Manual Transmission Conversion for my 1984 300SD - Page 2 - PeachParts Mercedes-Benz Forum

TylerH860 · #16 08-30-2016, 09:11 PM

Quote:

Originally Posted by Mike D

Darned shame you already sold the rest of the car. I've been looking for a 300D turbocharged 617 for my '81 300CD project.

I sold it to my mechanic who is doing the conversion like he's done this 100 times before. The motor is quieter than my 300sd and idles silky smooth, starts on the first crank. Everything topside looks dry including the IP. I'm sure he would be happy to do a compression test and sell to you at a reasonable price. 193,000 mile car.

cho · #17 08-31-2016, 05:50 AM

Quote:

Originally Posted by TylerH860

Thanks, looks like this one adapted well.

If a 5 speed ever pops up in my lifetime, I can swap it out. Wouldn't take much doing.

.

pops here

cheers

TylerH860 · #18 08-31-2016, 02:20 PM

Quote:

Originally Posted by cho

.

pops here

cheers

4 speed is already in. Let's see how I like it with the 3.08

Pirublues · #19 08-31-2016, 02:44 PM

This is exactly what I'm looking for. I have a modified om617 (vgt turbo, a2w intercooler, 15psi) with a 4spd manual in my 240d. It's fun and fast for what it is, but my 240d just looks like **** and doesn't have AC. Im looking for a nice 300sd or 300cd to swap my motor and trans into as one piece.

Can you or your mechanic email me the details?
What modifications did he have to make to get the swap to work?
Did he have to fab a transmission cross member?
Did the shift linkages have to be lengthened?

I'm capable of doing it myself but I liked to be armed with knowledge, things are easier and cheaper that way.

TylerH860 · #20 09-01-2016, 12:07 AM

Here is the comprehensive list of mods so far. My mechanic buddy is cruising right along on this.

Shifter Linkages lengthened 6 1/4 inch. Like yo mama said that quarter inch makes all the difference.

Shave pilot bearing to 1.33 inches. Lightly taps right in. The bigger 300SD has a tighter hole?

Cut away 126 trans mounts while keeping structure to mount the body, weld in manual transmission mounting points.
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I got really lucky with the driveshaft. It needs lengthened as well. Turns out a Generation 1 Honda CRV driveshaft barely slips over the Mercedes driveshaft. You slide the ends far enough so it will balance well and to desired length, then weld. It may need balancing, but probably not. My mechanic is a total genius for coming up with this one.

The 126 has an electronic speedo, while the manual transmission is a cable driven speedo. The W124 cable driven speedo fits the W126 cluster best, with the 1986-1989 300E being the closest match due to the similar rear-end ratio. The circuit board for the W126 speedo and turn signals are on the same panel. You have to cut out the turn signal part of the circuit board to fit around the cable driven cluster. There's no good way to mount the cable speedo other than with epoxy or JB weld. This has not been completed yet, but is documented by Sir Nik in another conversion thread.

Rooster300SD · #21 09-01-2016, 02:10 AM

Been following your project.
Nice documentation & pix.

I have a 300D manual tranny & 38# flywheel I pulled from PNP a couple
of years ago that's just been sitting waiting for me to retire or for my
auto trans to fail. Who knows which will happen first

I pulled the DL vibration dampener as well, which is larger than the one
on my 84 SD. Did you switch that over?
Also, (for others) I think SirNik told be that the crossmember from a W115 will work for this manual conversion.

Going to KC tomorrow to visit family.
If you were a little closer I'd swing by to meet and check out your ride

Jeff

iwrock · #22 09-01-2016, 01:59 PM

Paging SirNik!

TylerH860 · #23 09-01-2016, 10:00 PM

It's driving. Everything completely smooth. The driveshaft DIY worked perfectly. Now just sorting out the details, like figuring out how to get the cruise control to work.

Pirublues · #24 09-01-2016, 11:15 PM

The search for a clean 300sd is on. Thanks for posting this information!

gatorblue92 · #25 09-07-2016, 05:37 AM

I approve of this project.

Having both a OM616 with a 4 speed swap and a M103 with a 5 speed swap I can say you will miss the extra gear.

TylerH860 · #26 09-08-2016, 01:31 AM

All done. Made a video for you guys.

Welds are not works of art but are more than strong enough. I will watch them though.

https://www.youtube.com/watch?v=bVkl_rdmUSA&feature=youtube_gdata

Car runs around 200rpm less than with the automatic. The 4 speed works just fine.