Here is a comparison of the flywheels I have. Naturally the auto is on the left, the manual on the right.



These are the stock MB balancing holes on the flywheels. The holes in the auto flywheel are different depths The manual flywheel got poked full of holes it seems.

I did manage to find the indexing marks on both flywheels. The auto flywheel is first, manual second.




There was only one place I could go to in Santa Cruz that did flywheel balancing. GMP Speed and Machine, a hot rod shop. Pretty fantastic place where a lot of custom work was being done on cars from the 30s-70s. Price for a spin balance?.....$200...........each.

Yeah, that stings, especially since widening the search to San Jose didnt yeild much better. It was one of those moments...this wasnt something I could just skip and hope that things work out. Yeah, the price seemed high, but there wasnt an option of not doing this...It _had_ to be done. So you suck it up and take it like a man.

The machinist at the shop was of the impression that both the flywheels would be zero-balanced. If that was the case then there wouldnt be that much work to be done and perhaps I wouldnt have to pay for both flywheels and the spin/balance time (c'mon Mercedes quality). As it turned out the auto was off zero by 3g, the manual by 11g. The machinist mentioned that for American cars of the 60s-70s it wasnt uncommon to have drivetrain parts/assemblies off by 30- 40g or even more(part of the reason the speedshop had a full shop to work on engines of cars of that era). Comarative to that, German cars of the same era were precision machines. With little work to do, I got a $100 price break. Thanks mercedes.

Manual flywheel drilled out to be closer to zero balanced.



both flywheels with matched balancing marks



One thing that was a bit annoying was that the balancing marks didnt correspond to matching bolt holes. Ill have to live with the manual being off by a couple degrees. Meh..I think Ill manage.

Couple shots of the auto and manual bolts and the clutch alignment tool.





The auto flywheel bolts definely look like torque-to-yield bolts with the very narrowed shank. Not sure about the manual bolts however. The clutch alignment tool kinda sux. It says that its for chevy/volvo/mercedes, but its clear that it was molded for one of the 3 cars and not all. The splines have a taper to them making them a bit of a pyramid shape. The mercedes has square shouldered splines. The tool had to be modified a bit for it to work....sorta. The clutch is in so Ill see tomorrow just how well things are aligned.

Linkages are done as well.



For the eagle eyed amongst you...yes. Thats a coupler on one of the linkages. I managed to mung up the threads badly and had to regroup. Seems like messing up one of the linkages is a rite of passage for this swap so I feel welcomed.

I also pulled the hood from the car and removed the old crumbling-to-dust insulation. While int he junkyards looking at shifter linkage layouts I found a w123 with brand new replacement hood insulation. That goes on tomorrow.

Question to those who have done the conversion...how did you redo the wiring for the neutral safety switch and reverse lights on your cars?

Gavin

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Definitely a rite of passage! I managed to cut mine short and had to do the exact same thing.

Fortunately for me, the 240D was already manual so I didn't have to cut any wires for everything to work. The best advice I can give is to just look at the wiring diagrams and a manual 240D and use your common sense to wire it up.

HERE is the wiring diagram for a 1980 240D if that helps.

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Your work is very impressive.

My favorite machinist checked mine on his crank machine and did not charge me anything. If I had been a normal customer he probably would have charged twenty five. If he had had to balance them and not just check it would have been more but nothing near two hundred, I don't think.

Since my indie did the actual work, I don't know exactly what was done on the backup light wiring. I think it involved splicing wires.

Sorry you could not find anybody more reasonable.

Tom W

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Guess I missed that right of passage.

__________________
1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

Thats cuz you arent as cool as the rest of us....er, wait a sec.

Just to start this off, just a shot of a nifty find at the junkyards....



A brand new(used) hoodliner. It was luckily poorly glued on and didnt take much to remove it. Theres some 3M stuff thats supposedly "da bomb" for gluing things like this on and has a high heat tollerance. Ill admit, i kinda rushed things a bit and used a contact cement from DAP. It did say that it should withstand up to 200deg, so Im hoping itll manage with the underhood heat and not loosen its grip on the liner.


