What is involved in converting a W123 300D Turbo to FIVE speed? I have followed the 4 speed conversion posts and can't see why a fiver can be installed. BTW is the tranny/diff. gearing compatable? Anyone? Anyone?

The problem is that the necessary 5 speed transmission is virtually nonexistant in this country. You might want to contact forum member Gurkha about importing one from India. They still make them over there.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

The differential is the least of your problems. Just look around until you find a ratio of your liking. As mentioned above, they are more rare than 300 flywheels

Don

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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed

I can get the fiver. The question is more of the finer components. BTW, any potential probs with tranny tunnels? Will the 300D Turbo be too much torque for the 5spd designed for a 240D? What kinda milege are the 300D Turbo manual guys getting anyway? Any driver type reports would be nice...... My 86 5 spd 300E has a numerically higher diff gearing than the auto does. The 15% overdrive kinda gets lost, but the dependability would be worth it alone.

I seriously doubt that the torque increase is going to make a difference. Do you have a source for Euro parts in Denver? If so, let me know. I'm in Denver and have a 409d so any source for Europarts would be of great interest to me. The 409d has a 5 spd but not the kind you are talking about.

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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

I was told that the '85's rear end gearing's too high for the 5 speed to work. This is because, unless the gear ratio was changed, at legal speeds you'd be lugging the engine in 5th. Ideally, you want the cruise RPM's to be between 2000 and 3000, preferably between 2500 and 3000. This is where the engine's running at its more efficient.

I know this is a different story with '82-'84 300D's, but my '85 runs at 3000 RPM at 70mph. 2500 would IMHO be perfect, but the engine's quite happy there.

JUMP ON THOSE 5 SPEEDS!!! As mentioned before, they're rarer than hen's teeth...

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2001 VW Jetta TDI, 5 speed, daily driver
1991 Ford F-350, work in progress
1984 Ford F-250 4x4, 6.9l turbo diesel, 5 speed manual
Previous oilburners: 1980 IH Scout, 1984 E-350, 1985 M-B 300D, 1979 M-B 300SD, 1983 M-B 300D
Spark-free since 1999