Track/street alignment

[dede911]

Hi All,

I've been searching on the Pelican forums to find more info to set my alignment, but didn't found what I was looking for...

Here we go:

dual purpose, street/track
911SC '82 euro
Ride height will be a bit lower than euro (rear around 63 cm, front...if possible a litte bit rake..)
Rear TB 26
Front TB 19
Standard ARB's
Bilstein Sportlich Strasse
Front neg camber plates

For the track, I will be running Michelin pilot sport cups 205/55x16 and 225/50x16

What would you suggest?

Thanks,

André

[911st]

I have an 85 w 19/25's and 22/21 sways at 2700lbs with 205/245 MPSC's.

MPSC's have been discontinued. However I was told they need a lot of neg camber. Thus, I set mine for the max neg camber I could get I am at about -2 front ant -2.5 rear and could use more.

If you can get -3 each, take it. Lets put it this way, a full race 911 w 23/33 TB's and biger sways can run -3 and they sway less so they have less camber loss than us.

For a combo setting maybe -2 to -2.5 front and -2.5 rear.

I hear if you elongate the bottom hole toward the outside on the rear spring plates you can get more rear neg camber but dought you will get to-3. With your front spring plates if you find the shock top/can is hitting the inside of the fender you can remove it, shave off a wedge at the top so you can get more neg camber. Some fit a plastic expandable cover in place of it.

Also set front caster at max settings (but ballanced side to side) as this will give you more neg camber with a turn. Our cars lift a front wheel often so they can use more neg camber up front.

Front toe set ot zero pressed. Rear per factory.

Not an expert, just what I would do.

[aston@ultrasw.c]

The problem is if you still have rubber bushings in the suspension they will deform so much that 2 or even 3 deg negative will quickly disappear as the side loads increase.

You will find that despite all the -ve camber you are still killing the outside shoulder of the tires.

The only way to fix this is to pull the rubber and switch to polybronze.

[dede911]

Dear 911st,

I agree with the camber setting especially for the MPSC.

I also understand the point of maximizing caster, but the steering effort becomes higher...in some corners it can be hard...

Regarding the toe: what is understood with "pressed"?

Dear Aston,

I forgot to mention:
-front: top mount is uniball, other bearings are poly bushes
-rear: all is poly

André

[aston@ultrasw.c]

yeaaaaah!

[Bill Verburg]

Originally Posted by dede911

Dear 911st,

I agree with the camber setting especially for the MPSC.

I also understand the point of maximizing caster, but the steering effort becomes higher...in some corners it can be hard...

Regarding the toe: what is understood with "pressed"?

Dear Aston,

I forgot to mention:
-front: top mount is uniball, other bearings are poly bushes
-rear: all is poly

André

St's suggestions are good, MPSC like negative camber, you probably can't get enough w/ a stock suspension. Whether it's worth camber plates and other mods depends on how serious you are and the % of track vs street use.

pressed toe just means that static toe is set w/ a spacer pushing out on the tires(simulating road forces) spec is 15kp/33pounds/147N)

you'll have to decide how much castor to run, but the large forces generated are a reason p/s has become popular even on full race cars. I like as much as I can get, it's often difficult to even get to spec for castor

[911st]

Originally Posted by dede911

Dear 911st,

I agree with the camber setting especially for the MPSC.

I also understand the point of maximizing caster, but the steering effort becomes higher...in some corners it can be hard...

Regarding the toe: what is understood with "pressed"?

Dear Aston,

I forgot to mention:
-front: top mount is uniball, other bearings are poly bushes
-rear: all is poly

André

When the alignment is done the shop adds load to the front of the wheels when setting toe.

Running max caster is not adding very much is my understanding.

However, I have wanted to set the front of a 911 where is I could get enough front neg camber I would take caster down from about -6 to -3.5. That would do two things, reduce steering effort and make neg camber more consistent in a turn. I suspect that with a lot of neg camber like a 911 runs, we might get the tires at there ideal orintation to the track for the big turns, then we come into a tight turn, and the caster gives us to much camber and we push.

As to camber loss with deflection of rubber bushings. On the front if the length of the strut is about 18" total, each deg change is about .31" movement at the top, the bottom or a combonation of the to. I do not think it is possable for there to be 2 deg of camber loss as that would be about .62" of movement. I alwas thought it would be about .5 deg at the most front or rear but can not say for sure. I got that from two different sources that know a lot more than me but I could be in error.

[T77911S]

Originally Posted by aston@ultrasw.c

The problem is if you still have rubber bushings in the suspension they will deform so much that 2 or even 3 deg negative will quickly disappear as the side loads increase.

You will find that despite all the -ve camber you are still killing the outside shoulder of the tires.

The only way to fix this is to pull the rubber and switch to polybronze.

you mean inside?

for street, i have mine set to -1.5 rear and 1mm toe in to compensate so the tires wear evenly.

the guy that did mine sets his to i think -2.5 or 3 with 3mm to in for his street track car. he showed me his tires and i could not tell the difference between the inside and outside wear.

the last 2 sets of tires i had on wore very bad on the inside. i would like to put a nice set on but dont want them to wear out on the inside first like this last set did.

[dede911]

Hi,

All mods have been done.

Visited an alignment shop today and got following results:

Fr camber -1°11 and -1°19
toe -0°00 and -0°01
castor.... 8°47 and 8°17

It seems that I can not get it closer to factory specs...the camberplates are completely shifted to the front...especially on the left side

RR camber -1°50 and -1°54
Toe 0°09 and 0°09

What about the front castor?
Have wi done it wrong? Is this setting OK?

BTW, I changed my mind regarding the MPSC and switched to Toyo 888. Apparently the 888 should be better in wet condition, the MPSC is more a slick than a semi-slick tire...

The castor keeps me worrying..

What do you think?

Regards,
André

[Steve@Rennsport]

Andre'

JMHO, but thats FAR too much caster.

The factory spec is 6 degrees and honestly, I cannot see how one can get much more than that without major body modifications or weld-in Camber Boxes.

I like somewhere between 5.5-5.8 for street cars otherwise the steering effort is too high for today's sticky tires.

[dede911]

Steve,

I installed modified camber plates with monoballs.
The "monoball" support is completely shifted to the front of the car. Will this give max caster or min castor?

I also think this is to much..

On the other hand, steering is not heavy (turbo tie rods improvement?)

André