trail braking
Aug 23, 2004, 09:04 PM
#228
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Originally Posted by Mike W
The RRE car had in that SCC EVO competition and still has at this moment the helical (Torsen type) EVO V stock front differential.
One drive around the block with the EVO 5 differential and I could tell it was understeering huge compared to the nice neutral it was a few hours before installing the diff. Even with out hard driving.
Mike W
One drive around the block with the EVO 5 differential and I could tell it was understeering huge compared to the nice neutral it was a few hours before installing the diff. Even with out hard driving.
Mike W
The helical may be too tight on decel?
Aug 23, 2004, 09:23 PM
#229
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Uh, oh, well at least we're back on topic 
.... One of the nice things about a helical front is that it helps prevent locking one tire under braking, including trail braking. F1 teams actually found a significant gain in putting just an LSD (unpowered) between the front wheels of a formula car. Just as it applies more pressure to the tire with more grip under acceleration, it can help prevent an unloaded tire from locking under braking. It was ruled illegal before seeing any competition though.
.... One of the nice things about a helical front is that it helps prevent locking one tire under braking, including trail braking. F1 teams actually found a significant gain in putting just an LSD (unpowered) between the front wheels of a formula car. Just as it applies more pressure to the tire with more grip under acceleration, it can help prevent an unloaded tire from locking under braking. It was ruled illegal before seeing any competition though.
Aug 23, 2004, 10:03 PM
#230
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Originally Posted by Scottybob
Robi,
How are you measuring the downforce figures you are posting?
How are you measuring the downforce figures you are posting?
The next data logger has ride height potintometers and we will compare aganst the picture data.
Aug 24, 2004, 05:10 PM
#231
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Originally Posted by robi
Currently with pictures from the pit wall and you measure the ride hight differance and cal against the spring rates.
Aug 25, 2004, 09:23 PM
#233
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1st post here, just been browsing for a while b/c I'm considering buying an Evo. I've been racing Solo1&2 for 4 years and am currently an aspiring vehicle dynamics engineer pursuing a master's at Colorado State University.
The one thing I didn't see brought up in this thread (unless I overlooked it) was suspension setup for a particular driver. Robi, Cronohunter, and Siegel are obviously highly skilled drivers and can adapt their driving styles to account for deficiencies in vehicle design or setup. The goal of a suspension engineer is to setup the car (within any given limitations) to the driver's style. Some drivers love front LSD's and others hate them.
I race a FWD VW and it understeers so much that I can't take a traditional race line for fast laptimes. I have to adjust for the limitations of the car. Once I put a Quaife in, I had to "re-learn" how to drive it. My corner entry is now less responsive, but I make up for it by turning in earlier. Corner exiting is so much easier now, I can get back on the gas way earlier without fear of power-out understeer. I personally prefer being able to power out of a turn without plowing like a tractor, even at the expense of have to adjust corner entry technique, but then again FWD cars are a different beast all together.
If any of you know Claude Rouelle and his Motec-sponsored vehicle dynamics seminars, he tells some interesting stories at the end. Claude has been a principle engineer for F1 teams, Rally, IRL, CART, you name it. When he was setting up Arie Luyendyk's car (the year he won Indy), they had it perfectly neutral, even test drivers thought so. When Arie got in the car, he said he was terrified because the car gave no indication of whether u-steer or o-steer was going to put him in the wall. Claude had to carefully add in just enough understeer (by reducing front end grip) to give Arie enough indication that he needed to know when his corner entry was too fast.
So enough rambling, my point is that no suspension setup is "more" right than another. In the end, with the best drivers, it will come down to driver preference.
The one thing I didn't see brought up in this thread (unless I overlooked it) was suspension setup for a particular driver. Robi, Cronohunter, and Siegel are obviously highly skilled drivers and can adapt their driving styles to account for deficiencies in vehicle design or setup. The goal of a suspension engineer is to setup the car (within any given limitations) to the driver's style. Some drivers love front LSD's and others hate them.
