DIY Home Alignment Info

[cdb95z28]

Now for the most important tool. The custom alignment rigs that are used to string the car. If you watched the Grassroots Motorsports DIY String Alignment Stand video from the first post, you'll know what I'm talking about. Start at about 37 minutes in the video and JG starts to talk about the thinking on why these rigs will work the best. Here are mine that I made, hanging on my 1LE. The EMT conduit is hanging off the rigs. Now I have 2" square aluminum tube at the rear, and it does help to have one of them to be square, that way it doesn't move around when you start to string the car. Also, make sure the tubing is straight. When you buy it, go thru and look for the straight ones! Minimize variables. And always use the conduit/tubing the same way every time. Indicate which end goes where, The front conduit should be marked LF and RF, and LR and RR for the rear.

Notice the aluminum square at the rear and the EMT conduit at the front have very fine slots cut into them. Use the thinnest hacksaw blade you can find, or whatever means you can cut the notches the thinnest and most accurately. This is where the string will hook onto. These slots are the same distance apart on the EMT conduit as it is on the square aluminum. So when you string up the car, the strings are parallel to each other. This is important! The distance between the slots in each conduit/tube have to be identical. This is the most important foundation (more so than a level platform) for having accurate, repeatable alignments!!















Attachment 1055499

Attachment 1055500

Attachment 1055501

[cdb95z28]

And on the rear:













Attachment 1055494

Attachment 1055495

[cdb95z28]

The above photos show a dark green braided fishing line. I have since moved onto a bright yellow braided fishing line. Easier to see and work with. This is not you regular bass fishing line, I think it is used for deep sea fishing, very tough stuff.

[cdb95z28]

The rigs were fabricated from components from a company called 80/20.net

JG from the Grassroots video mentioned the 80/20 site on ebay. Unfortunately they do not have that page anymore.
1"x1" Quick Frame Tubing and Quick Frame Connectors is what you want.
https://8020.net/catalog/category/vi..._list_limit=36

https://8020.net/catalog/category/view/id/17/?cat=296



Here is a link to a company that sells the components, this site is a little better to see the components than 80/20's own website:
https://f-l-8020-store.myshopify.com...ns/quick-frame


They will even send you a huge free catalog:
https://8020.net/inquiry/index/requests


I started the fabrication by using some 1/2" square wood I had laying around and mocked up what the rigs might look like. I wanted the rigs to be able to sit on the car without anything having to hold them. So I made the rigs with little hooks so they would catch the front radiator support and at the rear the little recesses on the black plastic trim pieces above the rear tail lights (see above pictures). Also, I used some weatherstrip on the areas where the rig will lay against the paint. make sure the paint and the weatherstrip are always clean so you don't get any scratches. Plus, the weather strip adds some friction so the rig won't move around too easily once you have it where you want it.

Once I mocked up something, I took measurements to get an idea how much tubing I would have to buy. And I knew what type of tubing connectors 80/20 had by looking at their website and catalog. They have various angled connectors to choose from. Lots of versatility.

This will take an open mind and a vision of what you want. Sketch everything out, I actually printed a pic of a Gen5 Camaro and used it for reference for the side perspective of the rig.
Total cost for both the front and rear rigs are a little over $100. The rigs I did for my buddy for his GEN6 came in at $104

Here is one I did for a buddy's Gen6 SS 1LE. I will update this post with a better/more detailed drawing of this



Here is the Gen5 info below. These are my actual measurements from the rigs on my car pictured in this thread. The rigs are represented in black.






In order to get close with your rig, you have to figure out what your wheel centerlines are and where the string would connect at the front and rear rigs.

Imagine if you draw a perfectly straight line connecting your wheel centerlines and out past the front and rear of the car. This is the tight, straight string. That straight line must connect to the conduit at just the right height so both the front and rear wheel centerlines match up. Now this sounds hard, but I built adjustability in my rigs so that they would accommodate slight variations of and a change in ride heights, which ultimately alter where the wheel centerlines would be.

