There's a lot of speculation as to why turbocharged W123s were never sold with manual transmissions. Allow me to add to that speculation ...

1. Some have said it's because the transmission can't take it, but this isn't true because the same transmissions were put behind gas engines with equal or greater torque.

2. Others say it's because the turbo engine falls off boost too fast and thus the driveability didn't meet Mercedes standards.

3. Finally is marketing. There were only a limited number of turbocharged cars made. Most were for the US market, where we like automatics. The euro cars were all high-dollar wagons (and sedans?) loaded with options. The number of turbo / manual cars sold, had that been an option, would probably have been too low to justify demand.

Reasons 2 and 3 seem plausible. As it turns out though, all manual 616/617 diesels have a small dashpot or "shock absorber" in the control linkage near the IP. The purpose is to damp the control when the driver comes off the accelerator quickly, such as during a shift. Even the 300D manuals had it. Check out:

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=123130&M=617%2E912&GA=722%2E118405&GM=716%2E005++++++++++++++717%2E400&CT=M&cat=143&SID=07&SGR=165&SGN=05

It should be possible to retrofit this dashpot to the converted turbo cars here. When I bought a new one for my old 240D, it was only a few dollars and did improve shifting ease.

Question is, do you have to remove to IP to install the bracket it mounts to?!

Ted

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1983 240D automatic, Orient Red, 174K
1983 240D manual, Biscayne Blue, sold at 341K

I don't see any reason you can't install a damper on your W123 turbo. You should be able to buy a generic "throttle damper" someplace and make it work.

Regarding 300D turbo manual transmissions, I think the reason is simpler. AFAIK the turbos were only sold in the US market, and I do not believe MB was selling any manual transmission cars in the US by 82. As I recall, even the SLs were all autos by then. I think that was just the "package" they chose to sell in the US. If they wanted to sell turbo W123s with manual transmissions, they would have made it work.

I had a turbocharged diesel 5 speed and thought it was the greatest thing since sliced bread.

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5 speed '91 190E 2.6 320,000 mi. (new car, fast, smooth as silk six, couldn't find any more Peugeots)
5 speed '85 Peugeot 505 2.5l Turbo Diesel 266,000 mi. (old car, fast for a diesel, had 2 others)
5 speed '01 Jetta V6 (new wifes car, pretty quick)
5 speed '85 Peugeot 505 2.2l Turbo Gas 197,000 mi. (wifes car, faster, sadly gone just short of 200k )
5 speed '83 Yamaha 750 Maxim 14,000 mi. (fastest)
0 speed 4' x 8' 1800 lb Harbor Freight utility trailer (only as fast as what's pulling it)

They didn't sell turbo 123's in Europe? Aren't there some post-82 manual 240d's?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

1983 was the last manual trans w123 here.

They sold turbos in europe but all were automatic...

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1983 240D automatic, Orient Red, 174K
1983 240D manual, Biscayne Blue, sold at 341K

I forgot about the US spec 240D manuals, I don't think they sold a lot here.

Are you sure they sold W123 turbodiesels in europe? I thought the euro 300D cars were all non-turbo.

I rather doubt that having to include (or not include) the dashpot had anything to do with MB not offering the manual 5 speed with the turbo diesel.

the 240 was the only stick offered here in that era. and i dont know but i bet over half were sticks, or close.

there apparently were a few 617 turbos sold in europe. but they are very very rare.

my brother used to drive a turbo diesel delivery truck with a stick. it was a mitsu i think. he could shift that thing so smoothly you would have thought it was an auto. he just lagged his throttle foot, never quite letting it wind down. it was very impressive.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

To clarify some previous statements, turbocharged 300Ds were for the US market only. All 300CDs turbo and non turbo were for the US market as well. The 300TD turbodiesel was the only turbocharged W123 available for sale in both Europe and the US.

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

My Father-in law has a 1985 N/A manual that was bought new in CA , Do you mean turbo manual was last sold in 83?.

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1979 300D.

Agree completely. The reason they didn't sell turbo manuals here or anywhere in the world was that all the turbos were reserved for high-spec (luxury trim) cars. Even in Europe, most of the high-spec Mercedes are automatic. The super-rare S-class manual transmission versions, for example, were equipped with the bottom-of-the-range 280 engine.

The point is that the lack of manual-shifted W123 turbodiesels throughout the world was almost certainly a function of marketing, not engineering.

Nonetheless, some of those who have converted their turbodiesels to manual have said that the shifting is tricky since the engine loses revs quickly. My conjecture is that this would be the case with any automatic-->manual conversion. The special dashpot on manually shifted cars will probably solve the problem.

Unfortunately, it seems it would be very difficult to add the necessary bracket to the injection pump when installed on the engine.

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1983 240D automatic, Orient Red, 174K
1983 240D manual, Biscayne Blue, sold at 341K

It must have been a "grey-market" car since 1983 was the last manual-shifted W123 sold in the USA. Or maybe it's a 190 series?

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1983 240D automatic, Orient Red, 174K
1983 240D manual, Biscayne Blue, sold at 341K

An '85 N/A manual would be a Euro-spec car. Some of them did get imported into the U.S., as I would imagine a few U.S.-spec cars may have ended up in Europe.

I have heard that Mercedes did sell a factory manual turbodiesel, one year only. 1987 190D-not sure if this is factual.

It makes sense to me that demand was low for manuals in America. We manual transmission fans are a minority here. It puzzles me that more turbo options weren't available in Europe. Maybe it had something to do with the taxes on cars there?

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

No quite, 83 was the last year for the (non-turbo, W123) 240D, which was available with an auto or manual tranny. 85 was the last year for the (turbo, W123) 300D, which was only available in the US with an auto tranny. I believe the 190D was available in 85 with a manual tranny, but it's not a W123. Clear as mud?

I've got no problem with RPM/boost loss during shifts. The smaller KKK turbo is well matched for a manual. I have yet to re-install my T3 to see what it's like. I'm waiting for a pyrometer and a Super-60 compressor wheel kit before it's put back on.