Ok so heres the final push to get the car running. First...wiring.

Forcedinduction...Thanks for the PDFs of the 240s wiring diagrams. That along with charmalu lending me his shop manuals made me realize that I should have kept up a bit more on electrical engineering classes. But all was not lost, I stopped being dense for a second and realized that I had all the blueprints for the rewiring in my hand.....the automatic transmissions neutral safety switch.

PS....As I figured the color scheme on my car is dissimilar that that in this example. The colors on the safety switch on my car were... Brown, Brown/Yellow, White, Red/Black/Yellow. With that, I pulled the safety switch off the side of the auto transmission and cracked it open(rivets mean nothing to a man with a power drill). This is what I mapped out..



Its actually a pretty simple rotary switch. Two switches actually, one activated at park the other activated as the shift lever is moved to the reverse position. Both switches are independent of one another. Basically, all I needed was a splice to the reverse light switch on the shifter and a jumper wire for the ignition/park switch enabling the car to start.

Cake.

I dont like splicing unless its absolutely going to be a permanent thing. I also like reverse compatability so I tend to use connectors for stuff. Who knows...in a drunken stupor I might decide to go back to the automatic.....yeah I know, pretty unlikely, but Im trying to justify my excessive work over just doing some butt splices and crimp connectors

Here is what I whipped up.



One has plugs for the reverse lights and one (one on the left)is for the ignition. I made it a bit long as I might finagle something with the clutch ignition switch one day. Right now there is no clutch override ignition setup and I dont really see that as a problem, but maybe one day Ill do something with it. Right now its just a really long jumper wire. The male portions are actually modified from stock. I needed the pins closer together so that they would fit into the original Neutral safety switch plug.

Like so...



I pulled the NSS plug from its place in the transmission tunnel and brought it inside the cab. Its now sitting in the kick panel to the drivers right foot. If I need to change the wiring its easily accessable. Parking brake light connectors transfer over so thats easy.

FYI: on the passenger side of the transmission tunnel there is a single wire that goes to the transmission and the kickdown switch thats under the gas pedal. In general its unused and doesnt need to connected/grounded or anything. I tucked it away and left it at that.

There were still some mechanical bits that needed to be sorted...like installing the transmission.

This went impossibly smoothly. Lie on back, lift transmission on chest, reverse crawl under car, lift transmission(damn its light) and affix on the back of the engine. No seriously...it was just as "hard" as what I described and took about as long as well. The crappy clutch alignent tool does in fact work....its still crappy though.

I installed new driveshaft donuts and bolts, got them installed as well. This took a bit of effort as the splines of the 240D front/300D rear were really tight. A mini-sledge and a block of wood helped to get things fitted.

Nice and lined up with the balancing marks. New boot on the splnes as well.



Modified transmission brace.



There have been a couple other methods of using the 240D brace. Going diagonal, cutting and rewelding...I got this post Manual Transmission Conversion Vibration - A Solutions from charmalu detailing alternate mounts. I found that you can get the brace perpendicular to the rear transmission mount and have the hole on the passenger side match up with the existing hole in the tunnel. It will still be very much off on the drivers side, but the brace does overlap an existing screw hole there as well. So I opted for using the stock mount hole on the passenger side and redrilling a new hole on the drivers side.

Doing so meant that there would be a pretty sizable air gap between the chassis and the outside of the brace where the but would be seated(the stock holes are flat to flat). I didnt like that too much as its possible that, with nothing to support the underside, over time the motions of the engine/transmission may compress that air gap a bit and then there would be a bit of slop, maybe a loss of tension on the bolt, bolt falls out, trans gets loose, mayhem ensues.

