I need JP to take tire temps. I dont care what the number is. I need to know if the car has too much neg camber or not enough. He runs in the same place 90% of the time...so getting some numbers wont kill him. I agree they wont come up to temp. I just need the difference across the tire.
Oh.. I try to keep all 4 tires on the ground. 3 dont have the same traction as 4.
B
Full Version: Finally
Relating back to Sammy's post:
We the know the other guy is faster in JP's car. This guy (Chuck) will drive around any problem the car may have. If we help JP get the car a little more AX neutral..this guy will take top time of day. I have lots of "old guy" customers who will drive the wheels off of everything no matter how crappy the setup.... THEN help them out with the car and they flat out fly.
When Chuck takes TToD (not if) JP will know in the back of his head that the car is "right". He can then focus on driving and not F-ing with the car. Chuck probably doesnt even know what the car is doing... he is just doing whatever it takes to compensate.
JP.. its your car. Ride with Chuck on one session. Dont think about what the car is doing... focus on what Chuck is doing.
B
We the know the other guy is faster in JP's car. This guy (Chuck) will drive around any problem the car may have. If we help JP get the car a little more AX neutral..this guy will take top time of day. I have lots of "old guy" customers who will drive the wheels off of everything no matter how crappy the setup.... THEN help them out with the car and they flat out fly.
When Chuck takes TToD (not if) JP will know in the back of his head that the car is "right". He can then focus on driving and not F-ing with the car. Chuck probably doesnt even know what the car is doing... he is just doing whatever it takes to compensate.
JP.. its your car. Ride with Chuck on one session. Dont think about what the car is doing... focus on what Chuck is doing.
B
Now back to the simple stuff: Isn't Don's advice (loose car, inflate rear tires) just the opposite of what Brad and DD said earlier in the thread? I'm pretty old and easily confused! Which is it? I won't change springs, t-bars or front sway bar soon. My car oversteers. If I can help the problem a bit by playing with tire pressures, I want to do that.
QUOTE(jim9146 @ Mar 31 2003, 04:09 PM)
Now back to the simple stuff: Isn't Don's advice (loose car, inflate rear tires) just the opposite of what Brad and DD said earlier in the thread? I'm pretty old and easily confused! Which is it? I won't change springs, t-bars or front sway bar soon. My car oversteers. If I can help the problem a bit by playing with tire pressures, I want to do that.
Jim, I had the same set up you have, 180# rears and stock sized front sway bar. My car over steered like crazy. I recently put a 22mm bar in and it is like night and day. I guess Ia mtrying to say that tire pressure is very important, but I doubt that it will have a massive effect while you car is un-even as it is.
Jim,
Don is correct. You can dial in some understeer or dial out some oversteer by playing with the tire pressures. Basically you are balancing the car with a different method by raising and lowering the tire pressures. DD and I suggested making a bar adjustment. Both methods are correct. One takes more work than the other. Sometimes, you cant do enough with the tire pressures and a bar/spring adjustment has to be made.
I want JP to get the car corner weighted.
B
Don is correct. You can dial in some understeer or dial out some oversteer by playing with the tire pressures. Basically you are balancing the car with a different method by raising and lowering the tire pressures. DD and I suggested making a bar adjustment. Both methods are correct. One takes more work than the other. Sometimes, you cant do enough with the tire pressures and a bar/spring adjustment has to be made.
I want JP to get the car corner weighted.
B
Jim,
I need to go over what Don said: "When car is loose (oversteer) decrease front tire pressure, increase rear pressure"
This is counter what I normally do. If the car is loose I need more weight back there. To get more weight back there I would raise the front pressures or drop the rears. Don could be a 90 time SCCA AutoX winner.. I have no idea. But this goes against what I do.
Jeroen and I had a car that easily understeer'd. Jeroen dropped the front tire pressures. We could have made a even bigger change by pumping up the rears. This suggestion came from my Indy car guy who just bareley missed TTOD on the first and second day of the autoX. I told him I was going to raise the rear of car he said pump up the rears or drop the fronts.
B
I need to go over what Don said: "When car is loose (oversteer) decrease front tire pressure, increase rear pressure"
This is counter what I normally do. If the car is loose I need more weight back there. To get more weight back there I would raise the front pressures or drop the rears. Don could be a 90 time SCCA AutoX winner.. I have no idea. But this goes against what I do.
