Advice requested from those of you who have successfully checked camber at home

nospam,

Why do you constantly pollute this thread with your worthless drivel? You don't know the answer to *any* question asked in this thread. Not one.

Yet, nospam, you pollute the thread nonetheless.

Tekkie,

Why do you constantly pollute this thread with your worthless drivel? You don't know the answer to *any* question asked. Not one.

Yet, you pollute the thread nonetheless.

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!

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.

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":

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.

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.

And total toe is specified in degrees.

Hi Scott,

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've never changed brake fluid in 50 years of car/truck ownership. So it's not "normal" to me.

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:

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.

Now it makes sense. Thanks!

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.

Maybe the SCIENCE guys can help in interpreting these specs?

One thing I've found out that is new is that the angle measurement on many mobile devices (e.g., iPads and iPhones) is the off-the-shelf ST Microelectronics L3G4200D (apparently rebranded the STMicroelectronics AGD1

2022 FP6AQ for Apple products). Do you know if Android devices also have that same gyro? If so, that MEMS chip will be the ticket to us figuring out the angle accuracy.

On the ST web site, they list the "resolution" as "lower than 0.01 dps/yHz for zero-rate level", which I'm not sure how to translate into degrees of accuracy.

Another spec they use for the L3GD20H MEMS gyro is: plus or minus 2000/ plus or minus 245 full scale typ (degrees/s)

Do you SCIENCE guys know how to interpret those specs so that we can get an idea of the resolution of the chip in terms of degrees of accuracy?

Do the Android guys know if that chip is also in Android devices?

The old standard was always about +- 1 degree, when you had no other specs to go by. Enthusiast cars like the BMW have different needs for handling purposes.

That's not uncommon.

That doesn't sound right. 2 degrees should not cause early wear, so you really need to check the ride height. And recheck the camber.

Yes, caster will not cause wear.

That's not the reason for the order, but it's not important.

I hate to say this, but you can get pretty close just eyeballing toe and camber. Especially with camber, if you can't see any substantial lean, the camber is probably close enough that it won't cause tire wear. In a pinch, it works for toe, too.

It's not necessarily a repeatable test, though. The one time you do that, you might have gotten lucky.

They are expected to print out the readings, so it takes some effort to lie. I'm sure they usually find something, but that's only because cars do go out of alignment.

I'm pretty sure that none of the manufacturers expect techs to load a car before alignment anymore. The specs take into account average occupant weights.

And I doubt that it makes the least bit of difference.

You don't really learn that, except for each time you try it. You can get very different results on future attempts.

Oh. OK. You actually understand this stuff. Thanks for explaining that the thrust angle isn't necessarily the centerline, but, for our purposes, we'll assume they're one and the same.

We're delving off topic, but if you live in a wet or dusty clime, your brake fluid will "suck up" water and dust, which, on a 10-mile long mountain pass, might make a difference in not so good a way.

Even if it doesn't, the alcohol in the fluid will slowly erode your gaskets in your master cylinder (and slave cylinder if you have a hydraulic clutch).

It will likely still work all dusty, wet, and black; but it won't work as well if you live in the mountains.

What I am talking about is mostly that maintenance and repairs are different, and there are vehicles that require a lot of maintenance and if you don't do that maintenance you get repairs.

Maintenance you can do at your convenience in a heated or air-conditioned garage. Repairs are not so clean.

The Japanese cars... you don't do a lot of maintenance, instead you do a lot of repairs all at once. The BMW, you do a lot of maintenance.

I mean the big rubber hose going between the throttle body and the airflow sensor. It cracks and then the airflow data becomes invalid and the car starts running lean. You can patch the cracks with 3M weatherstripping adhesive for a while until after a while you can't.

The issue on this one is that the they are using that TO220 FET as a linear regulator to adjust the voltage on the motor, and it develops a lot of heat of course. In Germany it's not a problem, but in Florida it fails pretty promptly. There are a couple places that have retrofit ones with big heatsinks. There have been a couple people talking about making PWM retrofits but nobody has done it yet that I know.

If you are changing oil every 3,000 miles you shouldn't need to do any of this. Just swab it out when you cahnge.

Tried Formby's Furniture Refinisher or maybe just xylene on it to liquify the varnish and redistribute it?

This might be the same issue as the fan controller and the exterior rubber: stuff that works just fine in the German climate but doesn't do so well in places in the US.

If you keep changing the fluid, the rack seals don't fail. If you don't change the fluid, the rack seals will fail. Changing to viton isn't a bad idea at all, but constant maintenance reduces the need to do that.

I would tend to disagree, with a few exceptions like the cooling system which really IS shameful.

Okay, I was making the assumption of the manual transmission. Why would anyone get a BMW and then put a slushbox in it?

If you DO have a slushbox, regular fluid changes are even MORE important although not at as short intervals, because if you don't do it regularly while the transmission is young, you're going to get exactly into that situation when the transmission is old. (Note also that a fluid change is NOT the same as a complete flush.... the complete flush is a bad idea in any case... just drain what comes out and refill it. It won't change all the fluid in the case but that's okay because you're going to do it again soon enough anyway).

