Does it make sense to anyone that I have a 1982 300D with an AUTOMATIC transmission WITH a tachometer and a 1980 240D with a MANUAL transmission WITHOUT a tachometer?
I am thinking about swapping the entire instrument cluster from each to the other, then taking parts from the car with the tach and putting said parts on the car without, so that I can rectify the situation properly. I have done some preliminary searching and haven't run into any hypothetical roadblocks yet. Can anyone think of any?
One real problem is that the tachometer is non-functioning, and before anyone starts mentioning cigarette butts, have a look at the picture. It is of the end of a grey wire that is connected to the bottom of the trash-can, and was coiled nicely and tucked up underneath the hood. I suspect it is supposed to be attached to something tach-related, and is the reason why the tach is non functional. Any thoughts?

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"Frau Blue Car" 1980 240D think Frau Bluker, cue the horses, formerly known as "China" from JimmyL
"Gunther" 1982 300D.....Turbo!! A/C!! Sunroof!!
"Fraulein" 1975 240D----Donated to NPR

Looks like the crank position sensor.it should be attached to a flange/mount thingy near the harmonic balancer.

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1982 300sd from craigslist $800 greased on one tank with NO CONVERSION in the Hot Texas Sun. (currently dead & awaiting engine damage investigation and/or longblock swap)
new daily: '03 vw 5speed jetta tdi wagon. bagged&chipped

I never thought of that before -- the only W123 diesels that came with tachs were the ones that didn't come with manuals! That is very crazy.

Just to double-check, you do know that you can't swap speedos between the two cars, right?

EDIT-- I just saw that you are swapping tachs, not clusters... duh. Time for bed.

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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

No Joe, you were right, I plan to swap the entire cluster.......they look identical, except for the tach and a smaller clock. I actually like the bigger clock better....

(Inserts dumb question) Why wouldn't the speedo work?

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"Frau Blue Car" 1980 240D think Frau Bluker, cue the horses, formerly known as "China" from JimmyL
"Gunther" 1982 300D.....Turbo!! A/C!! Sunroof!!
"Fraulein" 1975 240D----Donated to NPR

You'll need the wiring harness from the tach amp to the cluster.

Broken gears on the speed-o? Not connected?

Your 240 has a crank position sensor of some sort, mechanics use it as a diagnostic port.

You'll also need the tach amp mount.

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83 SD

84 CD

There is very little point to a tach on a 240D or 300D other than purely informational. You have max downshift points on the tach and the IP will cut off way before you are going to do damage.

That said I am building my own tach as well using an arduino on a 603. On the 85 617 and 60x's there is a variable reluctance pickup on the adapter plate between the engine and trans (on 603 maybe its just part of the block). At any rate, I have strongly considered just using the W+ signal off the back of the alt, but am afraid that a voltage regulator failure will fry my stuff.

Need to see what the max output of the stock tach system is...

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1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
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