Jeroen and I had a car that easily understeer'd. Jeroen dropped the front tire pressures. We could have made a even bigger change by pumping up the rears. This suggestion came from my Indy car guy who just bareley missed TTOD on the first and second day of the autoX. I told him I was going to raise the rear of car he said pump up the rears or drop the fronts.
B
QUOTE(jim9146 @ Mar 31 2003, 04:09 PM)
Now back to the simple stuff: Isn't Don's advice (loose car, inflate rear tires) just the opposite of what Brad and DD said earlier in the thread?
Like B said, either may work.
The interesting thing here--tires have a range of pressure where they stick the best. This range is different from tire model to tire model. Some tires (notably the very sticky "competition" tires) work best when they have relatively low pressures, like in the 20s. Other tires, such as many or most "normal" street-type tires, grip best with pressures around 40 PSI or above! Going to higher pressure can lead to a loss of grip, and going to a lower pressure can lead to a loss of grip. Depends on where you are relative to where the tire works best.
This is a long way of saying that raising the pressure in the rear tires will often take out some oversteer, but sometimes it can actually add more! It depends on the exact tire.
--DD
I would vote to lower the rear suspension a little and have it corner balances...
It is leaning alot more than mine
23 mm front bars
180 lbs rears
front tires used to leave the ground when the front sway bar was to stiff, I softened it up and as Brad says, the rear sticks better...I actually spun for the first time with the stiffer front sway bar setting, but I was learning all about sway bars that day...
Mine is now neutral with no pre-load, and the back sticks like glue.
Rich
It is leaning alot more than mine
23 mm front bars
180 lbs rears
front tires used to leave the ground when the front sway bar was to stiff, I softened it up and as Brad says, the rear sticks better...I actually spun for the first time with the stiffer front sway bar setting, but I was learning all about sway bars that day...
Mine is now neutral with no pre-load, and the back sticks like glue.
Rich
QUOTE(Racer Chris @ Mar 31 2003, 04:09 AM)
JP, put a ty-wrap on all four of your shock absorber pistons to check if you are bottoming them out.
Yes do that. I fought a random oversteer/understeer problem for 1/2 a season back when I first started autocrossing my 914. I finally discovered it had been riding on the front bumpstops. I had lowered the car before the first event and neglected to check for travel.
Mike T
QUOTE(J P Stein @ Mar 31 2003, 09:16 AM)
....more butt time, I guess.
This is the key to fast AX times. Seat time. Set your car up, leave it that way and drive it at as many events as you can.
Also smoothness is key to fast times. Look ahead on course, set yourself up for the next pin or gate. If you can't remember the course, walk it more times. draw your own map if you have to.
If the whole thing is just too overwhelming find a part of the course that you feel you are weak on and concentrate on just getting that right.
Ask questions of the fast guys, watch their runs, car placement etc. Pretty soon those 2.5 seconds will melt away.
Mike T
I have a few suggestions about how to succeed at autocrossing.
1) Don't fuck with the car at the event. Learn to drive what you have, and work around the shortcomings. When you are concerned about what needs to be changed you aren't concerned enough with your driving. Obviously the problem is not the car if someone else can get in and beat you by 2 seconds. The most you should change at the AX is the tire pressures, but definitely not after only one run.
2) Use the first run for familiarization, not for time. If you try too hard you will lock up the brakes by going in too deep, and lose track of where the course goes. Figure out where the most time is to be gained, where the longest fastest parts are, and plan to maximize them. Most importantly you need to memorize the course without mistakes during the first run. If you were paying attention during your walk throughs (3 or more) then the first run should go smoothly. Also, the first two runs are to heat up the tires to operating temps, not to set FTD. During the second run you can begin to test the limits, but don't go for broke yet.
3) Don't use third gear unless the course is real fast. Time lost on the rev limiter will be made up by not shifting up and down. Make a couple of good runs, then try a different combination to see if something can be gained.
4) Don't try to corner on the limits until you have the course nailed. It's much more important to be able to go fast on the straights, which requires full control at corner exit.
5) Sometimes going wide to enter or exit a corner takes longer because of the greater distance travelled. Using all the road only works in the fastest sections. Make sure you can hit the apex cone with the tires, but don't.
