Hi there, here's a question: I have euro 280ce 4-speed that Im converting to a 5-speed from another euro 280 ce. It's puzzling that the crossmember for the longer 5-speed donor transmission does not fit on the recipient car? Is it possible the engine and drivetrain were pitched further forward in the donor car?

Do you have the driveshaft to compare?

Is the target body the same build date or newer? You car might have been built before the 5 was ever an option. If the build dates are close, they might have used up body parts from the 4 cars.

I know on a W123 when you do the 4sp to 5sp conversion the Cross Member is a totally different part number.




123 242 26 01

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What are the full chassis numbers of each of the cars?
Pics of the transmissions & crossmembers?

This is the correct part

Attached Thumbnails

 

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Thank you for that.

The recipient car is 1230531001961 from 1978. The donor with the 5-speed is from 83 or 84.

How the relatively wide crossmember on the long transmission could fit in the narrowing tranny tunnel is hard to explain -- unless it was bolted into the floor pan, which seems unlikely.

Ill get the number of the donor. (It's driving me crazy, but the auto shop doing the swap has mislaid the donor driveshaft, so I cant answer the driveshaft part of the puzzle yet.)

Finally,, there are four fixing holes for the tranny crossmember. The 5-speed would appear to need a crossmember using the narrowest set. Does that correspond with your piece?

I had not switched the bellhousing adaptor. My bad. Next question: the transmission shaft on the donor car side is different -- the splines appear thicker. I need a different clutch frictionplate .... but not sure which one

In MB-speak, the "adaptor" is known as an Intermediate Plate (IP).
In switching from an iron case 4-spd to an aluminum case 5-spd trans the method of centering the transmission axis to the crankshaft axis was also changed by Mother Benz. The iron case type is centered by a circular, peripheral ring between the clutch housing and the IP, while the aluminum case type is centered by a pair of dowels between the clutch housing and the IP. The early IP lacks provision for dowels, hence the IP from the donor must be installed, and centered to the crankshaft.

Re: Input Shaft
Measure the OD of the splines, and count the number of splines. Also measure the OD of the friction disc of the original installation, if that is the source of the flywheel and pressure plate to be used.