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Posted by: yeahmag May 12 2011, 11:14 AM

This was built using 80/20 hardware and a friend of mine on the mill:

Posted by: yeahmag May 12 2011, 11:14 AM

The sliders at the end are indexed every 5 mm

Posted by: yeahmag May 12 2011, 11:15 AM

I'm using string here just because it was handy for the demo. I will be using fishing line when I actually start working with it.

Posted by: yeahmag May 12 2011, 11:17 AM

The bars are *exactly* the same length and indexed *exactly* the same. So all I should need to do is measure off the front and rear (L & R) and I will have a parallelogram very quickly.

Posted by: PeeGreen 914 May 12 2011, 11:33 AM

Nice, This is very similar to what you would pay a few hundred for.

Now all you need are scales

Posted by: yeahmag May 12 2011, 11:38 AM

I know! That part is still killing me...

Posted by: URY914 May 12 2011, 12:10 PM

Leave them on and use them for curb feelers.

Posted by: Andyrew May 12 2011, 03:08 PM

String alignment works great for toe in/out, but IMHO I dont see it helping with camber or caster...

I use 2 4x4's and a tape measure and a buddy... Then drive to the alignment shop and pay the man $50 to tell me I did it right and give me a printout of camber/caster/toe/"walk".

I also use a bubble camber guage... Cross between the two below.

http://cgi.ebay.com/ebaymotors/New-Aluminum-Economy-Caster-Camber-Gauge-/200601769185?pt=Motors_Automotive_Tools&hash=item2eb4cc14e1
http://cgi.ebay.com/ebaymotors/Tenhulzen-Automotive-Camber-caster-alignment-gauge-/320698487662?pt=Motors_Automotive_Tools&hash=item4aab1e936e

Posted by: whatabout1 May 12 2011, 03:35 PM

For camber just get on flat floor (doesn't need to be level).

Put a framing square on the floor and against the tire so you have a 90 to floor.

Measure from square to bottom of wheel rim then measure from sq to top of wheel rim.
(Rim not tire) Figure the diffence and wheel diameter between measuring points
and do the trig or

http://www.furybusa.org.uk/camber.php

Not perfect but close enough.

Posted by: Eric_Shea May 12 2011, 10:34 PM

How much to do a second one?

Posted by: SirAndy May 12 2011, 10:55 PM

The problem with that is that a two wheel alignment does not ensure the whole car is square.

We use camber plates at the track for quick setups, but you're only setting the front or the rear at any given time.

If the car is not squared, you'll be crabbing down the road ...

Posted by: Krank May 12 2011, 11:27 PM

I was never a huge fan or "string" alignments that I used to do in the 70s and I am still not a fan of them. Too many discrepancies. Wheel track must be 100% the same between front and rear axles to get an accurate toe in measurement/setting. If you were to start with a true toe in setting of 1/8" and then widen the front axle wheel track by 1.00" your string method of measurement now reads a different toe reading. This is just to show the change in toe that is possible. Don't get me wrong, this method may get you close but using jack stands as string anchors would probably work just as well. Seeing as you are measuring the distance from the string to the tire 9 0'clock, axle center, and 3 o'clock positions to obtain a parallel line on each side of the car and give you an idea of toe in/out. If all you wish to accomplish is proper toe setting, a "toe bar" scribe method would be more accurate. To be honest, I have never looked up the wheel track or steer axle set back specs of a 914 and it may be exactly the same and work fine but just so you are aware that there are many vehicle that are not the same.

Posted by: yeahmag May 13 2011, 12:03 AM

This system does replace jack stands - and yes that works. That's how I did my last alignment... The relationship between the front and rear is arbitrary and only aided by the fact that the front and rear bars are identical in length and index. *ALL* that matters is that you have a parallel box around the vehicle to reference from. So what if the track width changes? Make a parallel box... A toe bar will give you the relationship between two wheels, but not the relationship of the center line of the car.

Assuming you have a perfect square, the strings method will give you the same reading as a "toe bar". If your center line is off on the toe, you will still get the same reading with the toe bar. I see a toe bar (or toe plates) as a secondary system. Which I intend to use at the track... Like the Longacre toe plate system.

