Opinions, opinions and opinions wanted.

[Wallythacker]

At least I got you thinking outside the box.

The pitfall of a car like the Mirage is that the aftermarket is slim. If you can weld, and you're not afraid of doing a little research, math and experimentation... there's nothing you can't do.

You can even solve the lack of good aftermarket shocks problem that exists by retrofitting a "similar" shock to fit. Particularly easy with the rear shocks (there are probably some standard shocks that will bolt up without modification). The fronts might require a little fabrication of brackets. With a bit of creativity, you could probably fit a set of Koni, Bilstein, Tokiko or similar performance shocks. Adjustable if you wanted it. Of course "good shocks" are going to cost you probably $400-600 for a set. Plus the modification. And that's why I opted for the $600 Godspeed coilover kit that is readily available. It was the easy button.

But, it all depends on your goals. "Good handling" can mean a lot of different things to a lot of people. If you're just talking "make the car FEEL better" vs. "make the car go around a corner faster than it has any right to and leave Porsche owners wondering what just happened", that's a little easier to achieve!

If you've got time and want to bake your brain, you can read more about my custom lower control arm / roll center correction project.
http://drivefast.org/forum/viewtopic.php?f=3&t=3064

And pretty much everything I did to my Mirage is documented here:
http://drivefast.org/forum/viewtopic.php?f=18&t=2932

I have some reading to do! You've really got me thinking my friend, I do have fabrication skills that are really rusty but they exist! At this stage of my life it might be fun to get back into planning, fabricating, testing, Hopefully my daughter will join in and learn a whole new world of skills. The adventure begins!

[Powershiftmatt]

If you're not competing and in need of ultimate grip, there's probably not much reason to spend more than about $75/tire for this car. And there should be reasonable $50 tire options. That's $200, not $500.

Wheels... on your budget car, look at some cheap OE take-offs that are lightweight. 90-2005 Miatas are 4x100. 14" wheels will weigh 11-12 pounds. 15's more like 13. 16's 14-15. And there are 17's available, too. Like any other car, all the cool kids are buying aftermarket wheels, and the stockers are available for cheap. MINI Coopers and a lot of older Hondas also have some decent wheel options. You can easily get a set for under $200... rather than $500.

Rear swaybar. Don't bother with the front. You could design your own bar if you have access to a welder, or know someone who welds. I made one out of steel tubing and some heavy angle. Less than $50 in materials.

Not sure you'll get springs much cheaper than you're already talking.

Camber bolts? Get yourself a 3/8" Carbide Burr, chuck it into your drill, and instead of fitting a smaller diameter BOLT to secure your strut, just slot the bolt holes in the strut. You can get the same adjustment by slotting those holes by about 1/8". Use the stock bolts. Be sure they're properly torqued. Cost will be about $15 total.

There you go. I just cut your $1500 suspension budget down to $465.

The bigger question is: Why aren't shocks on your list? Especially for the 2014. (caveat: Idunno what kind of shocks are available for this car... but, shocks are always a major suspension upgrade.)

If you want to have real fun, one of the coolest things I did to my Mirage to help it handle better was custom lower control arms that allowed me to fit taller ball joints and lower the roll center. Again, if you've can weld, or know someone who can... not all that difficult to do. Lowering the roll center effectively makes the forces that cause body roll DO less. It doesn't make the car stiffer, but it does magically make it roll less and FEEL more responsive. If you start with your existing control arms (I bought a spare set for $100), you're looking at something like $80 in parts, as I recall.

If you're lowering the car, that's changing the control arm angle, raising the roll center, and screwing up the suspension geometry. (which is actually pretty GOOD at stock ride height, it does what it's supposed to do) Fitting taller ball joints compensates for the lower ride height and brings the control arm angle back to normal. More of your turning energy goes into TURNING the car, less of it goes into creating body roll.

Messing with roll centers is something I never did before I got into the Mirage. It's mind-altering stuff!

