240 shift point

When I shift from 1st to 2nd under 20 mile, it shift pretty smooth. But I rev it up to 25 and above, it seems to cruch a little. Is there any adjustment I can make or my sycro. is going out. Thanks...

[william rogers]

when I bought my 74 240 years ago it did as yours I put a new clucth master cylinder on and it then shifted smooth as margarine ,but it then blew the slave cylinder first time out. I had to limp home shifting without a clucth.After replaceing the slave cylinder the clucth chattered as brake fluid from the blown slave cylinder had saturated the clucth ,I took the slave cylinder back off and sprayed a can of brake cleaner in through the opening ran it a few miles and it now shifted like new. Moral if you change master change slave.....
William Rogers.......

[JohnM]

300cd,

Mine is the same and it has always been that way since I got the car in 1986 with 36K miles. It crunches a little less with Redline MT90, I might add. I’m not sure mine is at the same speed as yours, but it is always between 1st and 2nd and only on an up shift. To avoid the problem altogether I shift at its sweet speed and there is no crunch what so ever. If I have to shift at a higher speed, I either pause between gears or after coming out of 1st, I move it over to between 3rd and 4th and then back over into 2nd gear (may be the same effect as the pause?). This all sounds goofy, but it is second nature and the transmission has never given me any trouble. So much second nature that I really don’t know what the sweet speed is. And if it ain’t broke……

[JimSmith]

300cd,

The faster the car goes in first gear before you shift the harder the synchro works, and most likely the more of a hurry you are in which also stresses the synchro. So you may have a weak synchro or are developing one. It also demands more attention by the operator not to over load the synchro. In general, the car will tell you what its natural pace is, and in my experience trying to change that is not worth the trouble.

As noted already, part of the problem can be bad timing and incomplete unloading of the gears due to a clutch that will not disengage fully, which is not an operator fault unless the operator is not depressing the clutch pedal far enough. Another possiblity is the lubricant in the transmission. This is the subject of heated debate regularly, so I am not going to steer you to any particular brand or type. I have identified that endorsing a particular lubricant is the event horizon for the black hole known loosely as lubricant discussions on this forum. Try a search if you have lots of time.

But, my inclination would be to stay at 20 mph or below as the last few mph typically comes at the expense of an assault on your hearing even without the crunch. With a crunch it can be offensive to your other senses as well. Good luck, Jim

Thanks for your help. The clutch and slave cylinder was change about 1,000 miles ago. And I replace the fluid with redline MTL ( which it did wonder on my volvo ), but still act the same. I guess I just have to live with it.

[dabenz]

20 mph? If you shifted at 10 or 15 mph then I'd bet a Coke that you would reach the 2-3 shift point in less distance and time than running up to 20 mph. And you'd get better mileage and less wear. Think of 1st as being a walking gear: get going faster than a fast walk and it's time to shift.

[Lycoming-8]

On my old 220D the shift points that seemed to work best were 12, 24, and 36mph. Always gave smooth shifts and you can see how well the tranny lasted, never was opened for the life of the car. As daBenz implied in the above post, 1st gear is almost a grannie gear.

Am I lugging the engine? If I shift that early, thanks...

[Lycoming-8]

Well, I never thought so. I was more than able to keep up with traffic on my daily commute and entering freeways I rarely shifted at any higher speeds. Did not drive it like it was a sports coupe though, it had too many doors...... However I would let others comment before you decide.

My feeling is as much as possible keep the engine turning at a steady rate that feels right. I ride the clutch a little while I run up the revs and shifting down i boot the engine out of it's idle before engaging the lower gear. Doesn't seem to affect fuel economy and the car has a much smoother ride. My own guess is that 2600-2800 is about right but I've never had a tach to test it. Judging from the tach in the 190 it might be more like 2300. Just don't try to go faster when you accelerate!

