...OK...what's the best way to operate the clutch to save wear-and-tear? Can I keep the pedal depressed at lights or while waiting, or keep my foot off the pedal altogether? The last "hard and fast rule" I remember re clutches was that they should be either "all the way in, or all the way out". I know not to "ride" the clutch...

Any insights?

The longest life possible can be acheived by only using the clutch to begin from a standing start. Apart from that, upshift and downshift without using the clutch and slide it into neutral before coming to a stop.
Probably not the kind of practice useful on a daily basis.

Holding the clutch in at a light probably causes more wear on the throwout bearing than not. But I suspect the effect is negligible given the wear caused by having the bearing go from still to high speed when engaging the clutch.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

well, mine has over 200k on it and i drive the s..t out of it. use synth tranny fluid, change often, use the best clutch and t-out bearings and just drive the hell out of the car.

.

You don't need to. Just pull it out of the lower gear when you release the accelerator and gently push the shifter into the next gear, as the rpm's drop they will match between the engine and next higher gear and it should slip into the higher gear. Takes a little practice but it works. The faster you are driving in the lower gear, the more time you have to make the transition.
It's good practice for getting home when the clutch goes out.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Hey Kerry,

Do you drive that way? I've heard this before, but wouldn't that be hard on the syncro's. I've never been able to do this with my 190d 2.2, but the tranny is a little balky anyway.

Sholin

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What else, '73 MB 280 SEL (Lt Blue)
Daily driver: '84 190D 2.2 5 spd.

I drove that way the day my clutch quit working due to a leaking master cylinder. Wouldn't want to do it every day, but the technique is useful when necessary. Clutchless downshifting is also possible, but more tricky because you have to use the accelerator to match the engine revs to the transmission.

To answer the original question, any time your foot is on the pedal, parts are wearing. Keep your foot off the pedal as much as possible.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

I thought that clutchless shifting was kinda obvious- If you shift w/o a clutch and the gears grind (obvious) or the car jerks **at all** then you are wearing something, and it'd be the synchros in a synchromesh gearbox.
Maybe some cases worse than others, but if you can shift with no clutch and no jerk **at all** (I've seen people do it, I cannot though) then you are probably doing no more wear on the synchros than using a clutch.
Actually maybe even less due to the fact that often when I shift with the clutch (I always use my clutch btw, I'm not that good) the intermediate shaft is NOT speed matched w/ the wheels for the gear I am about to enter (credit VW's huge 1-2 gear gap =)
someday I'll double de-clutch more than I do now, but untill then using the clutch is okay with me.

-John

__________________
2009 Kia Sedona
2009 Honda Odyssey EX-L
12006 Jetta Pumpe Duse
(insert Mercedes here)

Husband, Father, sometimes friend =)

I had an old Peugeot 504 that didn't have syncroes in 1st gear and I could down shift into first without the clutch

__________________
5 speed '91 190E 2.6 320,000 mi. (new car, fast, smooth as silk six, couldn't find any more Peugeots)
5 speed '85 Peugeot 505 2.5l Turbo Diesel 266,000 mi. (old car, fast for a diesel, had 2 others)
5 speed '01 Jetta V6 (new wifes car, pretty quick)
5 speed '85 Peugeot 505 2.2l Turbo Gas 197,000 mi. (wifes car, faster, sadly gone just short of 200k )
5 speed '83 Yamaha 750 Maxim 14,000 mi. (fastest)
0 speed 4' x 8' 1800 lb Harbor Freight utility trailer (only as fast as what's pulling it)

On clutchless shifting...... "floating gears" is what its called and can only be done with straight cut gears that ordinarilly required double clutching such as Eaton/Fuller 10 spd units. Its easy to do for upshifting, matching engine speed with speed of gear rotation...... takes much more skill for downshifting where you've gotta tap the accelerator/throttle to raise engine speed. Essentially, you float gears off the tachometer and accelerator on narrow power band multi gear diesels that are driven between 1300 and 1800 rpm's........ like 10 spd tractor trailers where you also skip gears like 4th and 6th.

Can this be done with MB synchromesh trannies?? Hell no, you cant even float from gear to neutral without using the clutch (first step to floating gears) - let alone finding the next spiral cut gear.

Otherwise, I dont think the 240D varies alot in power band engine speed that the clutch suffers so much as compared with wide band gasoline cars, hence clutch longevity.

One fellow i spoke with said he never downshifts for red lights and just glides in at 4th gear and then finds neutral..... I thought this was ridiculous as am constantly dropping and grabbing gears to keep my 240D operating at maximum power band..... hell, you should also be downshifting to slow down the car when takin exit ramps off highways. And yes, use the accelerator pedal to match engine speed with gear speed for perfect shifts.

