I was wondering how things were going Warren since it went silent for a bit.
Couple questions. If I come visit late summer/early fall to Atlanta can I drop by?
If I drop by can I drive one?
And if I have money how long am I looking at having to wait to get a spec A chassis?
Warren V, I most definitely like what you are doing with the car and looking forward to driving one some day soon!!
P_W_Fun wrote: May be you can help me to understand why Stuart Mills (U.K.) web-site as well as your site (Exomotive.com) do not state the weight distribution numbers of the Exocet? If they are as good as you say they are one would assume this would be a huge selling point in a light, nimble design such as this. In reply to Warren v:
Hah, I'm detecting a lot of suspicion in that comment. What has led you to believe it doesn't have a "good" F/R balance? My definition of "good" is from my experience of driving Miatas with different loads. In my experience, the Miata geometry is happy with anything from 52% (with driver) to ~47% front weight. Anything more forward tends to give a lot of weird transitional and trailing-throttle oversteer, anything further back puts too much of the roll couple to the rear and leads to unforgiving characteristics like snap oversteer. In theory there is a larger range of forgiveness when your weight and CG goes down, but I haven't had the chance to strap a bunch of ballast to an Exocet to figure out exactly where the limits lie.
To answer your question about why MEV or Exomotive doesn't publish a specific number: it's hard to pin down when there is so much possible variation. We're not hiding anything, we're just car guys that don't want to mislead anyone with exact figures. The reality is that every car is built quite differently. The Exocet is compatible with donors ranging two generations and 15 years of small revisions. Donor weights range from 2150-2550 lbs and stock WHP levels go from 95-160 hp. We get "number" questions a lot; and we don't like to BS people by giving them FMII-donor 0-60 times and weights from a 1.6L carbon-seat aluminum-celled stripper. In person (like at the Georgia Tech Auto Show today), we get the chance to explain the differences between donors and give an expected range for these numbers. We'd be lying to you if we spat out a nice three-sig-figs list of top speed, 0-60 times, final weight, front weight, lateral acceleration, cD, etc. Ultimately you decide the final numbers. We're confident in promising "balanced" or "near 50/50" weight. Our reference points are generated from a few full builds that we have done in-house.
With a standard UK chassis, depowered steering rack, A/C removed, stock 1.8L NA engine, stock NA fuel tank, removed heater core, battery behind the passenger seat, and stock NA seats, the weight is right at 1460. The Base US chassis comes with a substantial 1.75"x0.095" rollbar and downtubes, so expect about 15-20lbs more weight right in front of the rear tires than the double-hoop stylebar versions of the UK chassis. The "Sport" version adds a diagonal, a harness bar, and 7 other light tubes around the chassis to top off the massive increases in stiffness. The "Sport" version is still within 5 lbs of the MSA-Style 2012 UK chassis (Black car on our website). Ditch the seat sliders and pop in some Corbeau Forzas to get healthily under 1450. With the stock seats, front weight is nearly exactly 50% without driver, 48% with a 200lb 6'3" driver, 47% with a driver and passenger. NA seats weigh around 34-36 lbs with their sliders (and any speakers removed). For the tall guys, you can sit 8" further back than you can in a Miata, which affects that balance a lot.
By the way, even Mazda defines "50/50" as a generous range on their Miatas. Nearly all NAs/NBs are actually around 52.5-51.5% front weight. My completely stock DD NB2 is nearly 53% and it's still so much fun I can't keep a set of tires on it for more than 10k miles.
TLDR: As a general rule, your Exocet will be a little rear-biased from your donor Miata by about 1-2% and have a very noticeable decrease in polar moment. Don't believe our numbers? Think about this: you're eliminating a lot of weight from the front of the car (heavy glass windshield, power steering system, headlight assemblies, heater core, A/C compressor, all the HVAC business under the dash, sound system, baby teeth, etc). On top of that, a completely stripped 95+ NA Miata chassis has a balance point right at the back of the shifter hole. The exact balance of that tub is 49%F measuring from the F/R contact patches. The Sport Exocet's chassis has a balance point at 43%F. For some reason a lot of people think that the Miata tub is very rear-heavy and as such the Exocet will end up front heavy. That's just simply not true, look at the dozens of MEV build threads where people lift the tub with an engine hoist.