Posted by: SirAndy May 13 2011, 12:05 AM

I've probably done 100 of them by now and not once on a car that had the same track width front/rear.

I don't see how that would have any impact at all? Confused ...

Posted by: yeahmag May 13 2011, 12:05 AM

I would guess at least $200 in parts - probably not worth it. Maybe you and I could work a trade of some sort. Let's talk offline.

Posted by: Andyrew May 13 2011, 12:58 AM

Which is why you go to the alignment shop that has lazers and pay the men 50 bucks to do the car the rest of the way...

The 4x4 method works great for those quick jobs if you just did something and need to drive somewhere. I just dont see how a string method will do the car to the level that a daily driver should be at to prevent premature tire wear.

Posted by: Richard Casto May 13 2011, 07:08 AM

You don't have to have same front/rear track width to set toe using string method.

Richard

Posted by: Dave_Darling May 13 2011, 10:42 PM

As long as you get the strings referenced to the actual centerline if the car, you can get it as good with strings as you can with lasers. In fact, you get the exact same problem with the lasers; they have to be referenced to the centerline of the car to make sure the car doesn't crab.

The track widths are completely irrelevant, you measure the tire (or the wheel) against the centerline, not the front wheel against the back wheel.

--DD

Posted by: mrbubblehead May 14 2011, 07:54 AM

so how is the best way to find the center line of the care.

Posted by: BK911 May 14 2011, 09:18 AM

I use a setup very similar, but with electrical conduit. About $15 in parts and I get repeatable results everytime. Same jig works on my 911 and 914.

Posted by: sww914 May 14 2011, 10:56 AM

I've done hundreds of alignments with computerized laser machines. About 80% of the time when I'd test drive the car the steering wheel would be crooked and I'd have to jack the car up and move the tie rods again to center the wheel. That's a bad sign. I've done a hundred alignments with strings and in 100% of the cases when I was certain that my measurements were perfect the steering wheel was straight when I test drove the car.
To set up the box around the car you measure to the hub of each wheel and make certain that the 2 front measurements are exactly the same and that the 2 rears are exactly the same and that the strings are perfectly parallel. If that's true and the car's suspension isn't bent you have a perfect box around the car to measure the toe. I also measure between the string and the chassis (not the body) of the car to make sure that my box that is parallel to the hubs is also parallel to the chassis.

It does matter if the floor is level. It really matters. If you set the camber and the floor is 1 degree slanted to the side it will change all of your measurements by 1 degree. Let's say the car is sitting at a 1 degree angle and you want your front camber to be -1 degree. You set your camber 1 degree negative on both sides using gravity as a horizontal plane. Now you move the car to somewhere where it really is level and you have 0 camber on one side and -2 degrees camber on the other side. Front to rear level is a lot less important but side to side is critical because every bit of difference in the floor will translate exactly into suspension inaccuracies. You can shim the ca's wheels with thin pieces of plywood to get it sitting level. Before I had a rack for alignments I had 2' X 4' sheets of 1/4" & 1/8" plywood that I could put in the same places on my floor every time to level the car. 4 feet is long enough to have plenty of room to roll the car after you make adjustments so the suspension can settle again.

I could get a vendor to roll an expensive computerized alignment machine into my shop on Monday but I don't want one. If you want perfect, strings are better.

Posted by: SirAndy May 14 2011, 01:24 PM

You simply use the strings.
Measure the distance from the string to the wheel hub in the front left and right until they are even.
Then measure the distance from the string to the wheel hub in the rear left and right until they are even.
Double check front and rear until both are even left/right (Equal numbers per axle).
At that point, the strings are parallel to the car and have equal distance from the centerline.

Posted by: zonedoubt May 14 2011, 02:40 PM

...and the distance between string attachment points on conduit (or whatever you're using) on front and rear are the same.

