Hi Martin, i don't want to mislead you, so please note... I don't have an extensive experience with rebuilding MB transmissions, so anything I say or suggest it's just my opinion based on the recent MB transmission rebuild, some information I've gathered during my research on the subject and some knowledge accumulated over the years working as a mechanical engineer designing and building hydromechanical transmissions.
I can give you my opinions, but at the end it your decision how to proceed.
Now that we have this cleared .....
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The donor Transmission looks good. The oil was clean and the seller was confirming that trans worked well before removed. So I could be lucky.
I'll probably get it in sealing at the exterior and done. Not sure if it is worth pulling the primary pump and seal it...look if the pump looks fine?
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Here, I guess, you need to decide, do you install the donor transmission and leave it for good, or you want to rebuild your old transmission and put it back? Further actions will depend on your decision...
Like I said, if you want the donot TX just as a temporary solution then you can change all exterior o-rings if you want to do that, should be OK they are not hard to replace. Just use high temp grease ot ATF for o-ring installation, make sure you don't cut the o-rings. As for openning the primary pump...my dad used to say "
don't fix it if it ain't broke". What do you expect to see? If the donor transmission worked fine and no debriss (metal or aluminum powder) found in the oil pan, 99.9% that the primary pump is OK. If you open the primary pump you'll need to replace the o-ring and the paper gasket and since you are already there I'd suggest the primary pump front lip seal. By opening the pump you can just confirm that it's bad if you see scoring or wear on the gears, but then the TX would not worked well since the pump efficiency would have dropped down.
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The transmission to be renovated is a 1992 722.354 , at least this is what I thought. But cleaning the old piece that came out last weekend I saw that the aluminum case was sprayed over in grayish color. They sprayed over modulator, kick down solenoid and plugs/covers...
It looks like this was a re-builder's paint job? I don't think the original trans would be spray painted.
Any hints here?
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I don't know...but it doesn't make sence for MB factory to spray the modulator or kick down solenoid...
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Probably it does not matter much. It all depends on the inside condition of the parts I guess. If the planetary gears and other hardware are fine it should be rebuild-able.
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I think so.
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As the damaged transmission had a few symptoms of dysfunction I'd like to understand why it did behave like it did (before I found the steel chips and chewed up spring in the pan.)
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What symptoms?
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I got a 'Precision' Banner Kit for the 722.3 ..out of interest what is inside.
And I am not very convinced that the frictions are the best available. I'd probably get Borg Warner frictions for the rebuild. I am not sure and I have no idea/experience with friction disks.
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Usually banner kits contain:Transmission Overhaul Kit (seals and gaskets), and a standard set of friction clutch plates.
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You are mentioning updates... like the B2 update... yes...where do I get these parts from?
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You might be OK, Service bulletin "Delay engagement in all forward gears" for B2 piston update applies to MB 722.3 and 722.4 1980-1991, I see your's is 1992. You will know when you pull B2 piston out.
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steel plates are available too but not sure if they are needed for a rebuild
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It depends..usually they don't have to be replaced. You will have to inspect them when you take the TX apart. If there's some wear you will fill a ridge when you drag your fingernail across the surface. In this case you might want to replace them.
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Brake bands B1 and B2 should be installed new or are the old ones typically fine?
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Depends on the condition, B1 has thin friction layer and is not expensive so I'd change it, B2 is another story...needs to be inspected. Depends what failed in your transmission.
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Valve body: I think I need to open this one up and clean it from any debris/steel chips inside?
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Absolutely 100%. Please note, there's a seal kit for the valve body and it's not included with the rebuild kit, I had to buy it from MB dealer. There are about 25-30 teflon rings in the kit, but you will only need 8.
FEW POINTS:
- you have to flash the transmission oil cooler before you install donor transmission. Ask me how...
- be carefull, B1 piston cap is spring loaded, you better make a tool for removal / install, e-mail me for drawings.
- source ATSG 722.3 722.4 rebuild manual, it's a big help.
Im working on my valve body overhaul video, hope to have it finished soon.