Long Grain Wild

iTrader: (1)

I'm messing around with my hatch alignment and I want to make sure I understand the specs in the FSM...

Page 3-18 of the FSM says front total toe should be inward 1mm with a tolerance of +/- 2mm.

My question is that since that toe spec is given in millimeters (distance) and not in degrees, it matters where on the wheel/tire that measurement is taken. The geometry and the trig is easy. What I don't know is accepted convention.

Question is... Is that measurement taken at the wheel lip (about 15 inches between measurement points) or at the outside edge of the tire tread (about 23 inches between measurement points).

Any alignment whizzes out there that know the accepted convention? Do they take that measurement at the wheel circumference or tire circumference?

Long Grain Wild

iTrader: (1)

Nobody here knows anything about alignments?

B_Swapped93

try the suspension and brakes/road racking,time attack sub-section, mostly idiots here....are you "DIYing" an alignment

jbpnoman

Or you could just wait for someone who knows their ****. There's two or three of us here. We aren't paid to be here, we don't exist at your beck and call, we're on the forums when we feel like it, and answer questions when we feel like it.

this guy, right here.

Next time, use Google. This is a simple question to answer.

http://robrobinette.com/ConvertToeDegreesToInches.htm
http://www.trackace.co.uk/Manual/Conversion%20Chart.pdf
HERE is the math behind it.
HERE is a full explanation of what an alignment means, is, and does.

You're welcome.

Long Grain Wild

iTrader: (1)

Thanks for the help, but please help me out a little more?

Your first linked doc says "Shop Manual toe is measured at the tire tread"

Second doc you linked has nothing but conversions from mm to degrees for different wheel sizes and doesn't mention tires at all.

Third link is a discussion about how to convert from mm to degrees. I already knew how to do that. I said at the beginning of the thread, the geometry and trig are easy. But then at the very end of that thread, someone else asks the exact same question I did, and to date, it's unanswered in that thread.

Fourth link didn't work at all for me.

Haha! So I got one "at the tire circumference", one "doesn't specify but talks only about wheels", one "exact same question went unanswered" and one "divide by zero error".

And that mirrors my own findings when I googled and got unsubstantiated results. It's not like a resounding four out of four saying the same thing... Hence my coming here looking for experience. I was hoping that someone trained in the art knew the answer and could maybe even provide not just the "what", but maybe even the "why".

I've got my own theories already, but I've not been trained in the art...

Long Grain Wild

iTrader: (1)

Thanks for the suggestion about the other sub-sections. I don't spend a lot of time there. I figured it was a 92-00 question, but you're right, it's actually not generation specific.

About the DIY alignment... I'm considering it. Problem is that I'm not sure I can accurately measure to the precision required. Was just trying to get a handle on the requirements first.

jbpnoman

Sorry, there's some minutiae in the wording that takes some critical thinking to get through. I'll explain it a little more. Ignore the third and fourth links for now.

The first link specifies "Shop Manual toe-in in inches is measured on the tire tread at the axle level."

The second link is for "Converting Linear Wheel Alignment Values to Degrees˚ Minutes’".

To clarify, the first link works specifically at the tire level, as a standard alignment machine would, and requires all things to be the same (tire pressure, weight distribution, suspension functionality and geometry) to be exact. The second link is more theoretical, and is the "pure math" behind it. Assuming you want to apply this information to a car in the real world, you want to use the information in the first link. There are a number of links similar to the first one, but I chose that one specifically because it references a Honda FSM, rather than other manufacturers. Also, further down in the first link, there's a nice little FAQ chunk of sorts.

Take special note of the second and third points. Measuring toe-in at the tire tread is the standard, as is using the difference between front and rear.

If you're still not entirely sure, take a measuring tool to your tire tread and give me their measurements, and I'll tell you exactly what your degree toe should be.

I've done a DIY alignment before, using eight jack stands, string, and a precision engineering compass. It turned out great. That said, it takes a LONG time to get precise, and you're spending a lot of that time on your back under the car. In my opinion, it's not worth the time to do an alignment yourself. Pay a shop once for a lifetime alignment, and get your money's worth.

