Going Digital on Toe Settings

[CrazyCooter]

Correct but even in a shop with a rack and laser alignment system, you are still gauging off the face of the rim anyway

Yes you are correct in that the computer heads mount to the face of the wheel, but you have to perform a runout calibration by rotating the wheel for that method to be accurate. It's not as simple as just trusting that the wheel runs out true.......

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[ErrngeElise]

Yes you are correct in that the computer heads mount to the face of the wheel, but you have to perform a runout calibration by rotating the wheel for that method to be accurate. It's not as simple as just trusting that the wheel runs out true.......

Right but if you have a bent/untrued wheel or bad bearing both are going to produce inaccurate results

 

[CrazyCooter]

Right but if you have a bent/untrued wheel or bad bearing both are going to produce inaccurate results

This is why I suggest painting the tire and scratching a line on tire for the measurement. Everything functioning properly has a manufacturing tolerance. You can't put out a bad alignment just because the wheel has 1/16" runout or the wheel hub is .002 out no?

This is why the computer runs the heads out. Have a look here starting at 12:10....This is how you eliminated the runout error. Rotating the wheel advises the cornputer of any runout and it compensates.

 

[Lunentucker]

This is why I suggest painting the tire and scratching a line on tire for the measurement. Everything functioning properly has a manufacturing tolerance. You can't put out a bad alignment just because the wheel has 1/16" runout or the wheel hub is .002 out no?

This is why the computer runs the heads out. Have a look here starting at 12:10....This is how you eliminated the runout error. Rotating the wheel advises the cornputer of any runout and it compensates.

The mechanical slop in all of those plates and rigging would easily exceed 1/16".

 

[CrazyCooter]

The mechanical slop in all of those plates and rigging would easily exceed 1/16".

There is no mechanical slop in the head once it's locked down tight. When you flip the lever, the assembly bites into the tire and sucks it in tight. Then you perform the compensation roll. The slip plates have no bearing on what the actual runout of the wheel is.

 

[ErrngeElise]

This is why I suggest painting the tire and scratching a line on tire for the measurement. Everything functioning properly has a manufacturing tolerance. You can't put out a bad alignment just because the wheel has 1/16" runout or the wheel hub is .002 out no?

This is why the computer runs the heads out. Have a look here starting at 12:10....This is how you eliminated the runout error. Rotating the wheel advises the cornputer of any runout and it compensates.

Agreed, no you aren't going to get that level of precision. But you also aren't likely to make an adjustment for 0.002 either. I'm very familiar with runout as I have some machining experience, but I do appreciate the video. I'm probably going to finish watching that just because I find entertainment in stuff like that.
But we are talking about the simplest level of alignment here. A front toe alignment on stick axle vehicle. In absence of a true alignment rack/setup, if you want to do it right, it should be done like @Sandevino mentioned with known straight edges bolted to the hubs and yes at that point you should extend them out farther to something like 32"+ to get some more range/precision. However for a quick check of if you need to go through all that, I think this is a valid method. It will get you close and overall it has merit as long as you understand the limitations.

 

[CrazyCooter]

Agreed, no you aren't going to get that level of precision. But you also aren't likely to make an adjustment for 0.002 either. I'm very familiar with runout as I have some machining experience, but I do appreciate the video. I'm probably going to finish watching that just because I find entertainment in stuff like that.
But we are talking about the simplest level of alignment here. A front toe alignment on stick axle vehicle. If you want to do it right, it should be done like @Sandevino mentioned with known straight edges bolted to the hubs and yes at that point you should extend them out farther to something like 32"+ to get some more range/precision. However for a quick check of if you need to go through all that, I think this is a valid method. It will get you close.

It's not the .002" measurement at the hub that's concerning.........Its how it's amplified out at a 35"+ tire's diameter. I don't know how I could calculate that and explain it to you, except for the fact that a lever moves twice the distance at the end if it's 4" long than it does at 2'?

.002" runout at a 4" diameter It might be approaching .060" at the tires tread 17.5" away (radius)from center? 1/16" is .062" This is why the prefered way to resurface brake rotors is "on the car". It virtually eliminates the runout!

I'm trying to educate here, but I can go away if it's too far over everyone's head and you find it irritating? I've been in the undercar business over 31 years and have seen a thing or two......

 

[Lunentucker]

There is no mechanical slop in the head once it's locked down tight. When you flip the lever, the assembly bites into the tire and sucks it in tight. Then you perform the compensation roll. The slip plates have no bearing on what the actual runout of the wheel is.

I get what you're saying. I saw things shift when he moved the car, and with the front tires sitting on two different moveable surfaces I figured everywhere something has a bearing or a bolt has room for movement.

 

[jav_eee]

Because all you care about is the difference between the front and back sides to figure out the toe measurements.

but if the error makes it so that both measurement show an even 57” on both but you’re 1/16” long in the front and 1/16” short in the back then….

I’m probably overthinking it.

