Lightnin's Simple Alignment Test

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LightninBoy
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Lightnin's Simple Alignment Test

Post by LightninBoy »

Hey Folks,

Several people have asked me to repost my earlier video showing the alignment test with a tuning board and square. So I made this video. Hope this helps!


https://youtu.be/xugIvuuCSEw
Speedster
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Re: Lightnin's Simple Alignment Test

Post by Speedster »

Great job on the video. I've been using it at our workshops ever since you did the 1st video. The scouts Love it. I do too.
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Re: Lightnin's Simple Alignment Test

Post by chromegsx »

This is a great method to help understand alignments. Wish I had it when I was first learning. could have saved me a few hours of frustration and sleepless nights right before a race or two.

Digging a little deeper into alignments. It should be noted that this makes some assumption of how high the nose of the car will sit and doesn't necessarily account for the change in toe effects of putting the dominate front wheel/axle in at the desired drift amount. So if your nose ends up a little lower or higher than this test you may be changing your rear toe angle if using canted drill job or bent axles. Great place to start though.
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Re: Lightnin's Simple Alignment Test

Post by Speedster »

I install the DFW and measure the height with a caliper. Remove the DFW and set the car height the same.
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Re: Lightnin's Simple Alignment Test

Post by Gtdhw »

Speedster wrote:I install the DFW and measure the height with a caliper. Remove the DFW and set the car height the same.

This is how we plan on doing our new district build in the next couple of nights, for our first try using this method.

Excellent info.
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Re: Lightnin's Simple Alignment Test

Post by chromegsx »

Speedster wrote:I install the DFW and measure the height with a caliper. Remove the DFW and set the car height the same.
:thumbup:
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Stan Pope
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Re: Lightnin's Simple Alignment Test

Post by Stan Pope »

I have two concerns with rear alignment that this method does not address:
1. Assurance of correct alignment of the more lightly loaded rear wheel, and
2. Assurance that the rear wheels are tracking "off the rail."

Here are proposed solutions for those concerns:

1. Since the more lightly loaded rear wheel contributes drag but not directional control, its input can be forced. Do this by running the tests with front end support pin located left of center and then right of center. (Confirm with scales that the chosen pin locations do, in fact, cause the rear weight distribution to shift sufficiently.)

If the ballast is centered, then supporting the front end left of center makes the right rear wheel dominant, and it is the one that should be adjusted to affect rear alignment. And vice versa.

You should be able to identify pin locations that are suitable for all of your cars unless you really push the CM left or right.

2. To assure that the rear is tracking correctly (off the rail), draw two lines down the board, parallel to the edge. One should mark the location where the right front wheel would be if it were guiding the car. That is used for the pin located right of center. The right rear wheel should track approximately 1/8" to 3/16" to the right of the line.

The other line should mark the location where the left front wheel would be if it were guiding the car. That is used for the pin located left of center. The left rear wheel should track approximately 1/8" to 3/16" to the left of the line.
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LightninBoy
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Re: Lightnin's Simple Alignment Test

Post by LightninBoy »

Regarding concern #1 - There are likely several improvements that could be devised to make this approach more friendly to aligning bent rear axles. I've only aligned a couple of cars with bent axles with this technique so there are probably others more qualified than I here. But the challenge I had with it was simply around isolating which axle was off and therefore knowing which to adjust. The test as shown does a good job of exposing that something is wrong, but doesn't tell you which axle to adjust. So what I did was bias the weight/pin to isolate one axle. Adjust. Then isolate the other axle. Adjust. Then center the weight/pin again to see the results. It would normally take a few attempts and still feels more like an art than a science to me.

Regarding concern #2, if this is about detecting a dog tracking alignment, then that has been easily visible when pushing it down the board and pulling it up. Backing up, in particular, is highly sensitive to it because once the car goes off angle it just gets progressively worse as you pull up. Drawn reference lines might help but don't seem necessary. I used to beam a laser down the board at the center of the car to help detect dog tracking but it never exposed anything I couldn't already see with the naked eye so I stopped doing that.

Those are my experiences. I'd be interested in hearing other's experience because I do expect there is room for improvement particularly as it applies to adjusting bent rear axles.
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Stan Pope
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Re: Lightnin's Simple Alignment Test

Post by Stan Pope »

Great, LB!

I didn't find where you described biasing previously. :) If I understand, we described identical solutions for #1. This is important since the forward/reverse roll test is difficult with preferred tight hub-body clearance! And, I think, that test loses accuracy as the camber angle increases in magnitude. (Max V published some tests a couple years ago suggesting that increasing the camber beyond 2-1/2 degrees was advantageous.)

By moving the car body left and right on the pin you force a particular rear wheel to be dominant. Adjustment of bent axles in this procedure is always done to the dominant rear wheel. Reduces the need for "art." :)

Regarding #2, a common accident when drilling axle holes is that the drill press table has rotated slightly. Drilling against a fence produces compensating errors in each rear axle hole ... the holes are parallel to each other, but not perpendicular to the car's centerline! The result can be accidental, but otherwise excellent, dog-trot alignment which you may or may not catch "by eye"... a small error in tracking can put a rear wheel hard against the rail!

Further comparisons of methods:

1. Rear wheel load biasing can be obtained with this method without increasing the total rear end load. This would avoid flexing the axle camber angles if the body were to flex under the additional load. I have not noticed this actually happening, but it is a risk.

