201 Auto-to-Manual Tranny Swap
 

(Prelude: I've searched the forum, and got lots of great information, but not the answer to this particular question regarding fit between early and late model 102 engines.)

With that being said... I have a '92 201/2.3 with automatic transmission.

I found an '84 or '85 201/2.3 sitting in a parking lot with multiple dents and two flat tires... and it has a 5 speed manual transmission.

Will the tranny from this early model 201 be a direct bolt up to my late model 102 engine? I'd love to have a manual tranny in this car.

The only way I would even consider this as a project would be if I have an entire donor car (so that I have all the little parts required). So this car sitting abandoned really caught my attention.

Thanks in advance for your feedback.

Jeff Pierce

IIRC the early 2.3s have a different five-speed than the later model 2.3s. The early 2.3 five-speed is "lighter duty" than the later five-speed that was shared with the six, and the giveaway is the slightly different ratios. For example, the early 2.3 five-speed has a 3.91:1 first gear, whereas I'm pretty sure that the later model 2.3s had a 3.86 first gear that indicates the higher torque capacity box that was used with all M103 powered 124 and 201 six-cylinders.

In spite of this, I think there is a pretty good chance that all the parts from the doner car will bolt up, and having the entire donor car is definitely the way to go.

The one thing that can really bite you in this kind of conversion is the crankshaft if it doesn't have a provision for a pilot bushing. Check with a Mercedes dealer for the part number of the 2.3 crankshaft? Is it the same for an automatic and manual transmission? If not, then I think it may be a show-stopper. Even this may not tell you the answer. It's possible that in production crankshafts for autos aren't drilled for a pilot bushing, but all service crankshafts are so they fit both applications. A similar situation exists for radiators. Original manual transmission radiators do not have a provision for a trans cooler, but the service radiators all have that provision, so one service part fits both applications.

Duke

P.S.

I just checked my Model year 1984 manual, which has a good overview of the M102 engine. Though nothing is specifically stated, the cutaway drawings and photos don't show any obvious differences in geometry of the crankshaft end. The end is configured for a ball bearing pilot, and with a flex plate for an auto trans the ball bearing is simple not installed leaving a rather large center hole.

If you do the swap I recommend you buy a new pilot bearing rather than trying to remove and install the old. Also, carefully inspect the clutch and flywheel. Measure the flywheel for flatness and have it trued if at all in doubt. A new Luk clutch kit is not very expensive, so I would suggest buying a new kit. Given the overall condition of the car as you report I would imagine that the clutch is not in good condition. Same also applies to the hydraulic components. A new slave from Fastlane is only about $50. Not sure about the master, but be sure to disassemble it for inspection and rebuild it with a kit or buy a new one. This car is over 20 years old, and I doubt if it's had rigorous clutch fluid change maintenance, so I would bet that the hydraulic components are living on borrowed time.

Good point by Duke, as usual.

I'll just add that when they ask you "which year/model?" when you go to buy the new pilot bearing and clutch parts; use the year/model of the donor car. That may be obvious to most people, but I ran into some unforseen issues b/c I mixed the years up.

I would go for the swap! YOU will need the front section of the driveshaft from the OLD as well as they used a smaller dia. flex-disc.