BMW Blog

Can an alignment be a DIY for an E36? If it can, is there a write up anywhere, or is it in the Bentley Manual?:95

I don't think this is possible without about $1000 in special tools that most people would have.


Alignments really aren't that expensive - I got my 4 wheel alignment done for ~$70.

Did you go to a BMW specialist, or a do all mechanic. I'm pretty sure you didn't go the dealer, for a price like that.

Originally posted by Def
I don't think this is possible without about $1000 in special tools that most people would have.
$1000 worth of tools? No way. You obviously don't know much about alignments. Like you said in another thread, you might want to read up on things before you make uninformed responses.

You can do an alignment with under a hundred bucks (probably even less) of tools. You do need to be very patient and precise, and you need to know some basic geometry/trigonometry to be able to do the job correctly. It isn't exactly difficult, but it is tedious - if you don't have much patience, you might just want to pay a shop to do it for you. With the alignment racks, computers, and other tools that shops have, much of the tedius crap is eliminated or reduced, so they're able to do the job much faster and easier. But, if you're careful and willing to spend the time, you can do as good of a job at home.

The first thing you'll need to do is make a spot to work that's perfectly level - drive your car into your garage, mark out all four wheels, pull your car out, then use a level (bubble, water, or laser) and shims (floor tiles, cardboard, thin sheet metal, etc.) to level out the four spots. If you use floor tiles, you can put grease between the tiles so they act as slip plates. Otherwise, cover each stack with a plastic garbage bag folded into a Z.

Put your car on the level pads, and check your tire pressures - adjust if necessary. Make sure they're even from side-to-side.

At this point, you can measure and set the camber. To measure camber, you can use a level held vertically and a good steel ruler. Measure the distance from the edge of the rim to the level at the top and bottom of the rim, then use some trig to convert the measurements to degrees.

For caster, turn the front wheels until they're pointing 45 degrees in one direction, measure the camber, then turn them until they're pointing 45 degrees in the other direction, then measure the camber again. Add up the absolute values, and you should have your caster measurement. If the wheel doesn't turn 45 degrees, you can do the measurements at smaller angles, but then you have to do some trig before adding up the measurements. Unfortunately, I don't remember the equations and am too lazy to look them up - that's an exercise for the reader...

Next, you need to make some reference lines. The key line needs to be exactly parallel to the centerline of the car - if it's exactly on the centerline, that's great, but not totally necessary. Go under your car, pick a good point on your suspension, and use a plumb bob to mark that point on the floor. Find the exact same point on the other side of the car, and mark that point on the floor. Do the same at both the front and the back. Measure the distance from side to side between the two points, make a mark halfway between, then draw a line from front-to-back to mark the centerline of the car. If you plan on aligning your car all the time, you can use your plumb bob to mark the centerline of the car up on the car body itself. Makes it a lot easier to set up the next time.

Once you know the centerline of the car, you can string the car. What you need to end up with is a taut string on each side of the car, 6-12" from the car, perfectly parallel to the centerline of the car, high enough so it runs across the center of each hub. You can support the string with a jackstand or block at each corner of the car, or you can suspend a piece of pipe at both ends of the car (hook it on to the bumper, or use strings and hooks to hang it off the trunk opening, etc.) and use that to suspend the side strings. The pipe works better, because you can move the car without having to reset the strings on jackstands.

Once the car is strung, measure from the string to the front edge of the wheel, and to the back edge of the wheel - the difference is your toe. Be sure that the ruler is at right angles to the string, and parallel to the ground. Toe in the front is adjusted by changing the length of the tie rods. In the rear, it's adjusted by moving the RTAB console.

Precise, accurate, repeatable measurement is the key for getting good results. After making any adjustment, be sure to settle the car either by bouncing the suspension, or by rolling the car forward and backwards. Use a good steel ruler for all your measurements - a machinist's ruler is the best thing to use. Make sure that the ruler is always held level, and at right angles to whatever you're measuring from.

If you do a search on the web, you should be able to find more information on DIY alignments.

Jim

all u need is a piece of string! J/K.

Jim,

I thought about doing this because no one in the area will touch a lowered M3 for under $129 besides the dealer.:rolleyes: It's not like the suspension is that big of a deal... camber and toe in the rear and just toe in the front. My question is how to get the tires to slide once the adjustment is made.

Ok more detail. I am just going to adjust the rear camber because it's needed badly. So I adjust the camber one line at a time, and then drive the car back and forth to get the tires to sit properly? Or is there a way for them to slide once the adjustment is made? Does my question make sense?