6) Make sure you can apply all the power without wheel spin when entering a long straight. Give up something on the entry if necessary in order to straighten out the wheels early at the exit.
7) 914s can make up a lot of time in a slalom if you get the timing right. You want to already be pointed toward the next turn in point as you go by the previous cone. If you are still turning as you go by the cone, you are too late, and will have to turn more, which is slower.
I'm sure there is more. I'll think about it some.
As far a setting up the suspension, the 914 is pretty well balanced from the start. If only 3 tires are touching the ground you are clearly giving up some cornering traction. Don't compare it to a 911 on 3 wheels. I agree with whoever said to increase the front torsion bars. Then you can rebalance the car with the sway bar. With the way your car appears in the pictures, if you are getting oversteer it is either from trailing throttle or excessive throttle, not balance.
1) Don't fuck with the car at the event. Learn to drive what you have, and work around the shortcomings. When you are concerned about what needs to be changed you aren't concerned enough with your driving. Obviously the problem is not the car if someone else can get in and beat you by 2 seconds. The most you should change at the AX is the tire pressures, but definitely not after only one run.
2) Use the first run for familiarization, not for time. If you try too hard you will lock up the brakes by going in too deep, and lose track of where the course goes. Figure out where the most time is to be gained, where the longest fastest parts are, and plan to maximize them. Most importantly you need to memorize the course without mistakes during the first run. If you were paying attention during your walk throughs (3 or more) then the first run should go smoothly. Also, the first two runs are to heat up the tires to operating temps, not to set FTD. During the second run you can begin to test the limits, but don't go for broke yet.
3) Don't use third gear unless the course is real fast. Time lost on the rev limiter will be made up by not shifting up and down. Make a couple of good runs, then try a different combination to see if something can be gained.
4) Don't try to corner on the limits until you have the course nailed. It's much more important to be able to go fast on the straights, which requires full control at corner exit.
5) Sometimes going wide to enter or exit a corner takes longer because of the greater distance travelled. Using all the road only works in the fastest sections. Make sure you can hit the apex cone with the tires, but don't.
6) Make sure you can apply all the power without wheel spin when entering a long straight. Give up something on the entry if necessary in order to straighten out the wheels early at the exit.
7) 914s can make up a lot of time in a slalom if you get the timing right. You want to already be pointed toward the next turn in point as you go by the previous cone. If you are still turning as you go by the cone, you are too late, and will have to turn more, which is slower.
I'm sure there is more. I'll think about it some.
As far a setting up the suspension, the 914 is pretty well balanced from the start. If only 3 tires are touching the ground you are clearly giving up some cornering traction. Don't compare it to a 911 on 3 wheels. I agree with whoever said to increase the front torsion bars. Then you can rebalance the car with the sway bar. With the way your car appears in the pictures, if you are getting oversteer it is either from trailing throttle or excessive throttle, not balance.
So...JP...if ya wanna get rid of those 21mm torsion bars, let me know...... 
AXers around here have been gunning for Mr. Kotzian
ever since he got that '06 workin'. He had an off day at Topeka last year and finished 12th (IIRC) in SS. I went back and looked at 2 years of local SCCA results. Nobody in any Porsche has come within 1.5 sec of him in that time period (weather being equal) Maybe he was having an off day, but I don't think so. Another of his Corvette buddies was there keeping him honest. It was not a horsepower course, tho.
So, OK, I asked for advice.
Brad hit the nail on the head. Chuck drives thru difficulties that leave me lost.....maybe that's why I asked him to share the car
..and I was lookin' to get the car balanced a bit better...but
When any 914 is running equal with a FAST Z06 it ain't that far off.
He has 385 hp, monster Hoosiers, ABS and years of experience. ulf has 800 lbs less weight, season old Kumhos, a home builtonthecheep motor, a WAG at the suspension settings, and that's about it....it's really kinda funny.
I will take some selected advice and try it....then maybe, try some more.
As for my driving, I'll go for a ride or 2 with Chuck, but not take a camera.
Don't hold your breath on them t-bars, Chris.
ever since he got that '06 workin'. He had an off day at Topeka last year and finished 12th (IIRC) in SS. I went back and looked at 2 years of local SCCA results. Nobody in any Porsche has come within 1.5 sec of him in that time period (weather being equal) Maybe he was having an off day, but I don't think so. Another of his Corvette buddies was there keeping him honest. It was not a horsepower course, tho.
