Pettit Alignment Specs for 18-inch wheels
10-07-09, 09:56 PM
#1
Pettit Alignment Specs for 18-inch wheels
I am currently running the Pettit Alignment specs for 16-inch wheels under AutoX conditions on my FD.
However, I don't do AutoX anymore, and am doing mostly short circuit (2+ miles) tracks events (20-min. DE's).
I now run 18-inch wheels, with 285 race rubber all around.
I have AD coil-overs double-adjustable coilovers (450F/350R), Tri-Point front swaybar, and a PFS adjustable rear swaybar.
The Pettit alignment specs for 18-inch wheels on a short circuit track events calls for CONSIDERABLY LESS negative camber front (-1.8 vs. -1.0 ) & rear (-1.5 vs. -0.2) .
Why is that ?
Should I do it ?
What would happen if I don't and keep the 16-inch alignment specs ?
Thanks,
:-) neil
However, I don't do AutoX anymore, and am doing mostly short circuit (2+ miles) tracks events (20-min. DE's).
I now run 18-inch wheels, with 285 race rubber all around.
I have AD coil-overs double-adjustable coilovers (450F/350R), Tri-Point front swaybar, and a PFS adjustable rear swaybar.
The Pettit alignment specs for 18-inch wheels on a short circuit track events calls for CONSIDERABLY LESS negative camber front (-1.8 vs. -1.0 ) & rear (-1.5 vs. -0.2) .
Why is that ?
Should I do it ?
What would happen if I don't and keep the 16-inch alignment specs ?
Thanks,
:-) neil
10-07-09, 11:15 PM
#2
LOL, I haven't seen that setup sheet for years, but I can tell you it is way off for Autocross. The only thing that comes to mind is there is less tire deflection with the shorter side walls but I wouldn't worry about it, those numbers are very conservative to start with.
For Autocross, I run:
Front
Camber -3.2
Toe 1/8” out
Caster 5.0
Rear
Camber -2.5
Toe 1/8” in
0 trust
With 17” wheels
Hope this helps
Dan
For Autocross, I run:
Front
Camber -3.2
Toe 1/8” out
Caster 5.0
Rear
Camber -2.5
Toe 1/8” in
0 trust
With 17” wheels
Hope this helps
Dan
10-08-09, 09:05 AM
#3
Is Howard's recommendation not aggressive enough ?
TIA,
:-) neil
<SNIP>
Chassis setup is HUGE. You just have to get interested in it if you care about going fast and having fun at the track. I will give you a nice dual purpose setup and once you get to the track if you want to go fast you will be changing some of the settings.
Alignment of the FD is an easy task for a shop so don’t let them give you a big song and dance about it. Tell them you want the car set to these specs. Period. Further, arrange from the getgo to get a complete printout of the before and after.
Tire pressure 30 front 27 rear
Ride height if you have coil overs should be set at 25 inches at the top of each wheelwell.
Toe in front between a 1/16 and 1/8th inch
Toe in rear zero
Camber front and rear 1.2 degrees negative
Caster equal minimal
Zero rear thrust angle.
TIA,
:-) neil
Originally Posted by howard coleman
<SNIP>
Chassis setup is HUGE. You just have to get interested in it if you care about going fast and having fun at the track. I will give you a nice dual purpose setup and once you get to the track if you want to go fast you will be changing some of the settings.
Alignment of the FD is an easy task for a shop so don’t let them give you a big song and dance about it. Tell them you want the car set to these specs. Period. Further, arrange from the getgo to get a complete printout of the before and after.
Tire pressure 30 front 27 rear
Ride height if you have coil overs should be set at 25 inches at the top of each wheelwell.
Toe in front between a 1/16 and 1/8th inch
Toe in rear zero
Camber front and rear 1.2 degrees negative
Caster equal minimal
Zero rear thrust angle.
10-08-09, 01:26 PM
#4
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I'm not a suspension expert by any means, but I notice that the longer the event, the less negative camber they're recommending. I'm guessing that it might just have to do with tire wear.
I haven't been to many autox events, but their corners seem to be much sharper than most of the tracks I've seen. This could be another reason.
I haven't been to many autox events, but their corners seem to be much sharper than most of the tracks I've seen. This could be another reason.
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