300SDL Auto/Manual ?
 

I have read posts saying that one of MB's features for the older models, was the possibility of shifting gears if one felt they needed to or for performance increase. What kind of damage could be created from doing this, and what RPM's should someone shift at?

I think I blew the modulator valve twice by shifting at too high of RPM's before, because I was trying to manually shift from 2 to 3 to D at about 2K-2.5K Rpm's. Is this possible or did I just really mess the clutch packings or transmission up really badly?

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whatever you did, probably wasn't caused from manually shifting- especially at the RPM's you said. sometimes that RPM is lower than what the tranny would normally shift, so you're fine. i don't know where your problem could have come from. it could be vacuum related, try to troubleshoot- have you done any other work on the car? when did the problem arise? does it always happen?

see if in your post signature you can put your car make, model, year, etc and as much info as you can. i'm not sure what 300SDL you have, could be any year

I forgot to mention it's an '87. It seems like 2K RPM's is way too high for this engine. What would be adjusted to keep the RPM's below 3K?

What is the best ideal RPM to shift at and can shifting like this be done frequently? What is the best gear's to shift to. "3-D, or 2-3-D?"

Thank You for ALL replys! :D :thumbsup:

I manually shift mine from all forward gears to all the others, and the engine frequently sees 4500 rpm on freeway on-ramps and the like. Even 5000 isn't redlined provided it's under load, freewheeling at those speeds is a little rough on things.

if you look carefully at your speedometer, you will see three dots up somewhere around 80 mph. This represents the maximum safe speed, above which you may not shift DOWN into 3rd gear. Anything slower than those 3 dots, and you may go from D to 3 without harm.

Two dots occur at about 50 mph or so... wherever they are on your speedo... if you are going slower than those dots, then you may safely shift down to 2.

Shifting up is just a question of how the car feels.

Okay, an '87- puts us in the same boat. I have an '87 300D with the same exact engine. 2K rpm isn't too high at all, it's still short. These engines are noisy and it's something you have to get used to. I don't beat my poor car to the death but I'll rev her to 4K rpm without manually shifting, just taking off "in a hurry" every once in a while, it it's perfectly fine

It can actually be beneficial to get the car up in those higher RPM's, it blows carbon out of the engine and exhaust, and keeps your car purrrrring. Really though, you wont have any problems opporating your engine at any rpm under 5000.

And for your other question.. these car's have odd power bands, making it hard to say what rpm would be "ideal". If it gets you from point A to B and it's under 5000 rpm, then you're allll good ;)

Amazing! Never noticed those dots before; there's even 1 dot. Wow!

It's right handy.

When I'm trying to maximize my acceleration I tend to manually shift UP to the dots as well.

Using the one dot is kinda tricky, you have to go into 2 from a dead stop and then flip back up into 3 and then right back to 2 as you shift. That's the only way to manually get first and second on the stick.

I manually shift mine all the time, no issues at all.

The 603 is a rev-loving diesel, it will rev to 4-5k without complaint. 2k is nothing! :D

I manually shift a lot and rev mine up all the time, and it runs great! :D

So what you're saying is that these cars are not like regular automatics, where manually shifting would be devestating to the transmission, correct?

If thats the case, how often do you think you could get away with shifting like this without any harm? Is there anyway you could blow any transmission seals or the modulator valve by overrevving? I think my engine has been adjusted somewhere to shift at low RPM's.

Thank You for ALL replys! :D :thumbsup:

I'm not sure how "devastating" it is even on normal cars... but I can safely say that on these Benzes, you can get away with shifting every single shift yourself for the rest of your life and the car won't suffer for it.

Manually shifting an auto trans is not devastating to any car, unless you are a doofus and downshift into first gear when you're going 70 mph.

SUre you will wear out your shifter bushings faster but who cares.

NO.

I don't worry too much about exceeding the dots on the speedometer slightly. What, with the Finns screeching out 7K plus rpm and 500 hp on these 60x engines (although I wouldn't try throwing it into 2nd gear at 70 mph). The diesel is not exactly going to blow up like a gasser would. I run 94 mph in my SDL in third gear. And the dots start at 81 mph. WOT. Lots of times. Its been 80K miles of fun, and its never run so well.

The best power is achieved below the markings however. No reason to exceed them.

My car won't go past the dots. If I'm in a gear going UP through the gears, and it hits the dots, my car quits accelerating at exactly that point. I can't go faster if I want to.

I don't mind downshifting into 2 a little bit too fast for engine braking because I know exactly where it's going to be after it quits surging... but I don't test things.

Going up, mine won't pass the dots in any gear.