Lupa's Debut Event - Tuning Suspension

After months of installing parts and getting her ready, it was time for Lupa's first autocross in full STR trim. Although I had adapted a lot of Bumblestook's settings over to Lupa to try and mimic her balance, I knew it would take time to get her the way we wanted since we had no actual starting point to compare against. We were also on fresh RE71s that hadn't been fully scuffed in so their performance was going to be reduced. Still, it was time to focus on the important thing at hand which was to try and get the balance to a good starting point.

Lupa ready to run - NNJR SCCA - 8-30-2015

I took the first run as a general systems check to make sure there were no issues with the car. There was no rubbing and we were going over the undulations with ease. We were good to push hard now to find the limits. I immediately noticed a very large amount of understeer that needed to get dialed out ASAP. We softened the front shocks and Hez took it out for a run and it was a bit better but still pushy. We also started off running 33/29psi but started to decrease this delta to find the balance and gain traction. I brought my pyrometer but the battery ran out so we were adjusting pressures blindly here unfortunately.

We increased rear compression and added more rebound all around to try and find that perfect balance between being critically damped and keeping the weight where we needed it to be in the transitions and powering out of sweepers. The goal wasn't necessarily to get the fastest time as it was to push the car to explore the limits and make all the necessary adjustments to dial out any observed weaknesses. Every run Lupa was feeling more and more balanced and the setup was moving in the direction we wanted. On the final run, which Hez took, it was important to drive for time rather than for tuning so he drove it normally and set our baseline. We were only a few tenths off the fast STR cars at the end the the day. This is very promising. You can see the difference in how the car behaves in the video of our fastest runs. My time was set on my third run and Hez was on his last run. You can see how much less effort it takes to drive her fast in that last run. He looks like he's on an early morning Tofu delivery run despite clocking in a respectable time.

Our Fastest Runs - NNJR SCCA Autocross - 8/30/2015

I'm highly encouraged by Lupa's performance. She unfortunately still exhibits push under power coming out of the tighter turn arounds and could be faster in the transitions with quicker weight transfer. We also ended the event running as low as 27psi all around. That was just a bandaid to try and balance her out but I don't think this is ideal as I'm sacrificing some of that sharpness in steering. There's also too much rear toe preventing her from rotating under power the way I want. The RE71s also seems to not roll much under load so I think we can afford to reduce some of the rear camber and salvage some straight line speed.

Below are the changes I plan on making before her next event. I think she's going to be up there competing for the top spot very soon.


Sway Bars:
Front: 6/6 full stiff (current 5/6)
Rear: 3/7 stiffness (current 1/7)

Alignment:
Front: -3.1, a hair of toe out (current -3.1, 0 toe ....well actually unknown since it shifted due to tranny installation)
Rear: -2.2, 1/16" (0.06) total toe in (current -2.4, 0.18 toe in)

Pressures: 
Probably try 29/27 but bringing a pyrometer to make proper adjustments.

Also, big thanks to Kamil at Clean Cut Vinyls for making my awesome car/class magnetic numbers and other decals.

NESTR - Decals by Clean Cut Vinyls - 8-30-2015

Magnetic numbers by Clean Cut Vinyls - 8-30-2015

Clutch, Tranmission and Differential

One of the major mechanical issues with Lupa is 2nd gear popout under deceleration. This is due to a known defect that affected a small range of S2000s between late 2004 and early 2005 and is covered by TSB 05-009. Unfortunately Lupa's VIN falls into this affected range of cars  but I didn't trust taking my car to any dealer even for warranty service so I had originally planned to just have the transmission rebuilt professionally by Billman. However, after we swapped in an AP1 tranny in Bumblestook, I already had a perfectly known working low mileage AP2 tranny just sitting around so I decided to just swap it in instead.

Transmission swap - 8/15/2015

This time I employed the help of Jonathan (Soul Coughing on S2ki Metro) to do the swap for me. Jonathan had already done several clutch, transmission and diff jobs before and as a fellow dual S2000 owner, I felt confident he could do the job right. While we were going to swap the transmission anyway, I decided that even though I only had 55K miles on her, it would make good sense to replace the clutch as well. We put in a brand new OEM AP2 cluch, flywheel, pressure plate and bolts.

