Rx8 track testing with JDM S2 Transmission & ATS clutch
 

Bought this mint condion JDM S2 Transmission for quite while, always hesitate swap out my super nice S1 transmission , been performed perfectly

Due to my clutch issue (can check it out why from my other thread) https://www.rx8club.com/rx-8-racing-25/clutch-pedal-stick-floor-only-when-track-4-3-2-downshift-271434/page3/
So i bought a ATS carbon clutch to try out hope to fix the issue for my oncoming track day



Impressions from S2 Transmission
Shift quite nice as i expected, but gear ratio not quite up suit my home track
Comepare to my datalogger,u can see
On button bar is my rpm chat red is S1
Blue is S2 both with 4.777 final drive
Compare to S1 , S2 Transmission Rpm is like 600-700rpm lower thus 2-3km slower on speed, u really need 5.125 to take full advantage of S2

As ats carbon
Although some charter feel on start up
But
I like how it smooth engagement on WOT shift, i feel it will offer more protection compare to tradional metal clutch

the JDM version of both had some different gear ratios than USDM versions. Without stating what those ratios are to be sure then it doesn’t mean much for us here. I’m thinking it was only 3rd and 6th gear that were substantially different S1 vs S2 though. All the other gears were within 1 - 2 mph of each other at redline. Which isn’t that much rpm difference.

So you must mostly be using 3rd gear then?

According to rx8 magazine
They are
3.815
2.260
1.536
1.177
1.000
0.787

S2 ........ S1 ........ Delta
3.815 ... 3.760 .... 1.46%
2.260 ... 2.269 ... -0.04%
1.536 ... 1.645 ... -6.63% <——
1.177 ... 1.187 ... -0.84%
1.000 ... 1.000 .... 0.00%
0.787 ... 0.843 ... -6.64% <——

The NC Miata has a 1.640 3rd gear and 0.832 6th gear, but on a street car the taller RX8 6th gear is better for cruising with a 5.125 rear gear. 3rd gear swap might be possible as the 3rd gear pair can be purchased from Mazda. Some of the gears are integrally machined on one shaft or other and then that becomes much more difficult and expensive to address.


.

Place order of 5.3
Let see what this will perform !!!

After 10 track day with some 9300rpm no lift shift

Stock S2 Clutch throw out bearing finally failed
Cause Pedal to floor it , and Slavs leak too
And is about time to rebuild my ATS carbon cluch next year , I can see clutch pressure plate finger drop down a bit indicated a wear
And this might cause throw out bearing over extent ,
For now just get the new throw out bearing

The failure sign was not very obvious, only some bearings noise at cold , not unnormal engage
And it happens on the way to gas station

I have one of these ATS carbon 1-disc clutch/flywheel assemblies that I picked up used locally, they’re neither light in weight or cost.

Will you swap to the hydraulic throw-out setup? I don’t think you ever said what the USD cost would be.
.

Off shelf ATS clutch and flywheel set is more like high performance + track day , not full on race part
What i like it most not just weight , is less shock load at engaging in Wot , much smoother then full metal and better protection

Have not collect all the part yet
So just get a OEM throw out bearing to temporarily fix

Build a clutch stopper
To limit travel , so won't over travel of bearing
still need to find right engagement point