722.120 Rebuild (300SD)

I just ordered this Master rebuild kit which I believe includes friction clutch plates & standard steel plates, paper gaskets, O rings, lip seals, metal clad seals and sealing rings.

What else should I be expecting to replace after 260k miles?

[rs899]

Maybe the bands?

Good luck! Please keep us advised. A pictorial would be very helpful. If nothing else, at least take the pictures for yourself as you tear it down so you can figure out how it goes back together. You may have it apart awhile waiting for parts. I never took my 722.120 apart other than the front pump ( it only had 125K miles when I messed with it), but my wife's 722.315 is on its last legs.


Rick

Originally Posted by rs899

Maybe the bands?

Good luck! Please keep us advised. A pictorial would be very helpful. If nothing else, at least take the pictures for yourself as you tear it down so you can figure out how it goes back together. You may have it apart awhile waiting for parts. I never took my 722.120 apart other than the front pump ( it only had 125K miles when I messed with it), but my wife's 722.315 is on its last legs.


Rick

Doh! I think I too have a 722.120 (I guess I forgot, I pulled the transmission and replaced it with a used unit two years ago).

Anyway, I started a blog for this car here and I will definitely post pics.

[rs899]

Yes, you do have a 722.120. I'm not sure what a 722.2 is...

You might look for advice over at the Vintage forum. The four bolt tranny is pretty much a vintage item. Plus there are some pretty saavy people there (not that there aren't here, but there just arene't many of us inclined to tear down a transmission, methinks).

I see you mention Jaggi on your blog- good- you will need him...

Rick

[slojoexxx]

Please keep us posted on this, as I plan to do mine latter this year ans up date it with the K1 and B2 kits.

Originally Posted by slojoexxx

Please keep us posted on this, as I plan to do mine latter this year ans up date it with the K1 and B2 kits.

What are the K1 and B2 kits?

[rs899]

Tabor-

I don't think you and I have them in the 722.120. These are in the 722.3xxs.

What's so wrong with your transmission that it needs a rebuild? Symptoms? What was the first sign of failure ?

Rick

Originally Posted by rs899

What's so wrong with your transmission that it needs a rebuild? Symptoms? What was the first sign of failure ?

The front pump seized when it got full of metal shavings. Lots of metal shavings in the pan.

[rs899]

Catastrophic failure

There seem to be a lot of front pump/TC problems with these. Is your TC broken as a result (or as a cause?)?

Originally Posted by rs899

There seem to be a lot of front pump/TC problems with these. Is your TC broken as a result (or as a cause?)?

Yup, TC broken as result.

[sthompii]

I have a 1985 300D and am considering attempting to rebuild its transmission. It has been slipping off and on and rarely goes into 4th. I read extensively on the forum about vacuum and bowden cable adjustements and I checked all that without any success. I don't have a lot of mechanical experience so I've been looking for books, manuels, etc on how to do a rebuild, but I haven't found any recources so far. I just ordered the MBA Service CDs but haven't received them yet so I don't know how helpful they will be. Does anyone have any advice for obtaining information on how to do a rebuild? Is a mechanical newbie insane for considering a rebuild? I think it would be a good educational experience if nothing else.

[jshadows]

ATSG is the only web retailer out there for MB transmissions. You may be able to get a guide from MB directly.

Transmission rebuilds are not for the faint of heart. The tolerances in reassembly are micrometer level and cleanliness is also key. A transmission holding fixture is absolutely necessary unless you've got some other tool to hold, rotate, etc.

Fortunately, no special tools are really required best I can tell (at least I didn't use any when i did a 722.361) but I did have to make a few using clamps to compress the B1 piston and the pressure plate on the front pump.

I too will be interested in 722.120 rebuild since my '79 SD is showing signs of worn clutch packs and a possible failing/failed torque converter.

[Moorewr]

Wish you all were close to Livingston, TN, just pulled my 77 300D, 722 transmission, got the master rebuild kit and front and rear bands from Daaco, cookeville tn, they are on web and a rebuild book for $273, good friend who rebuilds transmissions, took it apart, front band was glazed, (sympton, no reverse and the band had been adjusted as far as it would go. Front seal also leaking. He replaced all the seals, clutch bands and didn't have any stuff left over. Put it back in and it will bark tires in reverse on a hill. Shifts very smooth, engine doesn't work near as hard. I gave him $200, though it also cost me a few beers. He says it is a small, simple trans. The clutches still had the stamped lettering and none were burned, as was the tc. Had 235K on the car, bought it new in 77. Difficulty in taking out is the top 2 bolts, and had to remove drive shaft, other than that, about 4 hrs out and 3 back in.
Ron

[rkpatt]

Did you get any pics ?

[Lonesome]

My 79 300SD did the same thing! Anyone know what causes it? I just replaced the TC and pump, I'm afraid it will happen again.