I race a FWD VW and it understeers so much that I can't take a traditional race line for fast laptimes. I have to adjust for the limitations of the car. Once I put a Quaife in, I had to "re-learn" how to drive it. My corner entry is now less responsive, but I make up for it by turning in earlier. Corner exiting is so much easier now, I can get back on the gas way earlier without fear of power-out understeer. I personally prefer being able to power out of a turn without plowing like a tractor, even at the expense of have to adjust corner entry technique, but then again FWD cars are a different beast all together.
If any of you know Claude Rouelle and his Motec-sponsored vehicle dynamics seminars, he tells some interesting stories at the end. Claude has been a principle engineer for F1 teams, Rally, IRL, CART, you name it. When he was setting up Arie Luyendyk's car (the year he won Indy), they had it perfectly neutral, even test drivers thought so. When Arie got in the car, he said he was terrified because the car gave no indication of whether u-steer or o-steer was going to put him in the wall. Claude had to carefully add in just enough understeer (by reducing front end grip) to give Arie enough indication that he needed to know when his corner entry was too fast.
So enough rambling, my point is that no suspension setup is "more" right than another. In the end, with the best drivers, it will come down to driver preference.
Aug 25, 2004, 09:53 PM
#234
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Originally Posted by Djazair
1st post here, just been browsing for a while b/c I'm considering buying an Evo. I've been racing Solo1&2 for 4 years and am currently an aspiring vehicle dynamics engineer pursuing a master's at Colorado State University.
The one thing I didn't see brought up in this thread (unless I overlooked it) was suspension setup for a particular driver. Robi, Cronohunter, and Siegel are obviously highly skilled drivers and can adapt their driving styles to account for deficiencies in vehicle design or setup. The goal of a suspension engineer is to setup the car (within any given limitations) to the driver's style. Some drivers love front LSD's and others hate them.
I race a FWD VW and it understeers so much that I can't take a traditional race line for fast laptimes. I have to adjust for the limitations of the car. Once I put a Quaife in, I had to "re-learn" how to drive it. My corner entry is now less responsive, but I make up for it by turning in earlier. Corner exiting is so much easier now, I can get back on the gas way earlier without fear of power-out understeer. I personally prefer being able to power out of a turn without plowing like a tractor, even at the expense of have to adjust corner entry technique, but then again FWD cars are a different beast all together.
If any of you know Claude Rouelle and his Motec-sponsored vehicle dynamics seminars, he tells some interesting stories at the end. Claude has been a principle engineer for F1 teams, Rally, IRL, CART, you name it. When he was setting up Arie Luyendyk's car (the year he won Indy), they had it perfectly neutral, even test drivers thought so. When Arie got in the car, he said he was terrified because the car gave no indication of whether u-steer or o-steer was going to put him in the wall. Claude had to carefully add in just enough understeer (by reducing front end grip) to give Arie enough indication that he needed to know when his corner entry was too fast.
So enough rambling, my point is that no suspension setup is "more" right than another. In the end, with the best drivers, it will come down to driver preference.
The one thing I didn't see brought up in this thread (unless I overlooked it) was suspension setup for a particular driver. Robi, Cronohunter, and Siegel are obviously highly skilled drivers and can adapt their driving styles to account for deficiencies in vehicle design or setup. The goal of a suspension engineer is to setup the car (within any given limitations) to the driver's style. Some drivers love front LSD's and others hate them.
I race a FWD VW and it understeers so much that I can't take a traditional race line for fast laptimes. I have to adjust for the limitations of the car. Once I put a Quaife in, I had to "re-learn" how to drive it. My corner entry is now less responsive, but I make up for it by turning in earlier. Corner exiting is so much easier now, I can get back on the gas way earlier without fear of power-out understeer. I personally prefer being able to power out of a turn without plowing like a tractor, even at the expense of have to adjust corner entry technique, but then again FWD cars are a different beast all together.
