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.