Overhauling a Transmission DIY
 

Hi
Anyone here ever overhaul the transmission, special tools needed? best place to buy the Kit? any advice?. Nothing big wrong with mine, leaks pretty bad thats all, but i would like to do the work myself and not put in a rebuilt one, Part of the reason i bought the car was to work on it and i have a another car so the Mercedes can be down as long as i like.
Thanks

Why rebuild then? Why not just replace seals? My motto.....If it ain't broke, don't fix it:D

Mine leaked pretty bad when I got it, we had the seals redone, and its been fine for 39,000 miles since then... :D

My motto is if it ain't broken it will be soon.
Ps i got the map pocket that you sent thanks again.

Which transmission series do you have? 722.3 or 722.1 for starters. These are slightly different beasts.

No special tools are needed except for maybe one(contrary to the manual) but I would HIGHLY recommend a transmission holding fixture. The B1 piston can be remove with an 18" clamp as opposed to the tool in the rebuild manual. If you are doing a full rebuild meaning you are also replacing the pressure springs then you will need the compressor tools.. You may be able to improvise with clamps, but it's a PITA and I'm not sure it's possible with the K1 and K2 clutch packs...it is with the b3 springs.

I lip seal remover/installer is very useful too, but only about $5 at your local auto parts store (looks like a dentists tool).

Then you'll need a micrometer to measure clearances. The clearances are VERY tight and require playing with shim sizes and outer discs on the clutch packs to get it all right. The problem here is you won't know which one's you need until your piecing it back together. Buying every combination is not cost effective as the discs are expensive.

This is all based on the 722.3. The 722.1 may or may not be a bit simpler though I know it has adjustable brake bands so this may get tricky too.

This is no small job. It is perhaps the mother of all of them and only rivals rebuilding the bottom end of the motor..might be worse.

As for valve body, I think the general consensus on this forum is get someone else who knows what their doing to do it for you. As another member pointed out, the valve body is more complicated than the entire interior of the transmission

Its a 722.118 tranny, my biggest problem is lack of info such as a manual,
i bought the ATSG, but thats hard to get the info from.
Thanks

Yeah the photos in the ATSG manual suck, plain and simple. I ended up using another manual (link escapes me but it's based on a '96 C220) and the ATSG when I needed a second opinion.

I can say this. If you follow the manual (ATSG or other), things will become clear as you disassemble the unit. It's far from obvious if you've never opened the box before. At least it wasn't for me.

Removal and installation of the transmission is a 2 day job if it's your first time. Installation of seals is quick and included in that estimate.

One manual estimates 11 hours for a complete teardown and rebuild. That's 2 days too, for a professional. I would at least double it for a first time. Your car could be out of commission for some time. If this is not a problem, keep plugging away. I think MB may have a service manual.

Anybody know if MB has a Manual for transmissions?
Thanks

i would be surprised if they don't. of course the challenge is to get your paws on one...;)

I think its a bit nuts to rebuild a transmission that works. Just reseal it and drive. I have done maybe 10 or so domestic automatic rebuilds. They were no more difficult than assembling an engine. The main problem as noted is having the correct tools and an assortment of parts. I was lucky and had access to this stuff at the time. If you are truly able to live without the car for a long period of time and want to learn how autos work, feel like buying some special tools and run around sourcing parts then go for it. It will be an experience. RT

ATSG is it. none for manual trannys that I have seen.

A paper manual does exist for automatic and manual transmissions up to the late 70's. It is not very detailed. You could probably take a manual transmission apart and put it back together with this book, but I wouldn't attempt it on an automatic.

any place where I can get a valve body? I replaced my bowden cable and my tranny is still in 4th gear before i hit 20, I figure its the valve body, but it may be the modulator. I have no clue.

If it's your labor and not shop labor, I would reseal the trans and replace the trans mount and flex disc at the same time. The aftermarket parts on the market today are not as good as the oem parts MB used, and if it shifts fine you are better off simple fixing just the leaks.

Btw, make sure the metal cooler lines aren't the cause of the leak. They tend to leak because of pinholes caused by the vibrations, and loose banjo fitttings at the trans.