I have a similar set up to yours except shocks and didnt feel the need for the rs rear side subframes, I kept the original gt2 items.
it all worked out fine, been running the same set up for a few years now and all good.
If my car was a turbo for example and didnt have the solid mounts I probably would have got
the rs subframes but didnt feel the need with gt ones already, I know the rs ones are different but I dont think it would make any noticeable difference too be honest over gt3/2 parts.

 

Suspension bits are installed, an alignment has been done to set the ride height and geometry, and I've had two days on the mountains. We set it to 105/120mm front/rear ride height (I'm on OEM wheel/tire sizes) and used the base settings Nitron gave. I have not installed the LSD and FD yet.

Alignment is -2.5/+1mm per side/7.5 degrees front, -2/+2mm per side rear. My plan is to break in the new suspension, dial in my street damping settings, then re-align and corner balance the car.

First impression is.... DAAAAMMMNNNN!! Night and day difference.

 

A few pics.

 

Changster! That’s exciting news. So what’s the verdict on the rear subframes (and front) you get it all setup with the regular 996 GT3 subframes?

 

Attached is the Porsche document describing the GT3 vs GT3 RS differences.

Front subframes are definitely not needed for the conversion as it’s the same.

Rear side members are indeed different but so far after setting my ride height, getting an alignment, inspecting the travel while moving the wheel full bump and droop, locking out the eccentric, and then driving the car at a fast pace through mountain roads I didn’t notice any weird behavior in the rear. It feels super solid.

Apologies for the confusion earlier on what I said about rear toe. I thought the shop had already set the ride height to exactly where it was before, but that was not done.

 

Some tools we invested in for the trans.

 

What would you account to RS Kinematics and what would you account to Nitron?

 

I would guess the Nitrons. Since the gt3 geometry is the same as a cup set up there is no way the rs geometry is of any benifit unless u r pushing the car to 10/10 on the track.

The cups crush it on the track and they r just a little lighter with 3way shocks. Maybe 30hp more.

 

Really? The RS wheel carriers lower the pickup point of the tie rod end back to nearer parallel which should significantly reduce the bumpsteer & tramlining tendency?

 

So u have bumpsteer? If so its easily fixed with front arms and washers. Not need to spend 4k in parts. Also i dont find my car to tramline and im sure most dont push that hard to feel it if it does happen. Maybe im wrong?

Have u have ever watched a 6-cup race and how hard they can push the standard geometry with an excelent shock? There is no way in hell i would ever push my car that hard on the track much less on the street so there is no way 99% of the gt3 owners would ever be able to realize the benifits of the rs upgrades. Im just saying the rs is the tip of the spear and its not needed if u r not driving 10/10.

That being said my car does have front rs uprights and ill finally be getting the rears this winter. I could just replace the front uprights for the same cost to gt3 uprights but that seems silly. So ill be driving 8/10 next year on the track in a car thats much better then i am.

 

Well the Nitron is damping and platform control and it's more of a general feeling of smoothness and compliance at all times. Kinematics is more what the geometry is doing during dynamic travel and I equate that to more of a feeling of precision and stability. I've done step by step changes of kinematics and coilovers on other cars and I know what the each feel like but it's a bit hard to describe. For this car I did it all at once because I had 20 year old 100k km OEM suspension and I felt everything was just tired.

One change I will make for sure is to get a longer rear spring. The current 140mm length springs (5.5"-ish) I think is too short for OEM tire sizes at standard Porsche spec factory ride heights. There is definitely too much preload at 128mm but somewhat ok at my current 120m rear height. Thus a 160mm (6.3"-ish) I think would be perfect.

The JRZ's by default I think comes with a 6" rear main spring.

I have 110, 140, 170, 200 N/mm main springs here (about 600/800/1000/1200 lb) to test and I'm on the 110/140 currently. I'm thinking I want to setup this car mainly for the touge which means I'm leaning toward using the softer side of the springs. If I use the stiffer mains I'm sure the preload in the rear would be fine.

 

I'm pretty sure kinematics affect how the camber and toe changes under the entire length of suspension travel, and thus if you change the pickup points it will affect camber and toe changes even before the limit. I don't think only at the limit do the geometry pickup point changes "kick in" if you know what I mean. What exactly those camber/toe changes are of course I don't know precisely. I do know with my old stock tired suspension I had weird behavior even at moderate cornering speeds before. Even at my base damper settings and without changing the diff that's laying here, the weird behavior is gone.

This is about the pace we go through touge roads here. Maybe 2x a week. These roads are also very representative of our touge roads. They're not huge canyon roads like Angel's Crest, but more of a narrow tight stuff over and over like Tail of the Dragon.

 

I've put about 20 hours of very hard touge driving thus far and all I can say is it's damn amazing. Night and day vs my old OEM suspension. I also got a chance to test drive my friend's 996.2 GT3 on a refreshed OEM suspension (all OEM components) and it's also night and day vs that. I have to say, a refreshed OEM suspension was also much better than my old non-refreshed OEM suspension. My current setup has way less body roll than either OEM suspension, much sharper front end, more confidence inspiring, etc etc.

Having said that, my current thinking is that the spring rate of 110/140 N/mm is just right for the touge but will be too soft for the track. I'll likely spend 3 days at the track 9/8-9/10 so will find out soon.

Cup FD and Drexler LSD isn't installed yet btw...

 

Hanging out with the big boyz today!

 

Quick impressions after today on the new setup:

- After dialing in more front rebound to help with locking the front down, I was happy with the overall balance of the car even with the front and rear bar at full soft.
- Car could use more platform. I will play with the ARB's first before stepping up in spring rates. I really do like these spring rates for the touge, but for sure more spring I can sense will be better on track.
- Car definitely needs more front tire. Apex's new ML wheel is like an E88 replica although coming only in 18x9 and 18x11, but it should let me run RE71-RS's in 255/35 front and 295/30 rear. At this point with this car's power level I don't think I need more rear tire yet, but we'll see. I'm currently on AD09's in OEM sizing.
- I can't wait for the Cup 4.0 FD to go in. There are many corners at my local track where I liked entering the corner in 3rd with more momentum, but was out of the right rpm range on exit. Whereas if I entered using second gear, the car slows down too much during the corner but I have great power on exit.