09-20-2009, 10:15 PM
Officially Welcomed to the 'Fest
Location: Omaha NE
Join Date: Mar 2006
Mein Auto: 1998 528i 5-sp 103K miles
- Old Bushings worn out:
- Car on Wood ramps when torquing the Thrust Arm and Control Arm Nuts. I had my 16-year-old and 11-tear old kids to sit in the front and that is good enough for me!
The Alignment DIY:
1998 BMW 528i (data from NTB Alignment Sheet)
Toe-in: -2 minutes to +6 minutes (or 2 minutes +/- 4 minutes) ---> Adjustable
Camber: -0.7 to 0.3 degrees (or -0.2 degrees +/- 0.5 degrees) ----> Unadjustable (unless you install a camber kit, off topic here!)
Caster: 6.0 to 7.0 degrees (or 6.5 degrees +/- 0.5 degrees) ----> Unadjustable
---> Only Toe-in is adjustable for E39.
1. If you did not sleep through your High School Geometry Class, then I will share with you this best-kept secret: Alignment DIY.
There are 60 minutes (') in one degree (A circle = 360 degrees); and 60 seconds (") per minute.
If you read Alignment Sheets, very often car mfg's misuse these symbols (') and ("). For the most part, it is minutes not seconds.
- Review Tangent and Arctan. Basically, for each stock tire front to rear rubber part is 540 mm.
Since toe-in is given as degrees and most of us don't have the sophisticated alignment tool to measure degrees, I measure using the difference (in mm) in front and rear part of the same tire (front and rear measurements).
Tangent (2/60 degrees) x 540 mm = 0.314 mm TOE-IN!
Tangent (6/60 degrees) x 540 mm = 0.942 mm TOE-OUT!
- Car with full gas tank. I by-passed the weighing business (150 lbs front seats, 150 rear seat garbage).
- Tires at 35 psi. All 4 tires should be the same make.
- Level garage at spots where car parks. Take measurements using Carpenter Level.
- 16-mm wrench for tierod adjusting bolt and adjustable wrench for lock nut.
3. The whole idea is to establish parallelism. Using the carpenter square and level coupled with Plumb Bob (see pic), measure the track width at wheel (Front and Rear) Hub Centers.
Drive car straight out garage. Calculate the difference between Front and Rear Tracks.
Published Values are:
Front Track Width = 1512 mm
Rear Track Width = 1526 mm
Difference is approx. 14 mm
4. Put car back to similar spot. Apply Parking brake and whatever you do, do NOT move the car after this step, otherwise, you will redo the whole thing again. Remove key and rock steering R and L to lock it. Make sure SW is dead center.
5. Now mark the Front and Rear track widths (with carpenter square) on masking tape on the floor. Since the Front track width on each side is 7 mm (14 mm/2) less than the Rear track width, SUBTRACT 7 mm from the REAR Marks.
6. Using a string (held by brick) and draw a straight line between FRONT and REAR marks. This represents the straight axis of motion of the car. This line will be used a reference line:
7. Now measure Camber. I have calibrated my device so when the bubble is barely out of the marks, it is roughly 0.50 degrees (or 30 minutes, which is half of a degree). In fact this is –0.50 degrees, so it was good:
8. Now measure the toe-in: -0.314 mm (TOE-IN) up to +0.942 mm (TOE-OUT). You can actually set it at zero. Some people set it at –1.0 mm, which is very typical of many cars.
A bit of TOE-IN is good because the crown of the typical road will have the tendency to bring the tires out a bit. Some people set TOE-OUT more than spec for aggressive track use:
9. Go for a test drive on a smooth highway.
- The chances are the SW is not dead center. Make a note.
- Let's say car goes straight but the SW points a bit to the Right.
- Bring car back to driveway.
- Now, when SW is turned dead straight, both wheels point a bit to Left.
- Then adjust in equal increments (for example, pull L side in and push R side out equally). Again do this in equal increments.
One complete turn of the Tierod moves the Tierod by 1 mm but mathematically it changes the tire difference readings by 2 mm.
- Use liquid paper to mark Tierod original reference position so you know how many turns you have done.
- Tighten the Lock Nut (do not over-tighten it) to lock the Tierod.
Go for test drive again and adjust the Steering Wheel position as appropriate.
Enjoy your Ultimate Driving Machine!!!
Last edited by cn90; 10-01-2009 at 07:40 PM.