Black Widow's 2nd track day.VIDEO UP!!!!
01-19-2009, 02:57 PM
#31
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there is a solid extension inserted into the steering arm which lowers where the tie rod attaches (adjustable) to level the tierod ...standard 911 racer stuff 
01-19-2009, 03:04 PM
#32
Rennlist Member
are you sure you are measuring from the measuring pads? no way that your car is 95mm in the front. the rear looks like i said, 145mm.
mk
mk
I should have some better tire temps in the afternoon sessions....my 1st session I was taking it easy and the 2nd got black flagged...so I should get some data later...
I did measure the ride height....the front is LOW....95-105mm in the front and about 150-147 in the rear...so the rear is HIGH....we will look into lowering it down about and inch...., BUT I don't want to drop it down to the point it bottoms out the shock and gets wicked oversteer from it?
It seems to be handling VERY good right now......but lowering the rear should even out the weight balance (55% front 45% rear now) which would be good too?
I did measure the ride height....the front is LOW....95-105mm in the front and about 150-147 in the rear...so the rear is HIGH....we will look into lowering it down about and inch...., BUT I don't want to drop it down to the point it bottoms out the shock and gets wicked oversteer from it?
It seems to be handling VERY good right now......but lowering the rear should even out the weight balance (55% front 45% rear now) which would be good too?
01-19-2009, 03:16 PM
#33
Rennlist Member
Good guidance, but let me make a couple of comments.
bump steer is not going to be an issue for Brian. the angles are very obsene as you say, but what does this mean? It means that under hard braking, that you will get some more dramatic changes in toe out (why we start at a slight amount of toe in with the front) AND, with the tracks he will be visiting, the bump steer around turns, will not be an issue , due to the duration of the turns, toeing in the compressed tire and toeing out the lifting tire. the lifting tire will now be skidding along, but not really doing much if any of the turning). So, with my experience, and I have some bad bump steer, there are no concessions. the car handles well and there are no bad tire wear issues. The only time , in california, that this will be an issue, is at Willow springs, where this issue will carve out the inside edge of the passenger front tire to the cords with in one day.
I always wondered about the bump stops being part of the suspension, and it sure seems to be as you say. Im on them, in a big way, down the corkscrew. never had ANY oversteer issues there, and it seems their compliance is pretty tuned for what the car needs through it. Ive measured the shock travel, motion ratio, etc, and I only start out with about 1" of space between the shock body and bump stop. the motion ratio is about 5:1. so when you see my 5" compression, you know the shock body is pressing on the bump stop.
mk
bump steer is not going to be an issue for Brian. the angles are very obsene as you say, but what does this mean? It means that under hard braking, that you will get some more dramatic changes in toe out (why we start at a slight amount of toe in with the front) AND, with the tracks he will be visiting, the bump steer around turns, will not be an issue , due to the duration of the turns, toeing in the compressed tire and toeing out the lifting tire. the lifting tire will now be skidding along, but not really doing much if any of the turning). So, with my experience, and I have some bad bump steer, there are no concessions. the car handles well and there are no bad tire wear issues. The only time , in california, that this will be an issue, is at Willow springs, where this issue will carve out the inside edge of the passenger front tire to the cords with in one day.
I always wondered about the bump stops being part of the suspension, and it sure seems to be as you say. Im on them, in a big way, down the corkscrew. never had ANY oversteer issues there, and it seems their compliance is pretty tuned for what the car needs through it. Ive measured the shock travel, motion ratio, etc, and I only start out with about 1" of space between the shock body and bump stop. the motion ratio is about 5:1. so when you see my 5" compression, you know the shock body is pressing on the bump stop.
mk
My two cents...only worth $.02:
There is always a problem when using other people's alignment and ride height numbers. Pay little attention to what others are doing...unless they have the exact same car, pieces, and tires that you have. Here's some clues/reasons that might help:
Don't worry about ride height. Instead, measure suspension travel on your own car...and be aware that as your driving improves, you will need more travel. You will also be using more of the "available" spring rate....as you improve. With a new, non professional driver, I always know that I'm going to be changing spring rates, as they learn. Putting a spring that a professional driver likes, in a non professional's car, almost always turns out badly. Put some sort of measuring device on the shocks, record how much travel you are actually using, and how much travel you still have. Keep track of this, as you improve...and compensate, as needed. If you never use the last 1 inch of rear travel, then lower the car some...but not the whole 1 inch, as you will use more, as you get more "seat" time. If you start "wacking" the crap out of the snubbers/stops....raise the car a bit. Keep in mind: hitting the snubbers is not always bad (and in most cases good)....they are usually progressive in nature. You can actually use them as part of the spring rate, as long as the transition from spring to snubber is not a huge jump.