Agreed that if you're stuck with a high mileage automatic that has been abused in its youth by a lack of proper fluid changes that the best thing to do is just keep your fingers crossed and hope it doesn't fail. (Well, really the best thing to do is trade in the car before it does fail but that's another story).

This is a case of repairs vs. maintenance again.

Nope, I'm just a guy who likes to drive cars for a long time, and I like BMWs for the reason that if you do put the proper maintenance into them you can just keep driving and driving them. I just rolled over 360,000 mile on the E28 this week coming home from work and it's still almost new.

I don't claim to be intelligent, I just claim to be able to keep cars running. A good argument could be made that if I were intelligent I would have traded the E28 in twenty years ago and I wouldn't be driving the 2002 at all. Certainly my wife makes that argument often.

--scott

And... on a Japanese car you can get away with that and not have any issues. Some of them don't even list the brake fluid on the maintenance schedule.

Unfortunately you _cannot_ get away with that on the BMW. It is NOT forgiving about maintenance.

--scott

I just looked that up for my two cars.

The Toyota spec for the front camber is -.6? to .9? which is exactly in the range you suggested.

The BMW rear camber E39 I6 and 540 models with "standard," "low slung sport" and "M-sport" suspensions spec is apparently -2 deg 10 minutes. The tolerance varies among options: either +/- 20 minutes or +/- 25 minutes of angle.

The M5 spec is -1 deg 50 minutes perhaps due to 275/35 section width tires vs 225/55 for I6 cars.

For the caster on the toyota of 1.7 to 3.2 degrees, I am not yet sure how to measure it for the Toyota but I won't have to bother for the bimmer because caster isn't adjustable.

For the camber of -.6 to .9 degrees for the Toyota, I think I'll use a magnetic base inclinometer such as the Husky 10-inch Home Depot electronic level.

I think I'll just set the toe to 1/16th of an inch less in the front tread (measured as close to centerline of the wheel as possible) than in the back tread to centerline of the vehicle.

That will give me a total toe of 1/8th inch on the Toyota. I'll use toe plates and a tape measure, I think.

True. But it would be free if I got lucky! :)

But if I align it first, it should be within spec, at least for what can be aligned, which is, for the toyota, front caster, camber, and toe, and for the bimmer, rear caster and toe and front toe.

The 500 pound loading on a bimmer is for a different purpose. You are supposed to put 100 pounds on the driver seat, 100 pounds on the passenger front seat, and 200 pounds evenly spaced on the rear bench and

100 pounds in the trunk.

That artificially "lowers" the car to a specific "ride height" which all BMW alignment specs are to.

There is much discussion of why BMW uses that artificial ride height to normalize all their specs, but it has absolutely nothing to do with the "typical" loading of a vehicle with a driver.

I mostly agree with you that when the tire shop torques *all* lug nuts and bolts to the same 100 foot pounds, it probably doesn't hurt anything. Nor if they fill up all tires to the same 40 psi, again, it won't kill anyone (even though BMW specifies different pressure for the front versus the rear).

That they pry off the BBS hubcaps with a screwdriver just breaks the plastic tabs. And that they don't remove all the old weights just makes them put more on each time (and increases the chances of an imbalance from a lost weight).

And that they don't mount the tire with the red or yellow dots to the valve stem or match mounting mark just means they'll use more weight than necessary.

That they don't even torque the bolts in a star pattern probably only makes the wheel slightly crooked.

So, I agree with you that the fact that no tire is ever mounted correctly isn't causing accidents left and right.

But it's still wrong.

Oh, yeah. I know it all too well.

My first smoke test for a lean condition showed a crack on the *underside* of that large ribbed tube. A few years later, my second smoke test showed that the tubes sticking out had leaks.

It would have been cheaper to just replace the damn things, instead of doing all those expensive smoke tests, which was your point, I agree!

Maybe you can answer a question which has irked me for years. As you know, the AC/Heating system is "fully automatic" meaning it's not intended for manual control, so, the blower starts at whatever settting it wants to start at when you start the car, no matter what setting you left it at when you last shut down the car.

I *always* adjust that, either to *off* or to the midway position.

But what I always wondered was, if the blower is on at all, whether the full on, or midway position caused less stress on the FSU?

I'm guessing from something a guy named cn90 and jim cash wrote that I found by googling, that the midway position is least stressful for that TO220 FET (there are three of those MOSFETs aren't there?).

Which blower position do you think is least stressful on that MOSFET driver if the blower is on?

1 bar 5 bars 10 bars

I know when my FSU failed the first time, it was so hot I burned my hand trying to get it out of those Germanic clips. The second one failed without heat, as did the others (where they failed in a way that gave the AC/heater controls a mind of their own).

Nope. I didn't know about that trick. Maybe I'll try since it's just the varnish that is cracked.

The ABS "trifecta" failing on the E38, E39, and E46 is also shameful. So is the trunk wiring loom fraying on almost every vehicle. And the headlight adjusters crumbling on some of the models like mine.

Thanks for your insight. Very interesting!