With 300 of these things on the road, an active owner community, and a whole spec series in the UK (MX150R), we really couldn't get away with lying to you about the car being balanced. It is, and it's fun as hell.
Jaynen wrote: I was wondering how things were going Warren since it went silent for a bit. Couple questions. If I come visit late summer/early fall to Atlanta can I drop by? If I drop by can I drive one? And if I have money how long am I looking at having to wait to get a spec A chassis?
Overall things are going really well. We have had some unexpected delays in getting the first round of chassis tubes from the laser cutter partner, but we have been told our (non-mandrel-bent tubes) will be manufactured this coming week. Expect some sweet laser videos on our Facebook page by Friday. The Exocet is a pet project for their engineers, programmers, and operators. As such, getting the setups, machines, mandrels, tubes, and people in place to make the first chassis has taken much longer than expected. That said, we have every part programmed for the machines, documentation is complete with QC checklists, we have an internal inventory control system in place to handle all the 127 individual parts that makes up a Sport Chassis. We have everything else in place to start production once we get the tubes. Just for fun, here's our jig table with the very last UK-imported chassis sitting on it before being shipped of to its buyer:
That table is ridiculously flat, we had it welded upside-down on a precision-ground 2" thick solid steel slab welding table. No crooked 2013s, that's for damn sure. By the way, that table top was laser cut with alignment marks and holes. The subframe mounts on the chassis are actually part of the clamping/jigging system to ensure that the subframes are located at the right distance for the Miata's PPF. All those bolts holding the table surface to the table frame? Yeah, their holes were laser cut, and the bolts dropped right in first shot. Why bolts? Because welds introduce too many distortions and make replacing the top difficult later on. But enough of the engineer porn.
With the volume of pre-orders, we have been forced to expand in space. We are negotiating a next-month move into an amazing new dedicated building in Atlanta-proper. If everything goes to plan, we'll announce that on our Facebook and website, so don't plan a trip up to Roswell just yet.
We love visitors, just give us a call/email beforehand. We work with a lot of vendors/partners and don't keep storefront hours every day. Our current Roswell location has us gun-shy on handing over the keys (crazy-soccer-mom traffic, Roswell PD right down the road, etc), but we'll definitely take you out for a ride. We have to scope out our new location and figure out insurance costs before making a decision about test drives in the secluded industrial zone of our prospective new location.
How long for a chassis? Once we get rolling, we will be able to immediately pump out at least 2 kits a week. MEV in the UK hand-copes their tubes and spits out 4-5 a week, we hope to be able to match that rate (the real limit is the fiberglass work). Our preorder list has us booked for the intial couple of months, but we think once things settle down we can get back to our old 4-5 week lead times.
Why aren't we in production now when the chassis design was complete in November? All comes down to the engineering saying of "Affordable, Good, Fast. Pick 2". All of our issues have been getting every tiny part and process perfect for the first chassis; we are very confident that once we have the first chassis cut out and bent, the following cars will be gravy. Our partner company has massive capabilities, it's just been a question of programming all the parts, sourcing all the tube (I'm notoriously picky about my seamless, DOMEX, and DOM), ordering all the right mandrels, and documenting all the QC measures for the formed parts. All that is just about wrapped up with the last custom mandrel to be delivered on the 8th.
Excellent responses Warren, I will be on that list.
