This may be a stupid question that's been visited many times here, but I'm gonna ask it anyway.

I know there are many of us that are unhappy with the slushy OEM TC in our cars - I am one of you. Has anyone ever come up with a replacement lock-up TC that would work with our cars? Are any of the newer TCs in the later model MBs that could be used/adapted to either the 617s or 603s?

I've seen the threads about adapting other manufacturers transmissions over to MB use, but never one on the lock-up torque converters. Seems this might be a way to improve mpgs & performance at highway speeds/

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1987 300DT
2002 Ford F-250 7.3 Crew Cab Short Bed

Complete 722.5 or 722.6 conversion might be comparable work and cost. The 722.6 must have a lockup TC. I don't know about the 722.5 which isn't fully electronic.

Sixto

Seems like a 700r4 or 2004r would be good candidates. Low first gear, OD. TV cable, no vacuum requirements... Cheap, durable...

No idea how it would act in our cars or if it would physically fit.

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My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

This fellow might make a kit for the 616/7 since there has to be a bigger demand to keep MBs rather than vintage Jags on the road - John's Cars - Broken Kitty

Sixto
87 300D

I think I read that the 722.5 uses the same converter and that there was a lockup version, but only on a certain AMG model. Probably not easy to put one's hands on.

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'82 300SD - Somewhere over 220k - Becoming reliable...

I've been doing a little reading. The lockup converter needs an extra solenoid to supply it with more fluid to lock, so even if one were to source a lockup converter, getting it to work on the earlier trans would have to involve modification to the valve body, plus switches to control when it functions.

The 722.6 has a fairy complicated tcu with adaptive learning, self diagnostics, limp modes, etc... I always wonder at these though: if all the decisions are made in the tcu and the wires from trans to tcu just represent sensor inputs and jumpers to activate various solenoids on the output. If so, one could just ignore the sensors and create a manually shifted auto easily enough, which would be kinda cool.

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'82 300SD - Somewhere over 220k - Becoming reliable...

Pow! Mercedes diesel info

I imagine that you'd be looking for a shorter rear axle ratio soon after the swap.

That looks good for those with a 616/617, but what about those of us with 603/2s?

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1987 300DT
2002 Ford F-250 7.3 Crew Cab Short Bed

The early mechanical 5 speed box does not have a lock up converter. As I understand things it's basically a 722.4 with an extra gear where the 2nd pump was.

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

Ah, didn't realize this was later engine specific. I've turned this over a bit myself, having a 603 of my own in the fleet. The 722.6 is the obvious choice. It's a full featured modern 5 speed trans that can be set up to handle what you throw at it. Somebody came up with some firmware to control it with the PCS trans controller, an "R. Drake INC", which is the major hurdle to overcome.

PCS - Powertrain Control Solutions - Transmission Control

Mercedes diesel info

You'd still have the driveshaft to deal with...

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My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

The crossmember, trans mount and speedo too.

If it would even fit the chassis. It's been done in W116 gassers.

__________________
My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

Driveshaft is easy. Just buy one of those yokes that bolt up in place of the flex disc flange and run u-joints like the rest of the world. I just can't really convince myself that running GM parts is in any way an improvement for a Mercedes - we've all got our prejudices.

If that PCS trans controller is so universal that firmware is the only differentiation between all those different transmissions, it lends credence to my feeling that these things are fairly simple in essence. Time to find a wrecked sprinter! Trans and turbo from the same donor!

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'82 300SD - Somewhere over 220k - Becoming reliable...

Yeah, most of the electronically controlled transmissions that I have direct knowledge of are pretty simple in operation, or rather, they have simple controls, IMO. If going the PCS controller route, I'd contact that Drake person and see if there is any info you'll need for trans selection. There is a yahoo group of folks who have made firmware to drive some later GM transmissions with one of the Megasquirts. This would be cheaper than the PCS route but it would require some serious skills and knowledge to make up some firmware to drive the 722.6. Here's a link to MS firmware page.

Automatic Transmission controller for Microsquirt / MS2 / GPIO

I haven't gotten serious about researching the operation and controls of the 722.6, but if I ever get to the point where I'm serious about the swap, would learn everything I can regarding the 722.6's shift and pressure control solenoids. The 5G-Tronic wiki page is short on specific tech info
5G-Tronic - Wikipedia, the free encyclopedia
The link at the bottom of the page is a little better
Jeep Grand Cherokee WK - Engines