OZ951

I just had a 4 wheel computer alignment done on my car, its the first computer alignment I have had since I got the car. Until now I have been doing the alignments myself because I was constantly pulling the suspension apart to upgrade it. I have always been curious to know how accurate I was setting the toe using the string lines etc, well today I found out. Total error 0.01 degrees. Damn ! String lines can work!

Still the computer alignment was good especially for setting the caster and rear which is hard to do without having the car on a lift.

Kevin Baker

Cool. I'd have thought that you'd be pretty good at the alignment what with the racing and all. I think racing a car what was poorly aligned would not be much fun.

Mike Buck

No, its always fun to drive.

The not fun part would be looking at your tires afterwards. A poor alignment can destroy a brand new tire in no time on track

johne

OZ951,
Is there any procedure that you follow for "stringing" your car. I know the basic theory about running strings parallel to your front and rear wheels but I don't know the exact details like how to mount the strings and such, or the measurements for our cars.

Also how did you do the camber on your car?

thanks,
John

Wormhole

I've been pretty successful using toe plates and the smart camber. However the plates are only good if the rear toe is already square, or if you only need to measure total toe.

OZ951

There are several articles on the web about doing string alignments, I have a couple of them saved somewhere if you cant find them. Since I figured i would be doing it several times I made a set of jigs to set things up relatively quickly. I mount those off the caster blocks and the rear torsion bar covers. They are basically pieces of PVC pipe that stick out from the car and they have markers on the pipe at a given distance from the centerline. I set the string lines over those markers using a plumb line. Toe is then determined by measuring the distance from the front and rear edge of the rim to the string line. I measure camber (roughly) with an angle gauge and a block of MDF that fits across the vertical face of the rim, it has a cutout so that the center of the wheel does not interfere.

Come to think of it I posted a thread on this a long time ago with some pics of the setup. Not sure if those pics are still around or not.

Duke

Oz, what alignment specs do you run?

OZ951

Front camber -0.4 degrees street plus an additional -1.5 (ish) track
Front Toe 0.09 degrees street. I have not measured what the toe changes to when I add the extra camber for the track.
Front caster 3.0 degrees

Rear Camber -1.3, toe 0.02

Duke

So you have toe out both front and rear, correct?
Does that make the car unstable at higher speed? But I guess the turn-in is very sharp!

I'm curious why you don't run more camber than 1,3 rear?

OZ951

When the front camber is decreased for the track the toe pulls in. Also at speed the car lowers and the toe pulls further in. The factory spec is actually for positive toe between +0.04 to +0.13.

I leave the rear camber at -1.3 because its a pain to change and if I set it any more than that I will end up with excessive tire wear from street driving. With a rear camber of -1.3 and my suspension setup I have not experienced rear traction issues, in other words -1.3 is working well for me.

I am really very happy with the overall handling of the car, it feels balanced and predictable, not twitchy or overly sensitive. I am sure the good flat torque curve I have ended up with from this motor is also a contributor to the feel of the car. I have heard of some modded 951s being somewhat difficult to keep in control when they have very peaky torque curves and non LSD transmissions. Mine does not exhibit those kind of problems thankfully.

About the only handling characteristic that I am looking at adjusting at this point in time is rear brake bias because I occasionally feel it get a little loose in the rear under threshold braking.

Red 944

I couldn't get my caster within spec, no matter how hard I tried. Was there something I was missing?

OZ951

About the only thing you could do is shift the caster block to the extreme of its mounting points and then adjust the eccentric. Was your caster adjustment done by a shop ? If it was try a different one.

SoCal Driver

PVC pipe?

Do you always have the same shop temperture when you align your car?

OZ951

Yes its Texas its always hot. No the garage temperature does vary but thats why I picked PVC pipe, I figured that of the available choices it was going to be the most stable, least susceptible to warpage, expansion and contraction etc that would occur with metals or timber.

SoCal Driver

Plastic has far more temp related expansion than metal or wood.

But what is surprizing is how close you were to specs.

Even the best alignment beds have to be set up daily.