TIA,

Originally posted by vjlax18
I am just going to adjust the rear camber because it's needed badly. So I adjust the camber one line at a time, and then drive the car back and forth to get the tires to sit properly? Or is there a way for them to slide once the adjustment is made?

Two vinyl floor tiles per side with liquid soap. Put the shiny sides together and squirt some soap (dawn, etc.) between them. That will let the wheels slide out when you lower the car back down.

Changing camber in the rear will also effect your rear toe... just be aware of that.

I've used the vinyl floor tile method as well as driving around the block.

Originally posted by John in Houston
Two vinyl floor tiles per side with liquid soap. Put the shiny sides together and squirt some soap (dawn, etc.) between them. That will let the wheels slide out when you lower the car back down.

Changing camber in the rear will also effect your rear toe... just be aware of that.

I've used the vinyl floor tile method as well as driving around the block.

Vinyl floor tiles sound good - I've got some of those.

I've got way too much negative camber, so when I adjust them, which way with the toe go. I'm hoping it will push the toe out. Right now there is too much toe in, but measuring it is a pain, and tire wear would still be even with toe in/out to a certain extent. So I was only going to adjust the camber. I marked the TA when I did the RTABs, so they're back where they were originally, so the toe was correct before. Thanks.

Originally posted by vjlax18

I thought about doing this because no one in the area will touch a lowered M3 for under $129 besides the dealer.:rolleyes:

Did you try NTB (National Tire & Battery)? They did mine for $89.

$1000 worth of tools? No way. You obviously don't know much about alignments. Like you said in another thread, you might want to read up on things before you make uninformed responses.

My my, a little snippy.

Yes, I do know plenty about geometry, and I know that doing an 'at home' alignment is possible. Yet it seemed outside the scope of this person's ability, and IMO is not as 'foolproof' as some might say.

Given the small angles and increments you are talking about in alignments - I doubt your method would get better than +/- 10% accuracy(which is pretty good for 'eyeballing' something). Given that, your alignment could be all over the place, especially if its your first time doing this.

The ~$1000 in tools were for laser operated toe measurement devices(which would be the hardest to get correct, and are really the only ones easily changable in stock suspension form). This would probably give you a 1-2% accuracy, and be very quick and easy. Now affordable is another story.

An at-home alignment is something you do when you are doing FREQUENT alignments and trying out different settings for competition use and whatnot IMO. $70 is less than 1 tire, and I went to a local mechanic(not dealer) and got to specify my settings while they used a Hunter machine.


Again, alot of things are possible for the DIY, but not feasible or reliable.

Originally posted by C///M
Did you try NTB (National Tire & Battery)? They did mine for $89.

The NTB across the street said that the front bumper would hit the front of the rack:rolleyes: I offered to take the bumper off in the next bay over, but they didn't want me to. I've been taking cars there for years, and they know me:mad:

Ok, the whole point of an expensive Hunter or equivalent machine is to get you in and out as quickly as possible. That's it...no more accurate than using very precise strings and a machinist's rule.

For example, competition race teams (I used to have a picture of a Cadillac LMP 900 doing this) use the string method in the field, and most race shops will use strings or equivalent on their race cars.

I use the string method (I have metal bars that are of equal length that I hang from the front of my car), and it works out wonderfully. Now, getting my tie rods to stop stripping is another story, but I'll get to that eventually ;).

Originally posted by vjlax18
The NTB across the street said that the front bumper would hit the front of the rack:rolleyes: I offered to take the bumper off in the next bay over, but they didn't want me to. I've been taking cars there for years, and they know me:mad:

That sucks. My car is about 1/2-way down on H&R coilovers, and my local shop didn't have any problems. Oh well, I dunno...

Jim & John:

I've used the string alignment method with good results. When I've done it, I've driven the car around the block between adjustments to settle the suspension prior to measuring. I don't understand what you mean by using vinyl tiles as slip pads - is this for settling the suspension? How does it do this?

Thanks,

Murray

Originally posted by EvanL
Ok, the whole point of an expensive Hunter or equivalent machine is to get you in and out as quickly as possible. That's it...no more accurate than using very precise strings and a machinist's rule.

For example, competition race teams (I used to have a picture of a Cadillac LMP 900 doing this) use the string method in the field, and most race shops will use strings or equivalent on their race cars.

I use the string method (I have metal bars that are of equal length that I hang from the front of my car), and it works out wonderfully. Now, getting my tie rods to stop stripping is another story, but I'll get to that eventually ;).


