Newbie getting wheels aligned. 77 911s

[Trackrash]

My $.02.

There are some other factors not mentioned. How sticky are the tires and what are the rim widths.

There will be some trial and error to choose the best compromise for your alignment settings.

I was running similar tire sizes and had about -1.5 degree camber front and rear. Zero toe front and 1/16" toe in at the rear. (sorry degrees confuse me, ever since I failed trig). I found that at the track the outer edges wore more, but on the street the insides wore, so it evened out.

Now I run more on the track with sticky tires so I went to -2.25 degrees front and rear. No problem with wear, but the straight line stability is not as good.

So start with about -1.5 degrees front and rear, then keep an eye on tire wear. Then adjust as you see fit. BTW, it helps that I do my own alignments.

[Bill Verburg]

Originally Posted by AndreasK

I missed that. Bill's chart says slight toe in rear. Tech article says slight toe in front. Which is it? I suppose rear. What does the rear toe in give me?

Here are the factory specs, look at the '76 C3 column or the '84 SC/RS column



Row height is 108+/-5 f and 12+/-5 rear, I run my C3 a little lower than the SC/RS height, ie @ 149/3,, you want a little rake to the car and use a rack spacer from ~120 down(remember 120 is lower than 108 and 145 is lower still)

front;
toe: 0 pressed is good, pressed means that the leading edge of the tire is under a separating force as when driven, relaxed toe will be a bit of toe in. For A/X toe out is often used to speed turn in, some guys run track w/ this but it makes the car darty in daily use.
camber: 0° to -10' is stock but up to 1° is fine and it gives some extra tire room at the lip, for track use you want as much as can be gotten, but camber plates are then necessary
get as much caster as you can, often it's not possible to get to the spec, the more caster the more feel you will get through the steering wheel.

rear;
you need some toe in for stability 10' is fine
camber you want ~ 1° more than whats used in front, again you additionally get tire room at the lips

[AndreasK]

Sweet! I think I now got a pretty good idea of what I want.
Front:
Toe; 0 pressed
Camber; -1 deg
Caster; 6,5+

Rear:
Toe; 10´
Camber; -1,5-2 deg

Only uncertainty is camber. Some say more neg. up front, some say more out back. Does it matter much? What are the benefits from the two approaches?

[Flojo]

more camber up front vs rear = better cornering, pronounced oversteer
more camber rear vs front = rear more stable

correct me if i'm wrong

[Driven97]

Bill V has charts but I'm pretty sure the rear suspension has better (more) camber gain than the front McStruts, though like the front the rate of gain diminishes with a lowered car.

The "1° more in the rear than front" approach is a rule of thumb that works well for a lot of people. It's not earth ending. There's a LOT of knobs to turn on these cars and a one degree change in camber isn't a huge twist of anything.

Any of your planned setups you posted should be fine, don't sweat it so hard. Don't try and overthink it. Get out there and enjoy the car. It'll be a hoot.

Just to illustrate things, here's a car (mine) with just under 3 degrees of camber up front and just under 4 degrees in the rear, and real big torsion bars. Pretty aggressive setup, but note how square the outside tires are to the pavement:



I wouldn't recommend such wacky settings to most people, but I drive my car on the street too, including 1200 mile road trips, and it's totally fine. The insides of the rears do wear faster with this much camber, but I blow off the outside shoulders at AX before it becomes an issue.

[Flojo]

Originally Posted by Driven97

The insides of the rears do wear faster with this much camber, but I blow off the outside shoulders at AX before it becomes an issue.

+1
that's what camber is mainly for: squaring the tires when cornering and compensation when the wheel is forced outward.

would it be straight (camber °0) it would get positive when cornering and loose traction.

[AndreasK]

Thanks a lot everybody. I´ve enjoyed the car a lot over this summer. Although my alignment probably hasn´t been the best. Its jut that when I now am going to have it done, I want it done well. I´m not after extremes, so Bill´s chart is the guideline. Thanks for making me a wiser P-owner

Roads are covered with ice and winter is coming, so no testdrives anytime soon

[Flojo]

Oh and one mor thing: save yourself an alignment if you have worn bushings and old shocks.
replacing these after alignment, will let you do it all over again as the car will sit differently.
when I changed to Bilstein Nürburgring I gained 2cm and camber was levelled out...

[AndreasK]

Originally Posted by Flojo

Oh and one mor thing: save yourself an alignment if you have worn bushings and old shocks.
replacing these after alignment, will let you do it all over again as the car will sit differently.
when I changed to Bilstein Nürburgring I gained 2cm and camber was levelled out...

Jepp. Shocks and bushings are good. Having Turbo ties and bump steer installed. Which is part of the reason for the alignment.

[Trackrash]

Originally Posted by AndreasK

Sweet! I think I now got a pretty good idea of what I want.
Front:
Toe; 0 pressed
Camber; -1 deg
Caster; 6,5+

Rear:
Toe; 10´
Camber; -1,5-2 deg

Only uncertainty is camber. Some say more neg. up front, some say more out back. Does it matter much? What are the benefits from the two approaches?

Getting to the point of splitting hairs. However the factory settings have the rear with more camber than the front, so that could be a clue as to the direction you would go.

Also, most drivers would not notice a change of 1 degree in camber in their driving.

[Flojo]

Originally Posted by Trackrash

Also, most drivers would not notice a change of 1 degree in camber in their driving.

up front I'd bet sure they would. better cornering but more nervous on straight at high speed