603 into w123
 

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?

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.

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

Mounts might be a problem, go for it.

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?

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.

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.

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

http://i3.photobucket.com/albums/y74...uvasto0571.jpg

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

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?

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 :(

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

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

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?

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

Sixto
87 300D

One thing you can do is compare 123.133 and 126.120 engine mount arms to determine how far apart the chassis mount points are.

I think someone I know in this area has one or both arms off an SDL. That should help you visualize how big a job it'll be.

Sixto
87 300D

did you see the picture I provided? The finns basically offset the mount on the engine to fit the w123

There's about 3/4" between the arm and the block. How does this work on the other side? Or is the 603 block narrower than the 617?

Sixto
87 300D

Sixto, I need to see your car next to mine (assuming you still have the 124). Maybe at the GTG or sooner to see if this is realistic.

I figure that I currently average about 25 mpg, and can get an absolute max of 32, but a realistic max or about 28-29. I think with the 603 on the 124 gets probably an average of 28-30, absolute max of 39-40 and a realistic max of 35-36.

So add in a 5 speed with overdrive, and a taller rear end, and I see a realistic average of 40, a max of say 46, and could realistically obtain 42-43 mpgs.

Does this sound realistic? I am going to figure out the weight differences between the 123, 124, 617, 603, and the two transmissions.

I'm disappointed in the mpg of my car. It goes like stink but I get 23 city/28 highway and I don't have a particularly heavy foot. That's with winterized fuel. It should do better because the 93 SD 3.0 did as well and it took a heavier foot to get moving.

If mpg matters more than 0-60, a 602 turbo might make more sense. It should do 30 city easily with a 5-speed.

Sixto
87 300D

Possibly, but I'm thinking with a taller rear end, the 603 have more power and torque, so it will be easier to keep the rpm's down. Also, its not all about MPG's. I'd love the additional power :)

So my research of weights is bad.
w123: 3500 lbs
w124: 3400 lbs?
617: 500ish lbs?
603: ?
4 speed auto: ?
5 speed manual: ?

as for the mounts I would just get some thick steel plate and a stick welder and make my own. Easy as that and your done. Same for the tranny.

I think the 603 is heavier but not hugely. The stick tranny will make the weight comparable with the 617 with auto probably.

Personally I love the 617 and its robust simplicity. Get it right and drive for years with routine maintenance.

I had the 603 in my 350sdl. Great power, fair economy but finicky and not easy to get right and would not stay right once it got there,

My wxperience.

I would put in a 617 na or turbo the 307 or 288 rear and go.

I get 30 highway and 20+ in town with my 83 240/300d four speed with 397. Yesterday filled after running a full tank and got 22.6 all city.

Tom W