I still refuse to believe that an 'eyeballed' measurement is as good as a laser. You can get it 'close enough' but if you're going for 1/8" toe-in, you make two measurements. Let's assume you can get it down to 5 hundredths of an inch(which is very good, and probably not possible for a long measurement with all the inaccuracies you introduce). Adding it up, you can turn 1/8" into closer to 1/4" with inaccuracies that are present in hand measuring something with just a ruler. Fab up parts with even the most careful measurements and you'll see that very rarely do you get things to even 5 hundredths of an inch.

Yet this is a good relative way of doing things(i.e. competition environment that I previously stated). If your ruler has a constant inaccuracy, you measure it 'the same way' each time and adjust things relatively the same - then I could see your changes being ~5% accurate.. maybe. Yet you really only care about relative things in a racing environment(i.e. setup 2 is 0.1 seconds faster than setup 1 - we're keeping it). On a street car, you could eat your tires up over ~5k miles with gross toe-in on the front when you thought it was very minor. Racing = relative changes, street cars need more absolute settings in regards to what 'matters'.

Originally posted by MDR
I don't understand what you mean by using vinyl tiles as slip pads - is this for settling the suspension? How does it do this?

It basically does the same thing that the 'slip pads' on a Hunter alignment rack does. It allows you to jack up the car, make an adjustment, set the car back down and have the wheels slip out to their loaded orientation.

If you jack your car up from the differential now, when you lower it back down, your wheels are in a positive camber, positive toe position.

You need to let the wheel/tire settle into it's correct position. The aligment racks use floating platforms that slide so that the car can settle into position. Using the vinyl tiles with soap accomplishes this same feat for only $2 of investment.

Originally posted by vjlax18
I've got way too much negative camber, so when I adjust them, which way with the toe go. I'm hoping it will push the toe out. Right now there is too much toe in, but measuring it is a pain, and tire wear would still be even with toe in/out to a certain extent. So I was only going to adjust the camber. I marked the TA when I did the RTABs, so they're back where they were originally, so the toe was correct before. Thanks.

So anyone?

All of your input has been great. This is a diy I think I would only do with someone that has done it before and on a regular basis. After hearing all of the responses I'm at least now a little smarter and know I could do it myself if I needed to. For me that is enough reason to know how to do something.

Thanks everybody

Well, my best guess at it (since I can't get under my car right now) is that it would be considered a 'front steer' application (being that the adjustment is in front of the axle).

With that being the case (as in the front of the car).... the more negative camber, the more toe-in you get. Removing negative camber would create toe-out.

Originally posted by Def
My my, a little snippy.
A little snippy? That's exactly what you said to someone else in that thread about catch cans. You didn't consider yourself to be snippy - I don't consider myself to be, either....

Given the small angles and increments you are talking about in alignments - I doubt your method would get better than +/- 10% accuracy(which is pretty good for 'eyeballing' something). Given that, your alignment could be all over the place, especially if its your first time doing this.

The ~$1000 in tools were for laser operated toe measurement devices(which would be the hardest to get correct, and are really the only ones easily changable in stock suspension form). This would probably give you a 1-2% accuracy, and be very quick and easy. Now affordable is another story.

First of all, a stretched string is as straight as a laser beam.

Second, how do you think those ~$1000 laser toe setups work? They use a laser beam onto a ruler. No magic there - you have exactly the same opportunity for error in reading as with a string, possibly more, depending on the the optics used in the laser, and the amount of dust and other junk in the air around the car.

Third, the less expensive laser toe plates rest on the tire, not on the rim, so add another opportunity for error. The more expensive systems use metal rods that rest on the edges of the rims - better than the toe plates, but unless you position them so that the rods are touching the exact same place on the rim on both sides, you will run into another source of error. Of course, when you're measuring with a steel ruler, you need to be careful to measure from exactly the same place, too.

Fourth, the laser toe plates and gauges only measure the toe of one wheel on one side relative to the same wheel on the other side. Unless you work off the centerline of the car, you will have tracking problems, where the rear wheels aren't centered with the front wheels. The only laser rigs that I know of that will do a true four-wheel alignment are either the ART Laser String (which are used in exactly the same manner as stringing the car with real string), or the very expensive professional alignment machines, which cost way more than $1000.

Fifth - you throw around accuracy figures like 1-2% or 10% - how accurate do you think those guys at NTB (or whatever chain alignment shop you use for 70 bucks) are? Just take a look at the printouts - the best that most of those guys can do is to be within 0.1 degree. I've used several of those shops for "quickie" alignments, and later had the alignment settings checked by my race prep shop on their state-of-the-art well maintained Hunter machine. None of the chain shops have been any better than 10%, even though they've all used alignment machines with laser beams. Half of the readings showed that the chain shop must have dropped the alignment head. Or the "technician" didn't take the time (or have the ability) to do a good job.

