (DGs Autocross Secrets) - Shocks

I haven't done any research on your shocks but you might be able to retrofit them with sleeves to work with your springs. Whether it would be financially feasible is another thing, especially if you are considering getting new hardware. Having adjustable sleeves gives you the opportunity to get a real alignment and get your cross weights and hopefully side weights even, which makes for a more predictable/balanced handling car.

Re: rear bar, I always ran with the rear bar (can't remember NA6 or NA8 right now) back when the car was still early in development and the balance was fine. Since it is an autox car (CSP) and it was about 100#'s overweight and I refuse to get rid of the AC, certain things had to go and the rear bar was one of them. It saved 7#'s IIRC, but it was also the last place where you would want the weight to come off (low/behind driver). The balance obviously went to push and 50# heavier springs were added to bring the balance back. This in turn introduced sporadic wheelspin in a car that barely had 120 wtq. This was with Koni Race shocks and 6" 2.5 Eibach springs. When I switched to ARE Penske's, he sent me 400# springs for the rear and I immediately thought the car would push without a rear bar. I was dead wrong and even now with just over 130 wtq, no wheelspin ever.

So that big wall of text was just to say, you gotta try things and see what they do. And certain things are compromises while other things just compromise the wallet.

i also personally dont understand spending money on an autox car, but that's me.

Well my thing is that I built the car with what seemed good and autocross was an afterthought. So i ended up in this class and figured i might as well try to have a car that can be near the others timewise

Troll much? Do you? Mr. Brain?

Philly pay no attention to Brainy. He spends all his free time playing video games and trying to become Milo Youknowhedonteatanypuss's next heterosexual boyfriend.

And he drives a Benz.:eggplant:

Brain, do you receive typically give the brain or receive it from Milo

HAHAHAHA! Brainy would be the hetero so he would do the poking.

autox is stupid. you literally spent $20-40, plus at least a 4-6 hour commitment to "race" your car about 4 minutes total. When you go down the path to modify a miata for specifically for autox, you end up with a car that sucks on a real track, sucks on the street, and you start finding yourself in debates about how .001ms of extra throttle response wins races. The best autox mod is learning how to drive your car. I was pwning STS in my 2000 altima.

I am proud and confident to say my Benz would beat Philly's miata in autox; no question about it. My shocks tune themselves w/AGILITY CONTROL, it has more torque than is generated when your mom sits, and the 4‑ETS awd system would make a wrx fanboi cry. Hell, I could still be sipping my latte and listening to tunes via bluetooth from my phone through 11 speakers, all while running the heated seats.

hey gays, ever heard of 69? it was invented for a reason. sharing is caring.

Brain I was a big fan of yours until you bragged about owning an Altima. And 69's just create too much confusion.

i didn't brag about owning it; i bragged about doing well in autox despite owning it.

Pictures of this glorious autox killer Altima please.

And since this is the suspension tuning section, what suspension tuning you did to beat the Mighty Miatas?
​​​​
Oh and was this at FedEx field? Ive been there for an autox at least three or four times. Love both lots.
​​​​​

it looked like a stock 2000 altima in platinum silver.

https://lh3.googleusercontent.com/g7...=w1310-h982-no

not many miatas to beat in STS.

no, I don't do MD.


what are you trying to accomplish here other than to gay bash?

Not trying to accomplish anything. Carry on.:party:

.

Wants to learn how to tune suspension and figure how changes "feel."

Goes to first ever auto-x on 215 tires.

Decides he needs 275 tires before the next auto-x.


Not quite the path I would have chosen. Maybe some 195s or 205s and a tunable suspension would have been a better place to start. Hell, no one has even mentioned alignment settings yet.

Whoa nelly!
I hope you don't plan on dumping all that into the car in one fell swoop. Stick with what you have and learn to drive it fast. Once you feel that you have exhausted all the adjustments to the car as is, then put money into making it fast.

I said 275s for future consideration. I built the car for me off of no experience, so I'm trying to learn more about it. By the way, you were great as the main antagonist in the hit movie "Sausage Party".

I never said I would do all of that at once. Just options for piecing it together over the next year or two. The car isn't even turboed yet and I haven't settled on what I really want out of the car as far as what I want to do with it. I'm just not limiting myself with options. I have a hell of a long road ahead with learning how to drive it properly.

I hear this rationalization not to get the best and have to disagree.

You know good food when you taste it, yet you are not a chef.
You know good music when you hear it, but are not a musician.
You know something beautiful when you see it, but are not an artist.
You know a god car when you drive it, but are not Lewis Hamilton,

You will appreciate better quality suspension. You don't need to be an expert driver.