Comparing initial alignment setting is good only for getting a starting point. Once you know how much travel you have, you can them start working on a "true" camber "picture. The reason: If your car sits higher (or lower) than someone else's car...your starting alignment number will be much different than theirs, since you are starting at a completely different place in the camber curve. For instance: Say that you and Mark (only for example) have the exact same spring, car, tires, wheels, etc., but his car is 1 inch lower. You set-up both cambers the same...2 degrees. Now, if he was to raise his car 1 inch, he would actually have an initial camber setting much closer to 1 degree, because he was at a different place in the camber curve.
Always remember that as a 928 travels farther in the front, the bump-steer (toe change) gets absolutely obsene. Measure your bump steer and do everything you can to improve it.
There is always a problem when using other people's alignment and ride height numbers. Pay little attention to what others are doing...unless they have the exact same car, pieces, and tires that you have. Here's some clues/reasons that might help:
Don't worry about ride height. Instead, measure suspension travel on your own car...and be aware that as your driving improves, you will need more travel. You will also be using more of the "available" spring rate....as you improve. With a new, non professional driver, I always know that I'm going to be changing spring rates, as they learn. Putting a spring that a professional driver likes, in a non professional's car, almost always turns out badly. Put some sort of measuring device on the shocks, record how much travel you are actually using, and how much travel you still have. Keep track of this, as you improve...and compensate, as needed. If you never use the last 1 inch of rear travel, then lower the car some...but not the whole 1 inch, as you will use more, as you get more "seat" time. If you start "wacking" the crap out of the snubbers/stops....raise the car a bit. Keep in mind: hitting the snubbers is not always bad (and in most cases good)....they are usually progressive in nature. You can actually use them as part of the spring rate, as long as the transition from spring to snubber is not a huge jump.
Comparing initial alignment setting is good only for getting a starting point. Once you know how much travel you have, you can them start working on a "true" camber "picture. The reason: If your car sits higher (or lower) than someone else's car...your starting alignment number will be much different than theirs, since you are starting at a completely different place in the camber curve. For instance: Say that you and Mark (only for example) have the exact same spring, car, tires, wheels, etc., but his car is 1 inch lower. You set-up both cambers the same...2 degrees. Now, if he was to raise his car 1 inch, he would actually have an initial camber setting much closer to 1 degree, because he was at a different place in the camber curve.
Always remember that as a 928 travels farther in the front, the bump-steer (toe change) gets absolutely obsene. Measure your bump steer and do everything you can to improve it.
01-19-2009, 03:20 PM
#34
Rennlist Member
I have an easier method.
just lay down facing the tire on the drive side. take you right arm and take the measuring tap to the measuring pads, WHILE looking through the tire rim. that way, if you havent done this before, you look directly at the measuring point, and it is extremely easy to measure the ride hight. EXTREMELY easy! same think on the other side.
Brian, THOSE PICS are awesome! the car looks fantastic. HURRY UP AND GET THAT RACING LICENCE!! I want to see that car out there!!!! By the pics, your ride hight looks really good. maybe just a little high in the rear, but not much. thats why you are seeing some tire lifting off the road in the rear.
mk
just lay down facing the tire on the drive side. take you right arm and take the measuring tap to the measuring pads, WHILE looking through the tire rim. that way, if you havent done this before, you look directly at the measuring point, and it is extremely easy to measure the ride hight. EXTREMELY easy! same think on the other side.
Brian, THOSE PICS are awesome! the car looks fantastic. HURRY UP AND GET THAT RACING LICENCE!! I want to see that car out there!!!! By the pics, your ride hight looks really good. maybe just a little high in the rear, but not much. thats why you are seeing some tire lifting off the road in the rear.
mk
Brian, remember an easier way than the WSM method to measure the front ride height on the ground (if you don't have it on a 4-post lift), is to measure on the outside (rather than inside) of the the lower A-arm rear bracket lip at the lowest point and add 10mm. If the ride height really is 100mm you may have a bit of trouble reaching it. I use a short metric ruler and a flashlight to illuminate it and reach this from behind the front wheel. Here's an example that would be 148mm.