Like I said, there are a couple of brilliant people in this particular subsection, you just have to sort through a lot of garbage sometimes. I'm good with general, theoretical, FSM-specific, and FI information. RonJ is AMAZING with electrical, and damn good at just about everything else. Esoteric occasionally pops up, and he's solid when he chimes in. NOFX is the be-all end-all when it comes to chassis-specific information. Deschlong is the king of all things CDM, and great at finding resources. We aren't the only people worth believing, but from what I've seen we are the most consistent. If it comes from one of us, within our purview, it's a safe bet we're right.

nub

I'm not an alignment tech but throwing two cents in on OP's question and jbpnoman's respones.

I think moving this to the suspension sub would be best.

Alighnment meaurements off the tire tread to me seem like they would be incossistant at best. Meauring off a surface that wears and could be inconsistaant out of the mold.

As stated out of the FSM the OP posted, it says "use commercially available computerized four wheel alighnment eguipment". That I'm aware of this eguipment has nothing to do with measuring at the tire tread. They have fixtures that mount to the wheel and measure from the hub centerline.

Some DIY alighnments meaure off the tire tread. Some I've seen have fixtures that mount on the rim which is a constant location, relative to the hub to make measurements and adjustments.

Measuring at the tread can be effected by air pressure alone...No?

jbpnoman

Yes, which is why I pointed out that "[all things]" need to be exact for a tire-to-tire measurement.

You do have to look at it geometrically, though. Standard tread depth is what, 11/32"? The wear bars are at 3/32". A² + B² = C² and all that hoopla, I'm not doing mid-level trig just to explain alignment, but suffice to say that the difference of 8/32" when applied to the short leg of a right triangle (the aspect of the line we need to look at for thrust angle and alignment) is border-lining on immeasurably small. The exact width, as well as the difference from wear, can be disregarded as a metric when calculating an alignment.

voigtcjva

There's two or three of us here. We aren't paid to be here, we don't exist at your beck and call

Long Grain Wild

iTrader: (1)

jbpnoman

Thanks for the additional help and I appreciate it that you came back second time with more help and less ego. I'm not sure I'm explaining myself thoroughly, so I'm going to tell you where I am...

I'm considering doing a DIY alignment. Why? Because if I'm capable, I just want to. However... If, after investigation, it turns out that I don't think I will be able to do it accurately, then I'll bail. Simple.

I'm completely and intimately with the necessary math. I had breakfast with Pythagoras this morning. I get it. The math is not the problem. As a matter of fact, I'm not even intending to use angular measurements. The only reason I even mentioned angular measurements in my first post was to illustrate the fact that I already understood the difference and how to convert from one to another.

So if the math isn't a problem, then what is? Accuracy and realistic measurements... Goes like this:

The nominal total toe alignment spec is toe-in 1mm and even though I haven't been swamped with unanimous corroborating sources that the correct location from which to take that measurement, I'm assuming it's to be taken at the circumference of the tires. However, I agree with nub and yourself above and don't trust taking measurements off the inconsistent molded tire rubber and with that in mind, I believe you must take measurements referenced to the wheel, not the tire. *

However, the wheel diameter is smaller than the tire diameter which means you have the scale the measurements accordingly. You can do this scaling by either converting to angular measurements or by referring to the geometry concept of "similarity" (as in "these two triangles are 'similar'").

Converting to imperial units and accounting for single side measurements provides the following result:

Using 15 inch wheels, the single side spec (nominal) measured at the wheel lip is 0.013 inches difference between front lip and rear lip of the wheel.

.013 inches measured to a taut string? A taut string lined up by a tape measure probed against the plastic wheel center cap? A string that's wider in diameter than the measurement being taken? With a tape measure???

Even considering the tolerance on the spec (+/- 2mm) results in an acceptable range:

Using 15 inch wheels, the acceptable range at the wheel lip is toe-inward .039 inches per side to toe-out .013 inches per side.