Heck, even the shop that I use, which has one of the best maintained, up-to-date, regularly calibrated Hunter machines that I've ever seen, being used by a guy who really knows his stuff and is a total perfectionist, doesn't get much better than 1-2% accuracy. So, I really doubt that the accuracy numbers that you're throwing around are grounded in reality.

Sixth, wheel alignments have been done for years with strings, before any of the laser alignment machines became available, with excellent results. A few of the shops that I know of still use the string-based machines, and do a better alignment job than 90% of the chain places with their laser-based machines. There are really two reasons why shops went to laser-based alignment machines. The first is as EvanL pointed out - increased throughput. If you look at the web sites for most of the alignment machine manufacturers, that's what they all push - increased productivity, faster setup time, more cars through in a day. Not accuracy. The second reason for going to the laser-based computerized alignment machines is that you can use a lower paid, less trained technician to run it. That, along with greater throughput, makes it much more profitable.

Seventh - in a later message, you mentioned something about all the inaccuracies adding up and turning 1/8" of toe into 1/4". Sorry, but that's BS. To make the toe measurement, you're measuring two places against a string, then subtracting the results. There isn't a whole lot of chance for cumulative error here. Worst case is that you set up the strings crooked. Say you set up one end of the string 1/4" closer to the centerline than the other. For ease of calculation, let's say that the string is 170" - it's probably longer, but offhand, I don't remember the length of an E36. Simple math tells us that if it's 1/4" off in 170", it will be 0.025" off in 17", or the diameter of the wheel. That's a bit less than 1/32" - nowhere near turning 1/8" into 1/4". To do that, you'd have to have your string off by over an inch - if your measuring ability is that far off, you should just give up and forget about it. And, if you have that hard of a time using a simple instrument like a ruler, there's absolutely no way that using a laser is going suddenly make you competent.

Jim

Originally posted by John in Houston
You need to let the wheel/tire settle into it's correct position. The aligment racks use floating platforms that slide so that the car can settle into position. Using the vinyl tiles with soap accomplishes this same feat for only $2 of investment.
What John said. I tend to like to use grease between the tiles, instead of dish soap - the grease doesn't dry out over time. Also, I usually have grease or oil around, but don't always have dish soap (I guess I could go into the kitchen and get some, but that's too much work... :D ).

Like I said earlier, you can also use a heavy plastic garbage bag folded in a Z as a slip plate. Even cheaper than buying two vinyl tiles and some soap...

Jim

Originally posted by Jim O.
What John said. I tend to like to use grease between the tiles, instead of dish soap - the grease doesn't dry out over time. Also, I usually have grease or oil around, but don't always have dish soap (I guess I could go into the kitchen and get some, but that's too much work... :D ).
Jim

I used to use grease too.... then I got married and got my a$$ chewed for getting grease on the floor :(

The grease works better... but the soap cleans up easier when you (inevitably) get it on the floor!

.... and when Mamas happy... everybody is happy:D

There are tons and tons of ways to set toe at home, some of which are most likely more accurate than a laser machine. They are, though, generally a big PITA.

When I changed my tie rods out recently (slightly more irritating job than expected, but it worked out), I looked into this. The methods that sounded most appealing to me involved marking a fine line about the circumference of the tire on the tread, and measuring from that. Then there is no doubt about the quality or trueness of the rim or tire. I quite like the idea of using the vinyl floor tiles + slippery stuff for turn plates. I was planning on using old magazines, but the tiles sound like a better hack.

I confess, though, that I wound up just taking a few measurements of the old tie rods and some reference points under the car. Cross checks checked out, and the car handles fine.

Jeez, don't check this thread for a while and look what happens...

A little snippy? That's exactly what you said to someone else in that thread about catch cans. You didn't consider yourself to be snippy - I don't consider myself to be, either....

The difference is that the person I said that to before added nothing to the thread. Useless one liners just shouldn't be posted if that's all there is to be said.


As for your other comments, I think what we have here is a difference of opinion. No reason to get all pissy, we're talking DIY alignments, not a pressing matter in my book.

I won't offer sequential rebuttals, but I will say this.

I realize one can do an alignment with a string based system. I also believe that getting an alignment on a more accurate laser-based Hunter system is just a more accurate solution, and really doesn't cost that much if one isn't doing very frequent alignments. BTW, my $70 alignment was done on one of the latest Hunter Machines.

