722.3 Trans help - PeachParts Mercedes-Benz Forum

Das Benz · #1 12-03-2013, 09:13 PM

Hey Guys, newbie member on the forum. Ive been a lurker of the forum for many years now, but have hit a roadblock and need some insight from the other experts on the site.

Ive been a Benz fanatic ever since I was a kid, and a die hard car enthusiast ever since. Ive thankfully had the opportunities to collect the cars ive always sought after, and my old 420sel winter DD, is part of it.

Ive always been my own mechanic on all my cars, its one of the main reasons I can afford some awesome rides, and a good reason to buy more tools

, something most folks could agree with. Anyways back on track. With winter here up in central Ontario kickin away ive been driving my 1990 420 sel. Its currently got 386,000km, and it was a bit of a basket case when I first got it (with the sole intention of a winter DD), ive been slowly working out the kinks and its been a wonderful, comfortable, quiet car to drive to and back from work each day; without the pain of the salt chewing away at a more expensive ride (sorry for sayin that guys

)

Anyways, the transmission has been getting a bit weak, reverse is getting a bit sluggish, after doing some research and getting all the rebuild manuals (ATSG, and BENZ) I know what im in for when I tackle it for a rebuild. (ive rebuilt a few 4L80E's to keep as spares for one of my other vehicles, so transmission work isn't too voodoo for me.

With the weather getting cold, and a bit a free time in the evenings, I decided to pick up a core 722.355 to rebuild, and have on hand if and when the original trans gets too tired.
Luck has it that the core I picked up looks like it just had been rebuild. There wasn't any history on it, but it had been freshly painted, and looked like it was installed. Probably for only a few 100 km's.

Tonight I started to dig into it, and sure enough, all new parts thru out. New bands, spick and span valve body, all new seals. New B2 seals, new governor, new looking governor shaft. (ill be inspecting the B1 assembly once I get a chance to fab up a cover compression tool.

I didn't dig into it too much, but after buttoning up the pan, I heard a whisper in my head to check out the B3 seals, and pull the front pump assembly off to check and see how everything was doing.

Before I pulled the pump off I noticed that the front input shaft (center shaft) had a tad of play in it. But if it is like other transmissions, the torque converter should have internal bearings to center the shaft and provide support.

So 10 bolts, I pull the front pump off, and Ah HA!, I find the culprit.

Heres where I need some insight.

It looks to me that the K1 drum has some sort of slop, and chewed away at the seals on the pump assembly. It scored the pump assembly a bit, and also slightly gouged the inside surface of the K1 drum.

What would of caused this. Is there a bearing surface that supports the K1 drum assembly? does the B1 band have any vertical/horizontal centering adjustment that would cause the K1 drum to shift to a side when applied? and rub against the sealing surface on the pump assembly?

Could this be caused by not applying lube on the shaft during assembly, and damaged during the first few revs until the pump primes itself?

Sorry for the non-pro pics, all I had with me in the shop was my phone.

If you need more pics, I can get them to show you the assembly

Any tips would be great!

Pump assembly with B3 cage

B1 inner drum

Das Benz · #2 12-04-2013, 08:48 AM

I think i found what is going on.

I looked more closely at the inside of the drum, and the outside of the pump shaft. And i noticed some minor wear indicating the presence of a bearing. However the bearing wasnt there.

According to the breakdown chart, im missing part 228

Looks like someone was snoozing when they put the trans back together.

A quick flip thru the ATSG manual doesnt mention anything about this roller bearing that i could see. I have yet to dig into the benz manual and see if theres any notes about it.

I cant find a P/N for this bearing, and help folks

Thanks

joshuajeeper · #3 12-04-2013, 11:52 PM

The bearing that goes into the K1 drum assembly (#228 in your picture) is A013-981-94-10. I've never removed that bearing nor ever seen a reason to remove it. I have no idea why its missing unless the reverse piston clearance was set up incorrectly and it just burned up and came apart. But considering the scoring on the reverse piston shaft, I'm thinking they removed it for whatever reason and forgot (or couldn't figure out how to re-install it) to put it back in.

Stretch · #4 12-05-2013, 03:58 AM

There's not that much you can do about that other than seeing if a new bearing will solve the problem. It looks a bit too messed up to me though. I don't think new PTFE rings are going seal that part anymore.