Call me skeptical? I just want to know if I'm missing something...

*There are some methods (like the pins stuck in the thread method) that wash out tire error, but they introduce other inaccuracies elsewhere like trying to measure all the way across under the car with a tape measure...

Long Grain Wild

iTrader: (1)

And to clear up... I'm not afraid of making measurements down to the thousandth of an inch. I do it all day. Problem is that you need a rigid, reliable, trustworthy, accurate point of reference from which to make that measurement.

I've got the equipment to make sub-thousandth measurements. I just don't have a quality reference plane from which to make those measurements. A string doesn't cut it.

Get it? String doesn't ""cut it" Thank you... Thank you... I'm here all night.

jbpnoman

It's a 25% accuracy, 75% time value thing to me. No measurement method will be more accurate than the lasers of an alignment machine. As for time value, everyone values their own personal time differently, but personally I put a $30/hr price tag on my own time. That has nothing to do with my paycheck, it's just what I value my free time at. That said, a one-time alignment around here will cost $60-$80. The one time I did a DIY alignment, it took four hours up and down trying to get it "within spec", let alone near exact. Better personal value to just give a pro my specs and have them do it. Before you dive into this, figure out what you value your own time at. If you're just doing it for the experience...go for it.

Remember you have to do toe and camber together. Adjust one, and it'll change the other. On top of that, you'll be dealing with rusted hardware, and I assume you won't be doing this on a lift - that's a lot of time on your back, on the cold floor.

So if the string doesn't cut...does that make it carbon fiber, or diamond string?

When I did it, I used wax string. It doesn't readily expand or contract like most string does. I've heard baler twine works, as well. Alternatively, you could use a very long, metal straight edge.

As for your measurements, if you trust your numbers, I'm not going to go over them again. I studied aerospace engineering, I'm also intimate with the math, but I'm an accountant now - Pythagoras didn't do dollar signs Just remember that, when doing your measurements, you need to take your thrust angle into account. Measure both wheels together, not independently. Whatever measuring device you use (string, straight edge, tape measure, whatever) measure from lip to lip, at the horizontal inside front and rear centers of the wheel. Find the widest part of the wheels, using a level to make sure you're at the true front and rear, mark it with a sharpie, and measure from point to point.

Long Grain Wild

iTrader: (1)

Prior to starting this thread, I made a fixture which presses into the center cap hole of my SI wheels. The intention is that this device will make it easier to locate the strings a consistent distance away from each wheel. I doubt the accuracy claims of the people sticking a tape measure against their wheel to locate their strings so I designed this fixture instead. I made just one so far, but the plan is to make four, one for each wheel with all four being the same length. I just line the strings up with a very accurately located distance feature on the fixtures. That gives me accurate locating points for my string datums on each side.

Then I was thinking that before I burned the time making three more of those center hole fixtures, I figured I better check into the alignment numbers and make sure it was even feasible. And it was at that point that I realized how small of a dimension I was actually hunting for and I started to doubt whether I was going to be able to measure accurately. I'm sure I can get it "in spec", but as for getting close to nominal... I'm not so sure.

I think I'll make one more of those fixtures and slap them on one side of the car and see what kind of measurements I get. If I can't get even ballpark correct numbers, it'll be a sign that maybe I should stop trying.

So a question before I tool up to make a second fixture... I found in the FSM (page 3-20) that the track widths front and rear are supposed to be the same at 1475 mm front and 1475 mm rear. Is there any reason to believe those numbers are suspect? In other words, have you heard anyone theorize that even though the FSM says it's supposed to be the same front and rear that it actually isn't?

slowcivic2k

The track width will change if the wheel offset is not the same, that will also mess use the scrub radius as well.

Some vehicles, vans in particular, use a wide front track width and the rear narrow to make the truck more maneuverable.

Is there any particular reason you are not using electronic alignment equipment?

Long Grain Wild

iTrader: (1)

Not sure what you mean by the track width changing due to wheel offset... I'm running SI wheels on my hatch, which aren't "stock" for the hatch, but were available stock on the SI model that year. And all four wheels are the same. By that, I mean, it doesn't matter which wheel I put on which corner. I could take the four wheels off, mix them up, and put them back on anywhere without causing any changes in geometry.