01-19-2009, 03:26 PM
#35
Rennlist Member
another good, maybe bad, depending on driving style, fact of bump steer issues, is that it tends to de sensitize the steering input. If you are getting drive induced oversteer for example, by "fixing " the bump steer, your steering inputs might be more precise, which could cause more issues, especially with someone new to racing this platform. having bumpsteer, toes the outside, loaded tire out so you need more input to make the turn. kind of like having a larger steerng wheel. I kind of like it and have become very used to it. especially when i went to the smaller diameter steering wheel last year.
mk
mk
01-19-2009, 03:32 PM
#36
Rennlist Member
AH HA! I just thought of something. You dont have your cage finished yet, do you ? Thats why you are getting that weird chassis twist with the tires coming off the ground. Finish the cage before you do much more testing. It will change the car quite a bit! Dont do any bar swaybar adjustements, as they will be all wrong when the cage goes in.
01-19-2009, 03:59 PM
#37
Former Sponsor
01-19-2009, 04:08 PM
#38
Former Sponsor
Mark:
Save some weight and take those useless springs out of the car...just run on the bumpstops.
or....
more spring rate.
BTW....as low as you are running your car and as low as it travels, you'd be amazed if you measured the bump steer. Those front tires are pointed everywhere, but together.
Save some weight and take those useless springs out of the car...just run on the bumpstops.
or....
more spring rate.
BTW....as low as you are running your car and as low as it travels, you'd be amazed if you measured the bump steer. Those front tires are pointed everywhere, but together.
01-19-2009, 04:25 PM
#40
Rennlist Member
Ive thought about that, but Im not too far off Anderson's settings now, as I think he is 800 and 500 springs. (but he has the bumpsteer angles fixed).
That curve down the corkscrew, is a little unfair to compare suspension action as the car is almost tossed off a cliff and is caught at the bottom. Joes and Marks look similar to this when caught in action.
Normally, you would never catch both tires compressing to this degree, and have to deal with the tremendous toe out, but, out of the turn, it doesnt really matter, as the inside tire is lifting up and barely contacting the ground anyway.
mk
but Im not too far off Anderson's settings now, as I think he is 800 and 500 springs. (but he has the bumpsteer angles fixed).That curve down the corkscrew, is a little unfair to compare suspension action as the car is almost tossed off a cliff and is caught at the bottom. Joes and Marks look similar to this when caught in action.
Normally, you would never catch both tires compressing to this degree, and have to deal with the tremendous toe out, but, out of the turn, it doesnt really matter, as the inside tire is lifting up and barely contacting the ground anyway.
mk
Mark:
Save some weight and take those useless springs out of the car...just run on the bumpstops.
or....
more spring rate.
BTW....as low as you are running your car and as low as it travels, you'd be amazed if you measured the bump steer. Those front tires are pointed everywhere, but together.
Save some weight and take those useless springs out of the car...just run on the bumpstops.
or....
more spring rate.
BTW....as low as you are running your car and as low as it travels, you'd be amazed if you measured the bump steer. Those front tires are pointed everywhere, but together.
Last edited by mark kibort; 01-19-2009 at 05:01 PM.
01-19-2009, 04:43 PM
#41
Race Director
Thread Starter
Guys
VIDEO IS UP
http://www.youtube.com/watch?v=0yUo5aeLQxo
I'm working on the others...including a nice session with a prepped 996 that nearly went off in turn 8!!!!!!!!!
VIDEO IS UP
http://www.youtube.com/watch?v=0yUo5aeLQxo
I'm working on the others...including a nice session with a prepped 996 that nearly went off in turn 8!!!!!!!!!
01-19-2009, 04:51 PM
#42
Race Director
Thread Starter
AH HA! I just thought of something. You dont have your cage finished yet, do you ? Thats why you are getting that weird chassis twist with the tires coming off the ground. Finish the cage before you do much more testing. It will change the car quite a bit! Dont do any bar swaybar adjustements, as they will be all wrong when the cage goes in.
Yes the front half off the cage is not done.....only the back half.....the shop could get it done fairly quickly...maybe a week....I'll talk to the owner....
I was gonna wait a little bit for the front of the cage....to save $$$ for more track time & to fix the remaining issues...like the DAMM fuel tank...but we'll see....in the video with teh 996 right before he almost looses it in 8 you can see-hear the car studder our of 6...
