There has been a lot bandied about on this top lately; some of it being
mis-informative. Having actually done this with a 1982 240D whose
automatic transmission broke, I think I can speak with some authority.
> The flywheel needs to be balanced to match the old one. On the 617 the
> flywheels are not neutral balanced, but balanced at the factory with
> the crank and harmonic balancer.
That is indeed what the manual says. The reality is somewhat different.
When the OM617 manual flywheel I had was messed up by a machine shop
cutting into the side wall when resurfacing the clutch surface, I had no
choice but to have it balanced by itself. I then put the flywheel on an
engine that previously had an automatic transmission. It's been working
fine for nearly 60,000 miles now.
> Note: the m617 has a different flywheel than the m616. While the 616
> flywheel is compatible, the 617 yields a better result.
Yes, the OM617 manual flywheel is quite a bit heavier than the OM616
manual flywheel. If you can locate one for an OM617 as I was able to, by
all means use it.
> I would suggest all new clutch components including the hydraulics,
The hard line that goes through the firewall can be reused and the rubber
hoses are cheap enough, as are new master and slave cylinders.
> have the driveshaft rebuilt by a reputable shop,
Yes. Most likely any stick shift driveshaft you locate will be quite worn.
And if you try to re-adjust the length of an automatic driveshaft, it will
be apart so there's no better time to replace the center bearing, the
staked-in U-joints, and the grease retainers. Note: there are very few
driveshaft shops that can balance the MB driveshaft because of the
arrangement of the flex joints on both ends. I used
Driveline Service of Atlanta (404) 361-9111
4652B Jonesboro Road
Forrest Park, GA 30297
> plus you will need to have the car re-aligned afterwards as the weight
> distribution does change and this will affect the wheel alignment.
The manual transmission is lighter than the automatic, but in my case the
OM617 was quite a bit heavier than the OM616. It does change how the car
sits.
> Also, while in the dash to replace the pedal block, I would suggest
> replacing all of the vacuum actuators for the klima. As you will be
> pulling the dash anyways, you might as well make the most of it.
There is no need to remove the dash to change the automatic transmission
pedal hanger to a manual transmission pedal hanger. While you're there,
though, make sure to get the parts to add the clutch actuated switch to
turn off the cruise control. It plugs right in just to the left of the
radio behind the left side of the console. If you don't, when you press in
the clutch with the cruise control activated, the engine will soar towards
red-line.
> Of course, shifter rebuild with new bushings all around too.
They're really cheap and make using the transmission a much more pleasant
experience.
> This is not a project for the feint of heart, but worthwhile if you
> fancy a stick shift. On a project like this you will not recoup your
> investment in labor or expenses should you resell, but for a keeper it
> is a fine upgrade.
I can't agree more.
> Researching the project it became obvious that MB uses different parts
> in a manual engine vs a auto engine. This is shown in the engine number
> (can't remember which one it is), so you may well have to strip down the
> engines and swap over the bottom end.
A naturally aspirated OM617 for a manual transmission has the serial
number 617.912-10-nnnnnn.
A naturally aspirated OM617 for an automatic transmission has the serial
number 617.912-12-nnnnnn.
>From what I saw in using 617.912-12-158157 (meant for an automatic
transmission) in my conversion, the only differences are:
- the manual transmission needs a pilot bearing in the rear
of the crankshaft which the automatic does not. The pilot
bearing, however, fits in with no difficulties.
- the manual transmission needs a different flywheel than the
automatic, with different mounting bolts. These, by the way,
are tightened to a certain torque and then turned 90 degrees.
They are stretched by this process and can be re-used only
a limited number of times. Buy new ones. They're cheap.
So, it is definitely not necessary to swap bottom ends.
> However MB may use a different diff ratio, so it may pay for you to swap
> diffs over as well.
You might double-check this. I went from a OM616 to an OM617 so I
definitely needed to change the differential. A four-speed manual in 4th
gear is 1:1, as is an automatic. In that case, changing the differential
would appear to be unnecessary. If you're putting in a 5-speed, you'll
want to check.
> One last thing, don't forget that you have to change speedo over as well
> I think or figure out if it is accurate with a 5 speed.
If you don't change the differential, you won't have to change the
speedometer. There is a "k" number written on the speedometer that is
correlated with the differential ratio (the speedometer drive is taken off
at the back end of the transmission). If you change the differential
you'll have to change the speedometer if you want an accurate odometer. I
lived in Austin, TX at the time and used
Rick Borth
Overseas Speedometer
100 Wallis Drive
Austin, TX 78746
(512) 329-8200
http://www.speedometer.com/index.html.
I drove to his place and talked with him. He's knowledgeable about MB
speedometers, so he can probably tell you what you need to do.
Hope that helps.
Craig