Old clutch and flywheel out, still in great condition - 8/15/2015

New clutch and flywheel in - 8/15/2015

Lastly we also swapped in Bumblestook's spare diff pumpkin which has a new ATS Spec III clutch type diff put together by Brian at Karcepts. The OEM torsen is more than capable but I prefer the feel of a clutch type diff and by keeping Bumblestook and Lupa on the same setup, it would be easier for me to continue a similar tuning philosophy and have matching spare parts.

ATS Spec III diff ready to go in - 8/15/2015

When Rad found his diff mounts were torn during the NJ ProSolo earlier this year, he found a method to just fill the OEM mounts with polyurethane for a cheap DIY poly mount alternative. I had him make a set for me too and we installed those along with the diff to minimize any play as we try to get power down to the ground.

DIY Poly filled OEM Diff mounts - 8/15/2015

Although we ran into a few annoying issues (mostly because of my swaybars, stiff mounts and dual exhuast was in the way), everything went in smoothly and she's now driving perfectly. I'll have to get another alignment since you have to lower the front subframe to swap transmissions on the S2000 but I probably won't do that until after I come back from Nationals. The good news though is that she's ready for her first event which should happen in 2 weeks barring any further issues. I'll have to make time to drive her quite a bit until then to break in the clutch and diff but that's something that I can at least enjoy. It's been almost 3 months since I ordered the very first part for this STR build and I can finally say all the major mechanical work is done and it's onto having fun and seeing how she stacks up against the other STR cars that have had several years to be developed already.

Huge thanks to Jonathan for doing a great job with this part of the project, taking his time to do it right. It's good to see fellow S2K owners who appreciate the need to do things right and not take shortcuts.

First Alignment for Lupa

After test fitting the STR spec wheels and tires, it was clear that I'd need an alignment ASAP if I wanted to have Lupa drivable and not ruin my tires or fenders. With SJF Performance unavailable, I was lucky to get squeezed in for an appointment at Camber Toe Performance in Lynbrook this past Saturday. 

First alignment - Camber Toe - 8/8/2015
Photo by: Joe Miranda / Camber Toe

Since I haven't autocross Lupa yet, I wanted to just set an initial baseline alignment based on some numbers I had been toying around with on paper. I'm almost certain I'll be re-aligning again before this season was over so a good ballpark would be all that was needed. I ended up with the following alignment specs:

Front:
-3.1 Camber
0 Total Toe

Rear:
-2.5 Camber
0.18 Total Toe In

I'm glad we did the alignment since I was running almost a full inch of toe in at the rear and definitely wasn't running enough camber up front so my fenders were in danger of some carnage if I got full compression load due to a bump or something. I also asked them to bend the fender tab in the front for a little bit more tire clearance. There's no need to do a full roll on +63 offset wheels with 255 sized tires.

We're almost there. I'm shooting to take her out to her first event later this month.

Wheels and Tires

After weeks of letting the springs settle and adjusting the ride height, I'm finally happy with where she sits so I decided to put on the wheels and tires I got for her to complete her STR trim. I didn't want anything expensive or too flashy for the wheels. I looked for something that came in the CR wheels silver color or something that would very closely match the Silverstone color of her body. I went ahead and picked up a set of Kosei K5R in 17x9 +63 offset in light gray.

Lupa in full STR trim - 8/5/2015

In pictures it looked like a good match but it was still a gamble since I hadn't seen these in person on a Silverstone S2000. I was pleasantly surprised to see that they were a perfect match and looked great without being overly flashy or attention grabbing. I was further happy to see that they came mounted with red anodized valve stems. It's a great complement to my black/red interior and soon to arrive red/black class letters/numbers.

Lupa in full STR trim - 8/5/2015

They're wrapped in super sticky 255/40/17 Bridgestone Potenza RE-71R all around. I could immediately feel the increased turn in response with the wider front tires. Next up is an alignment since the front isn't cambered enough and I'm going to have to bend the fender tab a little since it rubs a bit driver side but overall I'm very happy with the fitment.

Bridgestone Potenza RE-71R wrapped Kosei K5R - 8/5/2015

Not visible on the photos are the lug nuts. I went with EVS Tuning (Evasive Motorsports) "Super lap" open ended racing lug nuts made of forged SCM435 steel alloy since I don't trust aluminum lug nuts.