Did the full cage make that much of a difference in how the suspension works-the car feels?
01-19-2009, 04:57 PM
#43
Rennlist Member
Nice. Looks very comfortable for you now.
a couple of comments. (on the last lap starting around the 6min mark)
Turn 1 looks good, but into 2, take much more narrow approach. The early turn in and trail brake (if you want) will scrub off speed and give you a much faster way aroud that turn. You can go flat out through 7 and 8 looks good and you will go faster as you get more comfortable with it.
9 entry is good, exit is bad. take the exit all the way out to the left, as this is a straighter way down the hill, less forces on the car laterally, and you can get on the gas earlier that way.
entry /exit of 10 looks good, turn in a little earlier for 13, and the exit looks good along with quick shifts.
HANDS!! grab that f'ing wheel at 2/10 and dont move them unless you are shifting or getting out of the car!. You can get away with it now, but when you start getting the car on edge, that will be a hiderance with control.
mk
a couple of comments. (on the last lap starting around the 6min mark)
Turn 1 looks good, but into 2, take much more narrow approach. The early turn in and trail brake (if you want) will scrub off speed and give you a much faster way aroud that turn. You can go flat out through 7 and 8 looks good and you will go faster as you get more comfortable with it.
9 entry is good, exit is bad. take the exit all the way out to the left, as this is a straighter way down the hill, less forces on the car laterally, and you can get on the gas earlier that way.
entry /exit of 10 looks good, turn in a little earlier for 13, and the exit looks good along with quick shifts.
HANDS!! grab that f'ing wheel at 2/10 and dont move them unless you are shifting or getting out of the car!
. You can get away with it now, but when you start getting the car on edge, that will be a hiderance with control.mk
Guys
VIDEO IS UP
http://www.youtube.com/watch?v=0yUo5aeLQxo
I'm working on the others...including a nice session with a prepped 996 that nearly went off in turn 8!!!!!!!!!
VIDEO IS UP
http://www.youtube.com/watch?v=0yUo5aeLQxo
I'm working on the others...including a nice session with a prepped 996 that nearly went off in turn 8!!!!!!!!!
01-19-2009, 05:04 PM
#44
Rennlist Member
Yes, the cage will make a big difference. It stiffens the chassis up so much. the only reason you are lifting the rear wheels is because of chassis twist that will be stopped by having the cage in. with a cage, i get stuck going out of gas station driveways. I actually have to get out and push my car if i loose momentium. without it, that never happens. (just to give you an idea of how much the cage stiffens things up)
mk
mk
MK
Yes the front half off the cage is not done.....only the back half.....the shop could get it done fairly quickly...maybe a week....I'll talk to the owner....
I was gonna wait a little bit for the front of the cage....to save $$$ for more track time & to fix the remaining issues...like the DAMM fuel tank...but we'll see....in the video with teh 996 right before he almost looses it in 8 you can see-hear the car studder our of 6...
Did the full cage make that much of a difference in how the suspension works-the car feels?
Yes the front half off the cage is not done.....only the back half.....the shop could get it done fairly quickly...maybe a week....I'll talk to the owner....
I was gonna wait a little bit for the front of the cage....to save $$$ for more track time & to fix the remaining issues...like the DAMM fuel tank...but we'll see....in the video with teh 996 right before he almost looses it in 8 you can see-hear the car studder our of 6...
Did the full cage make that much of a difference in how the suspension works-the car feels?
01-19-2009, 07:33 PM
#45
Race Director
Thread Starter
More videos
http://www.youtube.com/watch?v=URWNY6u0928 In this one the 996 with M030 suspension and Nitto NTO1's who I was following for most of the morning almost loses it in turn 8 around the 3:30 mark...
http://www.youtube.com/watch?v=8ruPfGr9Je4 In this one is sunday with trackmasters...my friend Scott is riding shotgun to give me some pointers (typically hurry the hell up, your way to slow here...& here & here)...1 of 2
more later
http://www.youtube.com/watch?v=URWNY6u0928 In this one the 996 with M030 suspension and Nitto NTO1's who I was following for most of the morning almost loses it in turn 8 around the 3:30 mark...
http://www.youtube.com/watch?v=8ruPfGr9Je4 In this one is sunday with trackmasters...my friend Scott is riding shotgun to give me some pointers (typically hurry the hell up, your way to slow here...& here & here)...1 of 2
more later