Seeking Opinions on Alignment Specs
12-20-2008, 08:07 PM
#1
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Seeking Opinions on Alignment Specs
I want to set up my car for aggressive street use. I have searched this topic on this forum and here's what I came up with. Any comments appreciated.
Front:
Camber -.5
Caster 5
Toe-in .125 inch
Rear:
Camber max negative with stock adjusters for big tire clearance approx -1.5 to -2
Toe 0
Again, I'm not looking for autocross or racing specs but a good handling setup for the street. Tire wear is a secondary concern.
Front:
Camber -.5
Caster 5
Toe-in .125 inch
Rear:
Camber max negative with stock adjusters for big tire clearance approx -1.5 to -2
Toe 0
Again, I'm not looking for autocross or racing specs but a good handling setup for the street. Tire wear is a secondary concern.
12-20-2008, 10:59 PM
#2
Instructor
I just had my '89 Coupe done for aggressive street by TruLine in Seattle. The actual measurements vary slightly from left to right.
Front:
Camber -.6
Caster 5.8
Toe 2.7 mm
Rear:
Camber -1.4
Toe 1.8 mm
Seems OK to me...
Front:
Camber -.6
Caster 5.8
Toe 2.7 mm
Rear:
Camber -1.4
Toe 1.8 mm
Seems OK to me...
12-21-2008, 01:10 PM
#3
I think you want some rear toe in, it will make the car more stable under braking. Mine is about 1/16" on each side.
Caster at 5 seems low to me, but you could simply use the factory spec. It's more important that they match side to side. More caster will increase the steering effort, increase the self centering tendency and will also increase the camber change as you turn the wheel. Other than the increase in effort all the results of lots of caster are good for aggressive driving.
The camber difference front to rear seems too large. The rule for a long time was the rear should be about .5 more negative than the front.
For the record I run -3.4 in the rear and -2.8 camber in the front. Rear toe as noted above and a smidge of toe in the front. Caster is maxed (struts leaned all the way back) and matched from side to side. It's 100% track use these days.
More important than alignment specs is who is doing the work. They MUST be familiar with an early 911 and willing to put in the time to fiddle with old adjusters, frozen bolts and other nonsense. The rear suspension is a pain to work with and adjusts in ways other cars do not. BMW's with trailing arms for example, cannot be adjusted for camber or toe.
Are you corner balancing as well?
Caster at 5 seems low to me, but you could simply use the factory spec. It's more important that they match side to side. More caster will increase the steering effort, increase the self centering tendency and will also increase the camber change as you turn the wheel. Other than the increase in effort all the results of lots of caster are good for aggressive driving.
The camber difference front to rear seems too large. The rule for a long time was the rear should be about .5 more negative than the front.
For the record I run -3.4 in the rear and -2.8 camber in the front. Rear toe as noted above and a smidge of toe in the front. Caster is maxed (struts leaned all the way back) and matched from side to side. It's 100% track use these days.
More important than alignment specs is who is doing the work. They MUST be familiar with an early 911 and willing to put in the time to fiddle with old adjusters, frozen bolts and other nonsense. The rear suspension is a pain to work with and adjusts in ways other cars do not. BMW's with trailing arms for example, cannot be adjusted for camber or toe.
Are you corner balancing as well?
12-21-2008, 03:14 PM
#4
Still plays with cars.
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TT Over steer - it would help to know what kind of 911 you have. Proper alignment specs vary from one model to another.
A few guidelines are pretty universal. More caster helps not only with high speed stability but reduces understeer.
Front toe should be zero or a bit of toe in for faster response to the wheel On the other hand to little front toe will make the car a bit "darty" and require constant attention to keep it going in a straight line.
In back you need toe in. As a 911 (any of them) loads the rear suspension while cornering, the loaded tires tends to toe-out. That's why we have quite a bit of toe-in under static conditions. I'd speculate that 0 toe in back will make your car oversteer quite unpredictably and tend to zig zag under hard breaking. In short, don't do it.
