300SD Conversion to 4 speed Manual
 

hi all i am new here and would appreciate the advice, i am thinking of converting my 300 SD from automatic transmission to a 4 speed manual i have the transmission, cluch assembly,master and slave cylinders, drive shafts from the 240D, please advise if it is feasible and prctical.
thanks
bob

Hello and welcome to the MercedesShop. I have never heard of anyone doing this. I do not even know if the transmission would hook properly to the car. I do not know a lot about Mercedes, but I am sure someone here will know the answer to that.
Is there something wrong with your automatic?
I think it would be too costly to do.

thanks for the welcome Toni my car has 354000 miles on it with original engine that still is in very good condition does not burn oil at all and no other problems but last year the transmission gave up so i installed a used one from the junk yard and it been ok for the last 25000 mils but it flares between 2 and 3 gears plus i have 2 others with automatic so just wanted to have something diffrent i ahve driven 240d with manual and it is an experience so given the power of a 317 engine i think it would be nice to drive the SD with a 4 speed.
thanks
bob

Knowing the year of the car will help. A 300SD could be either a W116 or a W126. The swap is probably easier with a W116.

BTW, that's an OM617 engine, not a 317.

I would venture to guess that you'd have to fabricate a pedal setup, since AFAIK there was never a 126 sold in the U.S. with a manual tranmission (there's a couple Euro 126's with manuals, but they're extremely rare). I don't know on the 116's, though.

Beyond that and the shifter linkage, the biggest issue might be figuring out where to put the clutch master cylinder...

That's all that readily comes to mind; sounds like you have the engine/tranny side planned out.

Good luck!

Here's the thread I was thinking of. Looks like it was about converting a 300D, not SD.
http://www.peachparts.com/shopforum/diesel-discussion/24799-300d-manual-tran.html

sorry to have the year omitted it is 1981 300 SD 126 chasis the engine is 617.
i have the complete pedal set up froma 240D a flywheel and both slave and master cyls. clutch assy. i been told that it is very easy with a 123 chasis. the engine is 617.
thanks for the replies
bob

What makes the 123 easy is the fact that it was offered in Europe with manual trans... and they made the basics where you bolt on the manual stuff and sell it in Europe.. put the auto in and ship it to the US...
So check to see if you have the place where the clutch pedal would bolt to... etc.... but to be simple you may need to get the things you mentioned from a grey market or car in Europe.
Good luck..

i have been researching a project, putting a 300d turbo engine
in a 115 (because they are the coolest car :p ) and if possible
using a manual tranny. the only tranny that i know will fit is
the zf tx-18. the 240d uses the tx-17. the difference between
the two i dont know. the 300d turbo flywheel is 90cm in dia.
but the 240d & 300d is smaller and lighter. dont know that that
would be a problem.
the driveshaft should come from a turbo.
have been unable to locate a tx-18 new or used. they are
supposedly made in india by bajaj-tempo, an mb company,
but their web site is an email dead end. probably some other
car has used this tranny, but i havent yet found it.
if you can find he parts and have good hammers it should be
easy.

don

There was a old lady around there that was the neighbor of a friend I went to church with. I used to see her driving a 250SEL. I think it was a 250SEL or 250SE. It was the body like the 81-85 300SDs, but it had short/small bumpers. It sounded like an inline 6-cylinder. I remember walking by the car one day (it was often in the parking lot at the supermarket) and I noticed it was a manual shift car. I thought that was very strange- then I realized it must be a Euro model. So obviously some with that body style did have manual shift- just not the 300SD.

Check this out
 

This is a link that I found a long time ago... the only difference
is that this guy put the setup in his w123 instead of a w126.

well enjoy anyway!

http://www.dhc.net/~pmhack/mercedes/240d-300sd1.htm

I have a manual 240 and a81 SD and think that the SD is very well suited for an automatic if shift points are set up right and the turbo and alls it plumbing is working properly I don't think you would gain much performance with a manual.

I have done some engine conversions and though they look good on paper there is almost always some hellish unforscene problems unless the conversion is an often done one with parts and imformation at ready............
William Rogers.........

Both the TX-17 and TX-18 are of the same size and can be easily retrofitted to the OM616/617 engines and yes Bajaj Tempo India is still manufacturing both under license from ZF Germany. The TX-17 and TX-18 would roughly cost you $1100 new.

Since the W123 and W126 (with the OM617.xxx engine) both use a 722.xxx auto transmission, IMHO there's nothing significant to keep you from executing the same auto-> manual conversion on a SD. I'd be willing to bet that the W123 clutch/brake pedal assembly will alao fit in a W126. And, I wouldn't be surprised to find support cutouts already in the body for the manual transmission's rear crossmember/support.

But, it won't quite be a cake walk; there are a few issues you'll need to address:

1) The SD transmission has an electric speedo sending unit so you'll have to figure out how to mechanically drive the SD's speedometer (it might be possible to swipe the sender off of the old auto and adapt it to the manual replacement or, swap out the guts of a W123 speedo and install it in the W126 cluster)

2) Manual W123s use the brake fluid reservoir to supply the clutch master cylinder. Does the SD's brake reservoir have the same blind 'tit' to facilitate that connection?

3) You will defintitely have to fabricate a rear crossmember to support the back of the transmission.

4) The shifter may not be a drop-in and might require some modifications to the SD's body or the shifter to fit and work (just a guess)

5) Shifter rods will need to be lengthened/shortened. but, you have to do this on a W123 also

6) Driveshaft will need to be lenghtened.

7) An exhaust hanger will need to be fabricated.

8) The neutral safety/reverse light switch wiring from the auto tranny will need to be adapted to the manual shifter's interlocks.

If it were me, I wouldn't be doing all this on a W126; I'd do it to a W116...a much better looking car IMHO.

R Leo I sure agree on all points an SD is a wonderful hiway cruiser and still dose a good job in the city,I can see no possible reason to want anything but an automatic in them.

But a 116 or a 115 with a 617 and a manual might be worth the effort, I have a 86 Euro 500 SE with a Euro 420 engine,I could sure see a five speed and a turbo in it with its Euro supension and performance tires it might suprise a few SL's........
Any time you do a major conversion of any sort you need good shop space,three time the time you figured, meatal fab experence and plenty of tools.There is really nothing worse than a poorly done conversion to a nice car.........
William Rogers.........