Part 2
5. Chassis-specific terms5.1 Toe difference angle
- The toe difference angle (a) is the angle setting of the inner cornering wheel relative to the outer cornering wheel when negotiating a bend in the road. Steering is designed in such a way that the relative angular positions of wheels change as steering lock progresses.
- In ideal situations, the wheel axes intersect at Point D in every steering position (except for straight ahead).
5.2 Camber
- Camber is the inclination of the wheel from the perpendicular.
5.3 Toe-in
- Toe-in is the reduction in distance of front of front wheels to rear of front wheels. Toe-in prevents the wheels from moving apart when driving (wobbling and scuffing).
5.4 After-run
- After-run is the inclination of the kingpin viewed from the side and relative to direction of travel. The line through the center point of the spring strut support bearing and the control arm ball joint corresponds to the "kingpin".
5.5 Geometrical driving / symmetrical axis
- (1) The geometrical driving axis is the angular intersection point from total toe-in on the rear wheels. Front-wheel measurements are taken in reference to this axis.
- (2) The symmetrical axis constitutes the centerline between front and rear axles.
5.6 Wheel offset angle
- The wheel offset angle is the angular deviation in the intersection line of wheel contact points at a line drawn at 90° to the geometrical driving axis. The wheel offset angle is positive when the right wheel is displaced towards the front and negative when it is displaced towards the rear.
5.7 Kingpin offset / kingpin radius
- The kingpin offset / kingpin radius is the distance from the center of the wheel contact face to the intersection point of the extension of the kingpin axis.
6. Wheel suspension
Wheel suspension includes the components which connect the wheel to the mostly load-bearing floor pan components on the body which guide the vehicle in the desired direction. This connection involves axles or comparable construction elements, guided by trailing arms. The type of wheel suspension is one of the determining factors governing the driving characteristics of a vehicle. A distinction is made between two main groups: 1. The rigid axle and 2. The independent suspension.
6.1 Rigid axle
Description
On the rigid axle, both wheels or pairs of wheels are connected by means of a rigid axle body. Every change in a one wheel is transferred to a greater or lesser extent to the other one. If a rigid axle has been installed, it is now only ever as a rear axle. This is sharp contrast to trucks and buses where they are used frequently.
Advantages
No changes in camber and toe-in occur during suspension action. This means: low tire wear and good directional stability.
Disadvantages
Non-driven rear axles can also receive negative camber and this increases tire wear.
6.2 Independent suspension
Description
Based on the modern technology standard independent suspension is available on the front and rear axles of BMW vehicles. This development was prompted by inertia mass because a reduction in unsprung masses improves wheel and ground contact, enabling the wheel to maintain better traction. The tracking of independently suspended wheels requires transverse links and trailing arms which can be called upon to absorb occasional high levels of longitudinal and lateral forces.
Advantages
Independently suspended wheels do not influence one another.
Disadvantages
Depending on design, during suspension action, changes can occur in camber, toe-in, track width, after-run and wheelbase.
7. Wheel alignment / test procedure
7.1 Measuring options
The next section itemizes all the measuring options and values in an at-a-glance list (FA = front axle, RA = rear axle).
Note: The details for the measuring accuracy only apply when using precision rotational and sliding supports together with BMW quick release brackets.
7.2 Preparatory work:
Before the measurement can commence, preparatory work is required at the measuring station and on the vehicle (see BMW KDS, operating instructions). This preparatory work includes:
- Ease-of-movement of rotational and sliding plates
- Alignment of rotational and sliding supports to suit track width and wheelbase
- Driving of vehicle centrally onto the supports
- Apply parking brake
- Remove locking pins from the supports to prevent torsional stresses in the chassis and suspension when subjecting the vehicle to load.
- Check the wheel rim and tire size, tread depth, inflation pressure, steering backlash, wheel bearings and condition of the suspension and shock absorbers
- Secure measuring device bracket to the wheels
- Load vehicle acc. to BMW KDS specification
- Apply sudden load to vehicle with brakes released to obtain a stable center position.
- Secure the service brake by applying the brake tensioner
7.3 Input / output measurement
This measurement can be conducted as a program-guided measurement check, just like any subsequent adjustment work and the ensuing outgoing alignment check. The sequence of chassis and suspension measuring points to be called up and checked by the systems software. The individual procedural steps cover:
- driving in a straight line to obtain an accurate record of the toe-in and camber value for the rear axle
- touch-sensitive routine to determine after-run, steering axis inclination and toe difference angle
- Recording of toe-in and camber of front axle (prior to this, set the steering centerpoint)
- touch-sensitive routine to measure the maximum steering angle on left and right sides
- Checking the measuring value summary with nominal / actual comparison of all measured values.
7.4 Printout of the data
The report printout from the integrated DIN-A4 printer is subdivided into three areas:
- Headers with customer and vehicle identification data --> here, the customer data entered before the start of measuring work are printed out together with the vehicle data.
- Center section with vehicle data --> these include brand, type, model and model year of the vehicle, as defined during selection of the nominal data record. Furthermore, this section involves printing out the previously measured values for ride height, inflation pressure and tread depth.
