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Discussion Starter #1
The car seems to run fine but it shifts rough from 1-2 after it is driving for about 15 it improves but at beginning it gives a jerk as it shifts from 1-2... (did a complete transmission fluid and filter change). Any ideas.
(oh, also the rpm gauge has been acting weird it jumps randomly by itself; even when car at idle but it does not effect any speed of the engine ...)
 

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1981 Mercedes-Benz 300TD
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871 Posts
For the RPM gauge, its probably the tachometer amp going bad. You can re-solder the points yourself and save $100 on a new amp. I made a thread on how I fixed mine so check that out.
 

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1982 300D Turbo with newer engine (KKK Turbo)
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90 Posts
This shifting is normal, unfortunately. When you have the transmission rebuilt you can get a lower-friction band that will help, but otherwise these have a reputation for having a 1-2 shift that is harsh. If you try to adjust the transmission to smooth out the 1-2 too much then it will typically slip on the other shifts. There is not much that can be done without major surgery on the transmission or at least taking apart the valve body.

You may get some improvement by disconnecting the vacuum supply to the EGR system where it splits off from the transmission's vacuum supply, and/or by fixing the EGR system so it stops leaking. But this is a change that will make all shifts smoother by reducing the pressure in the transmission, so once again, if you go too far in that direction it is likely to start slipping for the other shifts. I'd recommend starting by getting a vacuum gauge and a long hose, connecting to the transmission's vacuum supply and driving while watching the vacuum reading. You should have 10-15" of vacuum at idle, dropping off in proportion to how much you push the accelerator, and zero vacuum by the time the accelerator is nearly floored. If you have less vacuum than that, it will shift harshly.
 

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2013 MINI Copper S Clubman, '84 300CD-weekend car
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Measure the vac inHg going to the transmission.

Connect a mity-vac, or similar device to the black line going down to the tranny from the VCV.

You want ~12 at idle and dropping off with acceleration, just rev up the engine.
 

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Discussion Starter #5
Got it. thanks...
I have already ordered the egr delete kit; so i once receive and install it; than i go ahead check the vacuum black line going to the transmission. I am assuming i'll just block off the line going to the egr before.....
 

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My solution 83 MB CDT 300 w 127k miles:
Tranny overhaul as internal leaks cannot be repaired by adjustments.
Overhaul the turbo for significant improvement throttle response below 2000 rpm.
Replace the two switchover valves top of valve covers due to vac leaks.
Clean injector pump with MSource kit.
Verify vac integrity of engine and tranny side.
 
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