Alignment done by Porsche
08-07-2009, 05:16 PM
#16
Under the Lift
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Aryan:
I didn't comment directly on your alignment. The major correction they made that may have helped the handling was the front toe. Everything else was close enough to begin with. They didn't change caster (it's fine), the front camber change is odd (no sense making the right lower), and they made rear toe and camber slightly closer. Better than most alignments.
I didn't comment directly on your alignment. The major correction they made that may have helped the handling was the front toe. Everything else was close enough to begin with. They didn't change caster (it's fine), the front camber change is odd (no sense making the right lower), and they made rear toe and camber slightly closer. Better than most alignments.
08-07-2009, 06:12 PM
#17
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RDK: how did you come up with those values to set at? I remember you had a thread about understeering and trying to get rid of it by setting the struts and stabilizer. Are your settings aimed at X-cross (or what do you call it 
) or do you have issues too driving "normal" roads?
Bill: thanks for the addition. I did some more road tests today and the thing that maily bothers me is the heavy feeling of the steering wheel when correcting from a turn - the car seems to want to keep going in the direction it is on. I think it as more todo with the heavy steering than with the alignment.
) or do you have issues too driving "normal" roads?Bill: thanks for the addition. I did some more road tests today and the thing that maily bothers me is the heavy feeling of the steering wheel when correcting from a turn - the car seems to want to keep going in the direction it is on. I think it as more todo with the heavy steering than with the alignment.
08-07-2009, 11:43 PM
#18
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Aryan: Well, the numbers kind of came up with themselves. My mechanic likes around 2 degrees negative camber. However, the camber and toe effect each other so...he put in as much negative camber he could get with just shy of 0 toe in both front and rear. So it is at the limits of toe out adjustment and negative camber cranked in until the toe is 0. Oh yeah, and get the same camber and toe left to right. He also set the ride height at the bottom of the spec. I don't want the car any lower because the performance gains aren't worth what the roads around here would scrape off the bottom of the car. You can get more camber with less toe-in if the car is lowered. We set it there as a starting point to see how it handles. I added the steroid drop links because the springs were stiffer than factory, the dampers and front sway bar were also stiffer than factory but the rear sway bar was stock. The drop links helped but wasn't enough so made us go back to square one and start over with the alignment. Were surprised to find it wasn't aligned to the specs the dealer said it was, which should have been fine and NOT caused the massive at the limit understeer I was experiencing.
The car didn't have issues driving "normal". Doesn't pull to one side, stays straight over bumps, drives and corners great up to about 9 tenths. That would be fine for most people as they typically don't drive past 8 tenths. I like my car setup to drive at 10 tenths of it's full capability. An example would be the braking. Most people thought the braking on my GTS was fantastic. I felt the stopping distance was a little long and the ABS was kicking in way too soon. I did two things. I put in a higher bias rear brake bias valve, and firmed the rebound on the rear shocks. Now I can put myself thru the windshield without the ABS kicking in and stop in about 1/3 of the distance.
I don't set up my car specifically for 10 tenths on the track or even our local autocrosses. I like to set up my car so it is neutral at 10 tenths mid-corner in an average turn, that's about 200ft radius or a standard skid pad. I have found that makes the car an all round great performer. What's the difference? A car set up neutral for a tight twisty autocross will have dangerous oversteer on a big fast track. A car set up neutral for a big fast track will have maddening understeer on a tight twisty autocross course. The radius of turn a car is set up neutral for can make a big difference even from track to track. That's why racers have adjustable suspension and there are practice sessions before races. Heck, I've heard of racers swapping gears, and cams to maximize the powerband for specific tracks. I don't want to go that far, I just want a good all round performer that is predictable and fun at that 10 tenths limit.
Neutral mid-corner means under just enough throttle to maintain speed both the front and rear tires are slipping a little, a slight four wheel drift. If the car is neutral, lifting slightly on the throttle makes the front slip a little less than the rear and the front will turn in more or rotate. Adding throttle will let the car drift out to make the turn wider. This is called throttle steering not to be confused with throttle oversteer. That's where you hit the throttle the rear breaks loose and comes round and you have to counter steer or opposite lock the steering wheel to keep from spinning out, or what is now called drifting.
