I'm on my 7th MB, and somewhere along the line I've developed a strong habit of treating my automatic transmission almost like a manual. For the sake of conversation, I'll use my 95 E320 as an example - Bottom line, I shift between 'D' and '3' a LOT. On a fifteen minute drive I might shift back and forth a dozen times (to help decelerate at traffic lights, and occasionally for faster starts). Sometimes I'll even use ALL the lower gears (in the case of the 95 E320, that would just mean 3, and 2) to help decellerate.

Here's the question:
Am I saving wear and tear on my brakes and possibly helping fuel efficiency, or am I putting dangerous, useless wear and tear on my A/T? If there is no clear answer to that one, perhaps you could just answer this - do you think it is a BAD thing, or would you guess it is mostly harmless?

Any opinions would be appreciated - the more educated that better!

Thanks for reading - thanks even more if your respond!

Brake pads are cheaper than transmissions.

The more you shift an auto tranny, closer you come to replacement!

You are saving wear and tear on your brake pads, however you are not helping fuel efficiency.

That being said, on downshifts, you are wearing the clutches in the transmission in lieu of the brake pads. The brake pads cost about $50. to replace. The transmission costs upwards of $1500.

On upshifts, you can hold the transmission in the lower gears for an extended period if you feel the need to do this. There is very little additional wear caused by a delayed upshift.

Around town, I frequently hold the SDL in third gear all the time, provided that the speed stays below 35 mph. This prevents the upshift to fourth, which is practically useless because of the next upcoming traffic light. It's probably not as practical with gears above 2.88, however.

do you make any attempt to match revs on your downshifts? a little blip of the throttle to match that 1000rpm jump as you flick into the lower gear.

sounds like your shifting on the rounds to the grocery store which is linkage wear and as you have seen by talking to the mechanics the A/T wear issue is more complicated, your car shifts gears and if you do it manually why should that hurt more? also the car has a fluid coupling between engine and gearbox which could soften things.

Gearboxes are pretty good at doing there job, holding a gear manually for better acceleration can gain a few-tenths depending on set-up.

If a downshift is needed in addition to full braking to slow the car to avoid a shunt that's cool. or if a downshift is needed to get throttle response in a turn or out of a turn or while doing some trail braking that sounds reasonable to me.

A lot of automatic transmissions have either lever or pushbutton activation on their steering wheels for manual changing, Mercedes is one manufacturer that does so.

Your car lack the failsafe computers like the other manumatics so your brain needs to show mechanical sensitivity and reasonable A/T maintenance.

If you choose the proper times and method for manual shifting it can bring much enjoyment.

Also consider some books, Vic Elford High Performance Porsche Driving for instance to learn how and when to shift.

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Living in a montaneous region, the shop manager at the M.B. dealer recommends to downshift manually to avoid constant braking (hence saving brake pads). The owner's manual on my cars also mention this factor.

I do manually downshift on my E 320 T, which works fine as long as the speed is correct.

On my S 500 L I am constantly amazed everyday: I leave the electronic 5-speed A/T alone at "D" and when going downhill it will AUTOMATICALLY downshift (up to 2 to 3 gears, depending on speed) to provide engine braking, saving brake pads.

Hence: why if it is inappropiate to downshift an automatic transmission due to clutch wearing, the electronic program on my 722.6 does it, and does it so remarkably well?

Any thoughts?

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A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]

I believe that you might be confusing two things:

1) The desire by M/B to have the driving experience for the driver simplified to the greatest possible degree. Downshifting the transmission for the driver will serve this purpose and thereby require the driver to utilize less braking force. The driver is amazed by this technology and appreciates it.

2) The desire by many of us on the forum to maximize the life of every component on the vehicle. We will do everything possible to ensure that these machines will last far beyond a "typical" lifespan for such a vehicle. Changing the oil at 3K intervals using nothing but the best synthetic oil money can buy, changing all fluids religiously, monitoring oil pressure and water temperature within several psi or degrees of temperature, all point to individuals that desire a vehicle to provide long term durability. This is in direct contrast to the function of your 722.6 transmission, whereby the driving experience is the sole factor utilized by M/B when determining the shift patterns.

