300d - 4 Speed Manual Conversion
 

First, I want to start off and say that im new to the forum. I am 16 years old and doing my first manual conversion, so I may not know everything about being a mechanic. I have a 1981 Mercedes 300D W123 with the OM617.952 turbo diesel and auto transmission from a 1984 300TD wagon that I swapped in.
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I was at a local Pull'n'Save and found a 1979 240D W123. It had the 4 speed manual tranny. I have already read so much about these manual swaps and decided i'll pull it out. So one Saturday morning, my brother and I pulled everything we thought we'd need for a manual conversion and for $140 dollars, I had a manual transmission, Flywheel, Clutch disk, pressure plate, Cross member, drive shaft, pedal, and shifter assembly, with all the bolts for everything.
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School is out on Tuesday, so thats when shes going up and I'm going to pull the tranny. I have researched a lot about this conversion, but i dont really understand about balancing the flywheel to the crankshaft? I dont know how to find out if my flywheel is neutrally balanced.
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Any help or tips about this conversion would be greatly appreciated. Thanks a LOT! -David

Hmm strange that you would pull a good engine out of a wagon to put into a sedan....wagons are much more desirable.....and what did you do with the sls pump on the head?

You won't be able to use the drive shaft from the 240....you will need to shorten the 300's shaft.

The proper procedure is as follows:
1. Mark with a punch the location of the automatic flywheel on the crank.
2. Remove the automatic flywheel and get it checked for balance. If it is neutral the new flywheel just needs to be neutral.
3. If your existing automatic flywheel is not neutral then the new flywheel will need to be match balanced to it and marked to match the existing automatic flywheel and installed in the same location as the existing flywheel was.

The percentage of flywheels that are match balanced to the crank is small but the risk is great. If you happen to have a crank that requires the flywheel to achieve balance the imbalance will shake your eye teeth out.

Good luck.

Do not hesitate to check back here for additional information. When I was your age the only recourse was to tear into things and figure them out. With this forum you have hundreds of friendly uncles to help out.;)

Thanks for the replies. The 81 models didnt have the turbo diesel motor. It was introduced in 82. I pulled the motor out of a wrecked wagon i have as a parts car. For the SLS pump on the head, i took the pump off and cut out a metal plate that i drilled holes in and bolted over the hole. i used some gasket paper and silicon, and no leaks.

If the flywheel is neutrally ballanced, then I can just bolt it right up to the crank? or is there a certain way it bolts on?

...not until you mark the original automatic flywheel, remove it and have it checked for neutral balance. If it is neutral and the new flywheel is neutral then you are good to go.

How do i check for neutral balance? Machine Shops?

You need to match balance the manual FW to how the balance is on the auto FW. Look for a mark on the Crank and FW before you take it off the engine. If you can`t find a mark, use a chisel or punch to mark the Crank and FW. the FW can go on 12 different ways. there is no alignment pin etc.

I took my FW`s to a Hot Rod shop that builds street Rods etc... and understood about match balancing the fw. most machine shops will just balance the fw, not match it to the auto one. there is only one place here in town that does this.

You need the trans X mount from a auto 240D or 280E. the X mount from a 240D with a 4-spd is a different mount and won`t work with the 300D/617.

You will need to use the front section of the driveline from the 240, and have it cut and rewelded and balanced. take the rear section along with the front section to the DL shop. they replaced the center support bearing and the bushings in the ends on the shafts. think it was $300.

Sounds like you have been doing some home work searching and reading before jumping in on this swap.

Welcome to the forum, there is a lot of help here and resources. these swaps have been done many times.

Where are you located?

Charlie

Do I use the 240 pilot bearing? I know that the 85's have a different size hole in the end of the crank, but for an 84, will the 240d pilot bearing work? And i know that the shifter linkages need to be shortened. What is the easiest way to do this? I am located in Franklin, Tennessee.

Yes, the 240 Pilot Bearing will work.

Take a look at the bottom of the manual shifter. notice each lever has a hole, and on each side is a plastic piece with a "V". when the shifter is mounted in the car, place a appropriate size nail, drill bit etc... in the holes. this lines up the shifter in neutral position.

I unscrewed the aluminum ends and mounted them to the shifter levers. then mount the shift rods to the transmission. hold the alum ends horizonally and lay the rod on top. then mark the rod with a felt tip marker where you want it cut. (make note where the threaded end lines up before unscrewing the alum piece.) then rethread the end and screw it on. then it just a matter of tweeking the rods to fit.

Remember, measure twice, and cut once.

You are a ways from me.


Charlie

I believe the stick transmission is shorter than the automatic so the driveshaft will need to be made longer, unless you have an original 240 driveshaft that has not been shortened for the original 300 swap....if you have an original un-shortened 240 ds then it can simply be shortened.

When you swapped in the 300 motor did you also swap the radiator, speedometer and rear end?

Yes, when I swapped the motor and trans, I put the speedo, and rear end, I think it's the 3.07? I also bought a new radiator.

And I also bought the 240 driveshaft because it was $12 :P

You are set then!

Good work so far!

Well thanks! Tuesday is the last day of school, so that's when I plan to start this project. I'll try to post as many pics as I can so that I don't screw anything up. Haha