603 into w123 - PeachParts Mercedes-Benz Forum

Boardmonger · #1 06-09-2008, 08:38 PM

Hey, so I'm looking at the possibility of a future project, and was talking about this with Garrett, and was wondering if anyone here has tried this. I've seen one of the Finn's cars with it done, and it was crazy, but I was wondering how difficult the swap would be. Obviously the motor and tranny, but what about other details? Like would the speedo cable from a 124 transmission work on the 123 cluster? Same with the tach amp and coolant sensors and all that good stuff. It wouldn't be an over night project, but I think the gains would be huge, both performance and efficiency wise, not to mention the idea of a much easier swap to 5-speed. What do you all think?

#2 06-09-2008, 08:41 PM

The 124 does not use a speedo cable, it uses an electric sender.

The only 123 to have an electronic speedo was the 1981 300TD.

Johnhef · #3 06-09-2008, 08:46 PM

Not quite- all 124's I've had clusters out of have the cable. The 126's have the wire.

babymog · #4 06-09-2008, 08:56 PM

Mounts might be a problem, go for it.

Boardmonger · #5 06-09-2008, 09:01 PM

yea, its the 126 w/o the cable, all 124's (and 201's) i've seen have the cable. I just don't know if it would work.

I figure mounts might be an issue, though I'm not sure how off they would be. Are the differences between the 300sd and 300sdl's that big? I don't think i've seen the 2 side by side, but that would help. Anyone have any pictures of the mounts on each?

Johnhef · #6 06-09-2008, 09:21 PM

I toyed with the idea of putting a 603 in a 300CD before (Im sure I posted about it too if you search) but after the deal for the donor car fell through I scrapped the idea.

How about just using the 124 speedo in the 123 housing? might fit with a little modifications I would think.

Boardmonger · #7 06-10-2008, 08:46 PM

yea, thats what I was thinking, but the shape of the two is a little off, and for the perfectionist in me, the font is just a tad different.

TheDon · #8 06-10-2008, 09:04 PM

I wanted to do the same thing, almost had an car to do the swap

here is a pic of the passenger side engine mount of a finnish w123

sixto · #9 06-10-2008, 09:44 PM

Zack, you can do better than a 603 -

http://www.offroad.no/forum/index.php?act=Print&client=printer&f=51&t=85980%C2%A0

Sixto
87 300D

Boardmonger · #10 06-10-2008, 11:24 PM

sixto, maybe, but there aren't the manual transmission options there. 5 speed is a big draw on my part. Is that finn mount just sitting there on the wheel well basically?

TheDon · #11 06-10-2008, 11:26 PM

IIRC the 5 speed from the om602 will bolt up...

I found a 603 in my area for 1k, including the car.. but it's a non runner

sixto · #12 06-10-2008, 11:29 PM

606 block is almost indistinguishable from a 603 block. I'm sure a 5-speed that will bolt-up to a 603 will bolt up to a 606.

C'mon, what's another $4000 towards this project?

Sixto
87 300D

sixto · #13 06-10-2008, 11:33 PM

Oh, you'll need a 603.97 sump if the 123 crossmember shares space with the 603.96 sump side extension. AFAIK an M103/4 sump will work as well. My 603.97 came with a 104 part number sump. EPC shows a 104 prefix oil pan gasket.

Sixto
87 300D

Boardmonger · #14 06-10-2008, 11:34 PM

Another $4000 is big money, and I don't know that economy would pay for that very quickly.

Ok, looked at the motor mounts again, and they look spot on, but the above photo looks like the arm was bracketed on.

Don, any more pictures of that car?
So other big hurdles seem to be the steering box and the power steering pump. I'm sure the later 124 pump could be used, but would the steering box fit in with the 603?

sixto · #15 06-10-2008, 11:38 PM

We need a PNP run to see engineless 123 and 126 side-by-side.

Sixto
87 300D