Loved reading some of your write ups. Going to be working on creating some tubular control arms for my car that cut weight and lower the roll center as well
I am however curious about why you’d skip the front sway bar because the stock one is quite skimpy and quite a weak point. Most people in motorsports will agree that a huge part of chassis setup comes from roll bar tuning.

[Top_Fuel]

Just a heads-up. Costco is starting a Bridgestone promotion tomorrow. I'm probably going to jump on this deal. I have heard that Discount Tire will price match Costco...so I'm going to try that. I'm not a Costoco member but I know someone who is.



Deal is valid 11/7 to 11/21

[Wallythacker]

Just a heads-up. Costco is starting a Bridgestone promotion tomorrow. I'm probably going to jump on this deal. I have heard that Discount Tire will price match Costco...so I'm going to try that. I'm not a Costoco member but I know someone who is.



Deal is valid 11/7 to 11/21

That is just what I need if it will apply to us Canucks. I hope the 422+ series is included. I'm hopefully getting some beautiful Kia OEM alloys soon. Worst case scenario; I head across the border and use my Costco membership there. It's important for me to calculate the exchange rate. There may be a ridiculous hit bad enough to kill the deal.

Thanks, we'll see how it plays out

[Fummins]

I've bought tires from quattro and pmc tire out east for pretty decent prices.

[Loren]

I am however curious about why you’d skip the front sway bar because the stock one is quite skimpy and quite a weak point. Most people in motorsports will agree that a huge part of chassis setup comes from roll bar tuning.

Apologies in advance, this is not a short answer.

There are definitely mixed opinions on the topic, and you're not wrong. Swaybars are definitely used for fine-tuning suspension. But, "real" suspension tuners will tell you to do the coarse suspension tuning with spring rates, and fine tuning with bars.

FWD cars in the "hairy edge of suspension performance" realm are quite simply fighting understeer. It's what they inherently do in a corner. 60-65% of the weight is on the front tires, and the front tires are driven. It's a recipe for understeer. So, MUCH of what we do when tuning the suspension of a FWD car is in an effort to fight the understeer.

If you're playing with swaybars, basic theory states that pretty much anything you do to stiffen one end of the car relative to the other end will cause that end to lose grip earlier relative to the other end. So, if you've got a car that oversteers (high-powered RWD car that wants to go tail out when you apply throttle on corner exit), you put a larger bar on the front, and a SMALLER bar on the rear to shift the bias towards understeer. The extreme example of that would be making the front roll stiffness SO stiff that the car lifts a front wheel... while transferring all of that weight to the rear. (theoretically, the opposite corner, but it gets distributed "some" to both sides of the opposite end)

Apply that same logic to a FWD car. You want a larger rear swaybar to transfer more of what little weight there is in the back of the car (we're talking about 40% weight on the rear, so 20% weight on one rear corner... that's the max you have to work with) to the front during hard cornering. Adding a larger FRONT bar would counteract that improvement in balance. You wouldn't get that transfer of weight to the front if you balanced it out with a stiffer front bar... instead, you'd just get a stiffer car. It might FEEL better because it's stiffer and much more responsive, but you'll still have the same understeer problem at the limit that you started with. And if you just put a big rear bar on, you lift the inside rear tire in a turn (just like the RWD car lifts the front), which is perfectly okay because the rear of the car isn't doing anything, anyway.

HOWEVER... MacPherson Strut suspensions are weird. They typically have a very poor camber curve (as opposed to something like a double-wishbone suspension that can gain LOTS of negative camber under cornering loads to keep the tire contact patch nice and flat). The body might roll 8 degrees, but the McStrut suspension will only gain 5.5 degrees of negative camber, leaving you with a compromised contact patch. (I made up those numbers, probably not accurate for anything, just making the point)

SO... some FWD cars, particularly cars like 80's vintage Golfs, actually work better with a HUGE front swaybar to simply lock down the front suspension. Make it so stiff that it never rolls more than 3-4 degrees. Then you have 3-4 degrees of static negative camber, and you have a good contact patch at full tilt.

They call suspension tuning a dark art for a reason! Everything affects everything else, and there are no easy answers.

