The problem I have is confusion about where the triangles are for toe, and it has absolutely nothing to do with high school math since the trig involved is easy (soh, cah, toa) if we only knew where the triangles are.
For example, total toe is specified in *degrees* of all things.
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Yet, total toe is simply the toe measured at the back of the wheel/tire combination minus the toe measured at the front of the wheel/tire combination, both of which are *linear* measurements.
Since toe angles are the same no matter what size the wheel/tire combination, how can total toe be specified in degrees when it's measured in inches?
Since the tire has the same angle the entire time, there is absolutely no difference in angle between a toe measured at the front of a wheel/tire and a toe measured at the back of that wheel/tire!
So, sure, I'm confused because total toe is specified in degrees. But the confusion has nothing to do with high school trig.
Summarized, if total toe is the difference between toe at the rear of the tire and toe at the front of the tire, yet, the angle of the wheel/tire combination to the centerline of the vehicle is the *same* no matter how large a wheel/tire combination is, then how the heck can total toe be specified in degrees?
If you can answer this question then it will show that you actually understand what you call *simple math*.
Here is the question:
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Summarized, that says: If total toe is the difference in toe between the rear and front of the tire, and if the difference in angles between the rear and the front of the tire are exactly the same (by definition, since the angle of the wheel/tire combination to the centerline of the car is the same no matter what size the wheel/tire combination is!), then how the heck can total toe be specified in degrees?
That is a nice total-toe-in-inches to degrees calculator, which takes into account wheel size, but I'm still a bit confused how total toe can *ever* be an angle, when the angle at the front of the wheel is exactly the same as the angle at the rear of the wheel?
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It's not the math (the math is easy); it's the concept of total toe having anything whatsoever to do with degrees when it's merely the difference in toe between the front and rear of the tire when the angle at the front and the rear is (by virtue of straight lines) exactly the same!
In this case of converting toe angle to inches, it's much easier to visualize why single-wheel toe is specified in degrees.
Here's a diagram I made which shows that concept, which I agree is very simple trig (soh cah toa):
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Thanks. It seems that the order is "caster, camber, and then toe", in so much as the two vehicles I have (toyota, bmw) both specify that you adjust in that order.
Caster affects camber which affects toe so that's why you do it in that direction.
Intererstingly, from the standpoing of tire wear in normal settings, the same curve applies which is that caster affects tire wear less than does camber which affects tire wear less than does toe.
So the order to think of the 3D axis are caster, camber, and toe (in that order) for the x, y, and z axis.
While what you said sounds easy, which is that if you can measure camber in degrees, why can't you measure toe in degrees, your truism ignores the simple unalterable but very basic fact that the tool uses *gravity* to measure angles.
That is, gravity-based tools work fine for measuring camber.
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But how are you going to shift gravity by 90 degrees in order to measure toe the same way?
I replied to your original question days ago, and you ignored that reply. Regardless of that, your questions have been answered repeatedly. Toe *is* an angle, but if you know the outside diameter of the tire, it can also be spec'd in inches, or any other linear measure. The conversion involves only the measure of sides of a triangle, which is really basic math. This is my original reply:
Inches depends on the outside diameter of the tire:
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Minutes to degrees can be found here:
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Regarding the needed accuracy, it depends on exactly what you are trying to achieve. There is a wide range in camber that will not cause any meaningful tire wear. Toe is much more critical, including for overall feel at higher speeds, but you are also dealing with runout, and there really isn't any good way to adjust for that at home.
The overall point is that even if you are off with the camber, the tires are not going to be worn out all that much earlier, so close can be good enough, especially if you bother with rotation. Toe is much more important, and if you want that exactly right, pay someone to do it right. You can get it close at home, but it's just luck if it's exactly right.
You also have to keep in mind that a rear drive car's toe out will increase with speed, and a front drive car will do the opposite. There is plenty of slop in steering & suspension, and you will get varied readings, especially if you are not using turntables. Sometimes trying to save money is not such a good idea.
At the same time, finding someone to do the job right can be a challenge, too. There's plenty of hacks out there.
