I'm toying around with the idea of doing a manual transmission swap into my 1988 300E, and was wondering if I'd have to track down an OE 5-speed (impossible here in the states as far as I've seen) or if an aftermarket transmission made by someone like Getrag or ZF would work? I'd sincerely appreciate any advice anyone could give me. Thanks in advance.

Note - I'd also like to know if an aftermarket one can indeed bolt to the engine, what kinds of transmission mount modifications would be necessary? Would a custom driveshaft be in order? I'd like to start getting an idea of how much I'm going to be spending on this project.

Since I think in 1987 or 88 you could get a manual 300E in this country. You should try to find either a nice one to drive or a junk one to get all of the parts you will need.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

No five speeds with six-cylinder engines in '87, but there are a few hundred '86 300Es with five-speeds; '86 300E five-speed were "on allocation" so dealers had to take them whether they wanted to or not, and they didn't like this arrangement because very few customers wanted five speeds, so MBNA relented in '87 and just cancelled the five-speed, but brought it back as a special order item for 124s and 201s with six-cylinder engines in 1988.

All use the same basic overdrive five speed, and the same axle ratio as auto trans versions of the same model. A DIY option for the 190E is the direct drive five speed from the 16V, but it requires the 16V driveshaft due to different transmission housing lengths and probably won't install in a W124 without a custom driveshaft length.

The overdrive five-speed was also available on sixes in later years, but however you cut it, they are rare.

Your best bet is to keep looking until you find a six-cylinder five speed in a junkyard, preferably from a W124. Take everything associated with the clutch, shift linkage, etc. and probably the driveshaft too. If in doubt about whether you need the part, take it.

Trying to adapt some other five-speed to a W124 would be a major engineering project unless you can find someone who has done it and documented everything needed for the conversion. I would not attempt it.

Duke

You'll bolt the trans on after you install a clutch and possibly a new flywheel and possibly a different crankshaft.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

it is not impossible to find an OE 5-speed in the US, just extremely, extremely difficult. At leaset 1 guy on this board did it, using parts he got from junkyard (trans, clutch, clutch cylinder, flywheel, etc.).

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2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car

Your are going to need a very good salvage yard or a complete parts donor car in your driveway. Its a lot of bits and pieces that will run you high $ if purchased from a dealer. I put an 86 trans into an 87, was intelligent grunt work. Everything bolts up, no fabrication, welding, cutting, etc. You need everything: bearing that goes into the crankshaft bore (bore was already there on two automatic engines I've had out), flywheel, clutch, pressure plate, pilot brg., trans, crossmember, driveshaft, exhaust pipe bracket, shifter, rods, clips for same, back-up light switch, pedal cluster, clutch master and slave cylinders, hard/flex line for same, a few rubber grommets. Don't forget the wood shifter sorround (also different). When done, its a different car. 4th has the same ratio as the old automatic, put it in 5th and its got legs. Shifter throw was very long, had it modified, much better, but could still be shorter.

The 88's had a different shift pattern. I wanted the early pattern to match my 190.

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Hanno
'79 6.9 Sold (after 27 years)
'83 280SL, 5 spd.
'94 E320 Sdn. 5 spd conversion
'02 E320 Sdn.(on loan to mom!)
'87 300E (5 spd. conversion) Sold
'05 E500 Wagon

A little data and correction to some of the things said in this thread.

In the 86MY there were about 750 US 300E's with 5 speeds. In the 88MY there were about 300. The transmissions were different in 86 than the 88 models. Reverse was in a different location.

Even though the transmissions were different, I would expect that you could interchange them between the two model years as long as you had the corresponding shifter.

Since the M103 was used in some 201 cars, you should be able to use a 5 speed from a 201 with M103 engine. It should bolt up okay, but that will leave plenty of problems to solve such as driveshaft length and clutch master cylinder.

I personally would NOT do such a transplant unless I had the entire donor car that had escaped any previous salvaging, ready at hand for getting the zillions of little pieces off of that I would need to do this in such a way that it would not end up being a butcher job.

I have given thought to selling my 5 speed 300E. I rarely drive it anymore, especially since I now work at home. If I could get a premium price for it I might consider parting with it, but I really can't bear to see it go. The manual transmission 300E IMHO is an absolute gem. The 300E was a GREAT car with any transmission, but when you put a manual into it, you make a car that is just beyond description.