On my Mirage, I was having a SERIOUS problem with the inside front wheel lift. The inside rear would lift, which is typical and normal for a hard-pressed FWD car. But, when the front starts coming up with it, you're dangerously close to being on your roof! I was doing everything I could to address that issue (the cause of which is simply that the car is narrow and tall, top-heavy, physics is working against us). The front swaybar inherently LIFTS UP on the inside front tire. That's what it does. Body roll forces the outside end of it up (relative to the chassis), and the opposite end of the bar wants to go up with it... unloading the inside tire.

In my case, I didn't want ANYTHING lifting up that inside tire. But, you're also talking about a FWD car without a limited slip diff... you really don't want to unload the inside front tire any more than it already is, or you'll just introduce wheel spin while you're trying to accelerate out of the turn. Which makes you delay your throttle input, and ultimately makes you slower coming out of the turn. So... I actually removed my front swaybar. I don't have on on my Mirage at all! I don't generally recommend doing that. But, in my case, I was fitting significantly stiffer front SPRINGS at the same time. So, I got my roll resistance from spring rate rather than bar... and spring rate doesn't cause inside wheel lift!

If you want to take that thought a step further, what I've learned through lots of experimenting with FWD cars, and then later understood by reading a good suspension book, is that when you fit that rear bar and it's stiff enough to lift the inside rear wheel (which doesn't take much... a LOT of FWD cars will lift the inside rear under hard cornering in stock form)... as soon as the inside rear wheel lifts, all of your roll resistance now transfers to the FRONT of the car, the rear bar is out of the equation at that point. If you've got a lot more roll resistance in the rear vs the front (big ass rear bar), as soon as the inside rear lifts, the car FLOPS onto the opposite front corner! That's another issue that I was trying to address with stiffer front springs. A smoother transition when rear wheel lift occurred.

Anyhow... the front bar on the Mirage is a beast to get to. You have to drop the front subframe to get it out. I opted to just cut mine in the middle with an angle grinder and pull it out. It's a convoluted piece. Would not be easy to make a replacement for it.

Oh, and you'd be adding weight to the front of the car.

For a street car, you're probably less concerned with handling at the limit, and maybe a larger front bar would help the car FEEL better. And in some cases, fitting a larger front bar is easier than messing with the rear (like the Mirage, which has no rear bar... and adding one makes the car ride rougher because it's taking away from the somewhat independent nature of the very twisty rear beam axle). My Driver's Ed car is a Kia Rio... and when we bought an almost identical Hyundai Accent, we learned that the Accent had much better steering feel. Same suspension! Same car! Turns out the Accent has a larger front swaybar. It's the only real difference between the two cars other than tire size. (the Kia has the better tires) So, when I was replacing shocks on the Kia, I hit up eBay and sourced an Accent front bar and installed it. Counterintuitive for COMPETITION purposes... but, it gave the car a little crisper steering feel and only cost me $60.

So, again, the dark art of suspension tuning. Or car tuning in general. Everything affects everything else. What YOUR specific goals and budget are is always a factor.

For competition purposes, FWD cars are almost always set up to where they almost oversteer. The suspension setup is so weird, and so biased toward reducing understeer that you're always one little driver input error away from being backwards! Dive into a slalom and drive it like you mean it, you're fine. Dive into a slalom, realize you're going to fast and lift off the gas while you're turning? As soon as you lift, you're shifting weight off of the rear of the car... and it's already got the absolute minimum on it already. You're going tail-out instantly. If the car is properly set up, and you're on your game, you can usually catch it by jabbing the throttle and transferring that weight back to the rear. But, if you put an inexperienced driver in a properly competition-prepared FWD car and tell them to go hammer it... they're going to spin.

Okay, I'm done rambling. Much of what I've said is not fully relevant to a street car. You shouldn't be tuning the suspension to that extreme. You don't want an "unstable" car on the street. Cars are designed to understeer a little bit because it's safer and more predictable. But, you can definitely tune out SOME of the understeer.

[Eggman]

Makes sense to me! We studied the basics of what you have described in a road racing training course. With some time on the track practicing what was taught, it saves time, money, aggravation (and worse!) to take it all into account.

