Four-speed manual Transmission Rebuild
 

The four-speed transmission on my 1983 240D recently failed. The shop said it was either the clutch or I need a new transmission, but they need to drop the transmission to find out, which was gonna run me upwards of $400, just to tell me whats wrong. I decided to attempt the task myself, in an unheated garage with standard jack supports. I have a Haynes repair manual, which tells me how to remove the transmission. I have a few questions for anyone who can answer them and would greatly appreciate any advice.
1. It says to remove the exhaust system, do I have to remove the entire system, or just what's in the way?
2. It says to remove the driveshaft, do I have to remove the entire driveshaft, or just the front section? Is that possible?
I'll probably think of more on the way.

Just need to remove the front section of exhaust and its better to keep the driveshaft as one or you may mess with the balance. Otherwise its just nuts and bolts.

Be sure to paint 'witness' marks on all the driveline stuff... everything....

That 4 speed is not all that heavy to lower down W/O a trans. jack. only weighs about 60# or so.

If you need to remove the fly wheel for any reason, paint some alignment marks on it and the crank. or punch marks.

Charlie

Transmission
 

You can get used transmissions at Pull A Parts for under 50 bucks....
Sounds like the shop is trying to skin you for a 400 buck diagnosis....
Might take some searching to find one or may be best to attempt repair yourself...lots of folks here on the forum to steer you down the right path.....

I'd love to find a MB manual tranny for $40... Heck, for under $400!

What is the transmission doing or not doing? I believe a lot of the trannies are condemned, when it's really a vacuum issue or a replaceable broken part. Search around on here before pulling the trannie.

Well, it's no longer transferring power from the engine to the wheels and it's a manual, so I don't think there are any vacuum components in the transmission. My pop thinks it could be a blown clutch disc. The car has 250,000 miles, I have records back to 190,000 with no clutch replacement, so it sounds plausible. I don't think I'll need a new transmission. But right now I'm just working on finding the best way to remove the transmission. What are 'witness' marks? Just paint marks to remember in what position everything was installed? As for the exhaust, from what I've read elsewhere, it's a real pain in the arse to disassemble. I don't want to have to drill or hacksaw. Is it possible to remove the transmission without touching the exhaust, besides the bracket that is bolted to the transmission?

I've done the whole trans out thing about 10 times in the last 3 months and its easy.

You can leave the entire exhaust in place, and you can leave the driveshaft in place just unbolt it and push it up and out of the way.

I bet you a nickel that its the clutch. If your going to keep the car then I would suggest getting the clutch parts before you start the job, unless you can have the car idle in the garage for a bit and have a good memory of how things go back together. I did mine a few months back and it took me just over 3 hours outside in the rain by myself. So I would budget a day if you have not done this sort of thing before. Get yourself a clutch kit that contain the pressure plate, friction disc, release bearing the shorter style (I had the longer one and the clutch would not fully engage) and a pilot bearing.

The MB trans is really light and if you drain the oil first even lighter. I don't even use the jack for the MB trans anymore, I just lift it into place but I would not try that until you have done it a bunch.

Disconnect the battery first

Then undo the shift rods, all you need is a flat head screw driver.

Then unbolt the driveshaft from the rubber coupling and slide it back out of the way. If I recall it requires a 8 or 10mm hex and a 17mm wrench.

A 10mm is needed to remove the speedo cable (you have to take the bolt all the way out to get the cable out)

The clutch slave is held in with just 2 13mm nuts, spin them off and pull the slave back and then other the tranny and just position it out of the way.

Then unbolt the exhaust hanger from the tranny, and u bolt from the exhaust

Then there are a bunch of trans bolts all 17mm some have nuts other bolt into the block.

There are also 2 starter bolts that are I think 12mm hex.

Now you should be ready to put a floor jack under the tranny and support it.

Then undo the trans cross member and remove along with the trans mount.

Now the tranny is ready to remove, you may need to use a flat head screw driver to pry the tranny from the engine as it has two locating pins that are usually firmly in place.

Once the trans is loose about an inch from the engine and is supported, have a friend control the floor jack while you control the position of the trans on the jack.

It will take a little "back" and "down", "damn it, up a little....ok down again" to get the pilot shaft clear of the pressure plate. After that just lower it to the floor and pull it out.

You know I think there is a DIY in the resources section too.

Sorry - was thinking 4-speed automatic.

What about upsetting the balance of the driveshaft? Someone arleady mentioned that and I read further in my repair manual and it also mentioned it.

4 Speed Transmission fun...
 

Just mark the relationship of the trans. output flange,front flex disk and forward drive shaft...
Also mark the front and rear driveshaft sections in line with each other..if you have to remove it...(forward and rear driveshaft sections are splined together at the center joint...)
Also a good idea to replace that front flex disk while you have it down.....just re-establish front driveshaft flange and transmission flange relationship when changing flex disk....

Wasnt there a guy on the forum that you could ship the trans to and he'd rebuild it for you?

Well, I am nowhere close to affording that, I can barely afford the clutch kit

I'm having trouble with the driveshaft. I have removed the three bolts connecting the driveshaft to the front flex disc and am having muchos trouble removing the three bolts that connect the transmission to the front flex disc. Also, how do I move it out of the way? Do I have to loosen the sleeve nut to compress the shaft? If so, how big are those nuts?