NJ-GT

What's the effect of toe in or toe at the front wheels and the rear wheels.

There is contradictory information everywhere I look at.

Thanks

Bob Rouleau

Front wheels - toe in makes the car more stable in a straight line. It also makes the car resist turning. For track a 996 likes just a little toe in. I have tried zero toe and found the car to be a handful on bumpy roads - on a smooth track it is acceptable and the car turns in very easily. NOte my location, bombed out roads are a fact of life and you may not need as much. Some Autocross mavens use a bit of toe out - very rapid turn in but, on the 996 chassis the car is quite unstable (darty is the term) and a bumpy road will cause you to change lanes. The 996 chassis is very fussy about toe settings.

At the rear you need toe in - the suspension tends to toe out under load which is why you need to set toe in under static conditions. Toe out at the back of a 911 will make the car very unstable in a straight line and oversteer in corners - my advice is don't do it! For track on a 996 my experience is that total rear toe of 5/32nds works well. On a 993, 3/32nds of an inch total works. The 996 likes more for some reason.

To understand rear toe think of a fire dept ladder truck. To allow the truck to navigate city streets the rear wheels ae steerable. The guy in back countersteers - i.e he turns the back wheels to the left for a right hand turn. Toe out in the back of a 911 has a similar effect and you're better not to go there, ever.
Best,

RedlineMan

Yeh...

What Bob said, large.

Toe settings are very car, driver, and intent dependant. For street, stay stock. For combination street/track, stay stock rear and no more than 0 front. Toe out in front can be really great, but it is labor intensive and not practical for anything but track only cars. 0 in the rear is going to be VERY dicey on a 911, but can work on a 944 IF you are good enough. Toe out in the rear is DEADLY.

SundayDriver

Here is a real world example, but not on a 996. Spec Racer Fords normally run ~1-2mm total toe OUT in the front and about 1-2mm total toe IN at the rear. A new guy shows up, with a new car. He is running almost 20 seconds off the pace, and spinning 3-4 times per lap. Turns out he has ~5mm toe OUT in the rear.

Too much OUT at the back makes the car wicked. Add that to what was already said.

Greg Fishman

First weekend in my race car the guy that did the alignment thought he was setting it up like he did his Sports 2000 and put around 5 mm toe out in the front. The car was wicked and would turn in with just a light touch on the steering wheel. My mechanic and I re-aligned the car with about 1-2mm toe in in front and about 3-4 mm in the rear.

bob_dallas

Echo the statements above but just as a reference point I have about 3' toe in the front (in other words almost none) and it's great on track and not twitchy on the road. Tramlines occasionally but pretty seldom and some of that is attributed to the tires and -2.5 degrees of camber. One warning about toe in on rear. I'd recommend not exceeding factory toe on the rear of your 996, I've seen a few tires torn up very quickly with too much rear toe.

Bob Rouleau

Hi Bob-D I'd say that 3' of front toe is "just a bit" (grin). As usual we agree.
Regarding rear toe, the 5/32"nd total toe is what I got from Roland Kussmaul for my GT2. It works well but you are right in pointing out that more rear toe results in more tire wear. In my case it doesn't matter because my tires die from heat cycles long before the tread is worn out.

Best,

bob_dallas

Yep, makes sense to me. I just like to warn people about excessive rear toe because I've seen tires destroyed due to it. 5/32 isn't "excessive" but it's just a little more than I like to run on a dual-purpose car. If it's not hurting the tires though, as you say, then it's ok. As you know - this isn't an exact science that you can simply plug numbers into - takes some real development to get exactly right and most don't want to spend the time/$$ to do it right. Thus you end up with "pretty good settings" and I err on the conservative side with others in this case.

So basically that was a long way of saying I agree

macfly

As a relative newcomer (all of 10 weeks now) to Porsches I had a lot of trouble with my GT3 at the DE/track days I enjoy so much. I spun the car at 100 the my first day out. Getting right back on the horse the next couple of days I constantly felt the rear was trying to over take the front, which is not a good feeling at turn 8 Willow. It felt much like the fire truck mentioned above.

I was really wondering what I'd got myself into, and why this car had so much positive press when it felt so unstable. When I posted about it Bob_R knew exactly what was up, and sent me the Roland Kussmaul specs he had for the car. I took it to be aligned, and low and behold, the rear end was toed out, just 1/32. Needless to say the change in the feel of the car after doing the alignment is just incredible, night and day.

It's a very long winded way of saying I agree with all the posts above, I've tried the alternative, and trust me, you don't want to!