Posted by: sixnotfour May 14 2011, 04:35 PM

ray scruggs wrote this booklet a million years ago;
http://www.raystrax.com/ha/914/Align914_TOC.html

string.... You have to think
laser machine ...just do what it says

Posted by: mrbubblehead May 14 2011, 08:34 PM

so the front track width is the same as the rear track width on our 914's? and when you say "wheel hub" do you mean the tip of the axles?

Posted by: SirAndy May 14 2011, 08:39 PM

No. Track width is completely unimportant for any of this.

When i say "hub" i mean whatever is in the center of the wheel. The strings need to line up with the center of the wheel and you measure from the string to the hub or any other reference of your liking.

To set the actual toe, you measure the distance of the front edge and rear edge of the same wheel. That difference can then be used to calculate your toe.

Posted by: John May 14 2011, 08:41 PM

Do what you will, but I will stick with my machine.

Posted by: mrbubblehead May 14 2011, 08:46 PM

right....the toe is the easy part. i replaced my rear bushing and i was told that i am crabbing down the road. i am still trying to wrap my head around this. so bear with me. i want 2 perfectly parrallel strings. 1 on each side of the car. say for example 5 inches from the end of the rear axel to the string. and then 5 inches from the end of the front axle. correct?

Posted by: sww914 May 14 2011, 09:15 PM

No, it might be 6 1/2" in the front to the string and 5" in the rear. It might be the same, it doesn't matter as long as both fronts are exactly the same, both rears are exactly the same, and the strings are parallel. Then you have 3 parallel lines, the 2 strings and the center line of the car.

Posted by: mrbubblehead May 14 2011, 09:41 PM

ok. that makes sense. thanks guys.

Posted by: SirAndy May 15 2011, 12:33 AM

Posted by: 914 shifter May 15 2011, 06:11 AM

i like to keep it simple


Attached image(s)

Posted by: fasthonda May 15 2011, 07:14 AM

You need to take the track width into consideration or the strings will not be parallel. The rear track width of the 914 is 1 icnh greater than the front. You need to add 1/2 inch when setting the distance from the front hub vs the rear to achieve parallelism.

Posted by: sww914 May 15 2011, 09:14 AM

Not if you measure the distance between the strings in front of the car and behind the car and make them the same.

Posted by: yeahmag May 15 2011, 10:51 AM

That's where the indexed bars come in to play. Set them so they are *exactly* the same width and at worst you are starting with a parallelogram.

I did the alignment yesterday and started with a steering wheel that was ever-so-slightly off... Ended that way too. Damn.

Glad I did it though. 3 off the 4 wheels needed work (I had redone my rear bushings). I also verified my ride height was at least close to where I wanted it on all 4 corners.

I'm sure I'll get better as this was my first time. I need to find a more level spot too!

Posted by: SirAndy May 15 2011, 12:55 PM

I think the confusion here is that the strings are on rods that are indexed. The rods have grooves for the strings to sit in.
You put the strings in the same groove on the front and rear rod. That way, the strings are already parallel to each other. After that, you don't move the strings on the rods, you just move the rod itself, which moves both strings.

With that in mind, the track width difference between the front and rear is completely irrelevant to the rest of the process.

You set the distance to the hub individually per axle. So the front distance might end up to be 6 1/2" left and right and the rear distance might be 5" left and right.

It's only important that the distance is equal per axle!


Maybe this will help, quick and dirty photoshop ...





Attached image(s)

Posted by: SirAndy May 15 2011, 12:58 PM

Before you start, brake lose the tie-rods and then lock the steering wheel into place. I use two wooden sticks cut to the same length.
That will center the steering wheel perfectly before you begin.

That way, you can use the tie-rods to adjust out whatever slight discrepancy you had ...

Posted by: mrbubblehead May 15 2011, 03:14 PM

couldnt you just pop the steering wheel off and then put it on straight?

does the steering rack sit in the center of the car?

then if you start off with the outer tie rod end at equal distances apart from the rack, your lock to lock wheel movement will be the same. then just drive the car in a straight line and re-index the steering wheel.

i ask this because i just finished my rear suspension and bushings. i will be doing the front end next weekend. tie rod ends, elephant bushings, torsion bars and a sway bar. i will be doing my alignment from scratch.

