I wanted to share the my alignment spreadsheet with this community. It's applicable to anyone doing a string alignment at home, with whatever tools and methods you're using. I previously shared a link to a similar version in someone else's thread, but I have progressed this file a bit since then.
Google docs to my setup spreadsheet LINK HERE
Link to SmartStrings Instructions
Note: the SmartStrings link changes from time to time so I've uploaded their PDF. It explains how to actually perform an alignment with strings. Once you understand the principles, my setup spreadsheet (link above) and the text below will make way more sense.
SmartStrings Owner's Manual_v1.pdf
While this is not a full flown DIY, I still thought it was worth sharing. The next time I do an alignment I will take photos and turn this into a true DIY. If you nerd out on setup, you may find this file useful. If you lack patience, you might want to look elsewhere.
I wish I had something like this when I started doing alignments, so hoping others will find it useful
Fundamentally, all string alignments start by creating a perfect box around the car (with strings) and then taking measurements from that box. I created this file several years ago and have tweaked it for accuracy, ease-of-use and repeatability whenever I did an alignment. I've used this for the M3, but also for other vehicles so the file has had probably 15 or so iterations to get to what it is now. It is the result of a LOT of trial and error, including screwing up the formulas within the spreadsheet and wondering why the car was doing super strange things after completing what I thought was a "perfect" alignment. I also learned I was taking measurements inconsistently and/or setting up the string inconsistently, so I've attempted to make the file as easy to use as possible. In a game where you are measuring down to a realistic 0.5mm of accuracy, a millimeter off here and there really adds up.
When I first started doing my string alignments on my own (without the help of a race shop), I screwed some things up royally. I had everything from the car dog-legging down the road, to pulling to one side under steady state, to pulling to one side under acceleration. I learned (far to slowly) that the key to making any an alignment work is a developing repeatable system. That starts with a dead-nuts-accurate setup. To that end, row 1 of this file is a reminder for me to follow the detailed steps contained within the file, even if I think I remembered everything from the last alignment. I don't do alignments everyday, so it's easy to forget a step that can have negative impacts which compound with every subsequent step.
Quick aside: I got incredibly frustrated by shops with the $80k laser alignment rigs that would have me driving down the road holding the wheel to one side in order to go straight. It all comes down to who is doing your alignment. Since alignments are typically flat fees, there is sometimes little incentive for the operator to take their time to really nail the alignment. After working with some race shops and helping doing alignments on my car, I decided I'd just start trying this on my own. When done right and combined with a fair share of patience, I firmly believe using strings nets you the best possible alignment, given other influencing factors that can impact a quality alignment at a typical shop. 100% this is my opinion, but it's also been my experience.
Measuring alignments is 100% about angles and this spreadsheet solves for angles in either degrees and radians using some basic right-angle triangles calcs. I casually say "basic calcs" but apparently I had no issues screwing them up over the years. Thus...
This file has a few key components:
Bryan
Google docs to my setup spreadsheet LINK HERE
Link to SmartStrings Instructions
Note: the SmartStrings link changes from time to time so I've uploaded their PDF. It explains how to actually perform an alignment with strings. Once you understand the principles, my setup spreadsheet (link above) and the text below will make way more sense.
SmartStrings Owner's Manual_v1.pdf
While this is not a full flown DIY, I still thought it was worth sharing. The next time I do an alignment I will take photos and turn this into a true DIY. If you nerd out on setup, you may find this file useful. If you lack patience, you might want to look elsewhere.
I wish I had something like this when I started doing alignments, so hoping others will find it usefulFundamentally, all string alignments start by creating a perfect box around the car (with strings) and then taking measurements from that box. I created this file several years ago and have tweaked it for accuracy, ease-of-use and repeatability whenever I did an alignment. I've used this for the M3, but also for other vehicles so the file has had probably 15 or so iterations to get to what it is now. It is the result of a LOT of trial and error, including screwing up the formulas within the spreadsheet and wondering why the car was doing super strange things after completing what I thought was a "perfect" alignment. I also learned I was taking measurements inconsistently and/or setting up the string inconsistently, so I've attempted to make the file as easy to use as possible. In a game where you are measuring down to a realistic 0.5mm of accuracy, a millimeter off here and there really adds up.
