Drive auto like a manual? - PeachParts Mercedes-Benz Forum

chazola · #1 12-08-2003, 04:33 PM

does anyone out there drive their automatic benz like a semi-manual car?
I'm used to driving a manual transmission car (most are back in the UK) and like the control it gives. If I use the 2 & 3 positions frequently on my 300e to give more control with it damage the transmission at all?

Kestas · #2 12-08-2003, 04:42 PM

How demanding are you of your driving? I think it's a waste of time. A well-designed and well-tuned transmission will pick the best gear for the given speed and load demand. Asking for a gear to perform outside of the set transmission design parameters is a waste of fuel. It won't ruin the transmission. Put it in Drive and keep it there. Only under extreme conditions is it necessary to drop it to 3rd or 2nd.

euronatura · #3 12-08-2003, 05:05 PM

All I can tell you is that in the 10 years that I have known my father-in-law (he drives his cars very hard) he has had the following cars and problems, because he treats an automatic like a stick shift (amoung other things.)

1985 MB 380 SEL (Bought the car new)
In 1993 he blew the motor and the transmission while in touring in Mexico.

1985 MB 190 E (Bought the car used in 1996)
In 2000, the transmission stopped working and before this I do not remeber when but I believe that he had to have the engine rebuilt.

1993 Chevy Blazer (bought the car new)
In 1995 he blew the transmission

1995 Jeep Grand Cherokee V8 (Bought the car new)
In 1996, while I was in the US, I had to buy him a tranny, rear differential and an engine block - do not ask me what he did I still do not understand.

1994 Lincoln Mark 8 (bought the car new)
In 1998 he blew the motor - had it rebuilt and currently the car is in the shop having the transmission rebuilt.

1999 Range Rover (bought the car used in 2002)
In 2003 I do not know what he did to it but it was in the shop for 5 months, in fact he just got it out of the shop a few months ago.

In between all these cars he has had a few Toyota/Mitsubishi Pick Ups (purchased used) that have not lasted him more than 6 months.

Needless to say, I never, ever, lend him my car. In fact, a few years ago he was borrowing one of his brother-in-law's cars and he blew the engine in that too.

So in answer to your question, I would state if you drive a car too hard, past its limitations, sooner or later you are going to pay the piper.......

Jackd · #4 12-08-2003, 08:02 PM

Driving an automatic car like a manual transmission car is not better or worst then driving a manual transmission car like it was an automatic transmission car.
Leave it in ''D''. You are not gainign anything. just wasting fuel
Jackd

cbdo · #5 12-08-2003, 08:22 PM

For a slightly different spin--
I'm known to use the box for a bit more control at times, though not near RPM limits and certainly not to exceed RPM limits. I may manually downshift before a lower-speed corner or an onramp simply because I like to have the new gear engaged as I go through, rather than waiting for the on-demand downshift, and there are other times when I'd rather make the decision myself. At my age, and knowing what service bills are like, I don't exactly overstress the machine; if I'm driving hard, I let the box work as designed.

AustinsCE · #6 12-08-2003, 08:28 PM

Yea, if its working right just floor it if you need to downshift. If its slow or early theres a cable you can tighten. I keep it in third since im in the mountains always going uphill, i like to get where Im headed but other than that D is good.

william rogers · #7 12-08-2003, 09:22 PM

Here in Costal Oregon most of our driving is on curvy 2 lane mt. roads I often down shift for a sharp curve that is on a steep grade rather than let the transmission do it but never run it up through the gears manualy.I would have to guess that blowing up that many trannys and engines is the result of constant over reving when upshifting and down shifting at high speed..........
William Rogers..........

deanyel · #8 12-08-2003, 10:47 PM

My advice would be to ignore all these people - the whole point of a gated shifter is to allow for manual shifting. This used to be endorsed in the Owners Manual. You're not hurting it as long as you don't do anything unnatural. I know exactly what you mean - sometimes you want to have more control or have a little more fun.

chazola · #9 12-09-2003, 07:09 PM

interesting to hear the opinions. Since i'm used to driving a manual i would never over-rev the engine in a gear. most cars seem to like to change around 2-3k rpm depending on road conditions, though the 300e transmission seems like it changes up fast and sometimes i don't want it to change that fast! I guess it's programmed to be fuel efficient that way so i should let it get on with it's job. Maybe i should have bought an older 5-speed version! I did read however that you can control the 1st/2nd gear start by manually shifting, though as mine is a late (dec)'91 model i'm not sure if i have the 1st or 2nd gear start. it certainly seems peppy enough off the line... At least it has a rev counter, my 5-speed s-10 pick-up doesn't have one, just an annoying 'shift' light on the dash that i covered in tape:-)