If all you care about is getting things close enough that there won't be ridiculously excessive tire wear, then have at it. But if you are trying to get things just right, both for handling and tire wear purposes, pay someone.
That is not at all what total toe means. 0 degrees of toe for a wheel is when the tire is exactly parallel to the centerline of the car (that is a simplification, but it's usable here). Toe is a measure of the variance in degrees from straight ahead. Total toe is merely they sum of the toe in degrees of both the left and right sides. So if the left is +2 degrees, and the right is -2 degrees, the total toe is 0 degrees. That means minimum tire wear (theoretically), but the steering wheel will be a bit off-center.
The difference between the front and back of the tires is used only for distance measure, not angles.
I'm extremely familiar with the BMW, but only you and I seem to know what we're talking about here.
Unlike Tekkie, nospam, & Jeorg Lorens (who can only troll), I'm intimately familiar that the cooling system overhaul is a standard maintenance item on the E39, E38, and E46 (all of which use essentially the same Meyle and Nissan components) and I am also intimately familiar with the metal-vaned (petersburgh) water pumps.
The gasket-less MAP thermostat isn't all that bad, but since the water pump has to be removed anyway, we replace them as a matter of course during the overhauls (I've done about four overhauls of my entire cooling system myself).
We all have the special counterholding tools for the fan clutch removal and we often replace the mechanical or hydraulic tensioners (it's arbitrary which any one bimmer has) and serpentine belt at the same time since all that stuff has to come off anyway.
We have it down to a science. In fact, most of us have replaced the expansion tank cap (I think the ORM is 1.2 bar but I'd have to look that up) with a lower pressure cap, which doesn't prevent anything from happening *other* than when it blows, it blows out the cap at a lower pressure so the expansion tank seams don't split.
We also all know to keep the coolant level LOW (at or below the max at all times) since too many people overfill the expansion tank. Admittedly, when it's full, it *looks* empty but that is the way it was designed.
I appreciate the advice, but offhand I'm not sure what you're calling the "air plenum", but if you're talking about that idiotically designed DISA valve which moderates the intake manifold harmonics, I'm completely familiar with the DISA valve engineering flaws and have long ago replaced the innards with re-engineered ones from Gary at German Engineering (replace the plastic pin with titanium).
Again, you and I are probably the only people on this thread who understand what we're talking about so I'm extremely familiar which what breaks on the typical E39, E38, and E46 (which are all essentially the same depending on the years designed).
There are *tons* of aftermarket FSUs, but I'm not aware of any design change to any other component than the FSU itself.
This one I'm also intimately familiar with, simply because, if you know the bimmer, you know one of the most difficult standard jobs is to overhaul the CCV because it's in the middle of the engine so to speak.
What we have all done is we have modified our oil dipstick tubes, because the CCV dumps cold oil into the dipstick tube, which hardens with contact with water vapor into the extremely badly designed teeny tiny concentric-circle space in the two-tubed dipstick.
Also we've all changed the CCV components into the modified cold-weather ones (insulated) but they're a bear to put in because they're fatter and there's precious little room in the first place.
Suffice to say that you and I are the only two people here who actually know what we're talking about (Tekkie, nospam, Jeorg, and a bunch of the other fools don't have a clue what we're talking about when they bash BMW).
It's nice to know that there are some intelligent people here. Thanks for being intelligent!
I left off a few things because that was an ad-hoc list, but just like the fact that *all* the cluster and MID pixels go bad, all the wood trim cracks.
It's not actually the wood that cracks; it's the super thick coating of varnish on the outside that cracks. It's a warranty repair and I had all my wood trim replaced under warranty, but the replacement wood trim cracked just the same.
It's a manufacturing and design flaw that they all have.
The good news about the windshield molding is that it doesn't affect anything other than looks and noise. It's not a weather item so it doesn't keep out water.
The bad news is that the Germans use too much recycled rubber, which is the problem with that windshield molding.
Again, I'm impressed that you're the only one on this newgroup who knows what he is talking about with respect to bimmers. You'll find I know my model extremely well (probably better than almost any non mechanic you have ever met).