If any of you know Claude Rouelle and his Motec-sponsored vehicle dynamics seminars, he tells some interesting stories at the end. Claude has been a principle engineer for F1 teams, Rally, IRL, CART, you name it. When he was setting up Arie Luyendyk's car (the year he won Indy), they had it perfectly neutral, even test drivers thought so. When Arie got in the car, he said he was terrified because the car gave no indication of whether u-steer or o-steer was going to put him in the wall. Claude had to carefully add in just enough understeer (by reducing front end grip) to give Arie enough indication that he needed to know when his corner entry was too fast.
So enough rambling, my point is that no suspension setup is "more" right than another. In the end, with the best drivers, it will come down to driver preference.
Excellent Post!!
Percy
Aug 26, 2004, 06:57 AM
#236
Originally Posted by Djazair
1st post here, just been browsing for a while b/c I'm considering buying an Evo. I've been racing Solo1&2 for 4 years and am currently an aspiring vehicle dynamics engineer pursuing a master's at Colorado State University.
The one thing I didn't see brought up in this thread (unless I overlooked it) was suspension setup for a particular driver. Robi, Cronohunter, and Siegel are obviously highly skilled drivers and can adapt their driving styles to account for deficiencies in vehicle design or setup. The goal of a suspension engineer is to setup the car (within any given limitations) to the driver's style. Some drivers love front LSD's and others hate them.
I race a FWD VW and it understeers so much that I can't take a traditional race line for fast laptimes. I have to adjust for the limitations of the car. Once I put a Quaife in, I had to "re-learn" how to drive it. My corner entry is now less responsive, but I make up for it by turning in earlier. Corner exiting is so much easier now, I can get back on the gas way earlier without fear of power-out understeer. I personally prefer being able to power out of a turn without plowing like a tractor, even at the expense of have to adjust corner entry technique, but then again FWD cars are a different beast all together.
If any of you know Claude Rouelle and his Motec-sponsored vehicle dynamics seminars, he tells some interesting stories at the end. Claude has been a principle engineer for F1 teams, Rally, IRL, CART, you name it. When he was setting up Arie Luyendyk's car (the year he won Indy), they had it perfectly neutral, even test drivers thought so. When Arie got in the car, he said he was terrified because the car gave no indication of whether u-steer or o-steer was going to put him in the wall. Claude had to carefully add in just enough understeer (by reducing front end grip) to give Arie enough indication that he needed to know when his corner entry was too fast.
So enough rambling, my point is that no suspension setup is "more" right than another. In the end, with the best drivers, it will come down to driver preference.
The one thing I didn't see brought up in this thread (unless I overlooked it) was suspension setup for a particular driver. Robi, Cronohunter, and Siegel are obviously highly skilled drivers and can adapt their driving styles to account for deficiencies in vehicle design or setup. The goal of a suspension engineer is to setup the car (within any given limitations) to the driver's style. Some drivers love front LSD's and others hate them.
I race a FWD VW and it understeers so much that I can't take a traditional race line for fast laptimes. I have to adjust for the limitations of the car. Once I put a Quaife in, I had to "re-learn" how to drive it. My corner entry is now less responsive, but I make up for it by turning in earlier. Corner exiting is so much easier now, I can get back on the gas way earlier without fear of power-out understeer. I personally prefer being able to power out of a turn without plowing like a tractor, even at the expense of have to adjust corner entry technique, but then again FWD cars are a different beast all together.
If any of you know Claude Rouelle and his Motec-sponsored vehicle dynamics seminars, he tells some interesting stories at the end. Claude has been a principle engineer for F1 teams, Rally, IRL, CART, you name it. When he was setting up Arie Luyendyk's car (the year he won Indy), they had it perfectly neutral, even test drivers thought so. When Arie got in the car, he said he was terrified because the car gave no indication of whether u-steer or o-steer was going to put him in the wall. Claude had to carefully add in just enough understeer (by reducing front end grip) to give Arie enough indication that he needed to know when his corner entry was too fast.