Since the rigs hang on the car at the top they actually can pivot off that top mounting. When they pivot at the top, the bottom will move in an arc, which moves the bottom up or down. It's not alot, but it gives adjustability. The exaggerated red arc shows how the rig would move.




Ok, you guys still with me?

How did I add adjustability?

I added adjusters! I used a non marring plastic inside each adjuster. Turn the all-thread and the adjuster will push the rig away from the car. Or allow it to come closer to it. This allows for very fine tuning of the sting line in order to get the string at the wheel centerlines. We need to get the string to the wheel centerline so we can get a measurement off the wheel hub to get the car centered in the "string box" we have created. The strings are parallel, so if we can center the car exactly in the middle of the parallel strings, we can get accurate toe and thrust measurements. But getting the string height correct is only part of it, you gotta get the car to be perfectly centered in the strings side to side.







The bottom of your rigs will hold the conduit. And the conduit will have the strings attached to them. You gotta get the bottom length of the rig very close so the conduit will be lined up to wheel centerline. It doesn't have to be perfect, but it is better to be a bit longer than shorter because once you start fine tuning the rig size, it's better to have to cut off too much length to get the length correct than have to order more 1" tubing because it's too short. Plus being longer just allows you to use some sort of spacer under the conduit if you need to get the conduit/string up to match your wheel centerlines. And don't forget, I have the rig adjusters to help fine tune the height. If you look at some of my pics, you'll see some spacers being used. When I originally set up my rigs, I did it with the OE 20" 1LE wheels. But my track wheels are 19s, which shouldn't matter because the car only sees the height difference of a tire change from the wheel centerline on down. But, Then I installed lowering springs! And that does matter for what we are doing! The car sits lower towards the wheel centerline. And since the rigs sit on the car we have to change their length. And I had to accommodate my setup to handle those situations. All without changing the actual rig dimensions. It worked out well.




Remember Geometry class?

Note that this "string box" does not need to be a perfect 90*, right angle rectangle. It just needs to be a parallelogram. Remember, all rectangles are parallelograms, but not all parallelograms are rectangles.
The front and rear conduit do not need to be at perfect right angles to the string. They will be very close, but the below drawing is going to be a gross exaggeration of any possible variance we might have.

We don't need to worry about that. If the rigs were built accurately, and are sitting square on the car (they will be if you center the car in the strings), and the conduit is straight, and your car's structure or suspension is not bent, then I can damn near guarantee it will be as perfect of a rectangle as you will need to do the alignment accurately.



As long as the strings are parallel, this will all work. And as long the strings are straight with no sag and at the wheel centerlines, we can confidently get accurate measurements off the wheel hubs and at the leading and trailing edge of the wheels (which gives us toe). When I say wheel hub, I am talking about the center of the wheel or near center. Sometimes a wheel center cap will be of a nature that we cannot get and accurate measurement there. Like my Forgelines, there is no cap so I measure to the next smooth, flat surface of their center. We are using the wheel hubs as the
reference point because they are the most centered and important part of the wheel/tire assembly. Even if your wheel offsets are different front to rear, it won't matter as long as the side to side on that axle is the same. But, if one wheel has a wheel spacer and the other one on that same axle (LF and RF) on the other side doesn't then you won't be able to get the car centered. Another variable to consider is we are wanting your current alignment to be fairly close. If one corner is way off on toe or camber that will have the hub tweaked a little bit, which can effect the centering of the car in the strings.

To get the car centered side to side in the "string box" we just move the entire rig, either or both the front or rear rig, side to side. This takes a gentle touch and some patience. I strive to get my hubs to within a 1/4 of a millimeter of each other. The left front hub measurement from the hub to the string must be identical to the right front hub measurement to the string.