Steve
In reply to Warren v: Thanks for the response. ("With 300 of these things on the road, an active owner community, and a whole spec series in the UK (MX150R), we really couldn't get away with lying to you about the car being balanced. It is, and it's fun as hell.") I was definitely not implying that you are "lying" about the balance of the design and do know there are variables that will affect the balance of each individual car (personal options) but taking this into account it just seemed odd to me that there is nothing on the website about the (potential) balance of this car. May be its just me but having something like the following on your site, quoted from your response above,("Ultimately you decide the final numbers. We're confident in promising "balanced" or "near 50/50" weight. Our reference points are generated from a few full builds that we have done in-house") <> would go a long way in generating initial confidence in the design and to have nothing at all about weight distribution on your web-site might lead the serious enthusiast to think (a) the potential for Miata like balance is very low (or), (b) May be they are not concerned with weight distribution at all. Just a little productive criticism based on my experience in researching the Exocet. Thank you for the confidence building response and looking forward to your great success >
Still making them with that silly bent "wouldn't want to roll that bar"?.
My understanding is that the Spec-A Warren is working on will not have the bent. In reply to kevlarcorolla:
kevlarcorolla wrote: Still making them with that silly bent "wouldn't want to roll that bar"?.
That photo is of the last UK-built chassis that we imported, not a new Spec-A.
The American-built frames will always be sold with CNC push-mandrel-bent 1.75" x 0.095" high quality DOM (75+ ksi) roll hoops with as few bends as possible. There is not a better way to bend tube, and a large portion of the development time was making sure those bends are perfect. No kinks, no large-radius bends, no pre-buckled tubes. The Base, Sport, and Race have the same exact main hoop; we didn't skimp on the DOM. The rear downtubes, harness bar, diagonals, and cage are made from the same material. The marginal cost savings of no longer needing to import the frames went right into the DOMEX, DOM, and seamless CDS.
In reply to P_W_Fun:
Oh, sorry, I didn't mean to come off as defensive or anything; tone doesn't carry well over the nettertubes. We love good questions, and I firmly believe that all good products/ideas/claims should be rigorously tested. The extensive explanation was for the many viewers that may be thinking the same thing. You're totally right about putting a little blurb on the site about the numbers. I'll add it to the 12ft long laundry list!
Everyone Else
I am proud to announce Exomotive's latest kit offering today!
LOL nice for the 1st of April. Well hopefully my game launching tomorrow does well enough my order in a few months won't be a joke :)
Good to hear on the proper roll bar desing Warren,sounds like you've done a bang up job on getting the manufactoring tolerences better than the MEV made stuff.If I didn't allready have too many damn projects I might be ordering one up.
Warren, I just wanted to say good job on improving the product and in the way that you answer questions. It shows that you care. Good luck, John
(Added to to-do list)
Are you working with the county/state for your expansion? Jurisdictions love jobs like that, and it might save you a pretty penny. If I can help let me know!
In reply to Enyar:
Thanks for the heads-up. I talked with the owner (Kevin); he's very aware of GA's generous manufacturing tax credits. I think that's part of the reason why we're moving to South Fulton. They might actually be enough to fund an LSx powertrain, now that I think about it...
Good to hear! If you guys run into any questions/issues let me know.
We made some nice headway and finally have laser-cut parts in-hand! I took some video on Friday and quick-edited it in the style of the "Trackside" series:
http://www.youtube.com/watch?v=gMj4XSxJkxA
You know, if you move further north, the tax credits are even better :) In my community, 70 miles up the road from Roswell, $4000/worker per year for 5 years in tax incentives, and the credits can be used for payroll taxes :D Yes, I'm on my local economic development board 
Just to keep you guys up to date:
I'm currently assembling the first US prototype chassis! Can't even articulate how excited I am to finally have the tubes in one place.
Can't wait to hoon this sucker and deliver the first customer cars.
Awesome progress Warren
Ooo pretty welds!
HF welding helmet FTW. No need to be fancy, just get the job done.
(...and yes, those welds are REALLY nice for MIG)
JoeyM wrote: HF welding helmet FTW. No need to be fancy, just get the job done. (...and yes, those welds are REALLY nice for MIG)
We have a lot of Harbor Fart in the shop. It's easy to hate on HF, but there is something to be said for having at least one of every tool you need on a startup budget. I will admit to hating on the helmet a little. If I don't close my eyes for the very start of the weld, I'll see some sunspots. The 1/25,000 of a second response time is, um, a bit optimistic. I miss the Miller helmets at Georgia Tech...
