Streetable Track Alignment?

[GForceJunkie]

I'm going to get an alignment to or close to these specs when I finish putting my front end back together.

-2.75 camber
maximum caster
1/16 toe out

I'm trying to decide if I could leave the alignment at track spec all year or not. Should I expect "excessive" inner edge front tire wear? I realize there will be more than normal, but I would only put a few thousand miles a year on it. The 18" 555's aren't cheap, but neither is 2 or more alignments a year.

If anyone could chime in with your specs, miles per year and if you feel you could live with the wear you are getting or not, I would really appreciate it.
Thanks. :rockon:

 

[MFE]

Why on earth WOULD you leave the alignment to track specs full time when it's so easy to put the camber back some place reasonable? And yes, that camber in conjunction with toe-out is going to wear out the inside edges.

All you have to do is take a tape measure and measure how far your strut tops are from the fender edge, and write the numbers down. Do it again when you have your camber at your track setting. Now you can move back and forth between street and track settings in less time than it took to write this.

Personally I'd leave the toe alone, but if you insist on it for the track, and the car remains toe'd out when your camber is taken back to street settings, then it only takes a couple minutes to adjust that, too, at the rate of about 1/16th inch total toe in change for every turn of a tie rod.

 

[GForceJunkie]

Why on earth WOULD you leave the alignment to track specs full time when it's so easy to put the camber back some place reasonable? And yes, that camber in conjunction with toe-out is going to wear out the inside edges.

All you have to do is take a tape measure and measure how far your strut tops are from the fender edge, and write the numbers down. Do it again when you have your camber at your track setting. Now you can move back and forth between street and track settings in less time than it took to write this.

Personally I'd leave the toe alone, but if you insist on it for the track, and the car remains toe'd out when your camber is taken back to street settings, then it only takes a couple minutes to adjust that, too, at the rate of about 1/16th inch total toe in change for every turn of a tie rod.

That sounds simple enough, I'll give it a shot. Thanks.

 

[sonic cobra]

I ran -1.5 with 1/16 toe in for 10,000 miles. Noticed the right front was badly worn on the inside edge and left side was OK. Checked alignment and left side was good at -1.5 but right side was -1.7 and tire was done.

 

[GForceJunkie]

I ran -1.5 with 1/16 toe in for 10,000 miles. Noticed the right front was badly worn on the inside edge and left side was OK. Checked alignment and left side was good at -1.5 but right side was -1.7 and tire was done.

Thanks Paul.
This is exactly the kind of info I was looking for.
About how many track days do you think you ran within that time?

 

[sonic cobra]

Four track days on Nitto 555 RII's. I like the idea of increasing camber for track days. I was thinking of scribing lines on CC plates for street and track, but wasn't sure if increasing the camber would change the toe.
I also got 40% more mileage out of the tires that I had heat cycled when purchased from Discount tire

 

[David Hester]

Hold on a second!!
Just because it is important, to get around corners we want a bit of TOE OUT, not toe in.
Why?
As you go around a corner the inside wheel makes a smaller arc than the outside. (go run through a puddle and compare the arcs). Ackerman angle (note your tierod end is not exactly in line with the center of the hub) takes care of some of this, but to help you add a bit of toe out so the outside wheel can make the larger arc without scrub. Toe in, the outside tire is trying to cut in and make a small arc.
Crappy turn in and lots of tire wear (scrub).
Camber is a good thing. I race with over 2 degrees-2 1/4 left, right at 2 right (most clockwise tracks have more rights. Of course, chamber lets you leave more rubber on the road as the chassis leans in a corner, just when you need it most. Bad part, you don't need any in a straight line, hence street and track settings.
As far as camber, a Sharpie will mark where your plates are for street and track. Loosen the nuts on the strut tower and have at them- finish playing and move them back. Let a shop set to factory, mark it, and then when you get to the track push in the tops of the tires as far as you can. I've not been able to get too much on either a Fox or New Edge chassis without notching the tower.
As far as toe change, you are moving the top of the strut, but the relative position of the bottom (where the tie rod lives) bearly changes at all. To get any change, you really need to get under there with a couple of wrenches.

 

[GForceJunkie]

Hold on a second!!
Just because it is important, to get around corners we want a bit of TOE OUT, not toe in.
Why?
As you go around a corner the inside wheel makes a smaller arc than the outside. (go run through a puddle and compare the arcs). Ackerman angle (note your tierod end is not exactly in line with the center of the hub) takes care of some of this, but to help you add a bit of toe out so the outside wheel can make the larger arc without scrub. Toe in, the outside tire is trying to cut in and make a small arc.
Crappy turn in and lots of tire wear (scrub).
Camber is a good thing. I race with over 2 degrees-2 1/4 left, right at 2 right (most clockwise tracks have more rights. Of course, chamber lets you leave more rubber on the road as the chassis leans in a corner, just when you need it most. Bad part, you don't need any in a straight line, hence street and track settings.
As far as camber, a Sharpie will mark where your plates are for street and track. Loosen the nuts on the strut tower and have at them- finish playing and move them back. Let a shop set to factory, mark it, and then when you get to the track push in the tops of the tires as far as you can. I've not been able to get too much on either a Fox or New Edge chassis without notching the tower.
As far as toe change, you are moving the top of the strut, but the relative position of the bottom (where the tie rod lives) bearly changes at all. To get any change, you really need to get under there with a couple of wrenches.

