Notes for checking shift points in selector lever position "D" on a test trip - AH27.10-P-9407-01A

Transmission 722.5 

The normal functions of the automatic transmission are checked by means of the test procedure described.

To evaluate the method of operation and any faults in the transmission of course requires experience in dealing with automatic transmissions. In the absence of this, it is expedient to use another automatic transmission of the same design which is in working order for comparison purposes. If irregularities show up on the test, the cause of the fault detected can be found using the "programmed repair" or the Diagnostics Manual.

Before starting the test, always check the oil level in the transmission, the running speed of the engine and the adjustment of the control pressure cable.

When testing, ensure that the transmission, in particular under load, is not shifted without an interruption. A lot of heat develops in the servo components during the shift process. The following should be used as a guide value:

Repeat a power shift once at the most within 15 seconds  .

test trip 

Check whether all 5 gears are shifted by means of a.

1. Put vehicle in top gear
   1. Selector lever in position "4"
   2. Accelerate vehicle to 90 km/h
   3. Accelerator pedal in idle position
   4. Then immediately shift selector lever from position "4" into "D"
   5. The 4 → 5 shift should occur
   6. Selector lever from "D" → "4" = downshift from 5 → 4 should occur
   7. Selector lever from "4" → "3" = downshift from 4 → 3 should occur
   8. If two downshifts occur = all gears present
   9. If no downshift occurred with "D" → "4" = one gear is missing.
2. Establishing speed ratio
   1. 10. Speed = 100 km/h
   2. 11. Check engine speed in selector positions "3", "4" and "D"

      3rd gear = approx. 4500 rpm

      4th gear = approx. 3150 rpm

      5th gear = approx. 2300 rpm

      Establish missing gear by comparing engine speeds.

3. In addition to the shift points, it is primarily the transitions during gear shifts which have to be checked on the test trip. At part throttle, the upshifts should take place so that they are only perceptible if attention is paid to them. With full throttle or kickdown, gear shifting is noticeable, but the new gear must engage smoothly and the impression of the strong pulling power of the engine must be maintained. For example, if the engine suddenly speeds up during an upshift gear change, this indicates a slipping servo component (brake band or clutch) which must be examined more closely.

   Automatic downshifts on a trailing throttle take place at very low speeds and are only perceptible if a lot of attention is paid to them (increase in engine speed). By contrast, downshifts using kickdown are associated with a detectable shift jolt in addition to the increase in engine speed. A downshift at part throttle to full throttle is possible in certain speed ranges.

   Downshifts using the selector lever are either downshifts with the throttle open (e.g on a mountain) or braking downshifts with the throttle closed (e.g. on descents or when decelerating). Downshifts with the throttle open only take fractions of a second for the gear shift, whilst braking shifts with the throttle closed take 1 to 2 seconds.

   The 1 → 2 upshift occurs only shortly before the maximum speed of the engine in drive position "2".

   All speed specifications are approximate values. They apply to the standard production rear axle ratio and tires. There may be deviations from the specified values, due to variances on the transmission side and in the speedometer display.

   Vehicles with selector program: shift position

   E=Economy

   S=Standard

   Note on shift points in selector lever position "2" and "3" 

   The 1-2 upshift in drive position "2" only occurs at maximum engine speed and the accelerator pedal on the full throttle stop. Shift points in selector lever position "2" and "3" are no longer provided for reasons of simplification.