Those pretty stacks are from our little welder tryouts, not from me. I'm just good for tacking and making fixtures. I'm a firm believer in getting tubes right the first time and avoiding the grinder.
We're waiting on the roll hoops to move on to the next few steps, but it all went together very smoothly once I sorted out all the mis-labeled tubes. Thankfully I designed the length of the tabs to make sure every tube had a unique overall length, or I would have been hosed. I definitely need to have the tubes laser etched with the part numbers.
I'm willing to bet at least one of you is a Miata expert questioning the fact that it looks like the front and rear subframes are mounted on the same plane. Don't worry, the rear has bushings and DOMEX mounting plates to offset it to the proper distance. You won't have built-in rake that screws up the camber curves and antis.
Warren v wrote:JoeyM wrote: HF welding helmet FTW. No need to be fancy, just get the job done. (...and yes, those welds are REALLY nice for MIG)We have a lot of Harbor Fart in the shop. It's easy to hate on HF, but there is something to be said for having at least one of every tool you need on a startup budget.
I agree wholeheartedly....I just buy a warranty with any electronic stuff.
Warren v wrote: I will admit to hating on the helmet a little. If I don't close my eyes for the very start of the weld, I'll see some sunspots. The 1/25,000 of a second response time is, um, a bit optimistic. I miss the Miller helmets at Georgia Tech...
I actually like mine.
Warren v wrote:JoeyM wrote: HF welding helmet FTW. No need to be fancy, just get the job done. (...and yes, those welds are REALLY nice for MIG)We have a lot of Harbor Fart in the shop. It's easy to hate on HF, but there is something to be said for having at least one of every tool you need on a startup budget. I will admit to hating on the helmet a little. If I don't close my eyes for the very start of the weld, I'll see some sunspots. The 1/25,000 of a second response time is, um, a bit optimistic. I miss the Miller helmets at Georgia Tech... Those pretty stacks are from our little welder tryouts, not from me. I'm just good for tacking and making fixtures. I'm a firm believer in getting tubes right the first time and avoiding the grinder.
If in fact there is a Miata expert out there I would love to learn more about the planes refered to.
I am doing a tube frame with Miata suspension and the goal is to replicate the exact geometry of the Miata.
What I am hearing here is that the suspension craddles and/or lower a-arms are not parallel to the chassis plate?
NOHOME wrote:Warren v wrote:If in fact there is a Miata expert out there I would love to learn more about the planes refered to. I am doing a tube frame with Miata suspension and the goal is to replicate the exact geometry of the Miata. What I am hearing here is that the suspension craddles and/or lower a-arms are not parallel to the chassis plate?JoeyM wrote: HF welding helmet FTW. No need to be fancy, just get the job done. (...and yes, those welds are REALLY nice for MIG)We have a lot of Harbor Fart in the shop. It's easy to hate on HF, but there is something to be said for having at least one of every tool you need on a startup budget. I will admit to hating on the helmet a little. If I don't close my eyes for the very start of the weld, I'll see some sunspots. The 1/25,000 of a second response time is, um, a bit optimistic. I miss the Miller helmets at Georgia Tech... Those pretty stacks are from our little welder tryouts, not from me. I'm just good for tacking and making fixtures. I'm a firm believer in getting tubes right the first time and avoiding the grinder.
Yeah, the subframes (sometimes referred to as k-members, cradles, cross members, c-frame, etc) are not mounted on a plane in the Miata. It's a small difference, but it's not negligible, especially for the anti geometry. Screw it up and you'll get some weird behavior under braking. It's bigger than the difference between the NA and NB's front geometry.
As much as I'd love to shout it to the world, I'm under agreement not to give out the exact Miata subframe mounting positions that we found through a lot of meticulous measurement. That said, I can probably get away with giving you a huge head-start. This is the best-resolution image publicly on the net from the Mazda FSM:
Unfortunately some of these numbers are misleading, as a few lead to the points of the studs and a few lead to the interface plates, and it's not labeled verbosely.
You'll need to log in to post.