Posted by: SirAndy May 15 2011, 07:44 PM

That'll get you close, but the splines on the shaft are pretty coarse, so rotating the steering wheel just one spline will result in a few degrees of rotation.

With the wheels nice and straight, there might not be a perfectly lined up spline for the steering wheel.

If you lock in the steering wheel perfectly straight first and then adjust the tie rods, you might end up with one tie rod 1mm longer than the other, but you'll never notice the difference.

But you sure notice if your steering wheel isn't perfectly straight ...

Posted by: wobbletop May 16 2011, 10:26 PM

That's close but the camber difference between front and rear will make the distance slightly different than the difference in track.

Posted by: Bartlett 914 May 17 2011, 06:02 AM

Not if you measure at the center of the wheel.

Posted by: tradisrad May 17 2011, 09:19 AM

http://www.smartracingproducts.com/pdfdocs/011410_smartstrings_manual.pdf from smart racing.

I am a little confused on his instruction where he says " Toe-in: the measurement is longer on the leading edge of the
wheel than the trailing edge of the wheel." This seems backwards to me and he has it switched with "Toe-out: the measurement is shorter on the leading edge of the wheel than the trailing edge of the wheel." Is he correct with his terminology?

Posted by: yeahmag May 17 2011, 10:22 AM

And here are some videos from yesterday's trip to Streets of Willow with PCA.


https://www.youtube.com/watch?v=fIr2D6OsyYY


https://www.youtube.com/watch?v=34Ontk23idE

Posted by: SirAndy May 17 2011, 12:05 PM

Yes, he is correct. The distance on the front edge (leading edge) of the wheel will be larger for toe-in.

Posted by: yeahmag May 17 2011, 12:09 PM

Remember it's the distance from the *outside* of the car to the wheel... So toe in will have a greater distance from the string to the front half of the rim:

| /

vs toe out which will have less distance from the string to the front of the rim (in relation to the back of the rim):

| \

-Aaron

Posted by: tradisrad May 17 2011, 01:14 PM

ah (or should I say duh), from the string. I am more familiar with toe plates...

Posted by: Rand May 17 2011, 01:39 PM

Just to clarify, your words make sense but your stick figures threw me because I usually see figures with front of car at top of diagram.

Look at your feet on the ground. Pivot on your heels, move your toes in. Toe in.
I walk like a duck, I like a little toe out so I can turn quicker.

Posted by: enderw88 May 17 2011, 03:23 PM

See the attached diagram. Remember you are measuring from the OUTSIDE of the car, not the centerline.

Posted by: karnak Jun 15 2011, 08:37 PM

Good info here. i have done a string alignment and then taken it to a shop and they had little to do.

however, i have to ask, since it seems hard to find here on the forum but this may be the best place for it...

[if i set the car up per the stock specs, all will be fine for the street...] but if i want to autocross the car then a different set of specs should be used.

does any body (from experience) want to post what they have used / found to be a good autocross setup...?

thanks!
Gary

Posted by: yeahmag Jun 15 2011, 08:43 PM

1/16" to in in the rear. 1/8" or more toe out in the front. As much caster and camber as you can get in the front. 2 degrees in the rear of camber.

I muck with it all the time though...

Posted by: mrbubblehead Jun 15 2011, 08:44 PM

this is the website i used to string align my car with. http://raystrax.com/ha/914/Align914_Forward.html he also gives suggested specs.

Posted by: dion9146 Jul 22 2011, 02:12 PM

I've string aligned my car a number of times before with limited success, but I really never executed a level of precision that I should have. I used the above method this time to redo my alignment again due to a nasty vibration that I was starting to get around 73 mph.

The only thing I did that isn't in the instructions involved building a set of 3" platforms to sit level under each tire allowing me to reach up under and adjust the tie rods without needing to lift the car. This made a huge difference and probably allowed me to get it right this time.

I took it for a short drive around the block and everything felt good. Then yesterday I drove it to a client meeting, and I was running late. I got on the highway and hammered it - decided not to look down until I started to feel a bit of vibration - 110 mph. I think it worked this time.

D