However a quick look on google with that part number provided by joshuajeeper shows pretty low purchase prices. If you can get the seals for a low price too and not have to pay for a whole reseal kit then it might be worth the gamble.

Das Benz · #5 12-05-2013, 07:41 PM

Awesome! Thanks for the bearing number, ill look it up and see what comes up.

Yea to me looks like someone forgot to put the bearing in, there doesnt look like there is any overheating on the pump shaft or inside the drum, so im guessing this drum came out of another trans and someone took the bearing out

Tonight i was able to polish up the races on the pump side in the lathe, i didnt take more then prob 0.0015" off so it should be good, plus its not a contact surface anyways. I really ddnt have to cut the race surface, i just touched the inner seal surfaces; the metal had just overlapped slightly. Then just hit the outer face with a emery cloth... Mirror finish.. Now the inner drum surface isnt too happy. I tried to polish it up but the gouges are just a bit too deep. So a new drum is prob in order. But i think i have a source on a few.

I have a spare benz complete seal kit that i bought for cheap, and its got a few spare white seals in the kit. Other then that, trans looks good. Cant wait to see if my efforts pay off

Das Benz · #6 12-05-2013, 07:48 PM

FYI, I quickly fabbed up a compression tool for the clutch pacs. If anyone needs dimensions dont hesitate to ask.

MAVA · #7 12-06-2013, 02:16 AM

Lucky you, that you mill one out. Us bottom of the barrel Shade-Tree-Mechanics use plumbing fittings.

722.5 transmission oil pump rebuid DIY - Mercedes-Benz Forum

Here is mine from a PVC coupling next to B1 and B2 piston. The hard part to remove is the B1 piston and install.

I suggest use get the updated EPC data for your vin as most of us here in the USA have. Here is what it looks like, and this is to my S320 with a 722.5(post 13):

722,5 tear down which side to start from

About your scored B1, look for a junk yard for junk transmission, FleaBay, CraigsList, or these guys:

MBZ 722.3xx

Do replace B1 because you will just eat-up the bearing in a period of time.

I do not know who's rebuild kit you are going to use, but nearly all aftermarket kits include all the seals for the valve body. You can get an American Rebuild kit with clutches for $180 USD.

I have lots of data on these transmissions if you need something let me know.

Best of luck,

Martin

Stretch · #8 12-06-2013, 03:09 AM

Quote:

Originally Posted by Das Benz

FYI, I quickly fabbed up a compression tool for the clutch pacs. If anyone needs dimensions dont hesitate to ask.

If you could show / tell more information and add it to this thread =>

Home Made Special Tools, This is where members can share how they made special tools

that would be great!

Das Benz · #9 12-09-2013, 09:07 PM

Well folks, great success!

I picked up the drum I needed, as well as a few other spare goodies... Actually a lot of spare goodies

Ill post pics up once I get them off my phone, and add the info for the 2 tools ive made.

SO I got a good K1 drum with my mystery bearing, and began transferring over the clutches and pistons.. Checking tolerances as I go.

I got a spare pump housing/B3 piston assembly, and a few other goodies to keep as parts for the trans that's in the car now once I take it out. And a few spare parts for my 560sel; not like it needs it though.. cross fingers

One thing I did notice is the plastic support carrier for the B1 band (part between the band and the B1 piston, looked a bit weird?.. like it began melting.. Anyways, I got a new carrier while I was at it. I wonder if a old B1 band overheated or something?

Im just on hold now because I need to go pickup a 30mm 12 point deep socket so I can take the tail nut off, and just double check everything in the back is ok.

Stretch · #10 12-10-2013, 01:52 AM

If you don't want to wait for the socket - this approach can work =>

722.303 in bits photo shoot

Das Benz · #11 12-19-2013, 11:45 AM

Monday i was able to tidy up the trans and its all back together with no missing peices

I got the tail nut off lol. I caved in and bought the socket. Mainly because i need a 30mm deep socket in my box for axle nuts, plus. Hey its another tool. Actually ill rebuild the trans i take out of my 420 once i do the swap, then ill have another good one on the shelf for the late future. Or as an emergency for the 560.

Theres a few things to note for future info.
These gen 2 w126 trans use a magnetic pickup for running the speedo. Just keep it in mind when your in the junk yard looking for a similar trans to swap. Also these 722.3 do not have a secondary pump, and the govenor is held in with this easy to use side swing clip. I read one of the folks on here was having a heck of a time with the c-clip on his govenor.
And these do not have the oiling spiggiot in the back that sprays fluid on the govenor gear.

