Misc.

Front upper shock mounts with spherical bearings are installed today.

 

Thinking more about the Contour camera, I really do like how simple it is to operate and the price was excellent.  However, any changes to the recording settings such as volume or picture resolution must be done through computer software; not something that can easily be changed on the fly.  And as mentioned previously, the .mov file output is not my favorite.

To get the most out of the camera, I decided to fabricate a mount using some scrap aluminum.  I wanted the mount to be behind the driver and high enough to easily see the course.  Some 1/8" x 1" angle was modified to mount to the passenger side hardtop bolt location which is standard on all NA and NB Miatas.  It stands about 19" tall and gives a good view.

I was worried that it may vibrate or sway with all the weight up high, but a quick video test drive around the neighborhood delivers good results. Sound is not great, but at least it does not pick up a lot of wind noise.  There is no remote on/off switch so I will have to deal with that too.

Data

  A Torque Android datalog using a cheap Amazon OBDII reader shows that my car tops out second gear at 59.2 mph at 7506 rpm.  This is with my 'street' tires that are about 1/8" shorter than stock. Data capturing was set at 500ms.  I was expecting to see at least 7700 rpm as that is where I told Dynotronics to set the ecu rev limiter.  For a planned ECU revision, I will soon be logging data with an Innovate LM2 which should be more precise and verify the accuracy of the bluetooth device. 

Action Shots

Pics from http://lateapexphoto.com/ taken at the January San Diego SCCA autocross.

Event #2

   Another championship SCCA autox event at the Q with a fast course gives me more valuable seat time.  The 4.30:1 rear gearing feels great but limits my maximum second gear speed, thus I was riding the limiter on this particular course for more than I hoped.  For faster courses I will need to shift to 3rd or extend the rev limiter beyond my current 7700 rpm - expected, but not something I am thrilled about. Fortunately, I expect most SCCA Tour, Pro, and National courses to be a tick slower than today's offering.




Sorry about the video's sound quality; it seems that youtube doesn't work well with .mov files and the sound is borked and then dropped halfway through the run.  Although the Contour camera was cheap and is simple to operate, the QT format is not my preference and something I was not expecting.

Transitionally the car is loose, especially on corner entry, but with great feel in the sweepers.  A rear toe measurement after the event shows I have 1/4" total toe in, and my rake is nearly flat with 1/8" higher in the rear measured at the pinchweld.  The traditional fender to hub measurement reads just more than 3/8" higher in the rear.  To help settle the car I have a few options including lowering the rear ride height or installing the 1.25" Racing Bear front sway bar.  The next autox practice is scheduled for March 3rd.

Event Results
Don't read too much into the results, as we had some rain in San Diego and the course was wet early morning and mostly dry by noon. STR ran 4th group in the dry.  Once again, the Toyo magic gave me an effortlessly quick first run that turned out to be my best raw time, but plus 2 cones. 


The lightweight Enthuza XR muffler got replaced by the Enthuza Speeder which will easily pass the local sound restrictions and yet has a great note.

Sunday San Diego

  Again, show up early to the Q and make some minor changes to the STR Miata after a promising practice event on Saturday.  Some used Hawk HPS brake pads come in handy and are quickly installed at the rear to replace the ultra grabby HP+.  Toe plates and a few wrenches bring to front toe measurement back to what I prefer, about 1/16" total toe in.

  Unfortunately, the sound meter placement on Saturday was beyond pathetic and as a result I did not get accurate sound readings for my minimalistic exhaust at the practice.  Sunday's meter location was decent and I was recorded between 90.2 db and 91.0 db on all four competition runs.  Acceptable per the region with a limit of 93 db @ 50 ft, but louder than I feel comfortable with.

STR class runs late morning in the second group with bright sunshine and warm temperatures, and the class was full of great talent in very well equipped cars.   My first run I find a down cone and get a rerun.  Get the water sprayer and hit the Toyos. My second run was my first official timed run and it was my fastest time of the day but plus one cone.  Water the Toyos again.  Second, third, and fourth runs were all consistent and clean, I think, but a tenth or two slower than my first.  Should have brought the Hankooks.





Final results put me in third place in STR, over a second behind first, with fourth through seventh places within a tenth. Official Results Here.

 With the brake and toe changes complete, the car was more predictable and easier to drive.  Balance is excellent, motor feels strong, and the Torsen LSD puts the power down smoothly.  Overall, I am happy that the car came together so quickly and that it performs well.

Planning to Plan

  The first autox event for my new STR Miata at California Speedway did not go as planned.  Simply stated, I missed the setup and the car was loose and slow, over 2 seconds back from the leaders in STR.  Slower than STS too.  Class results are HERE.  Briefly, a combination of wrong rear spring rates, poor ride height, limited camber, and uncertain front toe left me with an ill-handling machine. Aside from that the car felt great with good power and nothing broke or fell off the car.

  Following the problems the previous week at the CalClub autox, I showed up early for Saturday morning's autox practice at Qualcomm Stadium and installed softer 375# rear springs with new PES rear shock mounts and lowered the ride height approximately 1/2" at all four corners. Rear shock ziptie measurments from CalClub tell me I was running out of travel so the custom 20mm extended shock mounts should solve that issue.  Some old bumpstops are also installed.

   As a result of the spring change, the car was transformed and drove beautifully with a few minor quirks.  Previous owner installed Hawk HP+ rear brake pads which in my opinion caused too much corner entry rotation under braking.  Also, front toe out was causing me to literally hit every apex cone on course.  I can adapt to these issues and some would prefer a car setup this way, but I could feel the car working well beneath me without the alignment and brake bandaids. 

The 450# rear springs that I removed should be an ideal setup for grippier surfaces such as the concrete at El Toro or Lincoln Airpark.

Current ride height is near 4 1/8" front, 4 1/4" rear with 195 Toyos installed.

Maximworks

Maximworks header for any 1994-2005 1.8L Miata.  Currently has an EGR bung welded to the number three runner with a matching custom EGR tube, and the collector flange has been cut off in anticipation of mating it to my NB midpipe flange. 

I am thinking about selling it; make me an offer.

SOLD

Enthuza

   Jason from Enthzacar sent me a nice axle-back muffler that weighs less than 12 pounds, fits great, and has a good tone with minimal drone.  Although the previously installed catted midpipe has a decently sized resonator, I am not confident this full exhaust combination will meet out local sound regulations, 93db @ 50 ft.  San Diego is pretty strict about sound, so I am sure it won't take long to find out if I need to reinstall the larger, heavier, and quieter Roadstersport muffler.

Good-Win Racing's Roadstersport muffler waiting just in case the Enthuza XR is too loud.

Alignment

The front camber is maxed out.  I went a little conservative with rear camber, but then I have the easy adjustment upper control arms from AWR, and minimal rear camber should help me apply the power upon corner exit. 

Current ride height measured at the pinch weld (1/8 tank fuel and trunk empty) is 4" front, 4 3/16" rear, with a tire height of 22 5/8".  Both the R1R and RS3 have a new full tread height of 22 3/4". 

Shocking

Custom shock tops for the yellow Koni Sport and Race NA shocks, but specially designed to fit the NB chassis.  These tops are based on the original NB Miata top, and offer extended reach and a spherical bearing mount.  The shorter pair increase shock travel by about 20mm, the longer ones 35mm.  After my first autox and once the ride height, spring rates, and alignment are finalized, I will have a better idea of how much more bump travel may be needed, if any.  Regardless, the bearing mount design will make its way to all four corners eventually.
  

Send an email to Practical Engineering Solutions Inc. if you are interested in purchasing some of these mounts for you Miata.