722.416 trans vs. 722.303
 

i'll be taking my engine and transmission out in about 6 weeks to fix my rear main and was hoping to take this opportunity to work out my transmission conflict. before i owned my 85 300d cal. someone replaced the motor and transmission with that of a 84 300sd leaving me with no way to count miles or tell how fast i was going. i have the old 722.416 that shifted fine 7 years ago but spent at least 3 out side in the elements on its oil pan like it was dropped from the car. is it possible that its worth putting back in? or does anyone know a way to hook the 722.303 to a electric speedo and tac?

Ask Paul (mach4). He has a way to make your speedo wok.

I'm confused by what you're trying to do...

You have an '85 300D chassis which would have come with the mechanical speedometer.

In that car, you have an '84 300SD engine/transmission which would have come with an electronic speedometer.

You rightly point out that reinstalling the original 722.4x transmission would restore speedometer operation. (And I actually think that despite sitting out for a few years would not be problem, provided the torque convertor was fully seated and the dipstick was fully seated.)

So if your question is "how can you replace the speedometer head with one from an SD so it will work with the currently installed 722.3?" I'm not sure if that's possible. I think the heads are different, unlike other components like tach, oil pressure, fuel gauge, coolant temp, clock etc, which can be easily swapped from cluster to cluster.

Now if your question is "how can you replace the tailcone on the 722.3x transmission to go from electronic to mechanical?", that is theoretically possible, but in practice I don't think it will work. You can physically swap the tailcones (in fact I did this on my 617 -> 107 swap to convert from mechanical to electronic) The problem is that the mechanical tailcones have an oil squirter to lubricate the speedometer gear and I just don't know if the two are interchangable going that direction. (Stretch might know - he seems to be the tranny specialist around here)

On the tach side, your 85 gets its tach signal from the EGR controller (believe it or not) based on a signal that comes from the bellhousing (a VR sensor reads the flywheel teeth and feeds that A/C signal to the EGR controller) so you're kind of out of luck, unless you want to go to all the trouble to get an '85 intermediate plate and swap that in. Since you're working on the rear seal, this might be an option. Otherwise, you'll need to get a tach amp and install that along with the appropriate wiring AND swap in a tach module from any vehicle that uses the tach amp setup. (The tach amp gets its signal from a VR sensor and a tooth on the harmonic balancer.)

Go spend a couple hours at the junk yard looking at the various speedometer modules and see if you can find one that would fit (or could be modified to fit) your cluster.

If you can find an electronic module you can get it to work with most any transmission by using an externally mounted VR sensor and modifying the driveshaft to serve as a trigger wheel. (Here's a link to a pretty comprehensive discussion - http://www.peachparts.com/shopforum/diesel-discussion/312801-mechanical-electronic-speedometer-conversion.html

Good luck

Some 1985 300TDT (wagon turbo diesel) 123.193 chassis were fitted with 722.303 transmissions and electronic speedos

I'm not sure what type of speedo connection is on the 722.416 though...

Mechanical

to clear it up. someone change my signature. i dont own a 84 300sd, i own a 85 300d that someone has put the engine and transmission from a 84 300sd into. its a real pain in the butt, i would like to know how many miles I'm putting on the car and was wondering if anyone knows how the the 722.3 transmits the seed to the car. my understanding is the 126 had abs and therefore does not have a mechanical seed sensor. can i wire an electronic speedometer directly to the sensor or does it require the abs system?

Also, does anyone think the old 722.4 is possible any good at this point? i know an engine can sit for a few years and still be fine, but i know very little about automatic transmission.

Right I get it.

Mechanical speedo in dash - electronic speedo connection on 722.303

As you have the 722.416 that could be the solution - but why it wasn't used in the first place is a mystery to me. Could it be bust?

You say it has been outside for 7 years? I guess it will be dead.

I'm not sure how advanced the electronics for the electronic speedo are - it might be as simple as the tachometer - ABS isn't necessarily a problem but the biggest one is finding a W123 1985 electronic speedo => all in all I fancy your chances of finding a good 722.416 or a 722.315 more than I do one of those...

The 722.3 only has 140k compared to the 216k on the 722.4. Dropped the pan on the 722.4 and found what I feared. Water and white slime, will up load pictures.

wont let me up load the one of the white stuff. but the first one is of it after i used greaser on it.

White stuff is emulsion - that's a combination of water and oil (trans fluid).

That transmission is gone.

Transmissions need to be 100% free from corrosion on the insides and to be surgically clean inside too. Any sort of corrosion - made by water ingress - will have buggered it beyond repair especially after 7 years outside. If you had just driven the vehicle into a lake and were now pulling the transmission to pieces to save it you might have been lucky - but 7 years outside - sorry that's dead.

I also wouldnt waste my time trying out that water-logged trans...

Its not only the delicate plungers and springs in the valve-block, there's loads of needle-bearings in the gearsets and the brake/clutch linings are made of a paper type material.

We all know what happens to paper in water--and after 7 years....Well.....:(

Best thing for it--Strip it down for curiosity's sake, just to see how a trans is made, maybe save a few spares like the B2 piston and toss the rest....

yeah. i'm going to take it apart here and there to get a better understanding and see if its worse inside. there was only about 2 cups of water in the thing after it separated out and it came in through the screws for the trany cooler.