How to do a string alignment on an e46
I completed the string alignment and took the xi for a road test. Drove great with the suspension work (bilstien shocks, eibach springs, new bushings). I'm not going to take it for a more "professional" alignment because I feel I nailed it.
What you will need:
- A way to read the ECU (computer + INPA)
- Wrenches: 13mm, 21mm, 24mm
- mason string (home depot has this)
- jack stands to hold string
- anti-sieze compound
- trusty and familiar tape measure, prefarably smaller sized (6' variety).
- 8' x 1" aluminum tubes (I find this handier than just jack stands because it makes it easier to get a perfect rectangle around the car)
Step 1) make your tools:
a) String setup: I measured my 8' aluminum tube to verify equal lengths and drilled holes exactly 1' in from the outside. I then fed the string through the holes using a light down the middle of the tube. You can also just wrap the string around the tube, but drilling holes makes the system easier to setup. set it off to the side
b) alignment pads: Vinyl tile would be better, but I had scrap 1/4" plywood, so I cut approx 1' squares and sanded / greased the contact surfaces to allow slippage. Without an alignment pad it is very difficult to accurately set toe. set it off to the side
Step 2) Using INPA / Ediabas place your steering wheel at 0 degrees. Note that this steering wheel angle is very sensitive, and a couple degrees steering wheel does not = a couple degrees road wheel angle because of the gear reduction in the rack. Wiggle the wheels back and forth until you get it centered. turn the ignition off and pull the key out
step 3) completely dissassemble the tie rod linkages on both sides if you have never done this. Jack the car up in the air, clean everything, re-assemble with liberal anti-sieze. I just changed front components so I just loosened the front, the rear would be done as well for a rear alignment.
This was a big PITA for me. Judging by no wear marks on the tie rod themselves and how frozen everything was the car was probably never aligned post-delivery. I needed to break out the pipe wrench (13mm wasn't cutting it), the pipe extension, the torch, and use a bit of persistance. When done dissassembling one nut was buggered, so I went to sears and got 2 new 14mm x 1.5 nickel plated nuts for the stopper nuts.
step 4) reassemble everything with liberal anti-sieze and visually line up everything. Make sure your steering wheel is still centered. line this up by looking down the brake rotor at the rear wheel and walking around the car once. Put the tires back on and set the car down on your alignment pads. push down on the front and rear a couple times.
Step 5) set up your jack stands and string around the car in a perfect rectangle, equally spaced on each side from the center of each hub.
The wheels will not make a perfect rectangle, but your string setup should. This is the key to the whole aligment, get the strings exactly the same length from the center of the hub on each side.
Front to back is not as important, but I put the jack stands so I can support the rods with a few inches to the front and back bumper, and i measure from the wheel with a tape to get it close.
Tension the string as much as possible without lifting the jack stands off the ground.
step 6: fire up INPA again and ensure your car is at 0 degrees wheel deflection.
Step 7) adjust each wheel to give the desired toe (i gave each front just shy of 1/16 differential toe-in from front to back of wheel (actually measured from rim). This is 1/32 of toe-in. Use INPA to keep the wheel at 0 degrees
Check the backs even if you aren't doing them, they should have a little toe-in and be exactly the same... if not they need to be done too or you need to double check your string positioning.
Step 8) tighten down the backer nuts
step 9) take a walk around and re-check everything. Do not get lazy here, if something isn't right find out why and fix it. My toe didn't change by tightening the backer nuts.
Step 10) test drive (most fun), do some highway, turns, whatever... the auto should have a centered wheel, no strange bump-steer, and be very neutral and light feeling in a straight line.
Last edited by bikesandcars; 01-06-2013 at 02:45 PM.