I used 2 of the thick washers that the factory uses in the stock location under the brace to eliminate that air gap and another on the outside of the brace. I needed a longer bolt to span that gap..I used an M10x1.5 turbo manifold stud from my other car(mazda). I figure a grade 10.9 turbo manifold stud will probably be strong enough in this application.

Shifter linkages.




They all clear and dont interfere with each other. It took a couple attemtps to get them set to the right adjustment. Its a little easier to do this while the driveshaft is out so you have enough space, but Im not that smart and did it the harder way.

I prebent the reverse shifter away from the trans tunnel as I thought there may not be enough room, but looking at it all installed there seems to be plenty of room without having to modify it.

(more on next post)

EDIT: asleep at the spellcheck wheel

Gavin

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Pedal assembly...



Two pedals are better than one.

I tried installing the whole assembly with the master cylinder hardline connected..um, that didnt work too well. Better to take it off and reassemble laster. Its also probably a better idea to install the rubber feed line to the master before installing the assembly(man its cramped down there in the footwell and under the dash).

Bleeding the master and slave was pretty easy surprisingly. I disconnected the line going into the slave and bled the master first so there wouldnt be as much air to push, connected to to the slave and then bled them together. After the fluid started getting clear of bubbles I just let things gravity bleed for a while topping on the brake fluid resevoir and then closed things up. Works great.

The "control unit" (silver box about 6"x4" that does.....something?) was connected to the cast pedal assembly mount for the auto at the same area that the clutch master cylinder on the new assembly. I had to move it elsewhere as it wasnt going to fit in the same location with the new pedals. The kick panel also needs to be modified to allow for two pedals instead of one.





So thats all the fun stuff. How about the not-so-fun stuff? Glad you asked. Lets see, lets start with the pedal assembly...

The brake booster connects to the brake pedal by a clevis joint... The brake pedal from the donor 240D has a small through hole for an M6 bolt. Nice and tidy. HOWEVER the 78 300CD has a much larger hole cut for it. That hole then houses a flanged metal bushing(that also goes through the clevis), and then the m6 both goes through the whole mess. Well, that left me with half of a full set with a bushing that was going to fit the brake booster yoke of the 300CD, but wasnt going to go through the new pedals.

You can kinda see the largish hole on the auto brake pedal a bit below the brake light switch.



The fix?..well, with the hybrid setup I just needed the bushing to be on one side of the clevis. It didnt need to go through the other side or the pedal itself, so a bit of dremmeling gets me a modified bushing that fixes this mismatch.

Stock bushing on top and the clopped bushing on the bottom, I only need the section I am holding.




Next issue....Square Peg, Round hole(or alternately known as...the speedo cable mess). So, I had taken it for granted that the speedo cables were the same in all of the W123s...yes you laugh.

So as the transmission is in and pretty much everything is buttoned up and the last thing to do is install the speedo cable and....



Thats right...its not gonna fit. Manual tranny is set up for a square shank for the speedo cable and the one out of the auto is a long rectangle. Awesome.

I suppose the "solution" to this is to get the speedo cable from the donor car as well if you happen to have a car that comes with the rectangular male end on the cable....but thats not what I did. I busted out the dremmel again and started grinding away at the speedo cable(which isnt easy as it spins).

The square fitting in the transmission is made of plastic. Its width is also thicker than the speedo shafts rectangle so I couldnt just grind down the rectangle to make a square. It wouldnt fit as it would be too small(or wouldnt fit for long until it wore out a larger hole and started spinning. What I did was grind the ends of the rectangle to a 45deg point. and then inserted it on the diagonal of the square. That provided a lot more meat to hold onto and made things more secure.

Hmmm..oh yeah, the car wouldnt start. w_t_f?

Imagine this scene...Ive been up since 7AM working on the car making a push to get it done, now its midnight (I think I ate something..maybe a banana?), Ive been knocking down all the st00pid mismatches that have been popping up, the car is finally all together, I press in the clutch(I originally had the ignition wired through the clutch...10-15sec of holding the clutch before the glow plug relay energizes?....lame)..turn the key when the amber light goes out and.......nothing.