That's because I "think" about what I'm doing. And I collaborate with others to learn from them.
Which is the reason, after all, for this thread.
I have done an overhaul of the rubber from buna to viton long ago, and the worst were the SAP/SAS valves in the back of the intake manifold. They're impossible to get to under the best of circumstances.
The power steering isn't so bad if you clean the power steering reservoir filter once every few oil changes with gasoline (most people don't know that it's even there) and if you replace the oetiker (sp?) clamps with standard hose clamps and replace the hoses.
The V8 has special problems with the power steering pump bracket breaking, so a standard maintenance item is to check the bolts every oil change.
The I6 isn't bleedable so you have to suck the fluid out the reservoir with a turkey baster, but it's not all that bad to do. It's just ATF Dexron IV (now Dexton VI since Dexron IV lost its copyright long ago).
I learned of all the issues by running into them and then learning how to re-engineer them. My point is that most of these known problems span models, so, BMW *knows* that they build crappy components but they don't fix them. So that's just bad engineering on BMW's part.
All BMW cares about is the handling and performance, and, those components are engineered fantastically well.
I disagree with *some* of what you just wrote.
Most bimmer owners have learned NOT to change the "lifetime" transmission fluid for two key reasons. The first is that many people have had failures just *after* changing the fluid where the hypothesis is that "stuff" got mixed up and moved about (like crud). The second is that it's actually not trivial to change the transmission fluid because of the specific temperature requirements (which most people skip).
Just like most people skip the 500 pounds of weight to set the ride height to "normal" when aligning the car, most people skip steps when changing the transmission fluid - and problems arise as a result.
But I do agree that BMW used crappy BUNA rubber for things that get hot, such as the valve cover gasket (which fails on almost every engine!). BMW has since replaced BUNA with Viton but they didnt' tell their customers that so for years customers were replacing the buna VCG with another crappy buna VCG.
BTW, are you the "Magnum" "Scott" of BMW fame? If so, we actually know each other and we have common friends who have both beemers and bimmers.
Either way, it's a *pleasure* to speak with someone who is not only intelligent, but who knows what he's talking about (which most of the fools in this thread don't).
I think you're one of the few people who are actually *thinking* about what they are saying on this thread, and for that, I very much appreciate your sugestions.
It seems, from what Andy Burns intimated, that the smart phones use gravity-based accelerometers (with the compass) and not inclinometers, so, while they can be used for camber, the accuracy will be about plus or minus six minutes.
However, to use them for toe (as I think it was tlvp who suggested that), would be folly, I think, simply because toe is in a different plane where gravity isn't different for various angles of toe.
However, the laser beam is in the right plane for toe measurements! So is the centerline of the car.
So it should, in theory, be easy to do something like this: a. Attach a laser to the car centerline and mark where it hits a wall. b. Attach that laser to the wheel and mark where it intersects. c. That's the triangle!
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NOTE: I haven't calculated yet the *distance* it would take for the centerline and tire to hit the wall, which could be prohibitive.
That level is "accurate to 1/10th of a degree" (six minutes) so that must be the standard accuracy of the inclinometers in digital levels.
I think you hit upon a good idea which is to use the laser as the straight line for the vehicle centerline and for the tire angle, because where they intersect will be the triangle we need to measure.
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The only problem may be the length of the Adjacent (centerline) mark.
The trig is easy. soh cah toa. What's hard is figuring out what the triangles are for "total toe":
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Most people here don't even understand the question because they keep saying it's a math problem. But the math is trivial. My confusion is how on earth do they specific total toe in degrees when total toe is simply the difference in toe from the rear to the front of the tire/wheel but toe angles are the *same* at the rear and front of the wheel!
I'm sure the answer to that question is simple but everyone says it's a math trig issue but it's really a conceptual misunderstanding on my part.
Thank you Andy for staying on topic and helping to increase the tribal knowledge here with respect to the accuracy that a smartphone has for measuring angles.
Apparently a smartphone accelerometer is used for measuring angles, which fits a camber measurement application, but for the life of me, I don't see how a smarphone accelerometer can fit a toe-angle application.