Best,
A few guidelines are pretty universal. More caster helps not only with high speed stability but reduces understeer.
Front toe should be zero or a bit of toe in for faster response to the wheel On the other hand to little front toe will make the car a bit "darty" and require constant attention to keep it going in a straight line.
In back you need toe in. As a 911 (any of them) loads the rear suspension while cornering, the loaded tires tends to toe-out. That's why we have quite a bit of toe-in under static conditions. I'd speculate that 0 toe in back will make your car oversteer quite unpredictably and tend to zig zag under hard breaking. In short, don't do it.
Best,
12-21-2008, 04:52 PM
#5
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Thanks all for the great info. I especially appreciate the explanations of why each type of adjustment is needed and its associated result. For reference the car is a 1977 911S with stock front and rear tortion bars and swaybars. New Bilstein sport struts front and rear, lowered to a smidge below euro ride height. New neatrix rear suspension bushings and new stock bushings up front. This is not the ultimate setup, I know, but I will be making improvements a little at a time as I go. Future wish list includes turbo tie rods, larger hollow T-bars, fully adjustable swaybars, and polybronze bushings all around. For now, though, I'm just setting up a basically stock car running 205/50 goodyear eagle F1's on 16x7 fuchs for street use only.
12-21-2008, 09:16 PM
#6
Rennlist Member
Front: -1.5 with a total of 5 min toe in.
Rear: -2.0 to -2.5 with a total of 10 min toe in.
This was the my street/track set up, and the setup that I did for cars that were going to see the same kind of duty.
I was a tech back in the late 70s, but tire tech has change a lot since, so other numbers may be more appropriate.
Mark.
Rear: -2.0 to -2.5 with a total of 10 min toe in.
This was the my street/track set up, and the setup that I did for cars that were going to see the same kind of duty.
I was a tech back in the late 70s, but tire tech has change a lot since, so other numbers may be more appropriate.
Mark.
12-22-2008, 04:15 PM
#7
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Compromise is the key.
For the front: I would probably go -1.0 to -1.5 on camber in the front, but that's me. I've been told to push caster to the limit; which is what I have on my SC. (Now, the SC is a little different than the 77 you have, I recognize that.)
For tracking the car I have a toe-OUT of 2 to 3mm in front .... BUT it makes the car drift/wander in grooved surfaces, especially at higher speeds on the street. Toe-out makes for very snappy turn-in, but it's not "comfortable" for the street. You need to drive heads-up with both hands on the wheel at all times with front toe-out.
For the rear: I personally like -2.0 camber rear, with a toe-in of 2mm. With a front toe-out, rear toe-in is somewhat important for the car to "track" or travel in a straight line.
Compromise is the key. If you dial the car in for more performance driving, you compromise the comfy-drive quality; and vise-versa. So, determine the car's purpose as you consider the alterations, IMHO. Daily Driver/Concours/"Date" machine; or periodic/fun-run/hot-shoe/b*lls-to-the-walls adrenaline machine? I think you should choose the purpose, then choose the set-up. Either way, you'll be happy becasue it's a PORSCHE!
Good luck, be safe, have fun with it.
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12-22-2008, 07:08 PM
#8
Rennlist Member
Alignment settings are explained best by mentioning that on any given Formula 1 team, one of the two drivers will, at last resort, try their teammate's setup. Recently, Toyota had major difficulty building a car that both Ralf Schumacher and Jarno Trulli could both drive. I've read the above posts, and find that I've personally had trouble with all of them!
I would set the car as follows (this is a tough one because Bilstein Sport shocks aren't the best solution when combined with stock T-bars):
Front camber = .7 - .8 neg.
Front caster = 5.5 and as close as possible side-to-side.
Front toe = + 1/32nd each side
Rear camber = 1.0 - 1.2 neg.
Rear toe = Zero
Tire pressures = 31F/35R
Every driver feels things that other drivers don't, with the above specs you will be able to drive the car, get used to it, then fiddle with it. Remember, your car is in compromise land (engine weight more than original; rear T-bars too small for the engine weight, rear tires too small, etc.), so the best you can hope to achieve is a setup that works for you.