And the left rear hub to string # must be the same as the right rear hub to string. Along with getting the string heights correct, getting the hub to string #s the same takes some time and alot of patience. And a gentle touch. Remember you are giving from one side and taking from the other. You'll be walking from one side to the other multiple times till you get it perfect. But it must be perfect!

[cdb95z28]

The Grassroots video mentions SmartStrings. These guys have made a universal string rig setup that creates the string box. Lots of upfront cost, but it looks like a very high quality setup.

https://www.smartracingproducts.com/smartstrings

Here's an article with the SmartStrings. It also gives you another perspective on DIY string alignments:

https://www.turnology.com/features/e...cle-alignment/

[cdb95z28]

Next:
Camber and Caster.
These are easy to measure.

[h018871]

well done

[cdb95z28]

I'll be getting into working with the strings a bit more also. Ride heights can vary a small amount. This is not uncommon, especially if you have coilovers and the car was setup on scales. The thought on "scaling" a car is to get the weight distribution optimum, and this sometimes causes the ride heights to be uneven. And that is ok. But as far as what we are doing here, we might have to tweak our strings (vertically) to get them as close to the wheel centerline as possible. I will talk about a way to work around that.

There are lots of variables we have to try and control in doing this. Some variables like wheel runout, wheel hub thickness, manufacturing variations and tolerances can effect your accuracy. Today's cars are built to very tight manufacturing tolerances, but when we are talking about honing in on our measurements to less than .5mm, we have to expect somethings are out of our control. Some of these variables are known, but we have to decide whether they are tiny enough to not worry about them or we ask ourselves whether it would be too much work to eliminate them.

Like wheel runout for instance. I mean, we could control something like that, but that adds alot of time to the procedure. For example, Forgeline has a max lateral runout of .030" which is .7mm. So if I want to keep my measurements tight at .25mm, you can see that if my wheel is off by .7mm, that could alter my results. So, am I going to measure my wheel's runout every time I align it? No. I just accept that is a variable that can alter my accuracy, but it is not worth chasing.

BTW, (edited) The Camaro service manual states .030" lateral and radial runout maximums for aluminum wheels, .045" lateral , 040" radial for steel.

I guess part of what I'm saying is, the tighter you can hold your own tolerances, the better your results. Sure, you could say "damn, .25mm or even .5mm is damn tight, do we really need to be that particular?"

This big part about being that tight is when you are trying to get one side to match the other when you are setting your toe. If you don't hold the tolerance tight, you can get one side to have more toe than the other, and that will effect how the car drives. And how the tires wear over time, but the toe would have to be off a fair amount here. On our cars with the low profile tires, it matters. And if your are running your car to the edge of performance, like if you are tracking your Camaro as I do, the tires need to be optimized at every aspect. On my 2010 Sierra with big, compliant sidewall truck tires, not so much.

Would you say that since you are doing the measuring, could you be a big variable? Yes, if you are sloppy in taking measurements, then your going to get sloppy results. We need to control ourselves tightly to keep the sum of all the variables low.

[cdb95z28]

Originally Posted by h018871

well done

Thanks. Hopefully I'm not over-saturating this with too much info.

[Nick S]

Very nice write up cdb95z28! This is all some really great information!

[cdb95z28]

Originally Posted by Nick S

Very nice write up cdb95z28! This is all some really great information!

Thank You. More info to come!

[cdb95z28]

I came across this on Youtube today. Shows some of the procedures on string alignments:

[cdb95z28]

Thread is updated with a detailed drawing of my GEN5 alignment rig specs. See post #18

[cdb95z28]

Concerning the alignment rigs, I'm not going to dive deep into how I did the little adjusters at the bottom that allows the rigs to pivot off the top in order to have some vertical adjustability. I will say that I did use different tubing from 80/20 that has a small reinforcement. You can see it in some of the pics. It's part # is 9025. I used this as a way to capture a nut so I could turn the adjuster.

Some closer pics of the adjusters.