Can you?
Thanks for explaining that the accuracy of the MEMS inclinometer in digital levels is six to twelve minutes.
This Home Depot blurb says a common 10-inch Husky is "Accurate to 1/10 of a degree", which is in the range you stated.
I think you (yet again) completely missed the point.
The math for single-wheel toe is trivial which even you seem to understand.
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However, I said I was confused about total toe.
The toe in the front of a wheel/tire combination is the same in degrees as the toe at the rear of that same wheel/tire combination (and, in fact, no matter what size the wheel/tire combaination, the toe is the same degrees of angle).
Yet, total toe is merely the difference in toe from the rear of the wheel/tire to the front.
In the case of the brake fluid, most of us use the ATE super racing blue stuff (even though blue is not an official DOT color) and then the "amber" ATE DOT4 where we alternate from non-DOT blue to DOT-amber.
However, this is normal maintenance for any car, since brake fluid is hygroscopic,
The bimmer has 6 brake hoses though, two of which fray because they're too close to the exhaust manifold on the I6 (just behind the ABS control module, which is also too close to the exhaust manifold, even with the heat sheild that BMW added), so *they* have to be periodically replaced.
Again, I do appreciate that you are one of the very (very) few people on this newsgroup who know what you're talking about.
Many of the others (e.g., nospam, Tekkie, Jeorg, etc.) are clueless fools who wouldn't know a bimmer from a beemer if it hit them.
I had/have no problem with the trigonometry, since it's simple soh cah toa stuff, these triangles.
My main problem is where was the triangle.
It seems to me that, if toe is specified in inches, then the triangle should be specified at some known point off from the center of the wheel to the centerline of the car.
If they specify toe at any other point than a known point off from the center of the wheel, then they have to specify how far they are from that known point for any inches-to-degrees conversion to apply.
Isn't that right?
I completely understand that measuring inches from the tire tread to the centerline of the car and then using that as the "opposite" in the trigonometric soh cah toa, will come up with the wrong angle which will be more and more wrong the further the measurement is taken from the center point of the wheel.
When they specify toe in inches, why don't they just specify it from the rim of the wheel (instead of from the tread of the tires?)
I can convert with basic sohcahtoa trig but I need to visualize the triangles first.
I have learned a lot about this accuracy problem since I opened this thread, which I can summarize as no basic home tool will get the accuracy specified by BMW (which is 1 minute for camber).
However, you really don't *need* that accuracy (which is what you are saying).
An inclinometer will get us to about 1/10th of a degree (six minutes) of accuracy as stated on thisadvertising blurb:
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A typical smartphone apparently uses either a gyro or a magnetic compass and accelerometer, which can't get to the same accuracy (it seems) as an inclinometer can (or so I'm told).
However, in the end, a "smidge" of negative camber (about a degree or so) is probably in the accuracy range we really need, which a smartphone can do.
Static toe is actually easier to measure and harder to measure than camber, it seems.
It's easier because it's easy to measure distances and then convert those distances to degrees using basic sohcahtoa trig.
It's harder because you can't easily measure degrees of toe with a typical inclinometer level or smartphone gyro/compass/accelerometer because they're based on gravity which is in a different plane for measuring camber angles as it is for measuring toe angles.
BMW does not recommend ever rotating tires, but they don't care about tire wear. The camber is only adjustable in the rear and it's pretty high (I forget but it's at least 2 degrees negative camber for each rear wheel). That wears out the inner edge like you can't believe.
Me? I'm ok with zero camber but that can't be obtained (the last alignment proved that). But I think 1.5 or 1 degrees was what the guy was able to get me.
So, for me, the camber setting would be to simply put it at the lowest it will go (least negative) for the bimmer but for the toyota I have a wider range (where only the front camber can be set because the toyota has a solid rear axle so nothing is settable).
As for wear, it seem everything goes in this direction: 1. caster 2. camber 3. toe
In that caster is done first, then camber, and then toe, and in that wear is least with caster and then more with camber and then even more with toe (under typical settings).