- The final section with all chassis and suspension measuring values comprises 3 columns: incoming wheel alignment check, nominal values and outgoing measurement. The measured values are recorded separately in these 3 columns.
8. Special features
8.1 Wheel alignment with non-selective access
During wheel alignment checks with non-selective access, the selection and sequence of measuring points can be made in any desired order. When doing this, the following points must be observed in order to achieve the correct measuring results:
- Carry out all work as defined during the program-guided wheel alignment check.
- Before the alignment check of toe-in and camber values on the rear axle, the steering must be set in its 'straight-ahead' position to ensure that it is aligned with the vehicle's center axis.
- Prior to the alignment check of individual toe-in values on the front axle, the steering wheel center position needs to be determined to ensure that the steering wheel is in its correct position.
8.2 System settings
The following settings only need to be entered and set once: language, display format, date/time, promotional text, remote control with display, selection of rotary plate and printer setting. These remain saved in memory.
9. Comparison, BMW KDS (Bosch - Beissbarth)
10 Change in operation (menu)
10.1 Master key with display
The process of enabling the master key with display is described in the following procedural steps:
1. in the special functions (button "S"), call up the "Service" menu
2. In the"Service" menu, call up the "Master key" submenu
3. In the "Master key" submenu, select the "Master key with display" point - this is a once-only setting.
Important!
On devices without master key, this setting must be set to "No master key".
10.2 Summary of operating instructions
1. Switch on the master key by pressing the "ON" button (it is permissible to switch this on during the alignment check). The title screen then appears on the LCD.
2. On the measuring equipment cabinet, select "Straight-ahead driving" for the "Incoming alignment check", then "Adjusting procedure" or the "Outgoing alignment check". The following graphic appears on the LCD monitor for "Driving straight ahead".
3. Pressing the "Forwards arrow" calls up the next measuring screen. What next appears on the LCD display blocks are a designation of the measured value and a tolerance bar with measured value. If that measured value is within tolerance, this is depicted with black numerals on a light background. If that measured value lies outside the tolerance, it is then displayed in inverted fashion (i.e. light numerals on a dark background).
4. Pressing the "F" button briefly makes it possible to alternate between the designation of the measured value and the nominal value with tolerance within the display block.
5. To scroll onwards through the measured values, press the "Forward arrow", "Backward arrow" and the "Cancel" keys (red spot). The function of this button is identical to that of the buttons/keys on the graphics pad.
6. Even when opting for the "Alignment check with non-selective access", the measured values can be chosen in the same way as for the "program-guided alignment check" process.
7. Using the "Printer" button enables reports to be printed out during the alignment check. The remote control buttons are only enabled during the measurement and setting process (not in response to customer input, choice of vehicle, etc.).
10.3 Display support
- Measured values with nominal/actual comparison and tolerance bar (nominal values can be displayed by pressing the "F" key/button)
- Touchscreen icon for touch-sensitive routines
- Summary of measured values with the latest nominal / actual comparison
- Compensation for lateral runout on wheel rims
- With all other functions (e.g. customer input), the title image appears on the liquid crystal display
Note:
Whenever data transfer from the master key / remote control to the computer is interrupted, the master key icon in the lower right-hand corner of the screen changes colour from green to red and the image on the LCD display is depicted in inverted format, i.e. black becomes white and vice versa. This change over does not occur in the title image. Once visual connection is re-established, the master key recommences work at the point in the program where the interruption occurred. Continuous visual connection during the alignment check is therefore not necessary.
- The "Egg timer" icon on the LCD display indicates: "Please wait".
- The "Battery" icon in the upper right-hand corner of the LCD display indicates that the battery reserve has been reached.
- Switching off the remote control / master key: Press and hold down the "F" key for 5 seconds, then place in the charge bracket or plug in the charging cable. The title image then reappears as the charge indicator light.
- If the master key is placed in the charge bracket during the alignment check process, it must when required be switched on using the "ON" key.
11 Updating the software / nominal data
No more diskettes will be sent out to any BMW authorized workshops who in the past subscribed to "BMW KDS (Beissbarth / Bosch)". For reasons of cost, it is no longer possible to produce these diskettes in-house on the "DIS tester" or on the "TIS/EPC server". The data are updated on the TIS-CD on a regular basis
11.1 Prerequisites
- BMW KDS (Beissbarth / Bosch)
- Program status (Beissbarth) TIS-CD: from CD 12/95
- Program status EPC: from 12/95
- Program status (Bosch) TIS-CD: from CD 08/97
- Program status DIS: from V6.0
- Diskettes, 3.5", 1,44 MB (Beissbarth 5 diskettes / Bosch 1 diskette)
11.2 Procedure (Beissbarth)
1. Go into screen mask "Administration"
2. Select KDS button
3. Select Beissbarth
4. After request, load "diskette 1" and acknowledge with "OK" (program diskette 1 of 2 is created, perform labelling operation)
5. After request, load "diskette 2" and acknowledge with "OK" (program diskette 2 of 2 is created, perform labelling operation)
6. After request, load "diskette 3" and acknowledge with "OK" (program diskette 1 of 3 is created, perform labelling operation)
7. After request, load "diskette 4" and acknowledge with "OK" (program diskette 2 of 3 is created, perform labelling operation)
8. After request, load "diskette 5" and acknowledge with "OK" (program diskette 3 of 3 is created, perform labelling operation)