Are you kidding me?

I try again, and again, same results. Not a crank, bot a buzz, not a sputter..nothing. Its late, Im beat, its cold(low 30s is worthy of being considered "cold" esp for California), I lack nutrition and any ability to do any more brainstorming...I call it quits for the night.

Next day I recheck my wiring(and fix the silly clutch-in to energize the relay thing)its all fine as confirmed by a quick trip to the junkyards to pull some wiring harnesses. Maybe a fuse?..# 14 (think it was 14) was blown, says its for the automatic?? replaced that and a couple others that looked like they had gotten some heat to them(discolored metal, but not broken). I check the 80amp main fuse on the firewall and the outgoing lead to the glow plug cirquit is really toasty, crispy sheathing and all that. The fuse looks pretty bad as well, not broken, but some heat took its tool on a lot of the parts. I swap the lead for a new length of multi strand 10awg, clean up the terminals on the junction box and install a new main fuse and......fires right up. Hooray!!

After that it was going through the gears to make sure that the forward/reverse gears actually did something, they did(rear end made a lot of noise when the car was in the air though, I changed the diff fluid just as a precaution).

So far we have put about 15 miles on the manual and it shifts positively, smoothly and without noise. The engine sounds quite a bit different though. Maybe the engine had some of its natural noise damped by the torque converter? Combination of engine/manual noise vs engine/automatic noise? The car is definetly peppier for sure, things actually go when you want things to go, the girlfriend likes this....a lot. The clutch still needs wearing in as it was pretty much new when it was in the 240D. Strangely, even thought the release bearing was also new it make a bit of noise on idle, maybe thats how they all are? There is a bit of vibration, but its at a very low RPM, almost at stall speeds. Its more noticable in 3rd/4th, but only at about 10-15mph in those gears, which really you should never encounter anyway. At real speeds, there is no vibration and actually at cruising speeds the car has less vibrations in the steering wheel than when the auto was in place.

Final shot..



Looks nice doesnt it?(no comments about the seat covers)

Its still uncovered at the moment. I did get a shift boot from Fastlane and, no disrespect to them as the price was ok and shipping was prompt......but seriously, have you seen that thing up close? Molded rubber? It looks like crap frankly. Im going to see about getting a generic leather shift boot and whip something up for the car. It deserves better.

Some things still need to be done...
-The afformetioned shift boot, the shifter has a bit of rotational play in it at the bottom piviot point. Ill have to find a shifter thats a bit tighter in that regard.
-The car sits higher because of the weight difference between the two transmissions. I have heard some people have swapped the 240D springs, but from a couple measurements the springs seem to be of smaller diameter, that is, they are a softer rate spring. Not into that. Looking at the stock springs I am going to go in an unconventional and sometimes contraversial route...I am going to cut a coil off the stock springs(oh the horror). The bottom most coil is a "dead coil" anyway. Its already in coilbind and serves no purpose wrt spring action at that point, so thats the plan.
-Will also need to do a fluid change in a couple weeks. The transmission is filled with el-cheapo ATF just to clean it out. In a little while Ill swap that out for Redline MT90 since I have a lot of that around.
-Check to see how things are settling in over the next coming days/weeks. That should be it.


Id like to thank all of those who have contributed to this thread over the past couple weeks. I consider myself a pretty competent wrench, but this was not my car, I had a short amount of time, this is my first swap/conversion of anything of this magnitude and I did all of this without the aid of factory service manuals on a car that can be somewhat particular. I have flown without a net before, but Im usually that adventurous on my own car. This forum and its members were a help, giving solid advice and direction where needed and made things a bit more clear about where I needed to go/what to do/that it could be done. Thanks to you all.

