[Petrus]

Anyhow, while in the 90 mph range, I do feel a little sway,

Define ´sway´.

Sway bars, aka anti roll bars only counteract body roll.

Straight line instability can have several causes.

Wallowing/´floating´ through corners too.

Lastly, the concept of a mid engine can appéar instable at higher speeds. This again can be tackled several ways.

The chin lip mentioned is a very simple one which reduces the lift under the front (see photo) and with that a good part of the ´light´ feeling.

Oh and OEM wheels, tyre specs are best for the car.

 

[Petrus]

then next year, the coil overs

I suggest new stock shock & springs first.

And, só obvious it is often overlooked, alignment. Make sure the alignment is spot on.

@Meller; ARBs are very much about reducing body roll: That is what they dó and yes they are by there nature also instrumental in understeer/oversteer balance.
Taking it one step further, their prime practical function is.... ´increasing´ overall grip by reducing body roll. Between brackets because they don´t actually íncrease it but by limiting the load increase on the outer tyres a bit, those lose less traction because of tyre load sensitivity. Presto; less traction lost on the outside is less loss in overall traction.
And thát is why you can also play with them to increase/decrease overall thus relative front/rear traction.
I think them übercool.

The príce is some less conformation by defacto stiffening the suspension. Not much of an issue on a racing track or otherwise smooth surfaces but on real world roads... it is a cost.

Anyway, not a thing for Steve Miller quite yet

 

[Petrus]

Good thinking with the alignment. That is one thing off the list.

So first get the front lip under the bumper skirt. Should be dirt cheap. You can use rubber strip from Ebay listed as front lip. It has self adhesive strip and all you need is 4 self tappers to secure it.

Next is a rubber lip on the rear bum ríght after the engine lid. This will provide a break off edge for the rear turbulence and reduce the unrest in the steering wheel.
Again dirt cheap on ebay listed as rear lip.
Below is the best photo I have of mine.
(ignore the silly big wing; mine is well under 900 kgs and áwefully light under the front so needs it like the fletches on an arrow)

You will be surprised how much it does.

Now if you still want more, a third véry cheap one is cut two vents in the hood. This again reduces the lift under the front provided you take/have the vanity plastic out. Photo below too.

There ís a fourth dirt cheap one but that, even though it works and I can explain why, will see me lynched here so do the above ones first.

 

[Petrus]

@Steve Miller

plenty of rubber strips like
Fits 100 Inch Nissan Rubber Foam Front Bumper Lip Splitter Spoiler Trim EZ | eBay

For the rear too.

Simple and cheap under your fingers.

If you don´t already have that, I suggest you store the tool roll in the spare wheel well too and keep the washer bottle topped up.
For winter use you may even want to add an iron gym weight.
It will slow down directional changes at the front, mellow it.

First the rubber strips though.

And I wrote IGNORE the silly big wing. My car/use is not a yard stick for you/your use.


p.s. for the winter roads you mention I strongly suggest a second set or OEM size rims with proper winter tyres (less wide and higher section).

 

[Petrus]

you don't need to go modding it and making it look like a virginmobile to feel safe.

See?! @Steve Miller

There is no pleasing everyone here.

To mé the world is a more fun place with as much different approaches/tastes as possible.

Back to the topic; You go ahead as yoú please. My suggestions are just that; suggestions. Very easy/cheap ones at that so you can trý and like it or not without breaking the piggy bank.

The wheel ´spats´ Old Man refers to are a perfect illustration of the huge effect of minor aero changes. You draw your own conclusions

Have fun!!!!

 

[Petrus]

You can double the practical luggage space by taking the cubby doors out.

Btw very funny that referral as this Thusrday we are off to www.fincajohanna.com for a week. It is only an hour down to the coast but still nice to change venue and why go further when you líve in just about ideal holiday country?!

 

[Petrus]

It is the essence of the epistemological debate between empiricism and rationalism.

Even if véry strictly based on hard facts ´it´ is about as diverse as individual people because we all use the car to suit our own purpose. Never mind the variations in capability/experience.
Take the set up of the Spirit MR-S. As fast a Touge rocket as it was so horrible to drive it would be for nearly all mortals drivers

Now add taste and WOW!!!
The exhaust and tip of mine (you can just make out the bell mouth inlet too) 😍

 

[Petrus]

I tease you in good fun. There are some older pictures of my first mr2 on here somewhere, which I began modding in my early 20’s, and predictably I made some questionable choices both aesthetically and functionally. Granted, not on the same level of disaster that is your set of decisions, but im sure there are plenty of opportunities to have some fun at my expense, on which I will join you if the ball gets rolling.

Don’t feel bad. I am very difficult to please. I can’t even manage it.

Don´t worry; I feel as good as ányone

My take on the sabi of wabi sabi; honourable proof of a useful life:

and here one illustrating my own ´sabi´.
Was faffing with the wing angle while still on twin crutches. On board had them firmly wedged to keep them from distracting while on/over the boundaries of traction.
Meanwhile my son has 3D printed lighter replicas of the wing supports. Oh and the side uprights of it I made in pvc foamboard.

 

[Petrus]

It made a big difference for me on the highway, the car feels much more planted after installing it.

Go figure; an inch low strip under the front of the car! And then still there are those who maintain that spoilers don´t work for road cars

 

[Petrus]

Spoilers work. It is the wings that have questionable utility. There is popular confusion as to which is which, and there are a lot of purely cosmetic appendages around that add to the confusion.

Semantics. What you call ´wing´ is an inverted air foil and aka spoiler 🤪 And yes some are intentionally functional, some not with a wide range in between.

