We all know that the 616 flywheel is lighter than the 617's manual flywheel. It's also available and the 617 flywheel isn't so, while driving my wagon, I've occasionally experimented with keeping the acccelerator partially depressed when shifting between gears so that the engine doesn't loose RPM as rapidly, permtting smoother shfts and better acceleration. Doing that with your foot all the time is difficult, unreliable and distracing.

Some of the 616s I've looked at have a piston damper (looks like a mineature gas lifting strut) connected to power control arm on the injection pump. I suspect that this is to help eliminate driver-induced accelerator oscillations in low gear on manual transmission vehicles.

I wonder if this damper could also function to slow the engine unwind between gears on manual equipped 617 turbos that were without the benefit of a heavy (617 manual) flywheel?

Comments? Suggestions?

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Never a dull moment at Berry Hill Farm.

I'm sure that you could adapt it for the purpose intended. The damper would be ideal for preventing a sudden drop in rpm's when you lift your right foot.

Naturally, getting it setup properly would be a real PITA. If it dampens too much, when you put the clutch in, the engine will run away.

Without sufficient damping, the rpm's will drop below the shift point for the next gear.

My thought is that you are going to have to err on the side of insufficient damping. The diesel is all to willing to run away if the rack is not very close to idle.

The damping requirement will be dependent on the rpm's and the speed of the shift (operator dependent). At high rpm's, you definitely need less damping to bring the revs back down quickly. At low rpm's, more damping is required, or a very fast shift, is necessary.

Be an interesting setup.......if you could make it work for all conditions.

basically what you're describing seems to be a dashpot. You can make an adjustable one very easily with a small pneumatic air cylinder. Use a needle check on one end so there is no damping or resistance to push the petal down (for obvious reasons ) and the needle adjusts the flow resistance ahead of the retreating cylinder piston. Mount the needle near your shift knob so you can fiddle with it as you are driving.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Precisely; I'd forgtten what they were called.

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Never a dull moment at Berry Hill Farm.

I've found that on my 240D I can leave the idle speed adjustment adjusted UP but not PAST the point where it starts to affect the idle.

Using this, it baiscally holds the linkage a litlte bit "on" but doesn't change the idle speed noticeably.

I've noticed that when you let off it will slowly return to idle (not quite as fast) and this makes it a lot easier to drive.

The dashpot (of course) would be the RIGHT way to do it...just offering an alternative.