2. The method appears to require that the DFW be removed in order to use the method. This would be a problem if one were simply trying to prove that rear alignment was still good. By comparison, my weight biased method can use the race-ready DFW toe-in without change. However, I believe that raising the front end by 1/8" (to lift the DFW off the board) changes the rear axle angles too minutely to cause the test results to change. (Rotating the body 1/8" at 5" is 1.4 degrees. Since the rear angle changes from 0 (when the body is level) to 2.5 deg (when the car body is vertical), the error introduced in the rear axle is well less than 1.4 degrees.) I must make one of your boards to test these guestimates! :)

3. The slow motion relative to my weight biased method should be much easier to evaluate. As my eyes get older, that ease will be appreciated!
Stan
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Stan Pope
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Re: Lightnin's Simple Alignment Test

Post by Stan Pope »

LightninBoy wrote:Regarding concern #2, if this is about detecting a dog tracking alignment, then that has been easily visible when pushing it down the board and pulling it up. Backing up, in particular, is highly sensitive to it because once the car goes off angle it just gets progressively worse as you pull up.
This needs to be tested. I question it because the forward pull establishes the rear wheels ready to roll straight back on the reverse roll. The body is askew, but the axles are oriented correctly for a clean backward roll!

Regarding compensating error due to drill press table not perpendicular to the quill. Yes, the axles come out parallel, but the error introduces a dog trot alignment, risking that one of the rears may not track off the rail. My spreadsheet indicates a 1 degree error in the drill press table shifts the rears 0.087" (assuming a 5" wheelbase). By comparison, indenting the DFW 1/16" produces only a 0.063" rail clearance for the wheel following the DFW. Adding in the 1/32" hub-body clearance for the rear wheel still leaves that wheel at risk. Now, admittedly, 1 degree is a pretty large error on high precision equipment, but most of us are not so well equipped!
Stan
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Kindintentions
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Re: Lightnin's Simple Alignment Test

Post by Kindintentions »

Loving the ideas from this simple Alignment Test. Going to use it before installing the DFW and testing on my second alignment board to get my steer to 4 inches over 4 feet.
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Re: Lightnin's Simple Alignment Test

Post by Kindintentions »

One question I had is if the rear wheels migrate toward the body on the reverse test, is that indicative of steer in the rear wheels or something else?

When going forward the wheels migrate properly away from the body but in reverse I am seeing my wheels migrating back toward the body, but have not seen any steer when moving the front end support pin left or right of center (unless I am not moving the pin enough left or right of center).
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Re: Lightnin's Simple Alignment Test

Post by davet »

We used this method for years ever since LB showed us how. It seems dead on.
We use a balled up piece of duct tape under the front of the car, in the dead center between the axle holes. We ball it up to get to the same height as the car sits with the DFW installed. The duct tape stays stuck to the square as you pull it along.
If the wheels go out to the head forwards but stay at the body in reverse then you have toe out.
If the wheels go out the head in reverse but stay at the body going forward you have toe in.
Each time you start the test, either forward or in reverse, have the wheels up against the body.
I lay a flashlight down on the table behind the car and aim it at the rear of the car. This way I can see the shiny axles appear as the wheels migrate out to the heads.
Twist the axles until the wheels migrate out the heads at the same rate and get to the head at the same distance both forward and in reverse.
Once you get that you are dead on.
If you run a tight gap like .008" - .010" you can still see the axle appear as the wheel goes out.
Prior to installing axles we would drill 2 holes in the underside of the body along the axle hole on each corner. We use Elmers craft glue (white) and put the bottle right up tight to the hole closest to the center of the car. Gently squeeze glue into the hole until you just start to see it appear in the hole closest to the outer edge of the car (where the axle goes in).
Now, slide your completed wheel/axle assembly into the hole. The excess glue will come out the holes and not ooze out the axle hole onto the axle or wheel.
Wipe the excess glue away making sure not to get it on the wheel.
Set your gap where you want it and start tuning using this method.
Once you have it dialed in push your axle in tighter if it came out slightly from working with it and let the glue finish drying.
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Re: Lightnin's Simple Alignment Test

Post by Speedster »

WOW! 4 years have passed since this was first posted. Where does the time go?

Here's what we did this year.
All three wheels get 1 1/2 degrees cant with bent nails. (Following RULES). Rears are installed for Negative cant. Left rear wheel gets .030 clearance and right rear wheel gets .060 clearance using credit cards for spacers. Right front wheel is installed with Positive cant and car height is measured with a caliper. Piece of 3/8" wood dowel, graphite on one end and double face tape on the other, is placed in the center of the front. Car is pushed forward and backward on a very smooth section of Formica or whatever it is. Wife is not home. Rear wheels are adjusted so they stay at the axle heads while moving both forward and backward. Right front wheel is installed and car is set to drift 2" in 3'. That's the way it has ended up for a long time after taking it to the track so I just go ahead and set it up that way. Before taking it to the track I bring a section of my Best track into the house and set one end up about 4". It's really cold in Ohio at race time. That's why the section of track is in the house. Wife is gone. I check to see if the right rear wheel stays off the rail. It's close but it is always off the rail. The block is not narrowed 1/16" behind the Dfw. The End.
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Re: Lightnin's Simple Alignment Test

Post by davet »

Speedster,
Are you helping the local kids prep for their races? Is it just scouts or are you finding other avenues to help also?
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