PeachParts Mercedes-Benz Forum - Rebuilding 722.3 transmission - where do these these small black springs go?

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Rebuilding 722.3 transmission - where do these these small black springs go?

I'm almost finished with a rebuild of my 722.357 transmission.

I can't figure out what these 2 springs belong to. I'm guessing maybe one goes to the modulator thrust pin (shown), but it seems to keep it from fitting all the way into the engine. And then what does the 2nd one go to?

https://lh3.googleusercontent.com/kL...=w1070-h802-no
https://lh3.googleusercontent.com/t2...=w1070-h802-no

What ever they are, they have failed and need replaced. Lower one is nearly coil bound and upper bowed. Look at the ends of the wire, you might find this used to be one spring.

In any event, somewhere on this site there is a very detailed rebuild thread with pictures.

I looked and did notice that the bottom spring has one end that looks broken off. The bottom spring is of a thicker diameter than the top, which has no broken ends.
I think the top spring must go to the vacuum modulator thrust pin, since it fits pretty well. But it doesn't have a lot of spring force left. Maybe it's just lightweight on purpose? I guess I'm not sure where the bottom spring comes from or if it's even important - automatics seem a little needlessly complex if you ask me.

I can't say for sure but a good rule of thumb is that if the (unbroken) spring fits snugly on the end of the shuttle valve that's a good place to start (!)

I've got pictures of a 722.303 valve body in bits somewhere on this forum - need me to ask google for you?

{try => 722.303 photo shoot stretch site:peachparts.com }

Quote:

Originally Posted by nicholas (Post 3857769)

I looked and did notice that the bottom spring has one end that looks broken off. The bottom spring is of a thicker diameter than the top, which has no broken ends.

I think the top spring must go to the vacuum modulator thrust pin, since it fits pretty well. But it doesn't have a lot of spring force left. Maybe it's just lightweight on purpose?

On auto trans in general, a light spring is sometimes added to a modulator pin so it counters the modulator spring. This is done to fine tune the modulator system.

I guess I'm not sure where the bottom spring comes from or if it's even important - automatics seem a little needlessly complex if you ask me.

An auto trans is the most complicated system on a car. The gear train is complicated from a mechanical design standpoint, the valve body from a design and tuning standpoint.

Every part in a trans performs a function so you need to find where the springs go and replace any broken ones.

What would you do to make the trans simpler using knowledge / machining techniques from the 70's?

The 722.6 / NAG1 electronic shift 5 speed from 96 + is simpler from a mechanical assembly perspective but the electronic programming is mroe complicated than a hydraulic shift trans.

The ATSG guide does a good job of diagramming every valve, piston and spring in the valve body:

https://www.scribd.com/document/341541671/ATSG-Mercedes-Benz-Automatic-Transmission-722-3-722-4-pdf

See whether any of these manuals help.

https://www.dropbox.com/sh/vdn6vmzeheg75vy/AACKe93huTvd5KPapY9L96nZa?dl=0

The 126 menu quit working after XP but extract and run whatever swf file is appropriate. The pdf will be in your browser download folder.

Great, thank you for the links. I got the transmission put together sans the spring given input from Sun Valley transmission. I can add it in again if it will help the other issue I'm seeing. After getting it together and on the road, it now does not upshift. "Park" also does not work. It goes in reverse and 1st only. I have another thread on this started over here if any have any suggestions to help: http://www.peachparts.com/shopforum/diesel-discussion/395835-722-357-rebuild-stuck-first-gear.html

Quote:

Originally Posted by nicholas (Post 3859626)

Great, thank you for the links. I got the transmission put together sans the spring given input from Sun Valley transmission. I can add it in again if it will help the other issue in seeing. Agree getting it together and on the road, it now does not upshift. "Park" also does not work. It goes in reverse and 1st only. I have another thread on this started over here if any have any suggestions to help: http://www.peachparts.com/shopforum/diesel-discussion/395835-722-357-rebuild-stuck-first-gear.html

Park is a mechanical position - if it does not engage then you should check the selector linkage

If the selector linkage is "flapping about in the wind" then other weird things are gonna occur

OK, thanks. It does 'click' into the different positions and the linkage on the outside I think is correctly installed. Looks like I'll be opening up the rear cover to check the mechanism for that. I had a feeling something was not going to work when I put this together. I got a bonus of three things not working (the first was the ability to hold in fluid after forgetting to install the test port plugs - 3 quarts of high pressure ATF out the side of the transmission reminded me what those leftover bolts were for).