DIY Strings Alignment Setup Options

[sww914]

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.

[SirAndy]

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.

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

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.

(IMG:style_emoticons/default/bye1.gif)

[zonedoubt]

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

[sixnotfour]

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

[mrbubblehead]

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.

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

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.

(IMG:style_emoticons/default/bye1.gif)

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?

[SirAndy]

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?

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.

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[John]

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

[mrbubblehead]

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?

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.

(IMG:style_emoticons/default/shades.gif)

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?

[sww914]

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.

[mrbubblehead]

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.

ok. that makes sense. thanks guys.

[SirAndy]

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.

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[914 shifter]

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.

i like to keep it simple

[fasthonda]

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?

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.

(IMG:style_emoticons/default/shades.gif)

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.

[sww914]

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

[yeahmag]

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!

[SirAndy]

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.

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 ...

[SirAndy]

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

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 ...

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[mrbubblehead]

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

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 ...

(IMG:style_emoticons/default/shades.gif)

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.

[SirAndy]

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

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 ...
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[wobbletop]

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.

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