So enough rambling, my point is that no suspension setup is "more" right than another. In the end, with the best drivers, it will come down to driver preference.
Aug 27, 2004, 07:33 AM
#237
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I had them all out there yesterday:
1) loose Evo (still a touch of trail-braking)
2) balanced Evo ("needed"/utilized a bit of trail-braking)
3) STi ("stuff" it in to the slower corners under braking, power out with the front diff)
4) 996 911 TT (don't trail brake much with PSM switched off )
look for a full write-up with line drawings/differences early next week (we're moving Saturday)
This track has a high-speed sweeper, a big banked over 180 degree carousel, a decreasing-radius AND decreasing track-width "U-turn," 300 degrees worth of skidpad, and a heavy-braking combination corner.
Even with the loose EVO, on purposely over-pressured rear tires, which left a nice balance in the skidpad, there were still some corners that basically REQUIRED some trail-braking.
Even with the 911 TT, a bit of trail braking helps, but too much makes a BIIIIIIGGGGG slide
1) loose Evo (still a touch of trail-braking)
2) balanced Evo ("needed"/utilized a bit of trail-braking)
3) STi ("stuff" it in to the slower corners under braking, power out with the front diff)
4) 996 911 TT (don't trail brake much with PSM switched off
)look for a full write-up with line drawings/differences early next week (we're moving Saturday)
This track has a high-speed sweeper, a big banked over 180 degree carousel, a decreasing-radius AND decreasing track-width "U-turn," 300 degrees worth of skidpad, and a heavy-braking combination corner.
Even with the loose EVO, on purposely over-pressured rear tires, which left a nice balance in the skidpad, there were still some corners that basically REQUIRED some trail-braking.
Even with the 911 TT, a bit of trail braking helps, but too much makes a BIIIIIIGGGGG slide
Aug 27, 2004, 09:27 AM
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Before I do the technical write-up, I need to share this great story:
So we had our next Siegel Racing Driver Instruction Clinic yesterday. We had an STi, 2 Evo8's, a Cayenne Turbo, and a 996 911 Turbo. The highlight of my instructing career came when my hilarious sister-in-law came to check it out. She's an absolute sweet-heart, presently a Sophomore at Pepperdine. Likes nice cars and knows quite a bit about them, but hasn't ever really be in them. Here's the story:
My sister-in-law, Allison, was very excited even just to see a new 911 Turbo at a race track. When I told her that she could ride in it, she jumped at the chance. Alli had never been in any sort of vehicle on any sort of track, not even an auto-cross. Despite my confidence in Paolo, the owner, to take her out safely, and still amaze her with the cars capabilities, he generously offered me to take her out in it.
As we approached the car :
Allison: "Wow that car is beautiful"
Scott: "Yep, it's amazing to drive too."
Allison: "Be careful with me."
Scott: "Of course I'll be careful with you, and the very nice, expensive car too. Don't worry, this is my job, it's what I do."
Alli: "Yeah, be careful with me."
We get in and she's looking around at the interior:
Alli: "Wow, I think I want one of these."
Scott: "You and me both." (not that either of us will be affording one ANY time in the near future.)
So we get the helmets and intercom on and get ready to go. Realize that with the intercom I can whisper absolutely as quietly as I can and she can hear me perfectly. We can hear each other breathe.
The car is warm so I ease out of the pits. Short shift 2nd and 3rd and ease through Turn 1 and 2.
Scott: "We have 2 options, we can either just start going fast right away and you'll just trust me, or we can ease up on it."
Alli (with much concern in her voice): "You mean we're not going fast NOW?!?!"
Scott (chuckling at the thought of her first experience of 450 hp): "Nope."