DavidB29 · #10 12-09-2003, 11:27 PM

I partly agree with the original post that it is sometimes useful and fun to shift for yourself. Over the years, I have "played" with my Benz auto transmissions now and then and mostly enjoyed it. I had three 300Ds (both normally aspirated and turbos) and found there were times when choosing my own gear range was advantageous. I find I use it less with my current 92 300E.
But for the most part I have used it to choose a range, not actually shift up through the gears.
For example, in the automatics of certain vintages and certain models (such as my 1979 300D), the start was in second gear, as you mentioned (not your 91, though). So if one wanted a quicker start, one could downshift to L while stopped, and the tranny would shift to first and stay there, even if you shifted back up to D. Then it would run up through 1-2-3-4.
Another time I often use a lower range is local driving. I nearly always start out from my house or a parking lot in S, because that gives just a bit of engine braking (but less so than in the diesels), and it reduces the number of shifts in stop and go driving. I don't move it to D until I am on a road where I know I will get up to 30-35 mph or so and be able to stay there a while. (Note how automatically the shifter will stop at the S position if you just slide it back from park or reverse, and don't make a conscious effort to stop at D!)
Also, if I know I will be on a curving road I will sometimes choose a lower range to avoid shifting up and losing the control of having engine braking and rapid throttle response. Not for aggressive driving, just good control.
And one of the best uses is for descending a mountain, where the use of S or L will save your brakes from overheating. (The W124 series, and maybe others, require you to momentarily downshift to L to get down to 2nd gear, but you can stay there in S once it is selected until you reach a fairly high speed. This is explained in the owner's manual, though not well.)
But you can get into trouble as mentioned. Downshifting when the car's speed will force a rapid increase in RPMs is risky. There was a nice 300SD totaled at a national MBCA event some time ago when the driver downshifted at high speed from D to S. The engine could not accelerate fast enough for the lower gear, and the rear wheels spun, causing the rear end to slide and the car to go off course and crash!
I also met a guy whose family member had supposedly driven his Benz a long distance on a freeway in S, had over-revved the engine and burned it out.
One thing to note is that the transmissions change their behavior in response to pedal pressure. That is, if you hold the pedal down further, the upshift is delayed. This happens even in the older transmissions such as yours that have no electronic controls. And I think the shift points are also affected if you choose a range other than D. That is, if you choose L or S I think the shift points will be at higher RPMs for the same pedal pressure. (But I would not stake much money on that last comment.) So you can somewhat influence the way the tranny shifts for you, even without shifting it yourself.
So I think moderate use of the manual shift provision can be useful if used sensibly.

moparmike · #11 12-10-2003, 12:49 AM

I look at it like this: If you have to push harder on the gas in D, then you are wasting gas. If you maintain throttle level and drop a gear, then you are wasting gas. Either way, you waste gas.

I have a 380sel in a rather hilly part of Arkansas. If you dont shift manually, you will watch that econ guage stay all the way in the red until you get on a flat at about 40mph. It will be less red if you manually shift it. It doesnt have the low and mid-range torque to handle the terrain in town in 3rd and 4th. Now if I was in Iowa or Minnesota, I could keep it in D until I wanted to have some fun without a problem.

Drive your car according to the terrain. Guage the terrain by your car.

william rogers · #12 12-10-2003, 01:04 AM

It's pretty simple to adjust the bowden cable to change your shift points ...........

William Rogers..........

Kestas · #13 12-10-2003, 10:17 AM

Quote:

Originally posted by moparmike
I look at it like this: If you have to push harder on the gas in D, then you are wasting gas. If you maintain throttle level and drop a gear, then you are wasting gas. Either way, you waste gas.

I have a 380sel in a rather hilly part of Arkansas. If you dont shift manually, you will watch that econ guage stay all the way in the red until you get on a flat at about 40mph. It will be less red if you manually shift it....

Don't econ gauges simply measure engine vacuum? For the same vacuum, a higher revving engine will suck more gas than a low revving engine, so you may be fooling yourself if you think downshifting to get the econ gauge out of the red will save gas. The higher revs cancel anything you save by having higher vacuum.

On another point, didn't somebody post that older MB transmissions can be destroyed if shifted down at too high a speed? Unlike most American cars, older MB transmissions don't have a lockout feature for those conditions. This, plus a slip of the wrist by shifting down too far can destroy the transmission!

Zeus · #14 12-10-2003, 03:58 PM

I normally leave it in "D" except when I'm city driving - then I usually leave it in "3". I find this allows me to rev the engine a little higher without clobbering the throttle to get that extra zip you need when city driving. My M103 really picks up past 2800 RPM and I find if I leave it in "D" it shifts into 4th a little too early for my liking. Again, it all depends on throttle pressure.

jmfitzger · #15 12-13-2003, 11:48 PM

Implicit in the MB manuals for classic diesels is that one should not use the kick-down switch for downshifting except under emergency conditions. It is not a good idea to kick a diesel into a downshift. Even the best tuned diesels may not modulate well. So why do a heavily loaded downshift which uses alot of clutch and strains the tranny when you can downshift manually with near neutral loading of the tranny and then step into it after the shift?

Also it is a good idea to drive around town in S rather than D. Third gear has really nice power curve around 25-45 mph, you have better torque and power response. Sure, if you dont want to pay atention to it, put it in D. But it will shift thousands of times between 3-4 with no positive effect.

So I say drive that diesel hard but be gentle on the tranny. And dont worry about accidentally leaving it in 3rd on highway and overrevving the engine. Your ears will be bleeding long before that happens.