Topic: 240D manual 4 speed into a 300SD- Discuss!!
 

Have you done this? Do you know someone that has? I know someone who has all the parts needed to do the swap, except the drive shaft. It appears that a drive shaft from a w126 long wheel base would work. The 240D manual tranny is 6 inchs shorter that the automatic from the w126 300SD. My questions are:

1) What problems did you run into?
2) What did you do for a drive shaft?
3) How successful has the conversion been?
4) Would you do it again?
5) What else do I need to look out for?

My car is the '83 300SD. Donner was a 240D with ~150,000 miles on it.

Thanks for the help.

Also keep in mind that that the 240 engine is shorter than the 300 engine... I believe the final difference is actually around 4in, according to the often-done 300d swaps.

If you search you'll see that lots of people did it for the 300d, customizing the driveshaft/shift linkages, balancing 240 flywheel, etc.

As for W126, the LWB deal sounds interesting, but I would imagine that you'd run into more issues overall compared to W123 (will the clutch pedal fit for example).

A lot of people have done similar things.... and many have wound up with vibrations they did not want and have yet to find the cause of and correct.
Also, it is my theory that MB did not put the turbo with the manual transmission for one or more reasons.....many dispute my feelings on this...but are NOT able to articulate WHY MB thought they should not be put together...
Since I have read the FSM concerning the flywheels... I would certainly do everything possible to put a 300 flywheel on the 300 engine just like the FSM says to do...
Several have used the 240 flywheel and that MAY account for some of the vibration problems...

What is there to discuss? If you search for "auto manual conversion" you'll find several very detailed threads on this topic and many very happy converters.

Ignore leathermang on conversion topics, he must have something personal against it.

But that would involve no real time interactions with forum members.... only lonely searching in the archives... LOL

Yeah I have read but it is good to hear new thoughts. Thanks for the information.

Its not easy... First if you using an 85 SD, you are going to have to custom make a pilot bearing as the hole is 34mm in diameter rather than 35 mm. Second you will have to do alittle cutting on the 240D pedal assembly, There is no upper hook so you will have to cut that off. The pedal height is different but its managable. You will also have to live with just the 4 booster bolts because the W126 brake pedal assembly has a bracing arm that extends downwards.
The shifter does bolt in but is very short for a W126 console, you will not be able to use a 240D shifter boot or console section The shift rods are all much much too short, so you will have to make new ones.
Now the hard parts. The speedometer in a W126 is electronic, the 240D manual uses a cable. I cut up the W126 cluster to install a W124 Speedo head, you will have to come up with your own solution.
The driveshaft will have to be lengthened, I thought I could use a SDL driveshaft in a 500SEC but i needed to be lenghtened 2.25 inches. I was able to use the 240D trans mount and bracket by drilling extra holes in it.
The clutch hardline had to be made custom because the 240D one did not fit.

Thats pretty much it, Results, its ok, no I wouldnt do it again, I used a 240D flywheel that was suposedly matched to the flexplate, but its not and i have a bad vibration around 1600 rpm and at idle. which is currently set at 850 rpm. I cant start the car on a big hill because I used a 2.24 differntial.

I am going to balance the driveshaft and replace the diff with 2.47 and see if its easier to drive.

So as you can see by the list of stuff I mentioned its alittle more involved that a 300 D conversion.

Not it isn't. The 951 and 952 are the same.

IceFire, Thank you for that very informative and honest post.

That is a very different job than what we used to seeing..... doing this to a 123 where the factory also installed the manual trans in the same model... pretty much a bolt in situation if the donor and patient are both available...

Manuals were also available in the 280SE.

280SE... wouldn't that be a 6 cylinder gas engine with fuel injection ?
Are you saying that would fit something referenced in this thread ?

crashone has a 300SD. Last time I saw one in person, a 280SE was a W126 too.

I just saw this...

There are also many who have vibrations they can not find the cause of..

AND more importantly ... you NOT being able to explain why MB did not put the two together leaves a big chance that my objections are correctly derived from a problem in the nature of PHYSICS involved....and not personal...

You are wrong, in 1985 there was a switch, Please see TOMJ 's swap threads,

I have a 1971 280SE sitting in my driveway...but I don't look at the other numbers often..