Hey I do the same on the C230 722.6 and E320 722.4. Not really on the down shift to add breaking (unless you've got a racing bug and budget, why do it?), but more to hold the engine speed where I want it. On the 722.6 for normal around town driving, I'll often leave it in 3, moving to 4 or 5 only if I get up to a steady speed. For deceleration, say I'm crusing at 65 but then traffic slows to 40... move from 5 to 4 with a slight throttle blip, and have the engine, without a downshift delay, at the perfect speed to accelerate. On the 722.4 I hold it in 3 and move to 4 at speed. If I'm really putting about, (and once I'm past 1st gear) I'll move to 2 as needed. Talk about power coming out of a slow corner. I personally think this method gives superior fuel mileage, and is WAY MORE FUN.

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Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230

If you get off on manually shifting an auto tranny, you are driving the wrong car.

i suppose that if you are going down a steep grade it might make sense to put your auto tranny into a lower gear and let the tranny govern your speed.

alternatively, i can see that if you are going up a steep grade, and the auto bogs down in drive, then it might make some sense to manually select a lower gear so as to maintain speed.

but outside of those situations, manually shifting an automatic tranny makes very little sense.

as the previous poster said, if you want to play with gear changes, buy a car with manual transmission. that means that you will not be driving a us market benz.

you will like bimmers, porsches, corvettes, though. very nice manual transmissions.

a couple of years ago, i ran a e270cdi in the alps.it had a benz slap tranny. a great deal of fun. but that is another story, isn't it?

My humblest opinion is the gated transmission was designed for a reason and meant to be shifted. Go for it and tell us what happens. Personally, I would ease up on day to day engine breaking via downshift.

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Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230

Mileage comparison... we live in the city. Lots of putting about between 20 and 50. Rarely get above 50. My wife always leaves it in drive. I hold gears and shift up when I get to a steady speed. I get about 25% better mileage.

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Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230

The more you shift it the more the clutches wear due to the built in slippage during shifts.

I leave my automatics alone -- the torque converter does a decent job of pulling the car down (so does the compression). I've used lower gears on grades, but that's all.

I drive a standard just about the same way, though -- engine braking isn't necessary for me, just coasting down works fine, and the auto upshifts just about the same way as I do manually excpet for the occasional use of a lower gear when I'm going to stop soon anyway.

Higher revs burn mor fuel, and dragging the engine down at high vac can cause excessive emissions (although not with most EIF systems).

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I agree with most of the posters, you should be driving a car with manual transmission. Automatics should always be left in top gear (D or OD). Automatics are designed to choose the best gear for the car's speed and demand. The only exception is when the transmission is continually hunting between two gears such as when the car is going uphill. Then you switch to the lower gear to reduce clutch wear. Or when the car is going down a long incline and you don't want the brakes to overheat.

The triptonics and gated shifter designs are what I call "hollow engineering". They don't do any good for the car. They are simply there because the marketing people found they needed to come up with something for people with itchy fingers.

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95 E320 Cabriolet, 159K

Fiddling with your auto gearshift is just stupid macho fantasty. It will shift better than you can. Downshifting for engine braking (note spelling) in normal traffic is one of the stupider ideas around.

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Norm in NJ
Next oil change at 230,000miles

I'll go along with Brian, Psfred, and some of the others. Every shift an automatic makes counts toward the failure of the tranny. With every shift some of the clutch pack and band material are worn just like the clutch disc in a standard tranny. Also tranny brake bands are just like beer or soda cans. We all know what happens when you crease the middle of a beverage can and bend it back and forth a whole bunch of times. The same brake bands will eventually metal fatigue and snap. Using the transmission to hold back a car is somewhat of an ellusion anyway. The downhill compression of the engine promotes the the continued speed of the engine by forcing the crank to continue to turn. It is really gearing that is slowing the vehicle. If you really want to use compression going down hill, you need to install a Jacobs Brake like the truckers. A Jake Brake holds the exhaust valves open to relieve the compression that keeps the engine going. I just use my brakes. They are cheap. I know this isn't an oil thread, but I will disagree with Brian on one point. I use whatever major brand is the cheapest. I think synthetics are a waist of money unless you are using them in arduous service like heavy loads or extreme weather conditions.

Peter

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Auto Zentral Ltd.