Man, I typed a LOT. I must be really psyched for the autocross Sunday.
The car didn't have issues driving "normal". Doesn't pull to one side, stays straight over bumps, drives and corners great up to about 9 tenths. That would be fine for most people as they typically don't drive past 8 tenths. I like my car setup to drive at 10 tenths of it's full capability. An example would be the braking. Most people thought the braking on my GTS was fantastic. I felt the stopping distance was a little long and the ABS was kicking in way too soon. I did two things. I put in a higher bias rear brake bias valve, and firmed the rebound on the rear shocks. Now I can put myself thru the windshield without the ABS kicking in and stop in about 1/3 of the distance.
I don't set up my car specifically for 10 tenths on the track or even our local autocrosses. I like to set up my car so it is neutral at 10 tenths mid-corner in an average turn, that's about 200ft radius or a standard skid pad. I have found that makes the car an all round great performer. What's the difference? A car set up neutral for a tight twisty autocross will have dangerous oversteer on a big fast track. A car set up neutral for a big fast track will have maddening understeer on a tight twisty autocross course. The radius of turn a car is set up neutral for can make a big difference even from track to track. That's why racers have adjustable suspension and there are practice sessions before races. Heck, I've heard of racers swapping gears, and cams to maximize the powerband for specific tracks. I don't want to go that far, I just want a good all round performer that is predictable and fun at that 10 tenths limit.
Neutral mid-corner means under just enough throttle to maintain speed both the front and rear tires are slipping a little, a slight four wheel drift. If the car is neutral, lifting slightly on the throttle makes the front slip a little less than the rear and the front will turn in more or rotate. Adding throttle will let the car drift out to make the turn wider. This is called throttle steering not to be confused with throttle oversteer. That's where you hit the throttle the rear breaks loose and comes round and you have to counter steer or opposite lock the steering wheel to keep from spinning out, or what is now called drifting.
Man, I typed a LOT. I must be really psyched for the autocross Sunday.
Last edited by RKD in OKC; 08-08-2009 at 12:20 AM.
08-07-2009, 11:58 PM
#19
Rennlist Member
Picking my GTS up this afternoon from a more aggressive alignment. It's not the dealer this time as the dealer was very very reluctant to go out of factory spec. Front camber -1.6, rear -.9, also toe front and rear both to as close to zero without being zero and still get the most negative camber they could. Forgot what he said he put the caster at. The settings were nowhere near where the dealer's print out said the were a year ago.
They spent 5 hours tweaking to get both sides exactly the same and said I had way too much toe in both front and rear. Car was understeering horribly at the limits. Took it for an "is this better" drive and it feels right on the money now. Mid-turn as I increase speed the rear complains first then the front, then it goes 4 wheel drift. When want to tighten up the turn I just lift slightly on the throttle and the fronts grab better and it rotates without losing the 4 wheel drift. Add throttle back to make turn radius bigger while still in 4 wheel drift. Before it was understeering and I had to lift almost violently to get rotation and the rotation came from the rear getting light and letting go instead of front gripping a little and tucking in. We'll see how it does Sunday at the races!
They spent 5 hours tweaking to get both sides exactly the same and said I had way too much toe in both front and rear. Car was understeering horribly at the limits. Took it for an "is this better" drive and it feels right on the money now. Mid-turn as I increase speed the rear complains first then the front, then it goes 4 wheel drift. When want to tighten up the turn I just lift slightly on the throttle and the fronts grab better and it rotates without losing the 4 wheel drift. Add throttle back to make turn radius bigger while still in 4 wheel drift. Before it was understeering and I had to lift almost violently to get rotation and the rotation came from the rear getting light and letting go instead of front gripping a little and tucking in. We'll see how it does Sunday at the races!
