Xaendeau

OK. After spends many hours reading hundreds of pages here without shitposting about suspension, I've come to the conclusion that 550 front and 350 rear is probably good for an Exocet. They are too soft for most Miatas, but if you shave off 700-800 lbs, I think the spring rates are about right. Going to put them with some full length coilovers like Xidas XL or something.

Edit: 1500 lb Miata. I'm using the car for track use and HPDE with some autocrossing in there. I'll probably be using soft compound road legal tires since I'm making the vehicle steet legal and do not want to trailer it everywhere...yet. I'll get there at some point.

Buy once, cry once.

What should I do about sway bars / anti-roll bars? I've only used them in stock-ish class autocrossing to improve rotation...or as a poor man's way to improve roll resistance on gravel or shitty concrete without stiffening the spring rates. Even in simulators I've always left them alone because spring rates, dampening, and rebound are more important. I know how they affect everything but I don't know what is a good combination besides stock. I've spent time digging though the forums but apparently I am not keywording hard enough. What is the general consensus here about sway bars on Miata platforms for track use here?

Someone educate my ignorant *** on sway bars. People seem to do more harm than good with them.

Bronson M

iTrader: (1)

"Right" completely depends on the application. Those rates look completely soft and wussy for a track build if you ask me.....but I don't own an exocet. List your intended usage and goals for the car.

thommorud

I’m running 9k/6k (~500/325) on my exocet it’s turboed around 225hp estimate. They were much too soft when it was a Miata but find them bearable on the Exocet, I do think I’d go a little firmer next go and get a better set like the XLs now that I’m tracking it.

I run a hollow RB front sway and no rear sway. I do believe I would be better off tuning with coilovers better and running a small rear sway but the back comes around really easy for me. My exocet is around 900lb front / 675 rear weight so the back is pretty light.

I’m not running any aero right now but will be this coming season so can’t speak to how that changes anything till it happens. Don’t know what your aero plans are either way.

Xaendeau

Added.

Xaendeau

Thanks for the input. I might consider going a little stiffer then. Our roads are a little apocalyptic, so I'm wary of ultra stiff setups. I'm running 8k front, 6k rear with a fat rear sway on an SMF (autocross) turbo'd Fiesta around 2500 lbs with the back seats and spare out. I could have gone a tad stiffer in the Fiesta and it still would be streetable.

thommorud

I had my Exocet street legal for a couple years, it weighed in around 1650 when it had its windshield and all the lights and fenders. I did a couple long trips in it, CT to TN for Miatas at the gap. Ill advise you its not a comfortable car to drive on the street. The wind and noise is pretty bad and I would dread the drive home after AutoX since I just didn't want to deal with it. It is great for short trips or back roads but Highways are the worst.

Id advise against the Exomotive glass windshield if you were looking at it. It is only supported on the bottom and lower sides so it will flex with wind and buffeting from passing trucks which causes it to crack pretty easily. Mine lasted less than a month before it replaced it with Lexan and added a center and taller side supports.

Dietcoke

Don't pretend your exocet is a 1500# miata. They handle nothing alike, and respond to springs and bars completely differently - same reason they use much less camber then a miata - Exo has enormous lateral stiffness and a much lower CG relative to a miata. 550/350 is probably close on 200tw tires, but you are going to want way bigger rates on sticky rubber/r comps if you want to be fast.

emilio700

iTrader: (3)

550/350 should be a good place to start assuming 205/50 Street tires. Because of the subframe relocation in the EXO chassis, the car will end up being a bit loose if you directly copy Miata alignment and hardware settings. Miata is never faster with the rear sway bar disconnected unless you have a bad setup that we often see XO owners disconnecting the rear sway bar to get the rear end under the control. That is because of the rear subframe height. There is one very vocal opponent to this fact in the exosphere but you can ignore that. Another concern is that the Exo tends to be more nose-heavy the Miata as it is easier to remove weight from the rear of the exos than the front. So we suggest running Miata setup and setting the rear ride height roughly 3/8 inch lower than front. If you set the car level as mentioned before it will likely be very oversteery (fancy technical term) and you will have to Band-Aid the setup to compensate.

Sway bar choice is a function of ride height and grip level. As you raise the ride height the car gains roll stiffness so less sway bars needed. The roll moment is essentially how much force is making the car roll. That is directly related to the grip level of the tires. Stickierr tires means stiffer sway bars. Assuming a conservative ride height at around 5.25 inch I would suggest sticking with the stock sway bars both front and rear. if you were skeptical about that I would suggest trying it first and see how you like the way the car works. You can always add sway bars later if needed.

shutej

I've seen you say this elsewhere, yes:


https://trackhq.com/forum/regional-f...659#post218659

https://supermiata.com/miata-race-alignment-info.aspx


...and I've seen other owners refute it...


https://trackhq.com/forum/regional-f...691#post218691


Perhaps that's the vocal opponent?


Regardless, I have to figure out how to set rake myself, so I went out to my own workshop to get to the bottom of it instead of leaving it to the internet to decide.


I have a '99 sitting on 4 identical jackstands and Exocet chassis #358 sitting on metal sawhorses on its subframe points. Both are sitting next to each other on the same (very level) concrete floor. I took my Bosch laser measure with me which measures to 1/32". Like the other owner, my measurements showed that the front and rear jack points are level w.r.t. the front and rear subframe points, not pitched 10mm. However, unlike the other owner, I found the Exocet jacking points should be 3/16" (+/- 1/32") LOWER according vs. a similar Miata's pinch welds in order to have the subframe at the same height w.r.t. the floor.


Very respectfully (as I intend to buy more stuff from you, you've clearly done a lot of development work, and you seem like a pretty smart guy) ... how did you confirm this? When? Have you done so on a recent chassis (after #14 they have all been built on the same table)? Kevin, the owner of Exomotive, when asked ALSO said that they believe that both by design and in practice after execution, chassis after #14 should in fact be level.


As to the other points on the thread, sadly I have nothing else to add.

emilio700

iTrader: (3)

We performed our measurements about 5 years ago so it's possible that the Exo chassis have changed since then. Kevin then told us that Exo in the UK deliberately repositioned the rear subframe for improved gas tank packaging. We measured subframe mounting pads to the pinch welds on an NA and NB as well as the Exo chassis. The Miatas were consistent with each other and pretty square. The Exo was not square, LR and RR jacking points being 1/4" off from a straight line through subframe mounting points. If we see measurements like that on a Miata, it's totaled. That's not hyperbole, that's a bent tub. But judging by the weld quality and myriad questionable engineering decisions we observed on that Exo chassis, we assumed it was normal. The 3/8" adjustment in rake we recommended was splitting the difference between left and right. One side jack point was right at 1/2" offset from the subframe mount pad centerline, the other about 1/4".

When we adjusted rake to compensate for the subframe offset then added the shock spacers, made spring rate adjustments for the nose heavy weight distribution the car started to work acceptably well. Still not as balanced or fast as a Miata with the same power but at least it wasn't unstable.

We don't claim to be Exo experts. We measured one in the shop 5 years ago. We then began recommending a rake adjustment based on those findings and significant track testing with a pro driver. But more critically.. measure your own chassis. Beyond that potential subframe reposition, the altered motion ratios from the lower offset wheels, nose heavy weight distribution and lower curb weight remain.

We have no plans to get a newer Exo chassis in our shop and mess with it. We have our hands full with Miata projects. Folks seem to be really happy with Xida race and Xida XL's on their Exo's with our recommendations so we are apparently pretty darn close