Manually shifting a automatic 300E...is it bad??? - PeachParts Mercedes-Benz Forum

mike690003 · #1 09-17-2003, 11:49 PM

Hello Board,

While taking a friend to the store, a conversation came up about the 300E being a "slow" car. Well, I decided to show this person that the only reason why a 300E is "slow" is because it starts out in 2nd gear. Well i decided to take it for a little sprint. I reached a stop light and then dropped the tranny into "2", the light turned green, I floored the gas and shot off. After getting near redline, I shifted it into "3", and got to about 80mph. My friend claims that it is bad to manually shift the tranny because it is not "Tiptronic". My car has a 4 year old tranny with about 30k miles. Is manually shifting my auto tranny a bad thing to do??

I do tend to do this a lot. I like to "smoke" a lot of wanna be quick cars(is300, gs300, 330 BMW's, C240, c280 etc).

I win most of the time, not bad for an "old benz".

fahrgewehr2 · #2 09-17-2003, 11:56 PM

No offense...but it seems like your car has a new problem every week. Perhaps you need to take it a little easier. More upkeep, less dragracing?

To answer your question, the only time MBZ advises against shifting the car manualy, is when a lower gear is used to slow the car down. This information is in your owners manual.

Mike

Benz300 · #3 09-18-2003, 12:12 AM

hmmm I use the downshift to slow the car all the time. from D to 3. thought it was O.K. to do so. given i never read the manual i wasnt aware of this

anyone else does this ? is it really bad for the transmission ?

mike690003 · #4 09-18-2003, 12:21 AM

My car is a money pit!

Well I certainly have spend a lot of money into my car. But hey, it is getting better, the PO definetly did not take care of the car. I am forced to deal with it. I plan on having that car for about another year, I have fed it money for long enough, with no reward. After I graduate college,I am going straight to the dealer for a brand new Infiniti FX45!!!

ymsin · #5 09-18-2003, 03:33 AM

I sometimes manually use the gears to slow down the vehicle - though not often. Usually, the low gear is engaged on declining slopes.

But I don't see anything wrong with manually shifting up for more torque.

KNanthrup · #6 09-18-2003, 03:57 AM

I do this very often actually. I have been wondering the same thing, but I haven't had any trouble with my car as far as that goes so I figured it's probably ok. Makes for a little more fun

haasman · #7 09-18-2003, 12:43 PM

I think the question everyone is trying to answer, and I recently wondered the same, is: by manually shifting an automatic car, does it cause premature wear on the transmission?

It is my understanding the answer is yes, depending. If there are large speed differences between gears, the sudden change from say third to second will cause the transmission to have to "synchronize" rapidly.

Selecting a lower gear to accelerate and shifting manually (as long as one lifts slightly at the up shift) is A LOT less stressful on a trans than the example in the second paragraph.

One reason I like Mercedes (some people don't like this about them) is the rather deliberate transmission functioning. By how much throttle is applied, the transmission will automatically select the appropriate gear for the road speed and load.

Haasman

Kestas · #8 09-18-2003, 02:34 PM

It was I who - around a year ago - brought up the point of the Triptonic transmissions as an example of hollow engineering that does nothing to the performance or longevity of Mercedes vehicles. I also used the term "itchy fingers" to describe the people that use this feature. A bit harsh, perhaps, but it reflects the successful marketing employed by M-B to give certain consumers what they want.

Mike, ANY modern automatic transmission will select the optimum shift points needed for acceleration and economy, from the speed and demand (from the accelerator pedal) inputted to the transmission. You can manually shift the transmission, but you're only fooling yourself if you think you're getting more power from the engine. The engine has an impressive whine at these higher revs, but the torque and horsepower curve starts dipping beyond the optimum revs.

A properly designed and properly built transmission will pick the best shift points for you. Leave it in Drive and forget it. Don't even downshift to deccelerate. This'll prematurely wear out your transmission and throw off the balanced braking designed in your vehicle. It's always cheaper to replace brake pads and rotors than transmission components.

I know people get a thrill trying to manually shift their vehicle with an automatic and downshifting for decceleration, emulating a race vehicle, but that's all it is - a thrill. There's no technical merit to this activity.

A. Rosich · #9 09-19-2003, 12:53 PM

I live in a severely mountaineous region with incredibly twisting roads and out-this-world gradients.

Both, the owner's manuals on my cars AND the local service manager at the dealership strongly recommed to downshift manually your automatic transmission to conserve the brake pads.

If you do not do this, brakes pads will wear at a rate of 8,000 miles (or even less!!!) because of the constant braking.

My S 500 L will automatically downshifts for me most of the times, which is nice and convenient. But there are some instances that not even the electronics of the W140 will serve me right and I have to manually downshift to get proper engine braking.

The Mercedes-Benz auto transmission was especifically designed for this purporse and it wil not, in any way, affect reliabilty or durability. Now, drag racing is another issue. Any transmission, manual or automatic, will suffer badly from over abuse, it is just plain logic.

haasman · #10 09-19-2003, 01:23 PM

A. Rosich

I think everyone will agree with you, selecting a lower gear and using engine braking going down steep grades is appropriate.

I believe what some are asking is will the transmission suffer excessive wear by shifting it regulary, gear through gear, manually.

My understanding is that up-shifting, such as 2 to 3, 3 to 4 etc isn't hard on the transmission. You will probably not get as good gas mileage, and as long as there are not severe speed mismatches between gears, no problem.

But it is my understanding that pulling the gear selector from say 4 to 3, or 3 to 2 is hard on the clutches. Actually similiar to a manual transmission in that the differences in gear speeds must be compensated for. It is this type of use where excessive wear comes about.

Haasman

Pete Geither · #11 09-19-2003, 01:48 PM

I regularly downshift the 400E for added acceleration as it just won't respond quickly enough, and sometimes not at all. The SL is much more responsive to the gas pedal than the E, but I still manualy shift it just to get that first gear start. Keeping the shifts within the range of the gear you are going for doesn't seem like abuse to me. These cars are built and I don't think they have to be babied as long as the maintence is kept up.