It's just x y z planar stuff. :)
I have done my toe when I replaced tierod ends, pitman arms, and idler arms, and then when I took the cars for alignment, the toe was spot on.
So I think toe is easy, compared to caster and camber.
I'm an old man who has never had a FWD car and I hope that I die before I ever stoop that low.
So all my questions are for RWD vehicles.
The simple test is to set the alignment at home, and then take it to the shop for double checking. Many shops offer free tests if nothing needs to be changed; but I would hesitate to take them up on that only because they can always find something so I suspect that's just a gimmick.
Has anyone here ever gotten the "free test" actually for free if there was nothing to change? Or do they always find "something"?
Never in my life (and I'm an old man) have I seen a mechanic install a tire correctly (I use Tire Rack authorized installers), so I suspect it's the same with alignment.
For example, I had to bring 500 pounds of my own weights to my last alignment. The alignment guy *knew* how to do it right, he just knew that most of this customers don't have a clue.
It's the same with the tire mounting shops. They *know* how to do it right, but they also know most of their customers don't have a clue so they get lazy.
I doubt a single car tire is installed correctly, by the book, on any car taken to the typical tire shops (wheel works, goodyear, midas, etc.).
I think the summary is this simple.
A. Check the alignment at home for the things that can be adjusted. For my Toyota, that's only caster, camber, and toe in the front, and for my bimmer, that's only camber and toe on the rear and toe on the front.
B. Adjust if necessary (using a smart phone or inclinometer for camber, and a tape measure for toe). I'm not sure how to do caster in the toyota since I only just found out that the caster is adjustable on the toyota.
C. Take it to one of those "free if it's ok" shops, and see what they get for measurements.
If I'm perfect, it's free (I assume); if it needs adjusting, then I learn what can and can't be done.
If I misunderstand what "total toe" means, then that is probably the root of my confusion that toe at the front of the wheel is the same angle as toe at the back of the wheel, yet total toe is specified in angles and (I thought) that total toe is the difference in toe from the back to the front.
I don't understand why that is a *simplification* because it seems to be true by definition that if the wheel/tire angle to the centerline of the car is zero, then there is zero static toe.
Dynamic toe might be difference because a suspension uses complex geometry.
Yup. Toe is the angle difference that the wheel/tire is pointing versus where the centerline of the car is pointing.
Ah. If *that* is "total toe" then that's a completely different story!
If "total toe" is simply the toe at the front driver's wheel plus the toe at the front passenger-side wheel, then that is trivial to understand.
But that's not what others said "total toe" was. But, you must be right because if total toe was what others said it was (which is the difference in toe from the back and front of any one wheel), then it can't possibly be specified in degrees.
So what you explain is "total toe" makes far more sense than what others explained as total toe.
That makes sense if we use a definition of total toe which adds up the toe of each tire on the axle instead of calculating the difference of toe between the front and back of any one wheel on the axle.
So probably I was misled by someone's (I forget who) explanation that total toe was the difference in measured toe from the back of the wheel to centerline and the front of that same wheel to centerline.
The steering wheel is (mostly) unrelated to alignment but I know what you mean when you say that. I also know that you were using theoretical numbers which make sense.
In the real world, the toe is generally similar (if not the same) between two wheels on the axle (such as 1/32nd of an inch for each wheel, for a "total toe" using your definition of total toe, of 1/16th of an inch).
That statement makes sense because the angle at the front of the tire with respect to centerline is the same as the angle at the back of the tire with respect to centerline - which is why they put individual toe in angles - because angles are independent of wheel/tire size.
In summary, I was misled by someone's definition of total toe being the difference in distance between the front and back of a tire to centerline.
If total toe is defined as the combined toe of both wheels on the axle, then total toe can easily be defined in either inches or in angles.
None of my cars have dual-diagonal lines so I purge the brake fluid annually on each of them. A burst rusted brake line can be a memorable experience- it sure was for me. OTOH I wouldn't tell anyone else how to maintain their vehicles, YMMV.
Toe is actually the angle to the thrust angle, but if the thrust angle is not aligned with the center line, there is something wrong with the geometry of the car. It's easier for this discussion to just simplify it.
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