Orthojoe's track build journal
02-01-2015, 01:34 PM
#271
Rennlist Member
3) Alignment. After I went in to fix the rear toe, it was noted that the supension still settled at bit. Actual alignment numbers were zero toe front, 4mm total toe rear, -2.7 camber front, -2.4 camber rear. Front and rear sway bars in the middle position. The car drives near neutral with this. A touch of understeer at corner entry, and a touch of oversteer at corner exit. It's perfect. The only thing that needs to be changed is the rear camber. Keep in mind, my goal is EVEN tire wear, not ultimate grip. The front tires are wearing evenly, but the rear is still wearing a bit on the outer edge. I think I'll have the rear camber increased further to -2.6 or -2.7 (I should have just listened to Sam!)
02-01-2015, 01:59 PM
#272
Rennlist Member
Shop recently pulled all rubber out of 991 gt3, forged cup parts, some custom monoballs, etc. Comment from chassis guru is stock dampers are quite good, car is much more responsive and not harsh with the monoballs. They also did the muffler side deletes (same trick from the 997 cars)
02-01-2015, 02:30 PM
#273
Nordschleife Master
Thread Starter
Sorry for my ignorance, but I am relatively new to this and am trying to understand the idea behind the toe of 4mm at the rear. I am assuming it would be an outward facing toe to decrease mid corner oversteer at the limit, is that correct? Does this cause uneven wear for street use? I also wonder how active rear steering would affect the behavior of the tail at the limit, especially below 50mph when its turing the opposite direction.
Shop recently pulled all rubber out of 991 gt3, forged cup parts, some custom monoballs, etc. Comment from chassis guru is stock dampers are quite good, car is much more responsive and not harsh with the monoballs. They also did the muffler side deletes (same trick from the 997 cars)
02-01-2015, 02:38 PM
#274
Burning Brakes
That's somewhat speculative, since identical scenarios minus the roll bars didn't occur. But given what happened with the roll bars, risk of injury or death does seem to have been substantially reduced. Fatalities at track events are relatively rare though, very sadly, we've already had one RL member experience fatal injury at a track event in his 991 GT3.
02-01-2015, 06:00 PM
#275
02-02-2015, 01:23 AM
#276
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Now if you have toe out at the rear, you have the opposite effect. And even though that can help with making the car rotate more, it's not worth it because it creates natural instability when braking.
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02-02-2015, 01:27 AM
#277
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Shop recently pulled all rubber out of 991 gt3, forged cup parts, some custom monoballs, etc. Comment from chassis guru is stock dampers are quite good, car is much more responsive and not harsh with the monoballs. They also did the muffler side deletes (same trick from the 997 cars)
02-02-2015, 02:01 AM
#279
Rennlist Member
02-02-2015, 02:29 AM
#280
Rennlist Member
Edit: After doing some research in the forum, I see that the 4mm toe has been the setup that many ran the 997 GT3s. I wonder how the active steering will change things.
Last edited by gago1101; 02-02-2015 at 02:58 AM.
02-02-2015, 04:52 AM
#281
Burning Brakes
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That's somewhat speculative, since identical scenarios minus the roll bars didn't occur. But given what happened with the roll bars, risk of injury or death does seem to have been substantially reduced. Fatalities at track events are relatively rare though, very sadly, we've already had one RL member experience fatal injury at a track event in his 991 GT3.
02-02-2015, 10:13 AM
#282
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02-02-2015, 11:09 AM
#283
Nordschleife Master
Thread Starter
Thanks for the explanation Max. Is the active rear steering in the GT3 trying to achieve the same thing? stability above 50mph (steering the same direction similar to toe in) and rotation below 50 mph (steering the opposite direction, similar to toe out) Edit: After doing some research in the forum, I see that the 4mm toe has been the setup that many ran the 997 GT3s. I wonder how the active steering will change things.
02-02-2015, 06:03 PM
#284
What is the stock toe setting in the rear? The 1.5* rear steer max is about 2mm. So the 4 mm total toe is maintained, but now all 4 mm is on the outside and basically 0* on the inside. Of course no dynamic effects are considered here. We always set between 2mm and 7 mm in old 911s based on open vs LSD. Less toe in with LSD. Very interesting stuff! Gordon
02-02-2015, 06:04 PM
#285
Nordschleife Master
Thread Starter
What is the stock toe setting in the rear? The 1.5* rear steer max is about 2mm. So the 4 mm total toe is maintained, but now all 4 mm is on the outside and basically 0* on the inside. Of course no dynamic effects are considered here. We always set between 2mm and 7 mm in old 911s based on open vs LSD. Less toe in with LSD. Very interesting stuff! Gordon