9. Perform software update and /or nominal data input on the KDS in the usual manner using the manufactured diskettes.
11.3 Procedure (Bosch)
1. Go into screen mask "Administration"
2. Select KDS button
3. Select Bosch
4. Write a name on "Diskette 3.1", when prompted to do so, insert in the drive and confirm by pressing "OK" (2x) --> nominal values are then copied to the diskettes
5. Load nominal value diskette 3.1 in drive 3.1, load operating system diskette 3.0 in drive 3.0.
6. Boot device in the usual manner
Important!
When producing KDS diskettes, all data on the diskettes used are overwritten.
Note:
Whenever an error occurs, this is displayed and the program aborts. This process needs to be restarted from the very beginning, which involves deleting all data from the diskette. Possibly use a new diskette.
12. Creating, copying and editing nominal data
12.1 Copying
- Press the "C" button and select the vehicle which is to be copied.
- In the special function section, select menu item "Editing of nominal data". Set up a new vehicle record in the familiar way. Now the data input screen displays the nominal values for the previously selected vehicle. Re-enter the modified data and save the data record.
12.2 Create
- Press the "C" button and, in the special function, select the "Editing of nominal data" menu item. Set up a new vehicle record in the familiar way. An empty data input screen now appears. Enter the data and save the data record.
12.3 Edit
- Nominal data programmed in the factory cannot be deleted or changed. If these data are changed, a new vehicle record with those amended nominal data needs to be set up. New vehicle records set up by the user are designated as such in the selection menu with a "+". These vehicles can be deleted by the user by means of the screen button "-" or can be amended using the "
13. Special functions
13.1 Customer button for printer protocol
In the "Special function" menu, the "Customer-specific text" submenu can be called up. An input screen appears on the display. A name and address must be added to this input screen and saved by pressing the "S" screen button. The text entered is then imprinted in the header of the protocol / report.
13.2 Alignment options
- in the special functions (button "S"), call up the "Service" menu
- In the submenu "alignment", select the "Toe-in alignment" or the "Toe-in adjustment" option. The toe-in and camber alignment program guides the user step by step through the alignment process with the help of text and images. At the end of the adjustment process, the deviation in measuring value from every measuring sensor is displayed on the screen.
- These alignment values can be saved in the measuring pickup memory by pressing "Save" or the program can be quit by pressing the "Red button" without saving (a checking function). The alignment values can be printed out.
13.3 Turntable test
- in the special functions (button "S"), call up the "Service" menu
- In the "Service" menu, call up the "Turntable test" function. Rotate left and right-hand turntables and check the display on the screen. Important: The measuring range is ± 306 degrees.
13.4 View and delete customer entries from the database
- In the special functions in the "Database" menu, call up the "Delete" menu option. The data input screen then appears. Fill in the search boxes with the data to be deleted.
- Using the "-" button, this data record can be deleted. It is now possible to use the touchscreen pen to highlight and delete a new data record.
- The screen buttons "Arrow up" and "Arrow down" enable users to scroll through the entire database.
- To quit the Delete function, press the Cancel button (red spot)
14. Internal program change
Other internal program changes were made which only slightly alter the program run, but which do optimize the alignment check in terms of comfort and speed. This is described in the following pages:
- Optimization of compensation for lateral runout on wheel rims in relation to speed.
- Optimization of impact routines: Marking can still be corrected within the gateway. The message "Turntables not connected" no longer causes this routine to terminate. Measuring can continue after the turntables have been plugged back in.
- Standardization of screen colors with the colors on the panel.
- Extension of texts in some foreign languages.
- Elimination of program and cosmetic errors.
- Electronic water scales
- Discontinuation of wheelbase measurement
15. Faults
15.1 Tire faults
Error
1 Tracking, camber, toe difference angle and caster not correct
2 Too much toe-in or too much positive camber
3 Too much negative camber
4 Worn front axle suspension points on FWD cars
5 Incorrect toe adjustment
6 Play in wheel suspension caused by mechanical components (suspension, steering)
7 Insufficient inflation pressure in the tire
Impact
1 Serious tire squeak, even at relatively low speeds
2 Tires are worn longitudinally down one outside edge
3 Tire wear on inner edge
4 Amplified noise / Vehicle pulls away one-sided when accelerating
5 Radial adjustment of wheel settings / tire tread exhibits burr formation within the tread pattern
6 Washed out areas / wobbling on front wheel
7 Tire wear along outer areas
15.2 Front axle fault
15.3 Rear axle defects instructions.
Other notes on the topic of the "kinematics diagnosis system" can be found in the BMW KDS (Beissbarth / Bosch) operating
None of the function and system descriptions are covered by an update service. Availability of parts and scope for immediate ordering cannot be derived from this information. The specialist departments shall be in touch with the markets at an appropriate time with further details.