Author Topic: Shifting rpm  (Read 1766 times)

piddler

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Shifting rpm
« on: November 26, 2018, 23:32:17 »
Just got the car back from the shop getting some exhaust and steering work done. Weather and other commitments have kept me from doing much driving. One thing that I have wondered about is the shift between 3rd and 4th gears (automatic) It seems that the rpm is a bit high when shifting. It is not noticeable on the highway but annoying while driving in town in our hilly terrain.

While they had the car they replace the modulator diaphragm, valve body and adjusted the linkage.

At what rpm or speed should the transmission shift from 3rd to 4th?

MikeSimon

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Re: Shifting rpm
« Reply #1 on: November 27, 2018, 00:20:21 »
As far as I know, the shift point is not always at the same rpm point. It depends also on the throttle position, i.e.; the load on the engine.
1970/71 280SL Automatic
Sandy Beige
Parchment Leather
Power Steering
Automatic
Hardtop
Heated Tinted Rear Window
German specs
3rd owner

WRe

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Re: Shifting rpm
« Reply #2 on: November 27, 2018, 08:19:27 »
Hi,
attached the shifting points (approximate vaulues) of a K4A025 transmission.
...WRe
« Last Edit: November 27, 2018, 09:44:34 by WRe »

Tom in seattle

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Re: Shifting rpm
« Reply #3 on: January 07, 2019, 23:59:51 »
With reference to the first PDF, I believe mine shifts pretty much as to the chart.  I live in a pretty hilly area and the car shifts very frequently due to load.  But it does annoy because it can wish to shift yo and down a lot around 50-60 km/ HR as the road dips and climbs a small amount.
Tom Averill
1967 250 SL Auto Euro Spec