As for accuracy, in my experience with fabricating parts, hand-done measurements are very lucky to get within a hundredth of an inch or two. It's not unheard of to be almost 5-10 hundredths off in a handdone measurement(not a caliper) with all the inaccuracies you can introduce. Before you attack me again and question my competence with a ruler, I suggest you rethink all the inaccuracies you can introduce. As for cumulative error, what you described as not having cumulative error does in fact contain it. Each measurement you do is NOT 100% accurate, so each time you compare one inaccurate measurement against another inaccurate measurement, you are introducing cumulative error into your calculations.

BTW, I also think we are not seeing eye to eye on the definition of 'innaccuracies.' They are not a result of operator incompetence, but a result of the intrinsic error introduced by 'guessing' about the angle of your ruler, and the very act of reading off a measurement, inconsistencies in the ruler, etc. Just because you put a ruler up to something and say, "that's 24.15 inches", does NOT mean it is 24.15inchs. In fact, it could easily be 24.21 inches and you would never know it(in fact, I'd call that a pretty good measurement).

As for my percentages I was throwing out, there was some assumption done for those figures, but it's just math. Pretty easy to check. Compare your final error to the end result and then you can easily see the magnitude of error. Compare measurements between a few screws drilled into wood with a ruler and then a digital caliper. I think you might be surprised.


I still would question an alignment if it was done with hand-done measurements. I think that for a street driven car, it is just makes way more sense to find a shop that has decent priced alignments on a Hunter machine.

Hi Guys, I have set up many race cars and I always use 'string' for the tracking (toe), never had to use it for camber/castor as I had the gauges available but I see no problem with using this method for that.

Also Im dubious regarding the use of electronic equipment. I am sure that the equipment itself (as long as it is calibrated) is perfect; it is the operators that worry me.

I once attended a race by request of the driver who had some doubts over the performance of his car. It was a Ferrari 355 at the Ferrari finals. That had been set-up by the home team. Theses are teams from all over the world, usually The Ferrari main agents for that country (I wont name them here, lets just say x) who had used electronics. Anyway the driver had complained that the car felt odd, so I thought a check over was in order. |At this point I was stopped by the representative of team x who said no need to check the car, it has been professionally set-up by x using our new (insert a silly amount of money here!) equipment. Anyway to cut a long story short, the rear tracking was 7mm toe in on the left and 4mm on the right, (they claimed it was set at 2mm toe in overall) the front was a similar story but no quite so severe. The driver went on to be 3 seconds quicker.

Team x set-up all the road Ferraris for there country as they are the main agents, and Im sure that there customers have great opinions of them especially due to all the high tech machines in the workshop!

The moral of this story is just because they say it has been done or you think it is correct it might not be so accurate.

As for string it is an accurate as any laser beam (as Jim has already pointed out) what do you think Formula one use? It all comes down to the operator be it high tech equipment or string.

Rory

Hey, I just thought of something, while we're sort of on the topic...if I mark where things are now, drop my rear trailing arm (just one), pull the Powerflex bushing to regrease it, and put it all back according to the marks I made, will I really need a realignment, or will I be "close enough"? It's all the same parts, with precision of eyeballing marks I make all around, so it should be really close, shouldn't it?

Just wondering if I want to live with a squeaking RTAB until I have a better reason to spend $90 on an alignment, or if I can just fix it and not really need another alignment...

Thanks!

About being "snippy" -
Originally posted by Def
The difference is that the person I said that to before added nothing to the thread. Useless one liners just shouldn't be posted if that's all there is to be said.
And you originally said:
Originally posted by Def
I don't think this is possible without about $1000 in special tools that most people would have.

And this adds value how? Looks to me pretty much like a useless one-liner. You didn't add any info about what special tools you feel are needed, or your experience with this, or anything else.

Anyway, your original post about not replying to things that you don't have experience with was very good advice. I just wish more people would take it.

As for your other comments, I think what we have here is a difference of opinion. No reason to get all pissy, we're talking DIY alignments, not a pressing matter in my book.

Pissy? Geez, talk about people being "snippy". Anyway, it's not so much of a difference of opinion, but a difference in experience.

I realize one can do an alignment with a string based system. I also believe that getting an alignment on a more accurate laser-based Hunter system is just a more accurate solution, and really doesn't cost that much if one isn't doing very frequent alignments. BTW, my $70 alignment was done on one of the latest Hunter Machines.
Yes, but you're talking about a machine that's easily an order of magnitude or two more expensive than the ~$1000 tools that you were talking about. As far as I've seen, there are two sub-thousand dollar laser-based toe measuring devices out on the market. Both by ART - the laser toe plates, and the laser toe gauge. Neither will do a four-wheel alignment - there's no way to measure whether the front wheels are aligned with the rear wheels. Both work by projecting a laser against a ruler. The laser toe gauge is a little more accurate, because it works off the rim of the car, not the sidewall of the tire. Either one offers pretty much the same accuracy as working off a string, at least in the hands of a skilled operator.

