kyrocks

Had alignment done two weeks ago - not exactly what I wanted, but okay:

Front: -2.1 deg camber, 8 deg caster, 0 toe
Rear: -1.9 deg camber, toe in 0.2 deg (0.1 deg a side)

Did one track day and alignment was great, worked well, not quite agressive enough, but adequate.

Next track day:

Back end all over the place ONLY on right hand turns with application of throttle. Left hand turns okay. Left (driver's side) rear tire shredded compared to all other three. Braking from high speeds not as stable as last time, but decent. LSD seems fine when jacking up car and testing rear wheels.

Is my toe out on the left rear side?
(2011 GT3, 2800 miles)

Thanks.

911SLOW

Was it windy at the track?

Factory toe links can lose alignment if it was . : )

BTW
LSD is gone too.

LehmanZ06

Recommend going up to -2.5 neg in rear as more front grip (more neg front than rear camber......maybe biasing you towards oversteer)......rear gets loose and slides and rips tire.

tcsracing1

I vote that the LSD is gone.

you cant test the true preload by jacking up the car and rotating the wheels.

You are spinning one tire more then the other causing wear on the track.

johnr265

Your toe in the rear is not enough for the track. In fact, it is quite dangerous. Toe in refers to the rear tires pointing in, "pigeon toed" like this / \. Under compression, the rear heavy 911 will cause a toe out condition \ / where the rear of the car will start to steer when you don't want it too (usually in a high G situation). You want enough toe in so that under the maximum compression, the car never has more than zero toe | |. Generally, you want between .2 and .3 degrees of toe in PER SIDE, most people using about .25 in per side. So you have half the toe you should have.

Now, I've assumed that indeed, your toe was specified in degrees. Many alignment machines use minutes and 10 minutes of toe in per side is .16 degrees (10/60) which is better though still likely not enough for stability.

Still other machine uses inches of toe in as the unit (getting confused yet?) and .1 inches toe in per side us around .2 degrees per side.

As for the uneven tire wear and uneven handling, toe could easily be out. Too little toe on the left rear could cause oversteer in right hand turns. Like others said, rear toe arms/links with a locking plate will prevent the slipping that the factory eccentric bolts are famous for. By the way, if there is a difference of as little as .02 degrees from one side to the other you WILL feel it in a GT3. These cars are exquisitely sensitive to any small difference in rear toe. You can also feel this when you get on and off the throttle quickly, the car will feel like it is jerking side to side (steering really). When the toe is dead on, the car should accelerate and brake under hard applications on smooth pavement in a straight line. Feels awesome when it has previously been out of whack.

FFaust

Great explanation John.

kyrocks

Johnr265, I agree with you 100%.

911slow, yes it was windy at the track.

I refuse to believe its the LSD! I am in denial.

P-Car dealer is 100 miles away. Will start with alignment and if it continues ill get LSD checked.

Should I just trade it in for a Cayman R?

TRAKCAR

What tires do you run on track?

-2.5 camber rear is great for R6, but for MPSC and Toyo's -1.7 to -2.0 gives better tire wear.
Front i always good at -2.5 and drives fine on street with zero toe.

I run zero toe front and 2 mm, or about 0.1" each side.
I don't understand degree's or minutes not withstanding 911Slow's previous detailed teachings.

You need a CUP LSD and CUP tie rods in rear.

aussie jimmy

this thing is infiltrating a lot of minds. (mine, too)

johnr265

Nah, you'll really miss the power of the GT3. There is no question the setup can be a bit demanding but once you have it set up, you are going to absolutely love it. It really helps to find a shop that knows what they're doing (hint, most dealers do not when it comes to track alignments). The more you drive on the track, the more likely you are to need to get it "tweaked" during the season.

Izzone

Where are you located?

tcsracing1

bare in mind, the GT3 LSD only lasts 8-10 track day from new.....

kyrocks

I've done 2.5 with it.

kyrocks

No where close to a race shop. (currently in Iowa)

tcsracing1

it is not uncommon.