When I first started doing my string alignments on my own (without the help of a race shop), I screwed some things up royally. I had everything from the car dog-legging down the road, to pulling to one side under steady state, to pulling to one side under acceleration. I learned (far to slowly) that the key to making any an alignment work is a developing repeatable system. That starts with a dead-nuts-accurate setup. To that end, row 1 of this file is a reminder for me to follow the detailed steps contained within the file, even if I think I remembered everything from the last alignment. I don't do alignments everyday, so it's easy to forget a step that can have negative impacts which compound with every subsequent step.
Quick aside: I got incredibly frustrated by shops with the $80k laser alignment rigs that would have me driving down the road holding the wheel to one side in order to go straight. It all comes down to who is doing your alignment. Since alignments are typically flat fees, there is sometimes little incentive for the operator to take their time to really nail the alignment. After working with some race shops and helping doing alignments on my car, I decided I'd just start trying this on my own. When done right and combined with a fair share of patience, I firmly believe using strings nets you the best possible alignment, given other influencing factors that can impact a quality alignment at a typical shop. 100% this is my opinion, but it's also been my experience.
Measuring alignments is 100% about angles and this spreadsheet solves for angles in either degrees and radians using some basic right-angle triangles calcs. I casually say "basic calcs" but apparently I had no issues screwing them up over the years. Thus...
This file has a few key components:
- The file has light yellow shaded boxes where you plug in your measurements. All the calculated values then show up in dark blue font with no shading.
- With string alignments, you measure toe by comparing the distance from the string to wheel face at the front/leading edge of the wheel. Then take the same measurement from the rear/trailing edge of the wheel. The difference in those two measurement is toe at a given wheel and you here it quoted "1mm toe-in" for example. However, 1mm of toe (be it toe-in or toe-out) on a 15" wheel is materially different than on a 20" wheel. Thus, the diameter of the wheel affects the calculations if you're trying to get to degrees or radians, which I am. I drive towards end results quoted in degrees, rather than "1mm of toe in/out" as it's more accurate. After all, an angle is an angle. All that to say, the first step of this spreadsheet in row 5 is to measure the actual wheel diameter as it is used in the formulas which tell me what 1mm of toe equates to in degrees. I run a 18" wheel and at the farther point of the wheel where I measure equates to 488.95mm (19.25 inches). Once you have the wheel diameter entered in cell E5, the rest of the spreadsheet will work.
- Next is setting up the strings or the "box" around the car. This is super tedious. You not only need the box perfectly setup when looking at the car from above, but also want it at the same height when viewed from the side. I try to align the string so it's the same height as the axle at each wheel. To do this, I start by eye-balling the string height to get it in the ballpark. I then take 2 measurements off the vertical axis of the wheel (each wheel!) to the string, calculate the average - which is done by plugging values into the spreadsheet. When my left rear and right rear are the same, and then my left front and right front are the same, I know I have a perfect box. This is the table the STRING SETUP table starting in row 9.
- This file assumes that any corner balancing is done (ride height is set) and camber & caster are set before moving onto the final step which is setting toe. Note: I do not have caster in this spreadsheet as my car doesn't have adjustable caster... but that would need to be set before toe as well.
- Cell V54 has a "Toe in working table" where I plug in the front vs rear edge values to get to toe. After taking umpteen measurements, I seem to begin forgetting the numbers I just measured just 5 seconds earlier. So I created this table to enter the values in real time and let it calculate toe for me. It solves for toe in which is represented as a positive value, or toe out as a negative value.
- Around row 74, I started verifying my Excel formulas using a simple right triangle calculator on the internet. This is really just proofing my work. There is also the factory specs per the Bentley's manual for reference only.
- Row 91 - explains my setup process in detail, step by step and in the right order.
- After that is how to set preload and ride height on my BC Racing coilovers. They are by no means high end kit, but for how I use the car work just fine. They came with the car and when they need to be replaced, I'll likely swap out for something else. But honestly, they are good value for money. I will dive into flat ride at some point...
Bryan
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