Ah and the mythical ´balance´. Thát is better dubbed ´compromise´. Pick your choice and then add some throttle for a new balance 😎

Speaking of air foils, the whole ZZW300 is one. Hence lift at speed.

My car... well needs just a wee bit more rake still. Who needs top speed on the public road anyway? Traction and stability (as in keeping the course set by the steering input be that straight of bend) through... Interesting balance with a low moment of inertia rwd car 🤪

 

[Petrus]

Balance isn't mythical. A vehicle whose center of gravity and center of pressure for the aero are not aligned will suffer drastic handling changes depending on speed. Not ideal. And a spoiler is designed to spoil airflow to prevent lift. On a car it is usually employed to prevent air from flowing around (usually under) the car and lifting it at higher speeds. An airfoil generates lift (downforce if mounted upside down obviously).

My point being that it WORKS on a light road car like the ZZW30. Any arguments about upsetting balance support this.
Whether the effect is as one wants it or not is a totally different issue.
Point is that aero works at cycling speed! See the one inch strip and legal highway speed stability increase, which also affects the ´balance´ by the way

And centre of gravity.... that is a bit dfferent. Aero is weightless, ´just´ a force possibly creating a moment around the axle of turning which in this case can be taken as the rear wheels.
A rear wing, air foil, spoiler, means weightless extra traction of the rear tyres. This at no negating cost of extra centrifugal force through corners.
Yes it changes balance by changing, reducing, the drift angle of the rear tyres as cornering speed increases.
It does nothing to weight balance or moment of inertia.
To put the effect in perspective a quite large and effective rear wing increases the road on the rear axle with say 500N at 120 km/h. The weight of the car at the rear is some 6.000N....
Now have a look at the spring rates in the table: The ratio of OEM and after market vs the TRD ratio has a larger effect on how the rear suspension speeds up in relation to the front. Yet this seems to pass universally unnoticed.
Bottom line; balance is all relative

And please note that extra traction at the rear because of aero does not give you any less at the front.
You can also rephrase it into it reducing the snap of oversteer resulting from too much throttle or lifting it.
So, you balance the pros and cons 🤪

And regardless; we apparently all agree that it works

 

[Petrus]

A wing provides downforce. A spoiler interrupts airflow for the purpose of controlling turbulence. That is the origin of the name "spoiler." A spoiler on the rear deck is usually to reduce drag. A spoiler in a different location is probably very specific to the airflow at that point. A fairing or air dam is just supposed to exclude the airflow from a certain space.

If you insist on semantics than you are wrong.
A wing is an air foil. As a wíng the effect is creating líft. On a car it is uses as an inverted wing.

Whether upwards or downwards in effect, tt does so by interfering with.... air flow.

A spoiler on the rear deck, well. again, no, not that simple. How would you call a one inch rubber lip to create a tear off ridge for the flow?
Or what about the Gurney flap?

And ´fairing or air dam´.... Are those not too two different things? Not quite interchangeable words in mý aero dictionary.

Point being that you are using semantics as you see fit, totally confusing the issue.
I don´t care what tag you want to stick on which aero attribute. Even the flip up thingy behind the seats and mongos are ´spoilers´ of sort, changing the turbulence .... In mý dictionary is simply is all aero aids.

On mý car I have the OEM ´dams´ in front of the front wheels, added a chin lip, removed the spare wheel well, added bonnet (hood) vents, created some rake, have mongos, removed the undertrays at the rear, increased air flow through the engine bay, removed the rear heat shield opening up the rear exit, mounted an inverted wing, stuck a lip at the rear.... Ah and have a tonneau tarp which at one time was all but obligatory for spyders at LeMans 24H.
By all means you class the aero mods as dams, fairings, spoilers, flaps or whatever as you see fit.

Btw. a bloke on the UK forum did a nice before and after of the turbulence behind the front wheels of OEM mudguards. Quite effective spoilers

 

[Petrus]

Upon research, he claimed that the chin spoiler was not offered as an option until 2002 (mine's a 2001).

Correct.

Since you ´test´ at speed; have you noticed an effect?

 

[Petrus]

I am considering putting 215's in the back and 205's in the front

With what goal?

 

[Petrus]

A better car, of course. More specifically, higher straight line speed while not sacrificing safety. I realize this is a difficult combination.

Not that obvious, the more because wider tyres do not contribute to your goal.
Furthermore a higher top speed does not make a better car.
Lastly higher speed is per definition more risk. No way around that.

The pfl OEM size is pretty much the ideal for road use. Even pretty extreme, illegal speed, road use.
If you want it safe, simply buy the bést tyre for your purpose.

If (perceived) stability is your issue, then fit the toolkit in with the jack and spare tyre.
More weight further up front increases the moment of inertia (MR2). Some even add some ballast weight.

 

[Petrus]

It has been mentioned in this thread that wider tires produce a more stable drive. Do you disagree with this premise?

Well, the basic ´problem´ of ´instabiity´ is the low moment of inertia but as that is the whole reason for the concept of the MR2; heck it is even námed after it! the subject is a bit diffuse unless more specifically explained.
The ´instabilty´ makes it such a joy to flick through twisties.
It also means it needs less input for (apparent) change in direction when in a straight line at higher speed.

Wider tyres will indeed dull down the overall nimbleness of the car. So yes, also a bit at speed.

I took a lót of weight off the front end to make the car overall more nimble (less stable?) still and restored high speed stability with an already mentioned of aero.

Anyway, I´d stick with OEM pfl size, nót dumb the delightful car down and simply by the best in class tyre.