 

[Sandevino]

Agreed, no you aren't going to get that level of precision. But you also aren't likely to make an adjustment for 0.002 either. I'm very familiar with runout as I have some machining experience, but I do appreciate the video. I'm probably going to finish watching that just because I find entertainment in stuff like that.
But we are talking about the simplest level of alignment here. A front toe alignment on stick axle vehicle. In absence of a true alignment rack/setup, if you want to do it right, it should be done like @Sandevino mentioned with known straight edges bolted to the hubs and yes at that point you should extend them out farther to something like 32"+ to get some more range/precision. However for a quick check of if you need to go through all that, I think this is a valid method. It will get you close and overall it has merit as long as you understand the limitations.

My alignment sleds are 5' long and extend roughly 2' on either side of the hub and are good for getting the hubs parallel with each other.

It shouldn't have to be stated, but for completeness, the wheel has to be braced straight in the neutral position (not turned left or right) and no weight on the axles.

Get the front and rear measurements the same (if you're picky like me) or close within 1/16" of an inch. Any adjustment should be HALF of the measured value as you're making half of a change.

Once happy, mount the wheels and take it for a test drive.

 

[CrazyCooter]

I get what you're saying. I saw things shift when he moved the car, and with the front tires sitting on two different moveable surfaces I figured everywhere something has a bearing or a bolt has room for movement.

We're not concerned with any movement there in that video except the tire rotating. From this rotation the computer can calculate the prefect vertical and horizontal center of that head. From that runout it derives angle deviations from degrees off center.....These measurements are whats up on the screen and printed out in the end.

In the old days when alignment techs had to have skillz, we used bubble levels and ran them out to center which has zero accuracy problems assuming the tech wasn't hung over? This is why you flip your level when you think you have it perfect to verify its reading "accurate level"?

 

[CrazyCooter]

but if the error makes it so that both measurement show an even 57” on both but you’re 1/16” long in the front and 1/16” short in the back then….

I’m probably overthinking it.

Ya, you aren't envisioning it all the way through.

I'm seriously thinking about making a video for you guys. It's so simple, but hard to visualize without seeing it.

 

[ErrngeElise]

It's not the .002" measurement at the hub that's concerning.........Its how it's amplified out at a 35"+ tire's diameter. I don't know how I could calculate that and explain it to you, except for the fact that a lever moves twice the distance at the end if it's 4" long than it does at 2'?

.002" runout at a 4" diameter It might be approaching .060" at the tires tread 17.5" away (radius)from center? 1/16" is .062" This is why the prefered way to resurface brake rotors is "on the car". It virtually eliminates the runout!

I'm trying to educate here, but I can go away if it's too far over everyone's head and you find it irritating? I've been in the undercar business over 31 years and have seen a thing or two......

I understand what you are saying. I really do. I'm not disagreeing with you completely (mostly agreeing actually) or saying that this is now a substitute for a real alignment. What I am saying is that this is a valid method to get it close or through multiple measurements, go ahead and rotate the wheels too to see how the measurements change. In the absence of a real alignment, this is a start. I'm not a moron. I do 4-wheel string alignments on my track/toy cars before getting a proper one. It's not a substitute for a real one either but I've been within spec every time. And to your earlier point, no this won't work for them either as you really can't get anywhere near the axle centerline on those and are lucky if the bottom of the wheel is exposed beyond the frame and suspension.

 

[CrazyCooter]

I understand what you are saying. I really do. I'm not disagreeing with you completely (mostly agreeing actually) or saying that this is now a substitute for a real alignment. What I am saying is that this is a valid method to get it close or through multiple measurements, go ahead and rotate the wheels too to see how the measurements change. In the absence of a real alignment, this is a start. I'm not a moron. I do 4-wheel string alignments on my track/toy cars before getting a proper one. It's not a substitute for a real one either but I've been within spec every time. And to your earlier point, no this won't work for them either as you really can't get anywhere near the axle centerline on those and are lucky if the bottom of the wheel is exposed beyond the frame and suspension.

Yes you get it then!

Where toe is concerned, a guy in a garage can actually get a more accurate result than some POS computer where the heads have been dropped 5 times since last calibration IF the person uses an accurate method of measuring. Painting the line on the tire and using slip plates is the only way I know how to be this accruate. All these other ways I have seen advertised on the net are not very accurate and in this case maybe the computer "Could" maybe be better?

 

[ErrngeElise]

Yes you get it then!

Where toe is concerned, a guy in a garage can actually get a more accurate result than some POS computer where the heads have been dropped 5 times since last calibration IF the person uses an accurate method of measuring. Painting the line on the tire and using slip plates is the only way I know how to be this accruate. All these other ways I have seen advertised on the net are not very accurate and in this case maybe the computer "Could" maybe be better?

Right and I've also seen people who took a car that was mechanically sound (no bad bearings, ball joints, tires, wheels, etc.) and align a car, then park it. Another tech pulls that car in for an alignment on the same rack with the same equipment, sets it back up and says that its close but needs to be adjusted and get different results because a different person with a different experience level. It's all about understanding what you are working with and what you can expect.

Now if that tool can only measure in 1/16" increments well that is a pretty substantial limitation. If it is only accurate to 1/16" of an inch but can obtain repeatable measurements at a smaller increment than 1/16" then I really like it because I don't care what the measurement is. I care what the difference is front and back. Accuracy and precision, I care about precision here, not accuracy.

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