We dont get alot of clutch discussion on this board. One thing you can take to the bank is that it's bad idea to rest the clutch foot always on the pedal instead of next to it, then reach for the clutch pedal when you need it.

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Last edited by 300SDog; 01-06-2004 at 08:43 PM.

I don't have a 240d manual and I haven't tried it in my 409d. But I have done it on a variety of Chevy and Ford cars and vans. I can't imagine that their transmissions are all that different from MB car transmissions.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I've floated a 240D from 1st into 2nd, but wasn't able to get up to enough speed to try upshifting into 3rd (test-driving on residential streets).

I was forced to float gears in my truck last year when the clutch slave cylinder went out...while coming up to the toll plaza for the San Mateo Bridge with a finicky trailer in tow Good thing that I had taught myself how to do it in case I needed it...

Guys,

Our MBs have synchromesh manual transmissions, which have all the gears (which are typically helical in passenger cars for the last forty years or more) meshed all the time. So when you select a gear with the lever you do not disengage one set of gear teeth and then engage another set of gear teeth. Instead you deselect one set of meshed gears and then select another set of meshed gears.

The torque transmission path is not directly through the gear teeth to the output shaft, as the output gear is allowed to spin freely on the shaft (the shaft is more like an axle with a bearing interface to the output gear). For the sake of simplifying my task describing this, and your task if you accept it, reading and following this description, the following features are vastly simpified to merely show the torque transmission path. Modern transmissions have become a little more sophisticated and the geometry is very difficult to describe in words.

Torque is transmitted from the face of the gear, through some fairly robust lugs, to something called a dog-clutch, which has some mating lugs that engage the output gear lugs when the dog-clutch is moved axially along the shaft into position. When you move the shift lever, this is the thing you actually move. The details of this feature have evolved and can be quite geometrically complicated to describe, but they all do essentially the same thing.

The dog-clutch passes the torque from the output gear to the shaft via axially oriented splines on the shaft and inside diameter of the dog clutch. So, when you feel and hear the grinding when you either get your timing off, or try to shift without the clutch, you are banging these lugs together.

The synchronizers bring the angular relative velocity of the two disconnected rotating parts down to some minimum so when you engage the lugs, the lugs can engage before they hit the next lug coming around. Shifting the transmission without the clutch requires that you first take the torque load off the lugs by doing what I believe you guys were calling "floating the gears." By manipulating the throttle pedal this is relatively easily done. As you go to engage the next set of already meshed gears with a different reduction ratio, you have to use the throttle to adjust the input side angular velocity to match the output side which is connected to the wheels.

Once this speed synchronization has been achieved, the transmission cannot tell whether you did it with your foot, or the task of matching the speeds was done with the synchronizers, and the dog-clutch lugs will engage the selected gear ratio output gear lugs. If you don't do it exactly correctly, well, the shift can be jerky or you can begin to grind. The point of all this was to explain how you can shift these transmissions without the clutch.

I hope this helps, but if it is still not clear, a better explanation can be found in any text on synchromesh transmissions, probably available on the net. Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Don't have it anymore, but I purchased my '80 240D manual with 84k miles on the odometer. Gave the car away when it hit 300k miles, (I'm still kicking myslef for doing that.)

Had to have the mechanic replace something or other at around 250k miles. Can't remember exactly what was replaced, but he recomended replacing the clutch at the same time as it probably needed it (considering the miles on the car).

He gave me a call at work and was flabbergasted with the condition of the clutch plate. Said it was "like brand new".

My driving habit was "normal". I kept the clutch pedal in at stop signs and while waiting for red lights. (It had a light clutch, as opposed to my Ranger that has a heavy clutch.) I never "held a hill" using the clutch. In obtaining speed, would upshift as one would normally do, and more times than not, would downshift when coming to a stop or slowing down, (would let the engine compression slow me down). I only had to replace the brakes once while I owned the car.

Just my experience.

(A little side note . . . my '95 Ranger now has 235K miles on it. Had to have the throwout bearing replaced at around 180k miles. The mechanic insisted that he replace the clutch at the same time. I insisted that he did not need to, (remembering my 240D experience). He called and said I was right and the clutch didn't need to be replaced.) Just don't do stupid stuff with your clutch and it will last a long, long time. I sure wish my 300CE had a clutch in it. I really hate those stupid automatic transmissions. You don't have hardly any control over the car with those things.

The first time I shifted without using the clutch was actually an accident. I was a bit distracted by something or other, and I remember just reaching up an pulling the lever down to second. When I realized what happened, I thought it was amazing. So I did a few more times; not my standard practice, but if the sychros are in good shape, it can be done.
Car was a '64 Ford Falcon Sprint Convert, ( V8/ 4 spped( Warner T-10))