Not a lot to add except the following given that you have a Miata and wish to have a CaymanS: I gained a few shareable insights to the LSD plusses and minuses having autocrossed and/or tracked/ club raced (PCA), etc. 924S, 944t, 968, CaymanS, GT3 Cup Car and Miatas (SCCA) between 1990 to 2019. The LSD will do two things well if it's a good one. It will lessen inside wheel spin in a tight corner and it will also create a bit of "push" coming out of that same corner if the corner is not approached properly. I have a Guard LSD on my 2007 CaymanS and had a Porsche Race mechanic in Phoenix, AZ install and adjust it so that there is not much push at all. It has never spun an inside wheel. As many others have said, the CaymanS does not "need" an LSD for normal street and track use. It does, however, become very appreciated when driving speeds are elevated in downpours of rain where it puddles on a course or track in the corners. I like that it is separate from the braking and engine management techniques used. Hope that helps. Cheers.

 

Richie Fletcher- Maybe you could help me tune my PSM to work perfectly for my needs. Coming out of a tight 180 degree corner heading to the same crossover and straight to the next corner, I find I am sliding the rear end enough to trigger my yaw sensor. The work around is to turn off the PSM, but I find that its useful in other areas and it teaches me to stay with the 8 degrees of slip angle. However, I have read that if I had Sports Chrono, and had it engaged, the top yaw angle would be 11 degrees or so. That would be enough for me to rotate the car, while still not triggering the PSM. With the Wavetrac, it seems that that triggering of the PCM is much less than with an open diff. Its just a slight dip in power.

So, what can you do with the PSM to manage that system as well as have the features you want from the Guard setup the way you wanted. I know that some have put a cutoff switch for the yaw sensor, but then that would defeat any PSM activity. Some is on trailbraking and does help in snap oversteer as well. Let me know as I am interested in either a SC option without the wart, or a yaw switch to give me a little more yaw slip angle.

 

ochristofferson-Cantrell Motor Sports in Kirkland, Wa installed the Wavetrac. We used Motul 75W-90 Transaxle oil. Works just fine and is recommended by Wavetrac. This LSD does not have clutches as the above Guard LSD does. So Richie Fletcher may need new clutch discs sooner or later depending on his use. My Wavetrac will not need anything. One area where some Guard clutch setups are better is threshold braking do to lock up. Mine is does not lock up 100%, but does offer deceleration aid that prevents threshold wobble. The good news is that since its not locked up tight, trailbraking, apex throttle modulation, and slalom action does not cause understeer or oversteer. This is important as you can use more throttle earlier after the apex without worrying about snap oversteer, because the wave slider does not lock up totally, but close enough to burnout with both wheels spinning evenly for a straight ahead start.

I do wonder about a slight vibration on deceleration at very low speeds 20 mph or so, which I never felt with the open diff. However, I also changed to Function First Orange transmission mounts at the same time so who knows if its the LSD or the transmission mounts. I also have the F First Orange motor mount, so both are subject to additional NHV.

 

ochristofferson-Cantrell Motor Sports in Kirkland, Wa installed the Wavetrac. We used Motul 75W-90 Transaxle oil. Works just fine and is recommended by Wavetrac. This LSD does not have clutches as the above Guard LSD does. So Richie Fletcher may need new clutch discs sooner or later depending on his use. My Wavetrac will not need anything. One area where some Guard clutch setups are better is threshold braking do to lock up. Mine is does not lock up 100%, but does offer deceleration aid that prevents threshold wobble. The good news is that since its not locked up tight, trailbraking, apex throttle modulation, and slalom action does not cause understeer or oversteer. This is important as you can use more throttle earlier after the apex without worrying about snap oversteer, because the wave slider does not lock up totally, but close enough to burnout with both wheels spinning evenly for a straight ahead start.

I do wonder about a slight vibration on deceleration at very low speeds 20 mph or so, which I never felt with the open diff. However, I also changed to Function First Orange transmission mounts at the same time so who knows if its the LSD or the transmission mounts. I also have the F First Orange motor mount, so both are subject to additional NHV.

Noted - thank you.

 

So, just completed another PCA autocross today in GT3 class with my lowly Cayman S. This class was made for those racers who want to modify their rides with a 3.3 to 4.0 liter motor and no supercharger or turbo. Modified GT4's fit this class and I routinely get a lesson every time Keith Brown's shows up. This class also allows us to run Hoosier A7's, which I have.

After installing the Wavetrac, and finally tuning my car's suspension (Ohlin's, Tarett GT swaybars f&r, Tarett Cup LCA's to add camber and track width, etc). Now, I am finding that with PSM on, even with smooth driving techniques, I am getting a couple of PSM interruptions per run. I turned it off and found that I was faster with it on, staying just below its threshold.

Now that I am adding more throttle at apex, using the Wavetrac and Hoosier A7's, I am finding the back starting to oversteer slightly. I do not have Sports Chrono in my 987.1S. I know I can add this feature, but would it modify the 987.1 version of the PSM to up the slip angle just a little before intervention occurs. That would work for me this year if it works that way. Anyone with a LSD and sports chrono activated describe the difference between SC on or SC off and the activation of PSM while slip angle is above 8 degrees. I believe that 8 degree is where the OEM PSM system kicks in. Just want a few degrees more from the PSM before it activates. With the Wavetrac, the PSM activation is not nearly as invasive as with an open diff. So, it will not kill a run, but if you get more than 1 per run, you most likely have lost .5 seconds. The PSM intervention seems much shorter with the Wavetrac, so I can add power almost as soon as the PSM activates.

 

I did not ask Scott about the Yaw feature. Seem to me the maps he changed with engine related. If he did then it changes my search and result. I would then need a yaw switch rather than a slight change in slip angle. I still like many of the PSM features that work well with the ATB LSD.

 

After talking with Scott@Softronics, he said he does not change the yaw features of the PSM system. He did refer to a couple of modifiers who have put an on/off switch in the shifter/parking brake hump to remove the yaw gryo from sending info to the PSM. Scott says when shut off, many lights occur on the dash, mainly the braking systems. What Scott says is that the brakes work just fine, even with the dash light on.

Back to my plight is that I will just have to live with the 8 degree yaw for a while. It only affect my car on the 180 degree corners, and is throttle responsive. I still can turn off the PSM if I feel the need. I tried that in the past, but usually my times are almost a steady progression downward, so I will not benefit from the 4th run when I turn it off as its usually slower.