And, though your alignment was done on a Hunter machine, how do you know it's any good? How do you know if the machine was properly calibrated? Or if one of the sensor heads had been dropped? How do you know if the tech using the machine knew what he was doing? How do you know if the rack was level, or how well the tech settled your suspension before starting? Did the tech adjust your tire pressures before starting?

A machine is only as good as its operator. I've seen many, many, many places with state-of-the-art Hunter machines, who do lousy alignments. There's nothing magic in the Hunter machine that will make a mouth-breathing monkey-boy hack do a good job. Just take a look at some of the alignment readouts that have been posted on Bimmerforums - some of the "after" readings are off a huge amount.

BTW, I also think we are not seeing eye to eye on the definition of 'innaccuracies.' They are not a result of operator incompetence, but a result of the intrinsic error introduced by 'guessing' about the angle of your ruler, and the very act of reading off a measurement, inconsistencies in the ruler, etc.
Sure, I understand about inaccuracies in measurement. Yes, different rulers can give different results, there are errors in parallax, angles of the ruler, etc., etc., etc. However, there is really nothing in the laser systems that are available in the price range that you mentioned that eliminate these problems. These laser devices do not calibrate themselves, so there are still possible errors in the device itself. They still use a ruler, so that could be inaccurate. The laser beam itself has width, which adds to the measurement error. Depending on the design of the laser, there could be edge diffraction effects, which would also add to the width of the beam.

I still would question an alignment if it was done with hand-done measurements. I think that for a street driven car, it is just makes way more sense to find a shop that has decent priced alignments on a Hunter machine.
Problem is, you are putting way too much faith in the equipment, and not enough on the technician. I would much rather have a good technician with a string, level, plumb bob, and ruler than an idiot with a top of the line Hunter machine. I've had and seen so many machine alignments that have yielded poor results that it's just ridiculous. And that's at decent shops, not the chain places that use technicians that are one step up from the guys working at Oil Changers. I've had shops that depend on their machines align my car with a whole degree more camber on one side then the other - that's enough to see with the naked eye. But somehow their machine said that it was OK.

What you really need to do is find a shop with good equipment in excellent condition, run by people who really know what they're doing, and who care about the work they do. But until you find that shop, you can do just as good of a job yourself, with simple tools.

Jim

What you really need to do is find a shop with good equipment in excellent condition, run by people who really know what they're doing, and who care about the work they do. But until you find that shop, you can do just as good of a job yourself, with simple tools.

I agree with this statement. I watched my car being aligned on a Hunter machine, and even made the guy settle out my suspension twice. I know it to be accurate, and I doubt I could do a hand measurement to get it that accurate(considering you could barely press on one edge of the wheel with a hand and the machine could detect this change).

I also researched DIY alignments back when I started autocrossing my Integra. I never found one article that mentioned the error you could have in your measurements other than, 'be careful.' Sorry, but there are many many sources of error here. I think that strong advocates of this method are either ignorant of these sources, or just choose not to discuss them. Which is really not good advice, potentially even harmful, for a first-timer choosing to do an alignment themselves.

On the subject of error, I was not comparing the string-ruler method to that of an 'affordable' laser system(both of which I think are non-optimal, but the laser system takes more inaccuracies out of the equation). I was comparing the string-ruler system to a Hunter alignment machine.

As for my 'experience', I haven't seen anything you offer anything in this thread to justify your blatantly condescending tone.

We have a difference of opinion, yet you seem to want to pick out snippets of my posts, which aren't detailed articles on the subject at hand, and then read between the lines at what you 'think' I'm saying. Then proceed to pick apart your version of my post. Don't take things so seriously. It's only the Internet. By that token, don't assume you know anything about me. You really don't, and maybe by keeping an open mind, you can learn a thing or two.

I do apologize to the original poster for being very brief in my original response. I made an assumption(hello Mr. Kettle.. I know:laugh ) about his objectives, which was right, and made a short one-liner recommendation to the effect of, "don't bother, there are tastier fish in the DIY sea."

But Jim O., one does not need to be an Internet Discussion Nazi to have a meaningful debate on a subject. Stooping down to insults and derogatory remarks does not get your point across, nor does it make you look any better in the eyes of others.

So drop the air of superiority. You might have been around the block longer than I have, yet I refuse to believe you, or anyone else for that matter, has it all figured out. I might have a little more experience with some of the things I talk about than you realize...