So, if what you're saying is that the track width may not always be the 1475mm found in the FSM (depending on if I'm running steelies or SI wheels) then that's fine. The absolute number... that 1475... doesn't really matter to me at all. Just that front and rear are the same.

If the track is different front to rear, then it just makes it a little more difficult.

Why am I messing around with this?

Because I've never been completely satisfied with any purchased alignment. Steering wheel a little off, pulls a little, feels darty, etc.
Because so many others claim to be able to do this this, and if they're capable, then I should be too.
Because I hate other people touching my car. Always seem to create another problem.
Because I hate paying money for something that I can do myself.
Because I have little faith that the used and abused equipment at the alignment shop is still accurate.
Because I have little faith that the guy running the rack at the shop has a clue and/or gives a *****.
Because I have little faith that I could drive my car off the commercial rack and around the block and put it right back on the rack and get the same numbers as when I drove it off five minutes before.
Because I'm insane.

Who knows... This whole thing may fail miserably, and I'll go crawling to my local alignment shop with my tail between my legs begging them to bail me out of my own stupidity, or... I may actually end up with a good alignment.

Thanks for the input and let me know what you meant about the track width changing.

jbpnoman

If you REALLY want to do it yourself, buy yourself some tools to do it the right way. Don't just use string, or rope, or a ruler, or stacked ******, or whatever Joe Bob under the shade tree tells you to use.

http://www.quicktrickalignment.com/home/qt-products/

Buy the right hardware, save yourself a lot of headache, and know that you're doing it the right way. Even die-hard amateur racers use hardware just like that. They don't have access to a laser machine that costs tens of thousands of dollars while they're at the track, and tools like what I've linked above are what they use.

slowcivic2k

Wheels that are wider, provided the offset is zero, will place the alignment head in different lines. It does not affect the alignment in most cases unless you measure it, then you'll sit there and scratch your head going wtf? It will however, affect the way the vehicle handles/steers.

The reason I mentioned that is because some cars have different offset wheels front to rear. Pontiac firebirds used to be like that, and its kinda cool when you get one on the alignment rack and the "squareness" is actually a parallelogram lol.

I feel your pain with cut-rate techs doing shoddy alignments. I was a victim myself twice before I took it up professionally. I think your efforts would be better spent trying to find someone inside a shop that will let you align the vehicle, they are few and far between, but when the manager isn't there, money talks.

Long Grain Wild

iTrader: (1)

slowcivic2k, Gotcha. I've had experience with different F/R wheels on GM stuff in the past as well. Different offsets F/R wouldn't be the end of the road for me, but I would just have to know about it ahead of time.

There used to be a shop near me that had not yet disallowed customers on the shop floor. I would go there dressed for wrenching and the techs would let me do my own adjustments on the rack. The techs liked it because they could catch up on some paperwork while I turned the wrenches, and I liked it because I could dial my car in to whatever precision I had time for. Then one day, new manager, new insurance co, and no more customers on the shop floor, even if they are competent.

Worst one was my last one... Not a Civic... Look up from my magazine in the waiting room to see the tech under my car with the torch on one of the adjustment points. Seems he couldn't get the adjuster to turn. Problem was that he didn't know how to loosen it and was trying to turn it without loosening the locking mechanism first. By the time I got to him, the eccentric bolt and washer system was all blue and the rust protective paint was burned off for five inches around the bolt head.

At this point, if I can figure out how to get something accurate, I'm happy to spend a few hours trying to do my own alignments.

jbpnoman, Thanks again for the input. I'd seen that alignment system before, and I'm hoping that what I'm designing will be more accurate. What I'm working on would not fit a different car, but the intention is that I'm trading adaptability for accuracy. I did a quick and dirty test yesterday and I believe I can take measurements at +/- .020 so I can do "in spec". Next, I'm hoping with some more mods, I can actually aim at nominal.