Build Blog

Last weekend, with two weeks to go before the first track testing of this season, I was debating whether I should swap in transmission #2. From my post back in January, when trans #2 arrived I was able to confirm that the shifter rod was supposed to pivot – and that the pivot on trans #1 in the car was seized. That’s been the cause of my clunky/stiff shifter feel, which is one of two transmission issues I’ve been dealing with. Issue #2 has been with clutch disengagement, and this one everyone has noticed because you can hear the gear grinding in my videos. Having checked out everything outside of the transmission, we feel confident the issue must be in the relationship between the throwout bearing and the clutch. Can’t know for sure without getting in there. January was stuffed full with getting all of the updates/changes in the suspension and brakes on the car because so I can start out early season testing with all of that in place, so this is the earliest I’ve had a chance to turn attention to the transmission.

I already had measurements for the transmission side of things from trans #2 sitting on the bench. I even bought an MV5 (Camaro version of the transmission) to take the same measurements and confirm first-hand there weren’t any differences between the two variants (I’m using the Cadillac MV7):

To get the full picture, we also needed to measure the clutch and flywheel. Based on the nature of the clutch disengagement problems, we expected that when we got in there we would find the throwout bearing is too far from the clutch fingers, and that would be an easy fix – you just shim the slave/TOB assembly to the correct position. On Sunday I dropped the engine/subframe/trans:

I expected I’d pull a long day and have everything back in the car by night with the TOB shimmed to the correct location. With everything out, I measured the clutch and flywheel height, and that threw a wrench in the plans. The TOB wasn’t too far from the clutch, it was too close, and by a massive amount. With the trans bolted to the engine and everything at rest, the TOB would already be compressing the clutch fingers by 0.200″ (and the fingers only have an intended range of motion of about 0.400″). So the problem is the opposite from expected; I’m over-stroking the clutch.

Left everything on the ground and called SPEC Monday morning. Based on their notes, the stack height from flywheel/crankshaft surface to clutch fingers for their clutch/flywheel assembly should be 3.800″ +/- .005″. Mine is 4.1″

With the window of time to get everything back together quickly shrinking (The car still needs to visit the alignment shop and the dyno prior to the track) I overnighted the clutch and flywheel back to SPEC. They’re working on it now, no word yet but it would appear they manufactured the flywheel with the wrong thickness.

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2 days later:

Corrected items arrived back from SPEC yesterday. They say it was a machining error inside the pressure plate that affected the pivot. As soon as it arrived I measured things to verify, finger height from crank surface is now 3.85x” which leaves the TOB about 0.030″ of a gap from full compression. We’re in the ballpark now.

Reattached engine and trans last night. Should have the engine back in the car today, at which point I’ll be back on-track where I was a week ago, but now with one week to do two weeks of stuff. Still holding my breath, I won’t declare the transmission issues fixed until I’ve actually driven it on the track, but if they are then it was all worth it.

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2 days later:

Drivetrain is back in the car as of today, filled with fluids, test fired, bled, etc. So far I can say for the first time that the shifter feels great! Return to center in neutral feels natural and all of the “clunky stickiness” I had before is gone now. The shift rod pivot was definitely the problem there. Fingers crossed that the clutch engagement issues are equally fixed!

Pic to illustrate why more roll stiffness is needed. This is just a steady corner, not coming down off a bump or anything. Dragging the outer corners of the aero on the ground. At Chuckwalla I could actually hear the scraping as I would turn into “dropzone” at the end of the back straight. I run disposable delrin sliders on the underside of the splitter so I don’t destroy it, but am wearing through those quickly:

During post-season inspection I also found scrape marks on the outer front corners of the side skirts. Not sure what corner that was happening in, but definitely a sign of lots of roll.

Ok time for some updates.

2017 was a big success, and I’m really happy to have some solid baselines and results in the bag. Now, it’s all about refinement and MORE in equal parts. In Decemeber with SLB fresh on my mind I did a fresh examination of the car and rulebook and identified anywhere I had room left on the table to maximize performance.

Big on my list is to really hone the chassis and suspension to the maximum possible, within the Limited class rules of course. This goal encompasses both the systems on the car as well as the track-side setup and tuning. A car with all the potential in the world won’t do much without putting in the testing and tuning hours to get everything working in unison.

Enter 949 Racing. They need no introduction, these guys are good at a lot of things, but perhaps what they’re the best at is setting up a car and extracting every bit out of it. That’s not a small talent. Breaking new ground in an underdog chassis, I think a key to success is going to be in getting more out of the car than the competition, and there’s a lot I can learn from these guys.

With 949 on board comes a change to the suspension to extract everything possible allowed by the rules; GTA Limited allows 3-way shock adjustment. Ergo, XIDA triples:

I quite like the look of the coaxial top mounts in the engine bay:

Doing sub-1:50’s at Buttonwillow has me looking for more roll resistance, even on the street tires. With the downforce I’m seeing race tire cornering loads, and scraping the outer sides of the aero on the track. There’s no avoiding I need to go stiffer. The XIDAs come with another jump up in spring rate from my previous setup.