:wave: :redspot

Originally posted by C///M
Hey, I just thought of something, while we're sort of on the topic...if I mark where things are now, drop my rear trailing arm (just one), pull the Powerflex bushing to regrease it, and put it all back according to the marks I made, will I really need a realignment, or will I be "close enough"? It's all the same parts, with precision of eyeballing marks I make all around, so it should be really close, shouldn't it?

Just wondering if I want to live with a squeaking RTAB until I have a better reason to spend $90 on an alignment, or if I can just fix it and not really need another alignment...

Thanks!

Should be close enough, depending on how careful(anal?) you are.

Try to make multiple marks though and then line them all up just in case. Better safe than sorry.

Originally posted by Def
Should be close enough, depending on how careful(anal?) you are.

Try to make multiple marks though and then line them all up just in case. Better safe than sorry.

Just ask Bryan ///M3. He calls me "detail oriented" since it sounds better than "anal retentive." :D

I was thinking of putting marks anywhere I can (i.e. the visible parts of all three mount points of the bracket) with white paint or something like that (I couldn't see the marks made by a black Sharpie) before doing it.

Thanks!

Originally posted by Def

So drop the air of superiority. You might have been around the block longer than I have, yet I refuse to believe you, or anyone else for that matter, has it all figured out. I might have a little more experience with some of the things I talk about than you realize...

:wave: :redspot

Then please end your pissing contest and clue us in on some of your experience with MISalignment by correctly applied string DIY method. That's the kind of experience that might be interesting in the context of Jim O's (and others who have posted, who certainly give the impression of having a lot more experience than most) long-time experience of doing successful alignments with the technique. You have a nice theory about how hard measuring stuff by hand is, which is not apparently borne out in the real world of the DIY alignment.

There are experiments you could do that might shed light on this, as well. String and measure your car twice. What kind of repeatability do you get? Try two different methods of finding toe. Do they cross check? I would be stunned if one can't get well within acceptable tolerances for at least toe in on the first try of the string method.

Jeepers guys, settle down. This is not a black and white issue - there are many areas of gray.

I believe that you can get reasonably close with some patience and a bunch of string - on toe in. For camber adjustment, you can use the Smart Camber tool from Smart Racing Products. But you also must be on a perfectly level surface, or your measurements may be off.

If you have seen $28K alignment racks up close and in operation then you know that these things are way better than a piece of string. Some things should be left to someone with the proper tools - I believe the technology of these newer alignment racks makes it easy and super-accurate...

-Wayne

Originally posted by Wayne@PelicanParts
If you have seen $28K alignment racks up close and in operation then you know that these things are way better than a piece of string. Some things should be left to someone with the proper tools - I believe the technology of these newer alignment racks makes it easy and super-accurate...
One of these computerized racks, in top condition, and recently calibrated will be pretty accurate, and way faster and easier than stringing the car. However, there are a lot of these types of racks out there that aren't in good condition and properly calibrated. In a lot of shops, someone has dropped or banged one or more of the heads, or the rack itself hasn't been levelled since it was installed. In either of these cases, the readouts on the machine will look fine, but the measurements will be incorrect.

In my area, I've been to about a dozen different places to have my car aligned. Out of those places, only two were really accurate (verified by using a rack that had just been updated and calibrated by the factory, run by a guy who really knows what he's doing. And then checked again with another machine, and by stringing the car.). 3 were close enough for most street cars, but not quite close enough for what I wanted. The remaining 7 places were way, way off. A few of them were operator error, where the operator really didn't know what he was doing. The rest were machine errors - the readouts all looked fine, but the measurements were way off when we put it on a known-good rack.

Doing the alignment myself, manually, gives me results that are a little less accurate and repeatable than the 2 top places, but usually better than the next 10 places. Problem is that it's a pretty slow and time-consuming process to get it to a point where measurements are repeatable.

Anyway, I agree that if you can find a good machine with a good operator, you can get better results than using a piece of string. But if the machine is bad, or the operator is bad, you won't get any more accuracy out of a $28K+ machine than a piece of string. And, unfortunately, bad operators/machines are more common than you'd think.

Jim

Originally posted by document
Then please end your pissing contest and clue us in on some of your experience with MISalignment by correctly applied string DIY method. That's the kind of experience that might be interesting in the context of Jim O's (and others who have posted, who certainly give the impression of having a lot more experience than most) long-time experience of doing successful alignments with the technique. You have a nice theory about how hard measuring stuff by hand is, which is not apparently borne out in the real world of the DIY alignment.

There are experiments you could do that might shed light on this, as well. String and measure your car twice. What kind of repeatability do you get? Try two different methods of finding toe. Do they cross check? I would be stunned if one can't get well within acceptable tolerances for at least toe in on the first try of the string method.