I would set the car as follows (this is a tough one because Bilstein Sport shocks aren't the best solution when combined with stock T-bars):
Front camber = .7 - .8 neg.
Front caster = 5.5 and as close as possible side-to-side.
Front toe = + 1/32nd each side
Rear camber = 1.0 - 1.2 neg.
Rear toe = Zero
Tire pressures = 31F/35R
Every driver feels things that other drivers don't, with the above specs you will be able to drive the car, get used to it, then fiddle with it. Remember, your car is in compromise land (engine weight more than original; rear T-bars too small for the engine weight, rear tires too small, etc.), so the best you can hope to achieve is a setup that works for you.
12-25-2008, 03:29 PM
#9
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Alignment settings are explained best by mentioning that on any given Formula 1 team, one of the two drivers will, at last resort, try their teammate's setup. Recently, Toyota had major difficulty building a car that both Ralf Schumacher and Jarno Trulli could both drive. I've read the above posts, and find that I've personally had trouble with all of them!
I would set the car as follows (this is a tough one because Bilstein Sport shocks aren't the best solution when combined with stock T-bars):
Front camber = .7 - .8 neg.
Front caster = 5.5 and as close as possible side-to-side.
Front toe = + 1/32nd each side
Rear camber = 1.0 - 1.2 neg.
Rear toe = Zero
Tire pressures = 31F/35R
Every driver feels things that other drivers don't, with the above specs you will be able to drive the car, get used to it, then fiddle with it. Remember, your car is in compromise land (engine weight more than original; rear T-bars too small for the engine weight, rear tires too small, etc.), so the best you can hope to achieve is a setup that works for you.
I would set the car as follows (this is a tough one because Bilstein Sport shocks aren't the best solution when combined with stock T-bars):
Front camber = .7 - .8 neg.
Front caster = 5.5 and as close as possible side-to-side.
Front toe = + 1/32nd each side
Rear camber = 1.0 - 1.2 neg.
Rear toe = Zero
Tire pressures = 31F/35R
Every driver feels things that other drivers don't, with the above specs you will be able to drive the car, get used to it, then fiddle with it. Remember, your car is in compromise land (engine weight more than original; rear T-bars too small for the engine weight, rear tires too small, etc.), so the best you can hope to achieve is a setup that works for you.
12-29-2008, 05:37 PM
#10
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My car is for DE's and some weekend driving.
I set my front with all the caster I could get up front that matched. I think it was about 6 deg.
I worked hard at taking all the black sealer off the front strut mounts and blueprinted my bolt holes so I could get as much neg camber as possable up front. The best I could do with my car set up with the front A arms just above flat was -1.25 deg of camber. Front toe was set close to zero to just on the toe in side.
In the back I set the camber to -2.5 with a little toe in. That was about the most I could get. I belive our cars are rear traction chalanged unless we run a lot of rear tire size over the front, thus I wanted all the rear traction I could get. My tires can be fliped on the rims if I see any inside tire ware.
My suspention is stock and I just love my Dunlop Star Spec street class race tires. No screaming on the track, warm up fast, excellent in the wet, and let me keep up with a bunch of the Dot Race Tire guy's.
I set my front with all the caster I could get up front that matched. I think it was about 6 deg.
I worked hard at taking all the black sealer off the front strut mounts and blueprinted my bolt holes so I could get as much neg camber as possable up front. The best I could do with my car set up with the front A arms just above flat was -1.25 deg of camber. Front toe was set close to zero to just on the toe in side.
In the back I set the camber to -2.5 with a little toe in. That was about the most I could get. I belive our cars are rear traction chalanged unless we run a lot of rear tire size over the front, thus I wanted all the rear traction I could get. My tires can be fliped on the rims if I see any inside tire ware.
My suspention is stock and I just love my Dunlop Star Spec street class race tires. No screaming on the track, warm up fast, excellent in the wet, and let me keep up with a bunch of the Dot Race Tire guy's.