Good luck,

The 300E 5-speed is in fact a Getrag. I think the same unit was used in the 190's, and later euro 107's and 123's, so there are a fair number. Converting an existing car would be satisfying but expensive. A key thing to know is if the flywheel hub in an automatic engine would take a pilot bushing.

Concur with LB's comments. My 300E was a blast to drive.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Thanks for all the tips guys. I'll give it some serious thought before embarking.

How much of a premium are we talking? PM me so we can discuss this, because I love the W124 to death, and can't even imagine how great it'd be with a 5-speed.

Very likely

The driveshaft will most likely have to come from a 124. The clutch master cylinder was the same for all 201's and it's probably used in all manual 124's.

Good advice, especially considering the amount of time it would take to get all the needed parts, most importantly the flywheel.

Converting would be very satisfying, and if you can do the work yourself it'll be the price of the car and parts. The rear of the crankshaft in an auto 103 can accept the pilot bearing, if the trans. will need one there. The other possibility is for the pilot bearing needing to be installed into the flywheel, and you'll need to find a manual flywheel anyway.

BTW - no need to change the crankshaft.

IMHO, regardless of the shift quality or ratios of the 5-speed, the overall driveability of my 201 is much better with a stick than with the auto. I can imagine the 124 being greatly improved as well.

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1990 190e 2.6 - The only one I can really call "My Car".

1987 190e 2.3 - The donor car's up and running, only mods are Euros and a Sony headunit. My Dad's runabout now.

1990 300e 2.6 - The parents' ride.

Just any old 124 driveshaft would not work. It would have to be from a manual transmission car. Your best bet would be to have one custom built.

You cannot put a pilot bearing/bushing in the flywheel. The hole in the center is much too large. If the automatic 103 crankshaft is similar to the diesels I've seen, it does not have a pilot bearing. You will have to custom machine this item. Don't even dream about putting all this work and money together without a pilot bearing. If you do, you will be measuring the transmission life in minutes.

Again, the ONLY way that I would do this transplant is with the entire donor car close at hand. If you try it any other way, this will be a long involved project and will require having another car to drive while it is being done.

Good luck,

That's what I meant to say, I should have been more specific.
My experience w/ the 2.6 m103 in a w201 was that there are 2 different types of pilot bearings. The "older" version fit into the rear of the crankshaft (needs 2 of 'em). The "newer" version fit into the flywheel, and yes, it's a larger diameter than the one that fits in the crankshaft. My engine didn't have one originally b/c the shaft of the automatic has a larger diameter than the shaft of the manual.

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1990 190e 2.6 - The only one I can really call "My Car".

1987 190e 2.3 - The donor car's up and running, only mods are Euros and a Sony headunit. My Dad's runabout now.

1990 300e 2.6 - The parents' ride.

5 speed transmissions throught the model years remained unchanged, only the upper shifting mechanism has been changed. this is why the shifting pattern was different. All 1985-1993 260E, 300E and 300D transmissions are exactly same, I'm talking european models here, don't know if they went different to the US market.

My original transmission had the reverse next to 2nd pattern, swapped the shifter mechanism (diy job) with a sportline mechanism and now I have a dog-leg pattern just like in 16V models. Only if I had the closer ratio gears.

My next project: 6speed manual swap to my blueprinted and stroked 3.2L M103

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2001 E200 Kompressor Avantgarde
1987 300E 5-speed
1976 450SLC
1975 280S (sold)
1973 230.6 (sold)

You learn something new every day. I did not know that it was only the shifter that was different.

Also I had forgotten that I read a few years ago that the trans in diesels and gas engines of the same series are the same. That still probably means a different driveshaft length determined by chassis and trans combination.

Have a great day,

I recently drove an '86 300E with a manual transmission. What a dream and all the difference in the world from my '87 300E. This car had a new transmission but needed an AC compressor and had the original alternator. The car has been used as a tow vehicle behind a large motor home. It had towing rings welded to the frame that exited through the front bumper. They were asking $3500. By the time I invested in a new AC system (needed here in Palm Springs), a new alternator and a new bumper, I was looking at an '86 car with close to $6000 invested. The car has about 135K and I do not know what else was needed. The car had Texas plates but is currently in Colorado as the owner has something to do with the Colorado baseball team. I can probably find a phone number if anyone is interested.