Bimmerfest - BMW Forums - View Single Post - Philosphically, why do you choose NOT to perform a home DIY alignment on your E39?
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Old 08-22-2012, 09:10 PM
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bluebee bluebee is offline
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Originally Posted by doru View Post
To try and do it on sloped or uneven surface is foolish.
Most, if not all of the DIYs appear to make an effort to adequately take into account the level of the floor when measuring camber (and the ability to slip):

For example, most used shims:
The key to accurate alignments is starting with a level surface. To accomplish that, we built a set of wheelstands from 3/4-inch particle board and 2x6s to support each wheel. Using the technique outlined in the scaling section, these stands are easily shimmed with pieces of vinyl floor tile to create a level plane, and the extra height makes working under and around the car a bit easier.
Many used linoleum tiles (some even greased or powdered them for slip).

Some used newspapers (which also allowed the wheels to slip as on a turnplate).

Some measured levelness with lasers:

Others measured levelness with bubble levels:

Most also zero the gauge relative to the floor slope:

Here's one on a bimmer, where the gauge is zeroed beforehand based on the floor slope:
Measure the present camber with the car on a flat surface (like a concrete garage floor). I did it using a short piece of angled aluminum from Home Depot (about 5 dollars) held against the wheel edge. The angle was measured with a Wixey WR300 digital angle gauge (40 dollars from Amazon). If your wheels have machined flats then it is even easier. If your wheels are wider than the tires then you can buy a digital level and its easier still.
IMPORTANT: You will need to zero the Wixey gauge by placing it on the ground next to the tire and press the 'ZERO' button (the gauge has arrows to indicate positive and negative camber)."

This one even zeroed the leveling with the iPhone clinometer:

This Pelican Parts forum post shows the fanciest yet when it comes to leveled turn plates!
Note: See warnings later on by others to NEVER do this!

So, regarding the slope, most of the DIYs seem to take that into account when measuring camber.

All the more expensive camber gauges seem to have level zeroing procedures (see PDF already included in a prior post).

So, unless cn90 or someone else who has actually done the DIY objects, I'd say uneven floors are already taken into account in the good DIYs.

For example, here's a detailed approach when your garage floor is NOT level:
The more astute reader has realized that the camber gauge only reads true camber if the car is resting on a level surface, otherwise the angle measurement is meaningless. This brings up the first element of a home alignment; leveling the car. It's been my experience that level garage floors, and level concrete in general, only exist in mythology. My garage slopes about 1" over the wheelbase of the Miata, and about 1/4" over the width. This means that I can't get good measurements with the camber gauge unless I level the car. I cut one foot squares of 1/2", 1/4", and 1/8" thick MDF and hardboard to use as spacers. I used a length of 3/8" Tygon tubing filled with water to measure the height of each wheel. I used the bottom edge of the dust cap as a mark to set the water level. Various thickness spacers are placed under each wheel until the water within the tube is at the same level on all wheels. I used one wheel as the reference and adjusted the tubing so that the water level as at the dust cap, and took the other end of the tubing to each of the three other wheels and made sure the water matched the same point on each wheel. If you jack the car to place spacers under the wheels (rather than driving up on them), make sure you jounce the suspension to settle it before making any measurements (this isn't necessary to check for level). It's good to note that some sort of slippery surface must be used under the front wheels. The front wheels must be turned to measure caster and the suspension shouldn't be bound up trying to make that turn. I put a pair of the 1/8" hardboard spacers under each front wheel which were quite slippery against each other.
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Please read the suggested threads and add value, either by pictures or by descriptions, so the next person stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need

Last edited by bluebee; 08-27-2012 at 07:15 PM.
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