I want to rebuilt my manual tranny.
 

What im wondering is what are some of the things i should look out for as im rebuilding this tranny? its all alluminum and is there a guide/ parts list i can look at for hints? Thanks!

What is it and what is wrong with it?

Tom W

Its from a 1981 240d i do not know the number, sorry. Whats wrong with it is its starting to grind on second and fourth and i would like to rebuild it just so that i have something to do.

The much vilified Haynes Manual 63012(697) Mercedes-Benz Diesel 123 series, 1976 thru 1985 4&5 cyl has a section in chapter 7 showing some of the tear down of the inside of a manual transmission.
I bought mine used on Amazon.com (Ebay also has used ones) some times they are at the main library or even used book stores. You might be able to take a peek at one in the autoparts store and see if there is enough info for you buy one.
I have a 120 page book from ATSG (Automatic Transmission Service Group) that I bought on Ebay for my automatic Trans. the may also have books for manual transmissions.

Cervan, at least you have a manual tranny. I wish my W123 had a manual tranny.

Wow, you must be really bored.

When you get the prices for parts you might decide to get a good used one and rent a movie for entertainment.

I have an older 240d tranny that I replaced because of grinding gears and when I had my favorite machinist tear it down to see what went wrong he found nothing. We decided it was the shifter. It has been sitting in the corner of my garage for about 15 years. I think it has less than 150K miles on it.

I will sell it for parts for $25 plus shipping.

Tom W

tw is probably right- you are better off looking for another used one. I still see plenty of them pass by in the junkyards around here. You will find the older, cast iron one is more common and used on several earlier gassers.

What oil are you using in it? Perhaps if you switch to something like Redline MTL you might keep the synchros happier.

Rick

Syncros are about $100 a pop last time I checked. You are probably much better off buying a replacement and keeping this on the shelf until that one dies.

The manual tranny on my 240D 77 with about 350K was begining to feel a bit tired, slight grinding particularly when cold, shifter had lots of play etc.
Assuming that this thing needed an overhaul I priced the total cost at my repair shop, the mechanic estimated somewhere around $1k or perhaps a bit more, to replace all the synchronizers.
Last week I had my 240D in the shop for its big brake job, asked the shop to replace transmission bushings and they did, the mechainc said that the bushings were essentially gone.
The transmission now feels like a brand new, precise, no slop, shifts beautifully, no grinding, I am just amazed at this thing, it drived like a new car.

Vahe
240D 77 350k

Yes, a few pennies spent on replacing all the bushings on both ends of the selector shafts AND the bushings inside the selector "box" that sits on the tranny will make your car feel like new. I just used bushings I had lying around for everything except the one right on the tranny and it helped a lot.

Since you're looking for something to do, why don't you come on over to my place and replace the defroster fan in my '71 250C? That'll kill a day or so for ya!

I bought a 240d with a grind in all but 4th gear. I guessed it was a bearing on the countershaft, and I was correct. These bearings are standard parts and can be had for anywhere from $6 to $30, depending on whether or not you want to take a chance on a Chinese bearing off of ebay.
The Haynes manual is what I used to get it apart.
As luck would have it, at about the same time I found a bloke selling a good transmission for $85 on craigslist. I bought that and put it in my car. That was a much quicker way to get my car back on the road.
The old transmission is now a basket case, waiting for that new bearing it needs. I would also need new gaskets to put it together right, and expect that I'd pay more for them from a dealer than I want to pay. Maybe someday.
But hey, working on manual transmissions is fun! It isn't hard at all. If you don't enjoy this kind of thing, buy a new car and take it to the dealer every time it needs something.

No, it really isn't really hard at all to rebuild manual gearboxes. I have rebuilt two Triumph boxes, complete with Laycock overdrives. The issue really is parts pricing- parts for a Triumph box used to be fairly cheap ( whereas Benz bits don't seem to be)and it was impossible to find one in a boneyard that didn't need a rebuild. The benz boxes seems to be much sturdier and somewhat plentiful, if you are not in a big hurry and will accept an old iron case box.

Is the overdrive just a bigger gear or a 5thgear?