Thanks for the advice David, I have a couple questions.
With MM cc plates in a 96 Cobra with 01 Bullitt springs (@ .75" drop f/r), how much negative camber do you think I can get without notching the tower. Also, do you think 1/16th toe out is enough to acheive what you're talking about or would a little more be better?
Thanks again. :beer:

 

[David Hester]

I'm betting you can't get much more than -1.75to -2 degrees or so. The tops of the struts hit the hole edge in the strut tower. The spacers in the chamber plate help offset some, but the hole just isn't big enough to get a lot. That said -2 is probably more than enough. Too much and you screw up your straight line braking.
I roadraced my Fox for months with 1/4" toe out. I had set it up for autocross. Noticed last fall car Would Not turn at speed. I was just setting up everything for 45th at Birmingham and noticed how far it was off. 1/16th out works pretty well. 1/2" sucks! One heim joint had come loose and 1/4" had become closer to 1/2"!!!!:nonono: Note autocross you can be almost full lock so, it worked pretty well.
Wanna make a toe gauge for cheap?
I use a couple of spare 3/4" aluminum angle strips about an inch longer than my tire diameter (26" for me).
Strap them to the wheel with a couple of bungee cords so the edges stick out a tad farther than the tires. A couple of holes in the ends (even wth the tire edges) I drop a couple of long phillips screwdriver through so they almost touch the ground. Do the same for both sides.
Now hold a tape measure on the ground just under the points of the screwdrivers. By using the screwdriver "pointers", I didn't have to worry about all the things hanging down under the car, headers, oil pain, etc.
Backside of the tires measure 70", fronts measure 70 1/16"- 1/16" toe out.
Is it as accurate as high tech lasers? Do I care?
I think a jar of 10 bungee cords was $3.00. I had the screwdrivers, angle and tape measure in the garage and I can check it every weekend (at least after every change) for free now.

 

[MFE]

There's a lot more to this than "the outside tire tries to cut a smaller arc". The loaded, outside tire will carve the arc that is given to it by the steering angle, give or take any slip angle due to pushing it too hard. But as far as that tire is concerned, toe in, toe out, doesn't matter. The one that will or will not scrub in a corner accordin to the toe/ackerman situation is the one with less loading, that being the inside tire. Toe has a fairly dramatic effect on turn-in behavior, why? Because on turn-in, lateral load transfer has barely started and both tires have relatively equal footing and impact on the direction of the car.

The "more to it" part concerns straight line braking capability and stability, and bumpsteer behavior. Most cars front wheels toe out slightly under bump conditions unless they've been specifically set up to minimize the effect, or set up poorly in which case they toe in under bump. Bump front toe-out is built in to most cars for the same reason bump rear toe-in is designed in, to make them tend toward understeer to keep people from getting in over their heads. But I digress...the point is, if your car'd front end toes-out with bump, and you've set it up for toe-out at static ride height to begi with, then you're achieving even more toe-out in the braking zone, which doesn't do a damn thing for your stability under those critical conditions.

Be careful just slapping static toe-out on the front end of a track-bound car without knowing the ramifications.




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[GForceJunkie]

Thanks Guy's for all of the input.
Is it possible that I could put in too much positive caster?

 

[brkntrxn]

Some people are running as much as 8-9 degrees of positive caster. You probably won't be able to get that much... so, no.

 

[sonic cobra]

Wow, this thread is getting good. I'm taking notes! Maybe a good compromise for myself would be 1/16 toe in to keep the IRS in line and zero toe in the front for now. see how that feels. Aint I the cautious one!

 

[David Hester]

MFE.
Good point. too much toe and too much camber affects braking. It's all compromises.

 

[GForceJunkie]

Thanks for all of the input guy's, I'm going to have the alignment set to;

1.5-2.0 deg. neg. camber
Max. positive caster
1/16" toe out

After it's done I'll mark the cc plates. After the track event in June I'll get a street camber setting and mark the cc plates. From there I will try making the changes between the two myself. I'll make up something like Dave suggested to check the toe in/out and see how much if any it's affected by the camber change. From then on I'll be able to make small changes with the toe in/out and see how it works for me.

 

[MFE]

Here's an article I wrote on how to do your own alignments accurately and easily and cheaply.

A note about marking the c/c plate position: I suppose it depends on the design of the plates, but on my MM plates, the spacers and the plates can move in quite a range within any given setting and still achieve the exact same setting. I'm having a hard time finding the language to explain myself but the two "halves" slide over each other such that you could hold the strut top in one place and still move the plates relative to each other, or put yet another way, marking the position is no guarantee that the strut top itself is in the correct place. And it's the position of the strut top that determines caster and camber, not the plates themselves. That's why I recommend taking the reference measurements as directly as possible: from the top of the strut.

How to do your own alignments, low cost, effective. - Corral Forums

 

[9746Cobra]

Haven't been to the track in months but my daily driver/OT '96 Cobra is set up like this:

Caster 3.6 degrees L&R
Camber -1.3 degrees L&R
Toe in .05 degrees L&R

I've had no abnormal tire wear and car feels good at about 125, which is the most I've had it up to. Even though the specs are the same side to side it only has a slight drift to the right on a crowned road.

I do wish I had stiffer springs/quality dampers. Even though the Mach 1 springs I have (and got new for $75) are 50% stiffer than stock front and rear it's nowhere near enough. But thats another topic.