[dabenz]

300cd, the short answer: probably not. As I re-read your first post, I now wonder if you're shifting at the dots or dashes on the speedo. They're there to show you the engine red-line for that gear, not to show you where to shift. MB was smart that way; you don't need a tach. The real answer comes from the torque and horsepower curves for the engine. The old rule is to shift up at the rpm where the engine rpm is at 60% of rated torque, and not run the engine faster than 80% of the rpm at rated horsepower. Sounds confusing now but will make sense when you see the curves. A good test for lugging on the flat is this: if the engine stumbles when the foot throttle is lightly applied then you're lugging. Also watch the temp gauge when climbing hills. If it begins to creep up then you're lugging: shift down, drive at 80%, and enjoy the view after the temp comes back down (it will, and quickly if you catch it fast enough). daBenz will pull any hill in 3rd at 45mph and not heat up, which isn't bad for a 60HP engine.

[tradonguy]

Wow, I love these comments. I thought I was losing my ability to shift gears when I got my 240D last summer. The clutch fork actually broke so I replaced the clutch and shifting was certainly better but whenever I had a bad day, my shifting from 1st to 2nd was bad. I put in RedLine MTL and I noticed a dramatic improvement in the shifting overall but I still, once in a while, miss the shift into 2nd. Thanks for the comments on those marks on the speedometer. I really didn't understand why they were so high and my manual didn't seem to show anything about them. I shifted based on what felt the best. It sounds like I should get into second a lot sooner. Your comments are great.

[rk300d]

this discussion make me feel better too about my 1st to 2nd grind I get on my 300d 4pd. I just try to not get in a hurry until I'm in 2nd. Us diesel drivers know about that deep rumble in the low rpms...does that constitute 'lugging'? Making a very slow turn around a city corner I'll quite oftern leave it in 2nd, and I get a little rumble, but the same trick a little faster in 3rd will sometime have passengers aking what the hell is wrong with my car.

If you start in first, put it in second, and wind it up slowly and steadily you'll be able to feel where the torque cuts in. That is the minimum speed that the engine wants to run all the time. You can crack your head by lugging it- not recommended. (I mean the engine head, of course.) It won't hurt your fuel economy to keep your engine turning a decent speed. You can't turn a city corner in third and be doing it right. Learn how to drop it into second and make 90-degree turns at 23 miles per hour. This will teach you a lot about how the car should feel.

[300SDog]

'79 240D 117k miles, synthetic oil burns 1 qt @ 1200 miles or 3 tanks of fuel, gets about 24mpg.

Optiimum torque to me appears at 10mph below the shiift points -

30mph in 2nd gear - often taking 2nd up to 40mph then grabbing 3rd under acceleration, i like to accelerate into every upshift.

50mph in 3rd - hell, I'll even drop from 4th into 3rd at 50mph driving into highway slow-downs.... Gotta love 3rd gear between 45 and 55mph, great fun on back roads too with plenty of power that only diesels possess.

4th gear never sees anything below 50mph, and its never in use around town or on windey New England country roads.

Am treating shift points as optimum point for shifting into next highest gears. Each gear seems to be lugging to me at lowest point on its shift band.

For example, 3rd sucks below 40mph (its a long throw from 2nd to 3rd) - between 30 and 45mph is where most shifting occurs, both up and down. The car always loses at least 5mph between shifts.

One more word about 4th gear - on my engine it aint worth a damn below 70mph for climbing hills on highways and will fall below 60..... but maintains a very good 80 - 85mph on the curvey and hilly Taconic Parkway - creeping up over 90 on downhill runs.

Thinking diesel engines are creatures of habbit, am never letting my 240D fall into slug routine. I will frequently roll along at optimum performance speed for each gear, say 30mph in 2nd or 50 in 3rd.

Otherwise, constantly constantly shifting gears around town - having great fun.... using downshifts to slow down and grabbing higher gears under acceleration..... never jamming the tranny, easing through each shift - gently with feeling.