Thanks for the explanation Loren.

[Powershiftmatt]

Apologies in advance, this is not a short answer.

There are definitely mixed opinions on the topic, and you're not wrong. Swaybars are definitely used for fine-tuning suspension. But, "real" suspension tuners will tell you to do the coarse suspension tuning with spring rates, and fine tuning with bars.

FWD cars in the "hairy edge of suspension performance" realm are quite simply fighting understeer. It's what they inherently do in a corner. 60-65% of the weight is on the front tires, and the front tires are driven. It's a recipe for understeer. So, MUCH of what we do when tuning the suspension of a FWD car is in an effort to fight the understeer.

If you're playing with swaybars, basic theory states that pretty much anything you do to stiffen one end of the car relative to the other end will cause that end to lose grip earlier relative to the other end. So, if you've got a car that oversteers (high-powered RWD car that wants to go tail out when you apply throttle on corner exit), you put a larger bar on the front, and a SMALLER bar on the rear to shift the bias towards understeer. The extreme example of that would be making the front roll stiffness SO stiff that the car lifts a front wheel... while transferring all of that weight to the rear. (theoretically, the opposite corner, but it gets distributed "some" to both sides of the opposite end)

Apply that same logic to a FWD car. You want a larger rear swaybar to transfer more of what little weight there is in the back of the car (we're talking about 40% weight on the rear, so 20% weight on one rear corner... that's the max you have to work with) to the front during hard cornering. Adding a larger FRONT bar would counteract that improvement in balance. You wouldn't get that transfer of weight to the front if you balanced it out with a stiffer front bar... instead, you'd just get a stiffer car. It might FEEL better because it's stiffer and much more responsive, but you'll still have the same understeer problem at the limit that you started with. And if you just put a big rear bar on, you lift the inside rear tire in a turn (just like the RWD car lifts the front), which is perfectly okay because the rear of the car isn't doing anything, anyway.

HOWEVER... MacPherson Strut suspensions are weird. They typically have a very poor camber curve (as opposed to something like a double-wishbone suspension that can gain LOTS of negative camber under cornering loads to keep the tire contact patch nice and flat). The body might roll 8 degrees, but the McStrut suspension will only gain 5.5 degrees of negative camber, leaving you with a compromised contact patch. (I made up those numbers, probably not accurate for anything, just making the point)

SO... some FWD cars, particularly cars like 80's vintage Golfs, actually work better with a HUGE front swaybar to simply lock down the front suspension. Make it so stiff that it never rolls more than 3-4 degrees. Then you have 3-4 degrees of static negative camber, and you have a good contact patch at full tilt.

They call suspension tuning a dark art for a reason! Everything affects everything else, and there are no easy answers.

On my Mirage, I was having a SERIOUS problem with the inside front wheel lift. The inside rear would lift, which is typical and normal for a hard-pressed FWD car. But, when the front starts coming up with it, you're dangerously close to being on your roof! I was doing everything I could to address that issue (the cause of which is simply that the car is narrow and tall, top-heavy, physics is working against us). The front swaybar inherently LIFTS UP on the inside front tire. That's what it does. Body roll forces the outside end of it up (relative to the chassis), and the opposite end of the bar wants to go up with it... unloading the inside tire.

In my case, I didn't want ANYTHING lifting up that inside tire. But, you're also talking about a FWD car without a limited slip diff... you really don't want to unload the inside front tire any more than it already is, or you'll just introduce wheel spin while you're trying to accelerate out of the turn. Which makes you delay your throttle input, and ultimately makes you slower coming out of the turn. So... I actually removed my front swaybar. I don't have on on my Mirage at all! I don't generally recommend doing that. But, in my case, I was fitting significantly stiffer front SPRINGS at the same time. So, I got my roll resistance from spring rate rather than bar... and spring rate doesn't cause inside wheel lift!

