Transmission swap on 300TDT - PeachParts Mercedes-Benz Forum

gyrogear · #1 07-18-2017, 01:01 PM

I have a 1985 300TDT Cali with a blown 722.416 trans. I recently purchased a 1984 300TDT Federal for parts. It has a 722.315 trans in good condition. Can anyone tell me if I can swap the .315 for the blown .416 without major changes?
Thanks guys, I appreciate any info you can give me.

Sugar Bear · #2 07-18-2017, 01:20 PM

Heard that 85's had a better stall speed converter BUT I don't know if that is accurate. You may wish to ask Sun Valley Mercedes Dismantlers about using the 85 converter if it is still good. Good luck and please post the outcome.

Frank Reiner · #3 07-18-2017, 05:11 PM

Quote:

Originally Posted by gyrogear

I have a 1985 300TDT Cali with a blown 722.416 trans. I recently purchased a 1984 300TDT Federal for parts. It has a 722.315 trans in good condition. Can anyone tell me if I can swap the .315 for the blown .416 without major changes?
Thanks guys, I appreciate any info you can give me.

Your question is a bit off the mark; 722.3xx and 722.4xx represent two different series of transmissions. Although they share a common design, placed side by side, it will be seen that they differ in size; a 722.4xx is a junior version of the 722.3xx.

However, if all pertinent parts are taken from the donor car the 722.3 may be installed instead of the 722.4.

ROLLGUY · #4 07-18-2017, 10:09 PM

Do they both have the same speedometer drive (electric/cable)? If your wagon is electric, and the donor cable (or vice-versa), it will not work. If they both have everything in the same spot, and are the same length, they should interchange. Also what Frank said above.

gyrogear · #5 07-18-2017, 11:20 PM

Quote:

Originally Posted by Sugar Bear

Heard that 85's had a better stall speed converter BUT I don't know if that is accurate. You may wish to ask Sun Valley Mercedes Dismantlers about using the 85 converter if it is still good. Good luck and please post the outcome.

Thanks for the info on Sun Valley Dismantlers. I don't know if the converter is good or not. The trans is toast. No forward gears and barely a reverse. Fluid is black and smells burned.

gyrogear · #6 07-18-2017, 11:36 PM

Quote:

Originally Posted by ROLLGUY

Do they both have the same speedometer drive (electric/cable)? If your wagon is electric, and the donor cable (or vice-versa), it will not work. If they both have everything in the same spot, and are the same length, they should interchange. Also what Frank said above.

Yes, both are cable speedometers. I'm wondering about things like bolt pattern on bellhousing, pilot shaft and bearing diameter and length, transmission mounts and location.
Difference in length between the two transmissions I think can be solved by using the driveshaft from the '84.
Thanks for your input.

ROLLGUY · #7 07-19-2017, 12:19 AM

Quote:

Originally Posted by gyrogear

Yes, both are cable speedometers. I'm wondering about things like bolt pattern on bellhousing, pilot shaft and bearing diameter and length, transmission mounts and location.
Difference in length between the two transmissions I think can be solved by using the driveshaft from the '84.
Thanks for your input.

Yes, use everything from the donor, and you will be golden. Be sure to use the ENTIRE driveshaft. Wire it together before removing it, it is too easy to accidentally pull the two sections apart, and not get them back correctly.
The bell and everything up front is all the same. Use the torque converter that came with the donor.

Mxfrank · #8 07-19-2017, 07:48 AM

Also be aware that there are two versions of the 722.4. For the more powerful turbo cars, they are built with five clutch plates, for the lower powered cars, four plates. a 416 most likely has five plate clutches.

ROLLGUY · #9 07-19-2017, 09:48 AM

Quote:

Originally Posted by Mxfrank

Also be aware that there are two versions of the 722.4. For the more powerful turbo cars, they are built with five clutch plates, for the lower powered cars, four plates. a 416 most likely has five plate clutches.

Yes, especially if it came from a wagon.

gyrogear · #10 07-19-2017, 10:48 AM

Quote:

Originally Posted by ROLLGUY

Yes, use everything from the donor, and you will be golden. Be sure to use the ENTIRE driveshaft. Wire it together before removing it, it is too easy to accidentally pull the two sections apart, and not get them back correctly.
The bell and everything up front is all the same. Use the torque converter that came with the donor.

Thanks for the reminder on the driveshaft. I know it is balanced as a unit, so maintaining its original assembly is very important. If I have to disassemble it to remove it, I will be sure to have it marked so it goes together as original.
"The bell and everything up front is all the same." You just made this old man very happy with that info! I just hope I'm not too old to do this swap. Guess I'll find out when I get the cars up on blocks and start wrenchin'.

gyrogear · #11 07-19-2017, 11:11 AM

Quote:

Originally Posted by Mxfrank

Also be aware that there are two versions of the 722.4. For the more powerful turbo cars, they are built with five clutch plates, for the lower powered cars, four plates. a 416 most likely has five plate clutches.

I am not too concerned about the .416 in the '85 Cali, since it is toast. I have read, on this and other MB forums, that it was a poor choice for the TDT and was only selected to satisfy California emission standards. It shouldn't be a burn out with less than 180k on the odo. My '80 300TD (daily driver) has 280k on it and is still pulling fine. It is probably a good trans for the 300D/CD/SD, but for the 300TDT not so much. Just my 2 pennies worth; not chiseled in stone.