Track alignment

[maytag]

Originally Posted by Qingdao

That's a weird looking alignment sheet.

WTF is mm of toe? mm measured from how far from the center of turning?

And three digits on the camber measurements?



That's a Hunter printout, but I've never seen one look like that.


The loads of caster you had last time will make a car find strait faster. Maybe try to put all that caster back into the car.

All that caster had the wheels too far forward in the opening, meaning I couldn't get the tires i wanted in, nor the ride height.

Any ideas on that rear toe difference between last year and this?

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[JayG]

Originally Posted by Qingdao

That's a weird looking alignment sheet.

WTF is mm of toe? mm measured from how far from the center of turning?

And three digits on the camber measurements?



That's a Hunter printout, but I've never seen one look like that.


The loads of caster you had last time will make a car find strait faster. Maybe try to put all that caster back into the car.

there is no caster adjustment on a 986

[maytag]

Originally Posted by JayG

there is no caster adjustment on a 986

Yes there is, as evidenced by my two charts.
(Adjustable thrust arms were part of my mods over the winter ;-) )

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[JayG]

Originally Posted by maytag

Yes there is, as evidenced by my two charts.
(Adjustable thrust arms were part of my mods over the winter ;-) )

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correction...
there is no caster adjustment on a 986 with factory parts

[jmitro]

Originally Posted by maytag

If you look at the 2nd post, waaaay below, you see that last year they set the rear end at 3d POSITIVE, where this year they went 3d NEGATIVE. I really think they put a new guy on the rack, and he went the wrong direction. Last year's setup was AWESOME. This setup scares me over 90mph.

I'm confused about which printout is which. it appears that last year the rear toe was negative (toe out) while this year is positive (toe in). rear toe OUT would make the car feel pretty unstable, like the ass end wants to pass the front

My home grown method of measuring toe is to use Longacre toe plates to measure total toe, then a laser pointing on a reference point from the rear wheel towards the front (both sides) to make sure the thrust angle is zero

[maytag]

Originally Posted by jmitro

I'm confused about which printout is which. it appears that last year the rear toe was negative (toe out) while this year is positive (toe in). rear toe OUT would make the car feel pretty unstable, like the ass end wants to pass the front



My home grown method of measuring toe is to use Longacre toe plates to measure total toe, then a laser pointing on a reference point from the rear wheel towards the front (both sides) to make sure the thrust angle is zero

I should've widened the view on the '20 print, so it'd capture the date at the top left, the way the '19 has.

No mistake that last year it was stable as a rock, and, while I haven't had this setup to the track yet, at 90mph on the highway, I'm white-knuckled.

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[husker boxster]

My race alignment has the fronts at .05 deg toe in and .1 deg toe out on rears.

Not sure how your mm compare to degrees. If mm & deg are an apples-to-apples legit comparison, it seems you have a lot of toe out on your rears.

[maytag]

Originally Posted by husker boxster

My race alignment has the fronts at .05 deg toe in and .1 deg toe out on rears.



Not sure how your mm compare to degrees. If mm & deg are an apples-to-apples legit comparison, it seems you have a lot of toe out on your rears.

So husker is running a little toe-out.
MaxD runs zero.
All the rest of y'all are telling me you run toe-in.

I'm in a real head scratcher here.

One thing I THINK I'm still feeling, (I haven't been able to spend enough time in the car yet to be sure it's not my imagination) is a lift of the right-rear when I step on the gas, accompanied by a mild wandering-to-the-right in the front. I wonder if this could be explained with the new tarret bars? I've got their gt3 bar in front, set at half-soft, and their bar in the rear set at full-soft.

But I'm still inclined to blame the alignment.

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[jmitro]

unless he has GT3 lower control arms or adjustable caster arms like Elephant Racing makes.

maytag I'd take it back to the shop and ask why it feels different and why the rear toe this year appears different than last year on the printout

[Racer Boy]

Yeah, that looks why there's way too much toe-out at the rear, which is why it is scary to drive.