If you want to take that thought a step further, what I've learned through lots of experimenting with FWD cars, and then later understood by reading a good suspension book, is that when you fit that rear bar and it's stiff enough to lift the inside rear wheel (which doesn't take much... a LOT of FWD cars will lift the inside rear under hard cornering in stock form)... as soon as the inside rear wheel lifts, all of your roll resistance now transfers to the FRONT of the car, the rear bar is out of the equation at that point. If you've got a lot more roll resistance in the rear vs the front (big ass rear bar), as soon as the inside rear lifts, the car FLOPS onto the opposite front corner! That's another issue that I was trying to address with stiffer front springs. A smoother transition when rear wheel lift occurred.

Anyhow... the front bar on the Mirage is a beast to get to. You have to drop the front subframe to get it out. I opted to just cut mine in the middle with an angle grinder and pull it out. It's a convoluted piece. Would not be easy to make a replacement for it.

Oh, and you'd be adding weight to the front of the car.

For a street car, you're probably less concerned with handling at the limit, and maybe a larger front bar would help the car FEEL better. And in some cases, fitting a larger front bar is easier than messing with the rear (like the Mirage, which has no rear bar... and adding one makes the car ride rougher because it's taking away from the somewhat independent nature of the very twisty rear beam axle). My Driver's Ed car is a Kia Rio... and when we bought an almost identical Hyundai Accent, we learned that the Accent had much better steering feel. Same suspension! Same car! Turns out the Accent has a larger front swaybar. It's the only real difference between the two cars other than tire size. (the Kia has the better tires) So, when I was replacing shocks on the Kia, I hit up eBay and sourced an Accent front bar and installed it. Counterintuitive for COMPETITION purposes... but, it gave the car a little crisper steering feel and only cost me $60.

So, again, the dark art of suspension tuning. Or car tuning in general. Everything affects everything else. What YOUR specific goals and budget are is always a factor.

For competition purposes, FWD cars are almost always set up to where they almost oversteer. The suspension setup is so weird, and so biased toward reducing understeer that you're always one little driver input error away from being backwards! Dive into a slalom and drive it like you mean it, you're fine. Dive into a slalom, realize you're going to fast and lift off the gas while you're turning? As soon as you lift, you're shifting weight off of the rear of the car... and it's already got the absolute minimum on it already. You're going tail-out instantly. If the car is properly set up, and you're on your game, you can usually catch it by jabbing the throttle and transferring that weight back to the rear. But, if you put an inexperienced driver in a properly competition-prepared FWD car and tell them to go hammer it... they're going to spin.

Okay, I'm done rambling. Much of what I've said is not fully relevant to a street car. You shouldn't be tuning the suspension to that extreme. You don't want an "unstable" car on the street. Cars are designed to understeer a little bit because it's safer and more predictable. But, you can definitely tune out SOME of the understeer.

Nicely stated. I made the rear bar quite beefy to get help initiate lift throttle oversteer and it’s doing a good job of that. I do absolutely agree with setting up spring rates, and I’ve actually got some coilovers with my own custom rates for that reason how low was your car when lifting the front tire? How much suspension travel did you have?
I fully agree with your sentiments on roll bars and the balance they bring. It’s how I set up my track focused Veloster build. I’d noticed after the rear sway bar, unwanted alignment changes were rather minimal thankfully. Those cars also use a twist beam rear suspension.
Sounds like we’re quite on the same page, just slightly different approaches. Don’t think either is any more right versus the next, all in the fun of science
I’m also lowering my seat height to help bring that center of gravity down as far as possible. Also going to widen the stance as much as possible. It’s a new platform for me and one I’m super excited to exploit as far as possible.

[Loren]

I don't know how low the car was, or even how low it is now. The initial setup was stock ride height on stock springs with the Godspeed shocks. It would lift a front wheel maybe a half inch or so on occasion... something I'd gotten used to on the Festiva that I autocrossed before it. People watching were concerned, but it didn't feel unstable, so I didn't worry about it. But, eventually, I pushed it hard enough to get SERIOUSLY up on 2 wheels.