This.

Besides, unless you plan on upgrading pretty often (sounds expensive to me!) you WANT suspension that performs at a level greater than you are currently capable of. Gives you room to grow your skills as a driver and not be limited by your equipment. It also limits variables so you can better focus on where you need to improve.

As somebody that recently went from the Tokico/FM package to Xidas this year, I'm running over 2 seconds faster (comparing time differentials between myself and the fast guys) on a 50-second Auto-X course on the exact same set of tires I was running last year. Now I made I number of other changes too, but subjectively I will say that the suspension swap was most of that gain. Now, Xidas may be out of the budget and that'd be a fine reason for not going to that level right now. However, I don't believe driver skill is a good excuse.

ohh this excites me. I am currently running the Tokico/FM package and plan on moving to Xidas. I fully understand what an improvement it will make at speed, but what about in day to day driving?

Sorry, you know how message boards are... I sorta imagined you excitedly clicking "Buy Now" on all those things...

You have no experience, and this is your first build. You want to start at the "kindergarten level" and you want to know "how everything you have ties together."

In that case you should get some more reasonably sized tires, adjustable shocks/coilovers, and figure out what your alignment settings are and what the numbers mean. From there you should drive, drive, drive until you can put down good times and don't knock over any cones. Then you add the Xidas and 275s.

As your car sits, it has more grip than a Corvette but with the suspension of a Honda. You will learn nothing about how the car handles, or about how the changes you make affect the car's balance. All you will learn is that those tires are expensive and guys driving stock Miatas are faster than you. You will poke around with your sway bars and mess with tire pressures but the wide tires will hide the effects from you and you'll end up trying to tune out your bad habits through changing the car rather than having the skills to drive and understand the changes you should make.

Early this month I went on a 1600 mile roadtrip in my Miata with my wife. She didn't notice any ride difference between the Tokico/FM and the Xidas, and had no complaints about ride quality (within the context that a NA Miata isn't exactly comfy in general). For myself I can notice that the ride is more stiffly sprung than the previous setup but not necessarily less comfortable, just different.

That being said, my Miata is a toy/third car so I don't care so much about silly things like "comfort", "practicality", or "YOU SPENT HOW MUCH?!"

I'm in the same boat with my Miata. Thanks for the feedback.

No problem. Only other thing to keep in mind is ride height: Xidas will put you lower (unless you are going for the upcoming Xida XLs). That has had way more impact on day to day driving than the spring rate change. Of course, this isn't something unique to Xidas: all sorts of shocks will get you low and increase navigational hazards (curbs, speed bumps, etc.). The difference is with Xidas you won't sacrifice ride quality at low (but still sane) ride heights.

You are right If you simplify it. One thing is revalving to handle other spring rates which 95% requests. Second thing is fine tuning which is the most difficult part of shocks tunning.
To handle spring rates you need proper amount of damping in some areas, regarding to fine tunning You need to be experianced shock tunner and good test driver ( i mean not the fastest one) but someone who fells every small details.

Do You have some graphs comparison between hard s and MSM which You mentioned ?
I am curious to look on those values if you said that you use stock bilies with 800/450 and it drives properly.
regarding to Your calculation i was annoyng as well due to lack of forces in high speed area ( main demerit do digressive valve ). I prepared some upgrades with lifted hih speed area and i will test it soon.

https://cimg4.ibsrv.net/gimg/www.mia...cb69c89fbe.gif

These graphs have been floating around the interwebs for a while now. You can see the damper rates, I'll have to dig up my critical damping spreadsheet later this week when I get back from my trip.

Here's the rebound critical damping for an MSM bilstein with 600lb spring (I think assumed stock-ish weight ~2400lb)

Attachment 229897

They're pretty over damped at low speeds (< 3inch/sec), about right at 3IPS, and pretty under damped at higher shaft speeds. Compression low speed damping is better suited tho.

They could definitely be better, but you can see why they're workable for the higher spring rates people use them for with coilover conversions- plenty of low speed to control body movement.

Linear valve with high speed adjustability would be grear solution.
below my concept. I have not tested it yet on car.

https://cimg4.ibsrv.net/gimg/www.mia...b10dd3302f.png

I prepared critical damping calculations

front vs rear for stiff and soft springs setup
https://cimg6.ibsrv.net/gimg/www.mia...a254924cdd.png
https://cimg7.ibsrv.net/gimg/www.mia...146231b481.png