Does an W123 300SD 722.118 transmission fit on my W116 450SE ?

Started by geiz, 31 July 2009, 03:09 AM

Big_Richard

wow, they certainly are very different.

I'm starting to wonder if the 3 and 4 speed bell housings are even compatible with each other without modifications.

TJ 450

They are very different and I'm impressed with that arrangement. The arrangement of the ball bearing in the other transmissions does not exceed my expectations, but this does.

With the bearing's extension ground off, and longer stator shaft, that won't be a problem at all. Very creative work! :)

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

geiz

Yes, I was also surprised by the big differences. And yes, the bell housings are compatible (tried out before I started :D), the only difference is 2 extra M8 bolts on top of the 722.118 housing (you can see it on the last picture). I think that's also a improvement of the design. I can cut this extra 5cm on top of the gearbox completely off, or leave it there unused. I don't have decided yet.
Does someone knows if there is enough space above the gearbox?

geiz

Finally I (with some help) have finished the 4-speed gearbox project!
Next week I will install it in the car again  ;D

Here some pictures:


Home made tool for removal of the bolt around the out-going axle.




Big difference in size.


Installing a new oil filter.


he oil pan of the W116 is a lot bigger, so I decided to use this one.


Difference in oil filters.

The bellhouse of the W116 was 10mm thicker as the W123 bellhouse, so I had to modify it.


First we have to fill it up with extra aluminium to keep it steady. (thanks to Schaap)




And after that we have to mill it 10mm shorter. (thanks to OPA)


Finally the gearbox assembled!


A W116 bell house connected to an W123 gearbox house!

Big_Richard

wow! so many differences!

I cant wait to hear about the test drive

please video it and you tube it  8)

TJ 450

Awesome work! I bet you can't wait to get it back in the car.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

geiz

Yes, we have installed the gearbox in the car last week. The acceleration in the 1st & 2nd gear was impressive. It was raining that day, therefore it was not easy to accelerate without skidding wheels. A start with wide open throttle results in a very long burnout  :o ;D

But it was not all fun, the transmission was again leaking like hell, from between the torque converter and the gearbox.
Also the shifting was not perfect, the vacuum controlled shifting needs some attention, but I could not test it very well, caused by the oil leak. But ok, the setup is working together  ;)
I have removed the gearbox again this weekend (1st time it took +/- 10 hours, now only 3 hours) and the big O-seal around the oil pump was leaking like hell. (This is an new oil seal, but I think they give me the wrong size/thickness).

I'll keep you informed about the progress  :)

Big_Richard

your new second gear is what your old first gear was like before ;)

it should be quite easy to break traction with your new first gear, even in the dry ;)


awesome to hear it finaly works

geiz

Yes, almost ;-)

Original 3-speed transmission:

1st : 2.31
2nd : 1.46
3th : 1.00

The 4-speed transmission:

1st : 3.98
2nd : 2.39
3th : 1.46
4th : 1.00

Yesterday we have pulled back the transmission under the car. This evening I will continue with it and hopefully I will finish it early enough to make a testdrive again!

In the last days I have also studied the vacuum control principle of the Mercedes transmissions. I have some idears now how to improve the switchover behavure.

geiz

I've made yesterday a long trip with the car without problems!

The vacuum control problem was solved by creating an "pressure-divider" made of 2 nozzles. So the vacuum at the transmission modulator is always lower. It varies now in between +/- -0.4 and 0 bar, when the pressure of the inlet manifold is varying in between +/- -0.8 and 0 bar. Now it is shifting fine. Only some fine tuning is necessary, but that's fun to do.
I can imagine now why Mercedes created such a long 1st gear in the original transmission. A little bit too much pressure on the accelerator will result in a burnout ;-)

jpstuckey

Fabulous!  Outstandingly resourceful of you, and beautifully executed!  I think that the best thing about this conversion is that one could install a tall final drive and still have excellent low end whilst gaining relaxed high speed cruising.  Honestly, a good deal of the "sophistication" of late model autos is simply very tall gearing due to multi ratio boxes.

John
John