So, OK, I asked for advice.
Brad hit the nail on the head. Chuck drives thru difficulties that leave me lost.....maybe that's why I asked him to share the car
..and I was lookin' to get the car balanced a bit better...butWhen any 914 is running equal with a FAST Z06 it ain't that far off.
He has 385 hp, monster Hoosiers, ABS and years of experience. ulf has 800 lbs less weight, season old Kumhos, a home builtonthecheep motor, a WAG at the suspension settings, and that's about it....it's really kinda funny.
I will take some selected advice and try it....then maybe, try some more.
As for my driving, I'll go for a ride or 2 with Chuck, but not take a camera.
Don't hold your breath on them t-bars, Chris.
General concensus (wow fancy word!)...
The end that you tighten is the end that looses grip (and the other end will get more) and vice versa.
Judging from JP's report and the pics, my gut feeling says the front bar is too tight (even though that contradicts the above).
Why? Because it lifts the inner front wheel... (which makes me guess that the car understeers as well).
The swaybar alone won't fix the bodyroll. To take care of that JP would need bigger t-bars (and maybe bigger rear springs).
About the oversteer that JP reports... lower the rear pressure to get the temps even across the thread. If needed dail out some neg.camber in the rear.
All said, a lot of it depends on the driver too...
Chris made some good points in his post above.
I'm not really good at AX. I usually start too gung-ho (=too agressive) so on my first few runs I'm focussing too much on keeping the car under control while I should learn the course (this way, it takes longer to learn the course).
Basically, too agressive is slow but too smooth is slow as well.
Like I said, I usually start too agressive and smoothen out as I learn the course (times get better). Up to a point where I'm too smooth and times start to get worse again. Which is my call to get more agressive again.
AX is quite a bit different from track driving and the "ideal line" that works on a track usually only works on the fast parts of an AX course.
Like Chris sayz... it's better to sacrifice a little on your corner entry speed so you have a good clean corner exit (=faster accelleration on your way out).
That specially helps in slow/tight corners where you will suffer understeer when going in too fast (which will definatly f-up your corner exit - waaaay wide).
Oversteer can be used to set the car. But if you have the idea that you suffer from oversteer, usually, you're just too much on the loud pedal too soon.
Ok, I'll shut up now and let the fast guys do the talking
cheers,
Jeroen
The end that you tighten is the end that looses grip (and the other end will get more) and vice versa.
Judging from JP's report and the pics, my gut feeling says the front bar is too tight (even though that contradicts the above).
Why? Because it lifts the inner front wheel... (which makes me guess that the car understeers as well).
The swaybar alone won't fix the bodyroll. To take care of that JP would need bigger t-bars (and maybe bigger rear springs).
About the oversteer that JP reports... lower the rear pressure to get the temps even across the thread. If needed dail out some neg.camber in the rear.
All said, a lot of it depends on the driver too...
Chris made some good points in his post above.
I'm not really good at AX. I usually start too gung-ho (=too agressive) so on my first few runs I'm focussing too much on keeping the car under control while I should learn the course (this way, it takes longer to learn the course).
Basically, too agressive is slow but too smooth is slow as well.
Like I said, I usually start too agressive and smoothen out as I learn the course (times get better). Up to a point where I'm too smooth and times start to get worse again. Which is my call to get more agressive again.
AX is quite a bit different from track driving and the "ideal line" that works on a track usually only works on the fast parts of an AX course.
Like Chris sayz... it's better to sacrifice a little on your corner entry speed so you have a good clean corner exit (=faster accelleration on your way out).
That specially helps in slow/tight corners where you will suffer understeer when going in too fast (which will definatly f-up your corner exit - waaaay wide).
Oversteer can be used to set the car. But if you have the idea that you suffer from oversteer, usually, you're just too much on the loud pedal too soon.
Ok, I'll shut up now and let the fast guys do the talking
cheers,
Jeroen
QUOTE
So...JP...if ya wanna get rid of those 21mm torsion bars, let me know......
Me tooo ..........
I have stock front bar and #140 rear springs. I may want some day a little stiffer ride.
I want it just to not f-ing rain at the autox so I can actually feel how my car handles now. I don't have the hp JP does but mine doesn't have the body roll or the tire lifting trick unless the rear bar is hooked up.