The next step after that was to install the rest of the Godspeed kit and get the height down. That helped, but we got photographic evidence that it was STILL lifting the front tire by 2", even though it didn't really feel like it was. That's when I got into fixing the roll center with custom control arms and tall ball joints and all that. Which STILL didn't fix the problem.

I had another guy co-driving with me last season. The day I saw about 8" of air under the right side of the car and me and everyone else thought the car was gone... that's when I went full low with it. It's almost as low as it will go. Maybe 3-3.5" lower than stock? I think I bottomed out the rear and set the front to match, something like that.

I try to keep the travel set to maximize droop travel in an effort to keep the tires in contact with the pavement as much as possible.

The car feels really good as it is, and corners like mad! But, neither me nor my co-driver have full trust in the car. It's no fun autocrossing a car that gives you that uncertain feeling that it could toss you upside down at any time.

I decided before I even started this project that I had no intention of going "full race car" with this car. (did that with the Festiva) And after playing with it for two years, it's become clear that the only way to REALLY be able to trust this car driving at 10/10 with fat sticky tires would be to go full race car.

That would be things like you're talking about... lowering the seat, removing anything that can be removed from higher up in the car. Lowering it even more. Putting even stiffer suspension on it. Flaring the fenders to allow for wider track. There's still a ton of potential in the car, it's just not what I want to do with this car. At least not right now. My intent was to autocross it in near stock form, and it just can't be done safely. I've already done WAY more than I ever planned to do with it. Maybe if I still have it in a few years and get bored with my Miata again... The residual value of the Mirage will be in the weeds by then. I could get silly with it. If I don't sell it before then.

But, for now, when I get around to it, I'm going to put the ride height back to a more comfortable height and shift its priority back to "street car" vs. "autocross car".

[Powershiftmatt]

I don't know how low the car was, or even how low it is now. The initial setup was stock ride height on stock springs with the Godspeed shocks. It would lift a front wheel maybe a half inch or so on occasion... something I'd gotten used to on the Festiva that I autocrossed before it. People watching were concerned, but it didn't feel unstable, so I didn't worry about it. But, eventually, I pushed it hard enough to get SERIOUSLY up on 2 wheels.

The next step after that was to install the rest of the Godspeed kit and get the height down. That helped, but we got photographic evidence that it was STILL lifting the front tire by 2", even though it didn't really feel like it was. That's when I got into fixing the roll center with custom control arms and tall ball joints and all that. Which STILL didn't fix the problem.

I had another guy co-driving with me last season. The day I saw about 8" of air under the right side of the car and me and everyone else thought the car was gone... that's when I went full low with it. It's almost as low as it will go. Maybe 3-3.5" lower than stock? I think I bottomed out the rear and set the front to match, something like that.

I try to keep the travel set to maximize droop travel in an effort to keep the tires in contact with the pavement as much as possible.

The car feels really good as it is, and corners like mad! But, neither me nor my co-driver have full trust in the car. It's no fun autocrossing a car that gives you that uncertain feeling that it could toss you upside down at any time.

I decided before I even started this project that I had no intention of going "full race car" with this car. (did that with the Festiva) And after playing with it for two years, it's become clear that the only way to REALLY be able to trust this car driving at 10/10 with fat sticky tires would be to go full race car.

That would be things like you're talking about... lowering the seat, removing anything that can be removed from higher up in the car. Lowering it even more. Putting even stiffer suspension on it. Flaring the fenders to allow for wider track. There's still a ton of potential in the car, it's just not what I want to do with this car. At least not right now. My intent was to autocross it in near stock form, and it just can't be done safely. I've already done WAY more than I ever planned to do with it. Maybe if I still have it in a few years and get bored with my Miata again... The residual value of the Mirage will be in the weeds by then. I could get silly with it. If I don't sell it before then.

But, for now, when I get around to it, I'm going to put the ride height back to a more comfortable height and shift its priority back to "street car" vs. "autocross car".

Makes perfect sense! Nicely explained and I appreciate you responding. I agree 100% on getting the car settled on a wider track width, it’s an idea I’m toying with myself as well. It’s awesome you are autocrossing one of these, I totally love that.