So i wanted to take the back half of the trans apart and check the b2 band and k2 clutch packs. They looked ok, (k2's were really dark and questionable), but i was already this far in, new b2 and k2 set went in ( i picked up a good score of new MB trans parts from a good friend), and i checked the tolerances. All good.

So all in all fully rebuilding this trans was a fun experience. Even though someone was in here before and replaced all the seals, after getting in there and seeing some shortcuts were taken, i wasnt going to take any chances. Even though transmissions in general are a very voodoo thing for most; for myself as well. After digging in and getting a feel for these 722.3, they are actually very simple in design and definetly do the task at hand.
I cant wait to get into another one

Just follow the benz manual when it comes to tolerance specs, and get yourself a good digital caliper and depth caliper and youll be good to go. And use genuine benz parts whenever you can. Its not worth the hassle to me to tear the trans apart because a seal failed or a band cracked because it wasnt original merc part.

Das Benz · #12 12-19-2013, 12:00 PM

Heres the nasty k2 clutches

Old vs new

Das Benz · #13 04-25-2014, 06:09 PM

Hey folks, thought I would revive the thread.

So ive still been driving on the original trans since my last post, all throughout the winter. As reverse still kinda held in there. I was clever, I orchestrated only one reverse per trip; drove forward out of the driveway into the morning (slightly up hill), and was able to back into my spot at work (flat grown), then drove straight out in the afternoon, and backed into the driveway without a hitch. Man the things you think about when you barely have any reverse, I can just imagine what folks with low range electric cars feel like

Now that the warmer weather was showing up, and one event a few weeks ago involving a spot that faced down hill, I told myself I needed to swap the trans ASAP.

Last weekend, my pops and I spend a sunny Sunday and did the swap. It went pretty straight forward, but there were some hiccups and it was just pain cumbersome doing the swap in the driveway instead of on a lift. A 4ft socket extension was needed to get to the top 2 bolts holding the trans on the engine, but we got it. Started at lunch, got it done by 8. Fired it up, and voilà! I had movement! and REVERSE!! oh man the prestige of having reverse!

Heres where the fun begins though. So its been a week of driving, and fiddling with the modulator getting the shift feel and timing right. But now im running into issues. So the shift itself is ok, a bit too firm (just modulator adjustment), but it feels fresh and new, and engages quickly.
I think my problem though is either governor related, or valve body and its getting worse as the days go by. From a cold start, the car will want to say into 2nd gear for an eternity, then all of a sudden it will go into 3rd, and then everything is fine from there on in as things start to warm up. I don't like revving the engine upto 3000rpm when its cold.

It will downshift when you put your foot into it, and properly downshift gears as you come to a stop, and shift up as you take off. SO that's alright,however the boden cable is super sensitive (much more then before, and on my 560sel). Sometimes it will go into 3rd, then right away into 4th.. a bit too "narrow" if you get my hint.. And no adjustment of the boden will fix that, it brings a (warmed up) 2-3 shift too high, and 3-4 where it should be.

Any hints?? I have a feeling someone has fiddled with the valve body, and that is the only thing I didn't do a full once over on. I have a spare good one here right beside me, waiting to go in if it will help.

Stretch · #14 04-26-2014, 01:37 AM

Fine tuning a transmission involves making pressure and vacuum measurements.

But first I'd be checking fluid level - at the correct temperature

These transmissions are pretty pernickety

Das Benz · #15 04-26-2014, 03:06 PM

Quote:

Originally Posted by Stretch

But first I'd be checking fluid level - at the correct temperature

Yep, fluid is perfect. I have a vacuum extractor and set the level exactly to the upper fill line once she was all warmed up from runs up and down the road.

First thing im going to do is swap the modulator with a new one, I noticed the one that's on there now is ever so slightly seeping fluid into the vac line. Not much, but it is, the old trans line internally was dry as a bone, the hose being semi clear, you can see if there's fluid in it.

Things I kick myself for not doing when I had it on the bench.. Actually I wanted to do it; had the parts and everything, but was soo excited for a sunny trans install day it slipped my mind.

I just have an errie feeling that its the goveneor sticking, and causing the erratic shift points. I hope I can swap it out with the trans in the car, but im thinking not.