Please note there are some W126 manual transmission cars, mostly grey market, You could get a 280SE, with a 4 or 5 speed, If you could find one of these cars you could get around many of the issues I posted. The pedals would be direct fit, the shift rods direct fit, the speedo, driveshaft, flywheel etc. I was posting my results with using 240D parts in my W126 coupe.

Since you have an 83, you will probably not have the same pilot bearing issue that TomJ and I have had.

Good luck if you decide to proceed.

You only don't know the cause. Everybody else knows the cause as harmonic resonance and the simple solution is to not lug the engine in that revv range.

No, you are the only one that can't grasp that the combination was not sold here for MARKETING reasons.

The OM617.91x was sold with a manual transmission. The only difference the transmission sees between a 91x and a 95x is torque input. As proven by myself and many others, there is no physical reason why an 95x cannot be mated with a manual transmission with great success.

Please note that what you are quoting applies ONLY to late 1984 to 1985 engines. 951 and 952 makes NO difference. My engine block is an early 1984 951 (300SD) so I know for absolute fact you are incorrect since I use the standard 240D pilot bearing unmodified. Since crashone has an 83, none of that applies to him.

Do you not know how to tell a W116 and W126 apart? The difference is pretty big.

Forced, in my original post I didnt mention 951 or 952, I mentioned specifically 85 300 SD, So you are in fact agreeing with me in regarts to the late 84 & 85 OM617s requiring a different pilot bearing, but in your own smartass way. If you read my post you could not possibly disagree with me. it doesnt matter I shouldnt have even bothered to mention it since the original poster is using an 83 SD. We arent even disagreeing you just misread my post.

Exactly.

We are talking about the combo of turbo and manual transmission..

Lets assume you are correct about the reason it was not ' marketed' here in the US... cultural differences....

But that does not explain why that combo was not offered ANYWHERE in the world by Mercedes...
it was offered by others at times.... but the type of turbo and the type of injectors may have played a part in its acceptance...although I am not sure if the combo is still being offered even by others...

But the ability of the automatic trans torque converter to work fine without excess wear in getting the car going while the engine is winding up to the point that the turbo kicks in does...

Really? :confused:

I am correct in this case.

It does actually. USA got almost all of the 617.95x engines produced with the exception of the option for one in the 300TD. The 300D was the high-end W123 offered in the USA. Americans don't want a manual in the first place let alone in the high end luxury model. Europeans are different in that the 300D was a utility car and they do prefer manuals but high-output engines and expensive cars are heavily taxed. Nearly every turbodiesel MB has sold in Europe, with the exception of the high end models, has been offered with a manual from 1987 on.

It makes economical and marketing sense to everyone but you.

"Others" are not Mercedes.

Not in the least. The ONLY difference between turbo and non turbo injectors is 20bar pop pressure to make up for the difference in combustion working pressure (torque).

What combo? Turbo diesels and manuals? Nah. Only every semi in the USA, all the Dodge/GM/Ford pickup diesels, VW's diesels and almost every one of MB's diesel models in the rest of the world. MB does not sell any diesel manuals in the USA right now for the exact same reason they never have here, marketing.

No, that makes no sense whatsoever. Clearly you have never driven a turbocharged manual before. The clutch does not need to be slipped until the turbo kicks in.

I gotta agree with forced on this. They weren't offered with the turbo for marketing reasons...period. I can see no reason technically or mechanically.

Very interesting that yall can only give examples of other makes... or other type vehicles... or later models....

Then are sure that retrofitting this combo to the 1980-85 diesels is just hunky dory.

Then there is the potential problem of the balance of the flywheel to the engine. It is possible by accident that a retrofit flywheel can be placed on the engine and be the same position needed to work properly .... but having read the FSM concerning the care they prescribe even just replacing a flywheel on an engine which had a factory installed flywheel I would be concerned with following the instructions.... which are very explicit for some reason which I assume yall attribute to the instruction manual department filling up pages to justify their jobs....

OF those that have done this we are still working with a relatively short reporting time...and have to factor in whether people who get disgusted and sell or undo their project machine are likely to come back and report on their dashed dreams of the perfect car... and we are working with a very small ' N ' to begin with for a competent study of the situation.

