OM603/717.412 5 speed conversion question
 

I'm collecting parts in order to convert my 1987 300TD to a 5 speed. The engine is the factory OM603 and I have a 412 transmission.

Question: What flywheel and clutch kit do I need? Is there a Sprinter kit that can be used? Do I need to have a beefier flywheel custom-made in order to handle the torque of the turbocharged OM0603?

I've done a lot of searching online but I'm not confident I found the answers I need.

Appreciate the insight -- many thanks.

Corvo Gold

The .412 is a single mass transmission so you need a single mass flywheel that can take at least a 9” clutch kit the sprinter kit is for a dual mass application there’s a guy at the 190rev.com selling a single mass 9” flywheel

What differentiates a single mass flywheel from a dual mass as far as the transmission is concerned? Just the input shaft/pilot length? And why wouldn't you want a dual mass with the higher torque/impulse of a turbo OM603?

You can't mix and match single and dual mass transmissions and flywheels because of the pilot bearing location. For what it's worth my om603 is hooked up to a dual mass flywheel/transmission with an 8.5" clutch going on 45k miles.

I have a lead on a used flywheel for a 717.411 or 717.412, as well as a Sachs K7001301 clutch kit.

Think it'll work.

Yep: can't mix and match single and dual mass. I'm hoping the action on the single mass won't be too rough or jarring.

Corvo Gold

In other markets non turbo om603s were sold with both single mass and dual mass flywheel depending on model year so I wouldn't worry about it.

Have you figured out your driveshaft solution yet?

Here's a question -- does it matter if the flywheel has the tabs for the crank position sensor? Pretty sure the OM603 doesn't need those, but will they get in the way?

As for the driveshaft, my understanding is that the solution is to mate the rear half of a 260e driveshaft to the rear half of the stock driveshaft. The longer 260e rear half compensates for the fact that the manual box is shorter than the automatic it's replacing. The flange coming out of my manual box should be fine since the box came out of a 190 2.6e.

I haven't been into these cars for very long so please feel free to correct me if I write something completely asinine!

Corvo Gold

If you want the tach to work and the A/C to work, you need the crankshaft sensor to work. If you have an emissions-restricted area that does smog tests, you also need the crankshaft sensor to work or the EGR system won't work.

The 603 uses the crankshaft sensor for a tach pickup. The tach output feeds various things on the car. You can always get creative and bypass some of the things that are tach dependent, so not a huge deal, but will involve some rewiring.

Thank you -- I did not realize that I need a flywheel with the sensor tabs; that is news to me. But why would that affect the functioning of the a/c?

Corvo Gold

The Klima relay operates off of engine RPM. No tach signal, no A/C compressor. You can bypass it with some wiring hackery and some relays.

The tachometer on the om603 reads off the teeth for the starter motor for the flywheel. Any MB flywheel will work for this. You don't need the timing windows (sensor tabs).

You have the right idea for the DS. You'll also need to replace the imput flange to the diff. You can grab the one from the 190e. You'll need a special 30mm deep thin wall socket for this.
http://i.imgur.com/u8pAFoMh.jpg

Now I'm obsessed with sensor flanges. I've seen flywheels with both 2 flanges and 3 flanges. Which is proper for this application?

Also, can anyone recommend a heavy duty 9" clutch kit that can handle the torque but won't be a bear use in traffic?

Many thanks,

Corvo Gold

It doesn't matter. Any of the flywheels will work because the om603 gets it's RPM signal from the starter ring gear, not the timing windows. 4cyl gassers have 2 timing windows and 6cyl gassers have 3 timing windows. Diesels have no timing windows. Later 96+ flywheels have 64 timing wibdiws. You can install any of the 4 types of flywheels on the om603 and your tachometer will work. Your diesel doesn't need an ignition timing signal for the engine to work. It just needs a speed signal for the tach.

Use whatever Sachs clutch kit was designed for you flywheel.

I used a 190e 2.3-16v flywheel (9" clutch disc) on my car. I found a clutch shop to make me a stronger pressure plate but if I were doing it again I'd just use a stock 16v clutch kit for starters and upgrade if it slips. On stock power it should be fine.

I actually have the driveshaft combo you're talking about out in my backyard. I'd be willing to part with it if you want. I ended up with a different shaft in my 5spd w124 so I didn't end up needing it.