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The suspension obviously was setup for AWD. The alignment is close but the sway bars are much too stiff both in the front and rear.
The stiffness in the front was causing the car to push understeer if I turned in too early, where AWD I could hit the throttle and simply push through the apex.
The stiffness in the rear meant the throttle needed to be added with much more finesse through turns and directly linked with steering. Too much throttle and the car will begin to oversteer where the AWD system would simply pull through to the apex. Where I'd have my foot down exiting with AWD I'd have to lightly increase the power in relation to the steering wheel gradually getting back to center.
If the steering angle was too steep, the PSM immediately kicked in. Many times obstructively.
I took the PSM off a little prematurely and ended up coming out of a long turn sideways. Need to get the diff and axles out and corner balance as the combination of too stiff/heavy sway bars in the wrong places, opposite toe/caster for AWD vs RWD, really had the car fighting itself in undesirable places on the track the whole day but it was a ton of fun to try something new.
The lines required to get the most from the RWD system versus AWD are much cleaner, smoother momentum lines. I'm driving less 'aggressive' and more 'clinical' because of it which results in better times. The AWD system really masks a lot of bad habits and allows you to be faster than you are. I learned a lot today.
Any way, we're going RWD based on this:
Same suspension.
Same alignment (GT3 specs).
Same sway bar settings (middle on F/R of H&Rs)
Same brakes.
Same driver.
Same track conditions as many other days I've been there. 8 events this year.
Personal Times: AWD Best at the Ridge: 1:56:35 (June)
I can say its taken a whole season but I can now drive the crap out of the car with the AWD system. This is about the best I can do with that configuration.
RWD: Morning, Cold Track, Cold Tires: 1:56:50 (Today)
This was insane. It was 2nd lap of today. 9am. Cold. Windy. Bad tire pressures. You name it.
RWD: Afternoon, Hot Track: 1:54:30 (Today)
40+ laps today. Most under 1:57 on a poorly setup RWD car and I pull out my best yet.
It took multiple events over the past few seasons to break 2:00. Even longer and some add'l parts to get down to 1:58s.
30 minutes.
Drive shaft out.
40 laps on a bad setup.
2 seconds faster.
Still have 70 lbs of crap to remove.
Unreal.
Last edited by vandersmith; 07-23-2016 at 05:11 AM.
Gaining 2 sec with everything feeling off? Wow. You always hear 2wd is better on the track but this is the first real data I've heard on it. Congrats on the improvement.
Here's some track video from Friday's PCANW day at the Ridge:
Car was aligned, lowered and corner balanced at TruLine Bellevue to the GT2 Specs with new NT01s.
The car responded brilliantly but was a handful.
Took an entire day to get the line dialed as the car favored much more oversteer versus the predictable throttle and push thru apex that existed with the previous alignment.
Slow in fast out matters much more now as throttle application mid-turn requires much more finesse than before. Turn in was much improved.
Entry, Mid, Exit speeds are all relatively the same but the car is much more lively.
I dig it and will need a few more days to adjust. Lap times we're similar 1:55s-1:56 on new NT01s that weren't broken in. They should drop a few ticks as I acclimate and they break in.
Anyway, here's the final session's video chasing a few instructors and my buddy in his 930 Turbo.
After 17 Track events this season, I've finally worn down my new Coleman Rotors past their safe point, the slots are almost completely gone on my front rights. Front Pagid RS29s are also toast.
New ones are on the way so I can get back out there.
In the meantime:
Air Box - Going to take Raby's advice and try to source a 997 3.8 Intake Box and dyno against the EVO kit
Pedals - I've had a set of the adjustables from Rennsport in a box this whole season, time to install
Brakes - I've also had a GT3 Master Cylinder laying around, time to put her in
Goods for sale:
Plugs/Coils - Brand new
996 GT3 F/R Rotors with lots of life
Complete 996 C4S/TT Red Brakes (Rotors/Calipers/Pads)
Set of Hollow Turbo Twists
I'd take the coil packs and plugs, was on my list to do this winter. Also interested to know if you still have the mufflers. I'll look for your ad, I'm sure there are some other bits I could use!
Hey, I just noticed your thread, a lot of good info. I've done a LS3 GM motor swap in my C4S and ate the front CV joints pretty quick so I've converted mine to RWD also, Just yesterday I had someone post on my build thread about the front suspension geometry being different on the AWD vers the RWD and suggested I change the shock uprights. Wondering if you've heard of this. This is a copy of that post
"With the front drive disconnected, you also have the added benefit of being able to switch out the shock uprights. The turbo uprights are offset to accommodate the driveshafts while the GT2 (RWD turbo) or GT3 (RWD nonturbo) had more 'proper' uprights which go straight up. The difference in suspension geometry and 'feel' is substantial, with the proper uprights having a much more natural and intuitive feel on road and track.
Having driven a 996 GT2 vs my 996TT back to back, this is the first and most prominent difference I noticed between the two. Bump steer especially is terrible on the TT due to the uprights/geometry."
07-23-2016, 04:46 AM
RWD vs AWD