I have done my best to describe what I consider are the potentials for problems... yall are SURE of things which I have not seen evidence of... things which may actually constitute urban ( Mercedes ) legends made up to try to explain the situation after the fact.

The Mercedes people had very high standards.... their marketing and research department may have decided that while the car CAN be started up from a stop without slipping the clutch that many people would not want to accept that compared to being able to floor the accelerator .... that their reputation for putting together great cars would be at risk...

Please read again.
All of MB's vans, A, B, C, G, entry level E class models are offered with a manual. MB doesn't sell the E or Sprinter in manual here for marketing reasons even though they are both offered in manual elsewhere.

No there isn't. Its either neutral or slightly off balance. A match balance by a machine or race shop can make the manual flywheel the exact same balance as the flex plate.

4 years in my case, 5 in Randy's, almost 7 in Tom's and a few years for others is short? Tom has been using his for as comparatively long as the 617.95x was in production!

I have yet to see or hear from one.

"Not seen" and "not looking" are not the same.

The Americans don't so Mercedes determined what most Americans would want, power and automation. Simple as that.

So please explain why no 300D here was sold with a manual climate control or manual windows despite both early and late W123 bodies being sold with it elsewhere in the world and its 100% bolt-in? Thats right, marketing.

I have a very minor secondary vibration at certain rpm in my car. I think that that is characteristic of the five. I wouldn't be surprised if Mb decided that 'mericans wouldn't accept that in a high end car....and I bet they were right....back then.

In my case there was an additional flywheel thingie attached to the donut on the back of the tranny which my indie left off when they installed my five speed. I imagine that that would help minimize the current vibration that I am experiencing.

These are old and not too valuable cars now. Any way folks can keep them on the road is a good thing. Stick conversions seem ideal to me. Mine is far from stock but it is running 99.99% all factory parts.

MB didn't build them this way.....but I did.

WHHOAAA!!! 2 pages of discussion!!:eek:

Thank you, I knew a w123 to w123 was bolt in, but I was not sure how a w123 to a w126 would work. It sounds like some custom cutting and welding will get it done. I did make up a drive shaft for a 190D w201 5 speed conversion last year that is still woking so I guess I can try a w126 shaft.

Hopefully I will be able to change the '83 differential out with an '85 while I'm doing this. It won't be done overnight but maybe soon.:cool:

My main objective is to have some fun and end up with a 26 year old car that gets better fuel mileage than these new pieces of crap they are shoving out the door.:D

Tom, I seem to remember a change in the flex joints mentioned for the five speed trans... it might have been a later TSB as compared to in the manual... I do not remember for sure... that might take out that last little bug...when I find it I will send it your way...

The euro 300D has that damper. A call to the Classic Center said they are no longer available and the repair for a cracked one is to leave it off.

Thats good to know.

Greg, what is a TSB, please?

A TSB is a Technical Service Bulletin .... a little update from the factory to dealers ( and now available from places like ALLDATA telling what the factory suggests for fixing some problem they have been made aware of...
You can access just the TSB Title several places... then they want you to buy the service to get the whole picture.... but you can get the Title and number of the TSB and then go to the dealer and ask for the specifics..
Our old cars have hundreds of them each... some are general like recommendations for servicing auto trans... but some are really specific ... like engine number X to Y.....

Oh, of course, thanks Greg.

Tom, I found what I was thinking about... but can not say I understand it...and it is spread over several pages... so I can't scan and post right now...
but it is in the chassis manual number one for the 123 page..

On radially or tangentially soft companion plates on the driveshaft... one looks like it is warped and should be replaced..but is actually just made that way... the dates used, the front vibration dampner, all these things are hard to determine with the way the manual is written. but some combo might solve some people's vibrations... clearly there were factory installed vibrations which MB was doing everything it could think of to eliminate.

There's a lot of good information here.

Now how did you guys handle the driveshaft? I have cut and welded one for a w201 but they are shorter. I am planning on doing the same for this w126 conversion if necassary.

Thanks for the information so far.

mine was lengthened at a shop for less than 200 on my 82 300cd. On my 83 I just swapped in the entire drive train from the euro, then not long after that I swapped in the 307 diff. (and speedo)

I've used Triangle Driveshaft for all of my engine swaps (non-Mercedes) and they always do a perfect job. They're up a little North of Durham.