The front sway bar also gets an update. It was one of the last things that’s carried over in the build from pre-2017. At GWR we’ve been working with Karcepts, who make some really nice sway bars for the ND and a couple other chassis. I took some rough measurements and ran a few numbers and worked out that I just might be able to adapt some of the pieces of their ND sway bar to put together a 3 piece NASCAR style bar for this car. I ended up ordering a pair of their beautiful ND arms and their brackets/bushings for the S2000 because the measurements for those looked like they would work best, and a custom Speedway center tube:

Many times in and out figuring out dimensions, checking full range of motion, etc. Had to make a pair of adapter brackets for the sway bar brackets.. here everything is about 90% sorted but I needed to move the endlink bracket on the control arm forwards to shift the pivot slightly. No problem there because those lower arms need to go anyways…

In my factory lower arms I’ve been running an evaluation kit of press-in spherical bearings that replace all the bushings. Great concept, but unfortunately it turned out to not be the best execution in the product. Most people didn’t know that in the final week before SLB I discovered a critical problem in the bearings in the rear lower arms so I ran SLB (and Chuckwalla after that) on factory rear lower arms with 100k mile factory rubber bushings – because it’s what we had available at the last minute. Definitely not ideal. Time to get those arms out of the car and replace the front lowers as well to get the last of those bearings out and move on to something trouble-free.

V8R tubular pro series arms arrived. These arrived in bare steel so I could do the custom endlink mount on the fronts:

Then they went off to powdercoating to get finished up. Far more robust bearings in these, strong, awesome:

Just about everything is installed and sorted out at this point, and I’d love to show some pics of everything installed buuuut can’t really do that right now because this is the current state of affairs:

Yep, two weeks to go before first track testing of the year, still cranking away on things feverishly

We have the shifter feel/return-to-center issue finally pinpointed!

Trans #1 had a seized pivot on the shift rod from the start. We just didn’t know it because it was our first experience with a trans from this family. With trans #2 (an MV5 I bought to take comparison measurements from) and trans #3 (an MV7 to replace the one in this car) in our hands it became immediately clear that these pivoted differently than I recalled #1 doing. With the car back in the shop and on the rack I was able to disconnect the shift linkage last night and confirm the difference.

That pivot allows for the off-axis motion the shifter makes as it moves side-to-side. Without the pivot the shifter is binding with just about any motion.

A post about goals.

Those who have been following along with me for a while will recall I’ve posted about goals a couple times over the years. It started small, but years went by with goals achieved, each more ambitious than the last, and both the car and driver kept improving. Then I attended my first Superlap Battle. I realized I had built a quick Miata, but I wanted to make this little Miata something that is fast no matter what you stack it up against. I set my sights on breaking the 1:50 barrier at Buttonwillow (something a Miata had never done before) and taking a podium in Limited RWD at Superlap Battle. This year, I won the class and went 1:48.

Along the way I’ve had some amazing businesses and friends believing in these goals and helping along. Goodwin Racing has put its faith in this program and supported it in countless ways. Blackbird Fabworx made sure I was racing in a safe chassis and have been instrumental from concept to creation in many of the crazy ideas we’ve come up with. V8Roadsters made it possible for the car to have the powertrain it needs to compete on this level. Rocky’s Miatomotive has lent a hand more times than I can count. Feal Suspension put together a coilover that I could drive fast and confidently on. In the midst of this, Singular Motorsports was born. There was a time I was just racing for me, but these days the HyperMiata is about a lot more than that. There are a lot of businesses and people that I look up to behind this effort, and there are so many of you who have followed along over the years, contributing and cheering us on, these days we’re racing for all of you as well.

So, what’s next?

Re-building the car over the last two years, especially in the last few months, it was all push push push to get to SLB 2017. In the midst of that craziness, I had this funny kind of daydream idea that some day when I won at SLB I would sit back and relax. I didn’t expect to win LRWD the first year I returned, but the irony is that doing so has made me more hungry than ever to make the car faster. I can’t wait to get this next season started, to get out to the garage and start refining and improving things, to get back on the race track turning more laps and tuning.

In 2018 we return to SLB with a target on us. There’s no way to know what’s in the works in shops across the US that may be ready by next year, 1:48 was enough for the win this year but next year it probably won’t be. If you aren’t moving forward, you’re falling behind so we need to set a new goal to push towards. The track record for Limited RWD is 1:44.602, set by Cody Kishel in the seriously prepped Excelsior Motorsports C6 Corvette in 2014. That was the last year the class allowed flat bottom floors and 80tw tires, and nobody has run anywhere close to that before or since. That’s the aim. If someone else is going to take the win in 2018, they’ll need to be on pace for a new record because I intend to be.

3.881 seconds to find from this year’s time. Time to get to work.

Respecting our elders even as we strive to surpass them:

Flying out to PRI tomorrow morning. You can bet I’ll be doing some research for Hyper while I’m there.

Chuckwalla was anti-climactic. I turned very few laps due to a brake master cylinder that failed after the first session, and I didn’t have a spare.

The last two weeks or so have been refreshing, have been going home after work instead of spending long nights in the shop. It won’t last though, dreaming up lots of improvements to get started on soon.

Got wind that Speedventures is hosting a weekend out at Chuckwalla Valley Raceway this coming weekend. after the success – and also all the stress and long hours – of SLB, I figure it would be nice to finish the season off with a fun no-pressure event. Could even get some early 2018 testing in, plus CVR is just a great Miata track.

The plan is mostly to just roll the car out there in the same trim as it ran at Buttonwillow, but first I did a post-race inspection. Superlap wasn’t easy on the car, there’s several things that took some damage and need repairs, and a couple of those things need addressing before going to CVR.

First, the front upper ball joints decided to try to remove themselves from the upper arms. Going back through notes I realized V8R recommends tack welding these in to the arms to avoid this. Clearly, that would have been a good idea.

Took this as a sign it was time to improve the front upper arms. Switching to the V8R X-Lite front uppers. Spherical bearings throughout and track-side quick camber adjustment via shims. Also, 0.95 lbs lighter than the arms they are replacing (each).

Second, the mounting tab on each of the shorty mufflers broke. The safety wire was the track-side fix at SLB. These were made with really thin material to cut weight, clearly just a little too thin. Remaking them with thicker material today: