I just finished building and testing some alignment bars this weekend. I used some 1.25" square 6061 tubing from onlinemetals to make the basic bars which are 3 ft long. I purchased some laser rifle sights from Amazon and then built some mounting rails to attach them to the bars. After calibrating the lasers, I used them to verify my front end alignment which I had done using the old tape measure method. I was close with the tape measures, but not perfect. I thought I had achieved zero toe in but the precision of the laser system showed me I actually had about 0.10 deg of tow out. Using the laser bars, I was able to set the toe in to exactly 0.05 deg.

These laser alignment bars are a project most people could build if they want to do their own alignment. I have done my own alignments for many years and these new tools just allow me to get extra precision - which is nice. Keep in mind that 0.10 deg equates to just over 50 thousandths of an inch difference across a 26" diameter wheel - so it is pretty much impossible to get better accuracy with tape measures than I was already achieving. That has always been good enough for my other cars, but I wanted better precision for my Corvette.

Here are some pictures.


The laser sights are Pinty Hunting Rifle Green Laser Sights with mount.

I clamp the alignment bars to the wheel with small wood working clamps and use wooden spacers between the bars and the rim.

Here is the bar in use and you can see the green dot on my target board. Same setup on the other side.

To check alignment, i move the target board close to the end of the tubes and make marks on each side. Then move the target back to just in front of the rear wheels. That gives me 10 ft from the laser to the target. 0.05 degrees comes out to a 1/8" distance between laser dot and the mark at the ten ft target, so it is pretty easy to get the precision you want.

I was pretty happy with the way this turned out so I thought I would share. The only hard part was building the mounting rails for the bars, but you can buy Picatinny mounts and screw them onto the bars if you want to build some of these without doing any machining.

 

I have a similar setup for Thrust Angle, but it's overkill for Toe. I can easily measure 1/32" or 0.1deg using tapes, and tapes are faster for me. I can Sneeze on a car and move the toe 1/64"!

That's a nice rig though, whatever works for you. I'd take it over strings any day!

 

nice simple clean rig. do like!
I've been using tapes/blocks of wood etc which work pretty well, but a bit of a hassle.
Your rig looks like it'll be much more precise than the ability of the car to retain the setting
very clever, thanks for posting

 

Thanks! Yes - it is probably overkill for Toe. I built these because i am about to get into rear suspension alignment and I think a setup like this is needed to get Thrust Angle set right. But this does work well for Toe and is easier than tape measures for me. I also plan to use these to check bump steer on the rear when I set the rear caster angle. I plan to set rear caster angle to 0.7 deg as recommended by DSC but I want to see for myself what that actually does to toe as the suspension moves.

 

From what I see your target board is using the rear wheels as a reference point. Those wheels could be toed differently or moved in and out from the center line of the car by a distance as much as 3/8 of an inch. It seems like you don't have a good zero reference. Don't you need to know your toe is zero before you mark your target board? Just fastening the bars to the wheels and assuming all the wheels are pointed the correct way when you mark the target boards are place them against the rear wheels doesn't sound sufficient.

Bill

 

Bill,
The target board has nothing to do with the rear wheels. It is connected to another target board on the opposite side of the car. That way i get a reference from the laser dot on one side to the laser dot on the other side. I move the target boards close to the front wheels first and mark them, then move them back near the rear wheels. If the toe is zero, the laser beams will be perfectly parallel and line up with the same marks at either distance from the laser. If I then want 0.05 degrees positive toe, i adjust tie rod ends so I see the laser dots 1/8" wider than the original (zero toe) marks with the targets just in front of the rear wheels (hypotenuse is 10 feet and adjacent side is 1/8"). Also, with the steering wheel centered, the distance of the laser dot from the rear sidewalls needs to be equal on both sides of the car to set zero steering angle. If it is off, you need to adjust the tie rods (in on one side - out on the other side) to center steering angle.

 

Hi,

How are the target(s) controlled/calibrated to be at centerline? Using wood clamps to spokes (that may/may not all be precisely the same) introduces potential error. Fasten a runout gauge and spin the wheel to see, bent wheels are plentiful. Wood targets, hmmm.

Just asking, always interested in different alignment methods, like David I just use a tape off precision toe bars fastened to hubs (steering wheel locked straight). Call it at 1/64" because I can't read the tape any finer. Sometimes a tape can be read more precisely than a laser dot.

I am 100% sold on hubstands for speed and accuracy, off the outer rim is maybe ok if the rim is true, off tires - forget it (not you). Every bit of the car that you can eliminate to get right to the hubs is a plus IMO.

Subbed to thread. Not arguing or nit picking just putting 2 cents in. Dozens of alignments on 5-6 cars using many methods. If you haven't yet, maybe take a look at my vids, some folks claim they help. Haha.

Froggy

 

The targets are just a two small boards attached together by a long board that runs under the car. They are not aligned, calibrated or centered in any way. Move them up close to the lasers and make a mark where the laser dot hits the target. Then move them back near the rear wheels (or they could be out in front of the car if you have room for that). Once I moved the targets back by the rear wheels, I adjusted the target on one side of the car until the laser dot lined up with the mark I had made when the targets were close to the laser. Then go the other side of the car and check how close the laser dot is to the mark on that side. If the laser dot is on the mark, the toe is at zero. If the laser dot is away from the mark towards the car, you have toe out. If you want to know how much toe out, you can use trigonometry to calculate the angle.

The only thing important about the targets is that they have to stay relatively close to parallel with the axles, or you will get error in your measurement. They also have to remain the same distance apart and my picture shows I had the vertical boards clamps to a horizontal board. The clamps did not hold that well, so I built a new target setup where I glued the vertical pieces to the horizontal board and made some feet to hold it up. You lay it down and slide it under the car then stand it up.

Like you I used to use tape measures on those same aluminum bars and that got me pretty close. But how do you do thrust angle with the tape measure method? And how do you keep the steering wheel aligned? This laser method solves both of those problems plus gives me a bit better overall accuracy than possible with tape measure methods. It will also allow me to measure bump steer on the rear wheels to verify I like the rear caster setting I use.

Oh - you can also use the laser to check wheel runout by glancing it across the rim and rotating the wheel.

 

Rick,
In our discussion, I said, I use a magnet to the end of the rear axle, with calibrated lines, to get the first equal readings for the front wheels.
This would set the front wheels to straight ahead.
Then remove the axle gauge, leaving the laser and use a tube or 1 x 2 against the garage door in the picture. Set your marks to the laser dots.
Now point the laser to the front and use another tube or 1 x 2 marked the same as the rear. Center it on the marks. This becomes the "strings".
You should have something close to 20' to work from. (Twice as accurate)
If we need to talk again.... Jim McKamey 219-742-7456

 

Hey Jim! Thanks for chiming in. I could not find any laser levels like you use, so I made my own. I also do not have room in front of the car so I came up with the parallel beam method using the moveable targets. No, i won't have 20 ft of span to get quite as accurate, but 10 ft seems plenty good enough. It only takes a fraction of one "tie rod flat turning" on each side to get a measurable difference in the laser dots. Even just tightening the lock nut on the tie rods makes the dots move a little bit... I am waiting on a sway bar for the rear of the car before I dive into adjusting the rear suspension.

So, while I wait for the sway bar, am practicing with the laser bars to get a feel for how they work. So far I like them! I did have a problem that the laser dot was way too bright. These rifle sights are meant to show up at hundred yards in daylight! So I got some auto glass tint and made some filters to cut down the brightness. Don't want to have to wear welding goggles just to align the car!

The cool thing about these rifle sights is that they are adjustable for windage and elevation. That allowed me to calibrate them so that the beams are perfectly centered on the tubes. Your suggested method of flipping the lasers front to rear would be necessary if the lasers were not calibrated and my parallel beam method would not work.

After I calibrated these lasers on the bench, I measured them side by side (clamped together) and got 1.25" between the dots at 50 ft. Since the tubes are 1.25" across flats, that is the correct measurement. Then I flipped one tube and still measured 1.25" between dots at 50 ft, so they are pretty much perfect.

 

The laser dot is too bright/big/hard to read that close for runout - as you mention (filters)
In general I don't like wood for alignment projects, it bends/warps/shrinks/expands with ambient % humidity, not much but enough to screw repeatability of measurements from one session to the next, unless it's super special wood kept in climate controlled enclosure

Keep it up & you will learn tons as you refine the process & tools

Froggy