For whatever reason I decide that she'll be better off just jumping in, so I nail it. We approach "The Kink" at the top of 3rd gear, nudge the brakes and turn-in, rolling immediately back toward full throttle. Alli just starts screaming:
Alli (at the top of her lungs, on the intercom in my ear): "AAAAAAAAAAHHHHHHHHHG!!!"
Scott (ever so calm): "Stop Screaming."
Instantly she stops screaming but begins hyperventilating really loudly, again in my ear on the intercom.
Scott (still ever so calm): "Stop hyperventilating."
And she does. Instantly. Sudden silence in my ear. At this point we have just exited the kink and I'm rowing 4th, back to full throttle. I think "Wow, she listens really well. I had expected the hyperventilating to take longer to stop."
It turns out she had just immediately begun holding her breathe.
Fortunately by lap 3 or 4 she was breathing again
By lap 6 she was asking questions. On lap 8 she could recognize each time PSM cut in and I offered to turn it off and really show her what the car could do. She declined.
Good fun. Time to start on the next one.
SS
So we had our next Siegel Racing Driver Instruction Clinic yesterday. We had an STi, 2 Evo8's, a Cayenne Turbo, and a 996 911 Turbo. The highlight of my instructing career came when my hilarious sister-in-law came to check it out. She's an absolute sweet-heart, presently a Sophomore at Pepperdine. Likes nice cars and knows quite a bit about them, but hasn't ever really be in them. Here's the story:
My sister-in-law, Allison, was very excited even just to see a new 911 Turbo at a race track. When I told her that she could ride in it, she jumped at the chance. Alli had never been in any sort of vehicle on any sort of track, not even an auto-cross. Despite my confidence in Paolo, the owner, to take her out safely, and still amaze her with the cars capabilities, he generously offered me to take her out in it.
As we approached the car :
Allison: "Wow that car is beautiful"
Scott: "Yep, it's amazing to drive too."
Allison: "Be careful with me."
Scott: "Of course I'll be careful with you, and the very nice, expensive car too. Don't worry, this is my job, it's what I do."
Alli: "Yeah, be careful with me."
We get in and she's looking around at the interior:
Alli: "Wow, I think I want one of these."
Scott: "You and me both." (not that either of us will be affording one ANY time in the near future.)
So we get the helmets and intercom on and get ready to go. Realize that with the intercom I can whisper absolutely as quietly as I can and she can hear me perfectly. We can hear each other breathe.
The car is warm so I ease out of the pits. Short shift 2nd and 3rd and ease through Turn 1 and 2.
Scott: "We have 2 options, we can either just start going fast right away and you'll just trust me, or we can ease up on it."
Alli (with much concern in her voice): "You mean we're not going fast NOW?!?!"
Scott (chuckling at the thought of her first experience of 450 hp): "Nope."
For whatever reason I decide that she'll be better off just jumping in, so I nail it. We approach "The Kink" at the top of 3rd gear, nudge the brakes and turn-in, rolling immediately back toward full throttle. Alli just starts screaming:
Alli (at the top of her lungs, on the intercom in my ear): "AAAAAAAAAAHHHHHHHHHG!!!"
Scott (ever so calm): "Stop Screaming."
Instantly she stops screaming but begins hyperventilating really loudly, again in my ear on the intercom.
Scott (still ever so calm): "Stop hyperventilating."
And she does. Instantly. Sudden silence in my ear. At this point we have just exited the kink and I'm rowing 4th, back to full throttle. I think "Wow, she listens really well. I had expected the hyperventilating to take longer to stop."
It turns out she had just immediately begun holding her breathe.
Fortunately by lap 3 or 4 she was breathing again
By lap 6 she was asking questions. On lap 8 she could recognize each time PSM cut in and I offered to turn it off and really show her what the car could do. She declined.
Good fun. Time to start on the next one.
SS
Last edited by siegelracing; Aug 27, 2004 at 11:12 AM.