It sounds like the front sway bar needs to be looser then? Or bigger front t-bars to stop the front from digging in? How about stiffer front shocks setting, wouldn't that do the same thing if JP can adjust 'em?
I know very little about how to set up cars soo I am just trying to learn here.
Got the results from the last autox and my son took 2nd and I wuz 7th in GTU (I was atleast faster than E. Fry). Not too bad in the rain, Blair just drives the car and then flips me the keys saying "It goes alot faster now, Dad!"
We both are trying to figure out what the car is doing in kinda tough to do in the rain as I spun on every run except one slooow run.
22mm Front bar-set in the middle
22mm tbars
old Koni shocks set to firm
180lb rear springs
Bilstein gas rears
205 Kumho Victos on 7x15's
32lbs of air- WTF should a starting tire pressure be??
Still waitin for some 4mm shims from Brad so I can align the car.....
Geoff
It sounds like the front sway bar needs to be looser then? Or bigger front t-bars to stop the front from digging in? How about stiffer front shocks setting, wouldn't that do the same thing if JP can adjust 'em?
I know very little about how to set up cars soo I am just trying to learn here.
Got the results from the last autox and my son took 2nd and I wuz 7th in GTU (I was atleast faster than E. Fry). Not too bad in the rain, Blair just drives the car and then flips me the keys saying "It goes alot faster now, Dad!"
We both are trying to figure out what the car is doing in kinda tough to do in the rain as I spun on every run except one slooow run.
22mm Front bar-set in the middle
22mm tbars
old Koni shocks set to firm
180lb rear springs
Bilstein gas rears
205 Kumho Victos on 7x15's
32lbs of air- WTF should a starting tire pressure be??
Still waitin for some 4mm shims from Brad so I can align the car.....
Geoff
For rain settings, you could try to thighten the front bar to get rid of some oversteer
Beyond that you can raise the front tire pressure and/or lower the rear pressure
Do that untill you have more understeer than you like...
Still, you'll always need a "tender foot" in the rain to avoid oversteer
Dunno if JP has adj.Koni's or not... If he does, he could fiddle with those a little too. But I doubt it will take care of the bodyroll much though...
Same rules as on other parts (sways, springs, tire pressure)
Soft: add grip at the adjusting end, loose grip on the other end
Hard: loose grip at the adjusting end, loose grip on the other
cheers,
Jeroen
Beyond that you can raise the front tire pressure and/or lower the rear pressure
Do that untill you have more understeer than you like...
Still, you'll always need a "tender foot" in the rain to avoid oversteer
Dunno if JP has adj.Koni's or not... If he does, he could fiddle with those a little too. But I doubt it will take care of the bodyroll much though...
Same rules as on other parts (sways, springs, tire pressure)
Soft: add grip at the adjusting end, loose grip on the other end
Hard: loose grip at the adjusting end, loose grip on the other
cheers,
Jeroen
Shocks will only help in the very-very short term. They mostly affect transient stuff, the longer-duration things will get past them. (Think low-pass filter if you're an engineer geek.) It might help if the wheel just hops up very briefly, but I'm pretty sure that's not what is happening.
Personally, I'd consider the stiffer front torsion bars on JP's car and softening the front sway bar. I'd also consider an LSD and a rear sway bar. (Maybe even give it a try without the limited-slip!) But I'm not sure I would actually do any of the above! It sounds like the car is doing quite well as it is, and focusing on the wheel-lift may not really help much in the long run. So I'd just try to get the alignment where I wanted it, work out the tire pressure issue, and drive drive drive drive drive!!!
Don't you worry, Chuck will beat that Vette one'a these days!
--DD
Personally, I'd consider the stiffer front torsion bars on JP's car and softening the front sway bar. I'd also consider an LSD and a rear sway bar. (Maybe even give it a try without the limited-slip!) But I'm not sure I would actually do any of the above! It sounds like the car is doing quite well as it is, and focusing on the wheel-lift may not really help much in the long run. So I'd just try to get the alignment where I wanted it, work out the tire pressure issue, and drive drive drive drive drive!!!
Don't you worry, Chuck will beat that Vette one'a these days!
--DD
I'm bettin' JP will too, it'll just take a little longer.
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