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Question about the Gear shifting

1K views 8 replies 4 participants last post by  Diesel Benz 
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#1 ·
hey i have a w202 and a e38 740, in the bmw it has a 4th gear or "S" instead of "D", and it happens to allow for quicker acceleration. in my '95 w202 it has "D" and the gears "3" and "2". i have always wondered what the 3 and the 2 gears are for, when should i use them instead of "D" thanks
 
#2 ·
From the car manual (for 7G-tronic):

3: The automatic transmission
shifts through third gear only.
With this selection you can use
the braking effect of the engine.
2: The automatic transmission
shifts through second gear only.
Allows the use of engine’s
braking power when driving:
- on steep downgrades
- in mountainous regions
- under extreme operating
conditions
1: The automatic transmission operates
in first gear only.
For maximum use of engine’s
braking effect on very steep or
lengthy downgrades.
 
#4 ·
oh boy!! even it says "D" it has 5 gears . so if you go on "D" youll be using the 1,2,3,4,5 all of them automatically. but if you use the D3 youll be using the 1,2,3th gears only . then D2 is 1st,2nd gears only which means it wont go further than 2nd gear. got it ? thats why he gave you the examples of mountain. so if you were going down the mountain you should use your D2 or D1 that way your car wont speed up by going D3 or up...
 
#5 ·
In theory, 3 should give you better acceleration, because with less gears used you will hit a higher RPM before the car will shift again... You could also try '2', and then when it revved up high, switch to 3, and then D manually - this should almost give you the 'manual' effect.

If you do drive in the '3', let off the gas for a while, and after several moments you will feel the 'braking effect' (especially when the car downshifts to the 2nd gear).
 
#7 ·
At least with the modern electronically controlled auto-boxes I bet nobody "ordinary" driver can beat the car doing gear shifting in auto mode, just use "kick down".

If you select "3", it means gears from 1 to 3 are used. If you accelerate on "3", the car would behave exactly as if you had selected "D", at kick-down. This at least with the modern ones, assuming the same program has been selected (depends on the car, W/S, C/S etc. etc.).

Note that there does not have to be any difference when selecting "3" after "D", on a 4-gear auto box if you are already driving on the lower gears (1 to 3), the car would maintain the same gear. If the car was using "4" when "D" was selected, then you would get "3" selected when changing from "D" to "3".

I don't find any use for the lower gear selections other than deceleration without using brakes.
 
#8 ·
Well like previously stated, the gear you are in is just the maximum upshift gear. As to the acceleration question it depends on whether you mean from standstill or from rolling. If you are from a standstill then unless the transmission starts off in second gear it does not actually matter what gear you have it in, however if you are driving on mountain roads and want more responsive acceleration through curves and up hills then you need to select a lower gear.
 
#9 ·
Diesel Benz said:
I don't find any use for the lower gear selections other than deceleration without using brakes.
Quoting myself, I do agree dahappybanana, another use for the manual selection is to get the car "to the right gear" for an anticipated acceleration, to avoid time spent for shifting lower gear.

I guess I find this an issue so infrequently and too stressing that I didn't even consider this use case, but certainly a fact.
 
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