I wasn't going to respond to this, but since this thread is still gargling for breath, I'll step into the ring again.

When I speak of error in measurements, you must realize that ALL measurements have an error in them. Just because you put a ruler up to something and it looks like it is EXACTLY 1" long, does not make it 1" long. The ruler could be very slightly crooked, you might be looking at it from an angle, etc. Heck, *EVERY* measuring tool in existance has some range of error. Buy a really nice tool to measure something(clock, weight scale, anything) and it will probably have the possible error in the device listed somewhere.

What does this have to do with DIY alignments? Well, it has to do with every quantity or property that one can measure.

Just because you say your DIY alignment is dead accurate does not mean it is. It might 'appear' to be accurate, but even if you make PERFECT measurements, down to 1 thousand of an inch(impossible with a ruler), you STILL have a margin of error in the ruler itself. Are the tick marks evenly spaced, has the end of the ruler been worn down?

Now, you might get a 'good enough' measurement, but that still doesn't make it 100% accurate. Depends on how much 'fudge' you're willing to accept, or deem acceptable in your final answer. Keep in mind that your final answer will have a possible error range that is cumulative of all your measurements. So the more quantities you must measure to find out, the more inaccurate your results will be.


This is general theory here. This is not disputable.


Earlier in this thread, I was not 'damning' DIY alignments. I was merely trying to question them and see if anyone had any solutions to error, since it does seem that there are numerous sources of error in most DIY alignments. No pissing contest from this end.


Does that answer your concerns?

I'll agree that there is error in all measurements. I'd just like to add that sampling error/measurement error is present in every alignment machine out there, including the Hunter machines everyone is so keen on. The top-of-the-line machines, with the holographic targets and digital image processing, are a little less likely to be out of calibration, but there is still some error involved. I just spent a little time cruising through the Hunter web site - thought it was really interesting that I couldn't find any sort of accuracy specs for their alignment machines....

Anyway, everything in real life has some sort of error involved. The problem that I see is that the error in a computerized alignment machine is hidden from the user. You're presented with a display/printout that has measurements out to two decimal places, but you really have no idea whether the machine is accurate enough to make either of these decimal places meaningful. But, since the computer presents you with a number like that, you assume that that's the "true" number...

Just something else to ponder.

Jim

Originally posted by Jim O.
I'll agree that there is error in all measurements. I'd just like to add that sampling error/measurement error is present in every alignment machine out there, including the Hunter machines everyone is so keen on. The top-of-the-line machines, with the holographic targets and digital image processing, are a little less likely to be out of calibration, but there is still some error involved. I just spent a little time cruising through the Hunter web site - thought it was really interesting that I couldn't find any sort of accuracy specs for their alignment machines....

Anyway, everything in real life has some sort of error involved. The problem that I see is that the error in a computerized alignment machine is hidden from the user. You're presented with a display/printout that has measurements out to two decimal places, but you really have no idea whether the machine is accurate enough to make either of these decimal places meaningful. But, since the computer presents you with a number like that, you assume that that's the "true" number...

Just something else to ponder.

Jim


Agreed, all measurements on ANY machine/tool can only be so good. After machining numerous parts I've measured out with everything between a tape measure, 1/64 division ruler, and all sorts of calipers, using a pretty accurate(down to 5 thousands) mill. I'd still put more stock in the Hunter machines(which probably are accurate to +/- 0.01 degree).

Of course, nothing beats watching a mechanic do the alignment and getting on his ass when he takes shortcuts! :devillook

Originally posted by Def
I'd still put more stock in the Hunter machines(which probably are accurate to +/- 0.01 degree).
Unfortunately, most of the ones that I've seen are nowhere near that accuracy.

Jim

First of all, a stretched string is as straight as a laser beam.

Jim


Not arguing with your methods, but this statement isnt true. Hang anything flexible like string, wrope or wire, and its impossible to make it perfectly strait. That would defy laws of pysics. Unless it was in a zero gravity environment.

Wow old thread from the dead...

Wtf are u trying to say? Say you are adjusting toe settings. The elasticated string is pulled tight between two points, obviously overcoming the force of gravity.

I'm not going through this again but put it this way, F1 teams still use string to adjust toe.

Wow old thread from the dead...

Wtf are u trying to say? Say you are adjusting toe settings. The elasticated string is pulled tight between two points, obviously overcoming the force of gravity.

I'm not going through this again but put it this way, F1 teams still use string to adjust toe.

I think it is impossible to have anything be perfectly straight, perpendicular to gravity.


Anyway, what the heck is F1, any old shmuch can do it with the string and claim its the best


If F1 teams use it, it must be acceptable