A "race" alignment shouldn't scare the crap out of the driver. It will feel more "nervous" to drive for sure, because of the lack of toe-in, but it shouldn't be white-knuckle time.

Time to go back to the alignment place again!

[Racer Boy]

Sway bars won't cause what you are feeling. It's an alignment issue.

[Quadcammer]

I'm personally of the camp that I don't want any rear toe out.

I run a touch of toe out up front for crisp turn in, and likewise have a touch of toe in for the stability in the rear.

For me, using toe out to get stability under heavy braking doesn't make sense. Generally in a straight line rear axle stability is not an issue under braking and when i'm trailbraking, I want the rear to come around, so I'm not really seeing the benefit. I'm no alignment expert, but I've been quite pleased with my setup as described above.

[MaxD]

Originally Posted by Quadcammer

I'm personally of the camp that I don't want any rear toe out.

I run a touch of toe out up front for crisp turn in, and likewise have a touch of toe in for the stability in the rear.

For me, using toe out to get stability under heavy braking doesn't make sense. Generally in a straight line rear axle stability is not an issue under braking and when i'm trailbraking, I want the rear to come around, so I'm not really seeing the benefit. I'm no alignment expert, but I've been quite pleased with my setup as described above.

I am in total agreement.

I personally don't like toe out in the front, tested, my preference is no toe. Toe "in" in the front is for folks that want to take their hands off the wheel and talk on their cell phone.

For the rear - Some toe "in" makes your car planted on corner exit. I run zero in a Spec Box per Brad Roberts. No problem if you run a little toe "in" but I might be 1/3 a car ahead of you at the end of the straight or ... not.

[Quadcammer]

Originally Posted by MaxD

I am in total agreement.

I personally don't like toe out in the front, tested, my preference is no toe. Toe "in" in the front is for folks that want to take their hands off the wheel and talk on their cell phone.

For the rear - Some toe "in" makes your car planted on corner exit. I run zero in a Spec Box per Brad Roberts. No problem if you run a little toe "in" but I might be 1/3 a car ahead of you at the end of the straight or ... not.

indeed, I'm talking about very minor amounts on each (i'd have to go back to look at my measurements, but I believe I aim for 1mil toe out in front per side and 1 mil toe in per side in the rear). All a matter of preference at that point.

[MaxD]

I came across this: Track Alignment - Race & Track Driving (formerly Win HPDE)

It touches on a number of alignment concepts that have been brought up in this thread.

[jmitro]

great discussion and great link MaxD.
I'm intrigued by this concept of running 0 toe all around or even slight toe out in the rear. I might have to try it my next DE event

[Gilles]

Originally Posted by jmitro

I'm intrigued by this concept of running 0 toe all around or even slight toe out in the rear. I might have to try it my next DE event

Jmitro:

I am guessing that this would depend of the type of track you will be running, as the person (Steve Alarcon) that did the corner balancing and alignment on my car a few weeks ago, left the car with 1.5mm of toe in at the rear axle as he wanted the car to be stable at relative high speed 80-90 mph, which is the speed everyone usually drives on the So.Cal toll roads.., yes this is true

BTW, Steve Alarcon is a long time racer with the POC, and he specializes on Porsche race cars alignment, and his shop has very good reputation.

When I ask him the reasoning, he mentioned that when you run on a tight course without very high speed straights is when you dial your car with slight toe out to help you rotate the car, otherwise you dial toe in to help the car stability on high speeds.

However, I am no expert on this matter whatsoever just relying what I heard a few weeks ago.

[bcrdukes]

Use the theory of running zero toe all around (or even slight toe out in the rear) should be used as a baseline. Depending on where you drive, the track you spend most time on, and use case of your Boxster (or whichever car you have) you may need to adjust accordingly. The part about SoCal folks hitting 80 to 90MPH on toll roads is quite the norm. Us plebeians cannot afford the use of the tolls and therefore, stuck on the Interstate at crawling speeds.

[husker boxster]

Here are a couple of videos and link that I just ran across.



.
https://en.wikipedia.org/wiki/Ackermann_steering_geometry
.

[Gilles]

Thank you Husker, nice videos!