PeachParts Mercedes-Benz Forum - View Single Post

ktlimq · #9 08-05-2004, 01:53 PM

I had vacuum modulator adjusted.
It feels better, but I still feel shake at some up shifts.

What is the definition of partial throttle and full throttle?

Full throttle means literally pressing the accelerator pedal to the end?

Then I should rarely feel the shift.

Below is from Alldata.

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Test Drive

During the test drive, it is necessary to check not only the shift points but, particularly, the transitions during a gearshift.

Upshifts at partial throttle should proceed in such a way that they can only be felt by concentrating on them. At full throttle and kickdown, the gear changes should be clearly felt, at the same time, however, the new gear should engage smoothly and the impression of the power of the engine must be retained. For example, if the engine revs up suddenly when the transmission shifts up, this indicates that a servo element is slipping (brake band or clutch) and this must be examined more closely.

Automatic downshifts without throttle are performed at very low speeds and can only be felt by concentrating (increase in engine speed). By contrast, a downshift at kickdown involves not only an increase in engine speed but a perceptible gearshift. At certain speed ranges, it is possible to perform a downshift at partial to full throttle.

Downshifts with the selector lever are either downshifts with the throttle depressed (e.g. on a hill) or braking downshifts without use of the throttle (e.g. on a downhill stretch or for slowing down). Downshifts with the throttle depressed need only a few fractions of a second for the gearshift whereas braking shifts without the use of the throttle require times of 1 to 2 seconds.

During the test, ensure that the transmission is not constantly shifted, particularly under load. During the gearshift, a lot of heat is developed at the servo elements. A reference value in this connection is:

Do not repeat a shift under load more than once within 15 seconds.
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