EDIT:1am posting=spelling errors

Gavin

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YOur work and photos look just first rate. I am concerned about the cross member under the tranny though. It looks like you have the tranny sitting toward the driver from center. On my cd we drilled two new holes so it would stay centered. If this is correct it should be pretty easy to remove the member and drill the new holes and reinstall.

Other than that everything looks better than it has to be....clean and everything!

Tom W

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I would initially say that I was pretty sure things were nice and inline with the driveshaft, but with a floor jack supporting the tail of the transmission and a lot of work to get the bolts in, its possible. I will check this weekend to see if thats the case. If it is I can readjust the mounting positions.

Gavin

I checked the crossmember this weekend. Loosened screws, let hang shook assembly a bit and then raised the crossmember with a jack. As it was the transmission and driveshaft were in line...BUT, it turned out that the crossmember was a bit clocked to the drivers side(Drivers side bolt was lined up but the passenger side was off by about 3/4"). I redrilled that hole and mounted the crossmember so there wasnt any torque on the rear rubber insulator. Maybe I am imagining it, but there seems to be less engine/transmission vibration now than with the old automatic. really smooth(er).

Funny thing, when the engine bay is clean it makes it easier to track down leaks. Go figure. Managed to track down a couple leaks from the power steering and under the engine.

Lastly.....



Got the shift boot on to complete the whole effect. Its just a generic leather shift boot trimmed to size and fitted to the underside with a couple brads, screws and a bit of epoxy. I think it turned out pretty well. Much better than that awful rubber thing thats supposedly the factory replacement.

The only thing really left is the front springs. The car sits about 1/2" higher in the front than it does in the rear. I was planning to trim a dead coil off the front springs but no one seems to have a coil spring compressor locally to rent. Ill take my time with that as its not mission critical right now.

Gavin

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Personally I would not touch anything for a measly half inch. Just replacing the rear shocks might do the trick. New ones will make it ride a bit higher because of the nitrogen in it.

I like your shift boot, where did you get that?

YOu're right the factory ones are nappy!

Tom W

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The FSM specifies that the flywheel bolts are one time use only, I read this after doing my install .

How many nubs are on the front and back spring pads? I do not suggest cutting them.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

I dig those pimp seat covers

__________________
2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
-------------------------------------
'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

I believe lots of folks do that on purpose, but I wouldn't. Prolly fine.

Tom W

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

You may very well be right on this it is a lot of work just for the small amount of height adjustment(anyone spot the irony here after I just went through a whole transmission swap?). Its the whole "complete the project" mentality that I have. Its the final point, but really...eh, maybe it can be left as is. Again, not mission critical.

The shocks are new(1 yr old at least) Bilstien HDs. The previous shocks were blown. Theres lots of speed bumps in the area and the GF likes taking them at speed.."see how smooth the ride is".. "yes dear" (mental note, change shocks ASAP). Im trying to cure her of that habit.

The shift boot is a generic thing from wheelskins (SBU01 black). They make a lot of leather steeringwheel covers. It was in a local truck accessory place.

Gavin

Speak to me about this.

Does the FSM actually say the flywheel bolts are torque to yeild? And if they do is there a spec that should be checked?

I did notice that the shank of the manual flywheel bolts are thicker than that of the automatic flywheel bolts. There are a fair number of flywheel bolts, lessening the individual load felt by each. The flywheel is of less weight than what would be offered stock lessening the outward forces being felt by the bolts(unless there is a 5cyl specific set of bolts).

Not to poo poo the FSM as it usually has the final word, but I have found that sometimes the information is er...overly protective?(not that this is a bad thing) The FSM for my mazda states clearly that the F2/F2T is an interferance engine. I have popped a timing belt and found that wasnt the case and others concur that it is not an interferance engine.

So what is my realworld exposure to danger in reusing the flywheel bolts? A little? A lot? Not to be concerned? dont take a chance OMGWTFBBQ!!? Just want to weigh the options.


SW...I swear to you, the seatcovers wernt my Idea

Gavin