722.118 Automatic transmission rebuild (Monster DIY) - Page 3 - PeachParts Mercedes-Benz Forum

Stretch · #31 09-09-2011, 05:04 AM

Make sure the internal surfaces and the mating surfaces of the casing are clean.

Assemble the primary pump in the same order in which you took it apart.

Fit a new sealing O ring and mount it onto the hollow shaft so that the holes in the pump match up with the holes in the casing. If you don't match these bits the pump won't pump.

Torque the bolts for the front pump as specified above.

Stretch · #32 09-09-2011, 05:05 AM

Please note:- The ATSG manual says you should fit the output shaft to the main gear set (remember those fragile roller bearings in two cages?) prior to installing it in the main casing.

To install it this way I guess you'd have to have the dedicated transmission stand. As I don't have this bit of kit – and I couldn't find any detailed pictures of it to replicate it (and to be honest with you I couldn't be bothered even thinking about it) – I assembled the gear set in the main casing with great care.

Warning:- You need to be patient and careful so that you don't damage the two fragile roller bearings when following the instructions below.

Begin by fitting the output shaft with its sliding transitional fit bearing into the centre casing. Please don't rush this – do not fit it in askew. As mentioned before you really don't want to knacker the hole in the casing (see LINK to information given earlier).

If this seems too risky to you, you could attempt to fit the whole gear set as suggested by ATSG. If you do so I would get someone to help you so that you could fit it vertically – lowering the gear set (whilst holding the output shaft) into the casing. I'm a one man band so I ended up doing it this way...

You can now fit the tail cone section. Don't forget to fit the pressure absorber spring and the retainer...

[Sorry again folks - I couldn't find this photo - here's the best I can do. When I take my second box to bits I'll try and remember to get a picture of this bit and ask the mods to replace this one]

...take your time to make sure that the output shaft goes smoothly through the governor, the secondary pump cam, and the speedometer drive ring. Torque the securing bolts to the tail cone section.

Lift the gear set and place it onto that prosthetic limb coloured bit of plastic that slides into the top of the main casing as shown in this picture.

Here is that prosthetic limb coloured bit of plastic again by itself in the main casing

When sliding the gear set into position the idea is to make sure that this plastic guide (the prosthetic limb coloured one) does not pinch the brake bands; that it goes into the recess in the casing; and that the arm on the oil feed sleeve in the middle of the gear set connects with its slot that is in the main casing as shown in the picture below.

If you are fitting the output shaft to the centre casing first and then fitting the rest of the gear set don't forget to fit those delicate roller bearings...

...and when the gear set reaches the output shaft in the casing; lift the gear set slightly to meet it and then slowly turn the output shaft so that the sun and planet gears mesh. Don't shove, push, or slam this bit into place. Think of those delicate roller bearings again!

Once you've got the gear set in place you can fit the output shaft yoke (and shim) and tighten the nut on the output shaft to the designated torque. This time you will have to select park to stop the output shaft from spinning so be careful.

Stretch · #33 09-09-2011, 05:05 AM

I think it is important to stress why you need to be attentive assembling this part of the transmission.

Take a look at this altered schematic.

The gear set is supported along its length by the ball bearing at the front of the gear set; the sliding fit bearing at the back of the centre casing; and the bearing on the output shaft in the tail cone section.

When installing the gear set – when the front bearing is not in position – the gear set can move in a longitudinal direction. The position of the output shaft is longitudinally held in place by the bearing in the tail cone section as the yoke and the output shaft nut are tightened up against it.

By torquing the nut on the output shaft you will have positioned the sliding transition fit bearing situated at the rear end of the centre casing. If during assembly you get to the stage of attaching the nut on the output shaft but you can't reach the threads on the output shaft, you will need to firmly push the gear set further into the casing. BUT don't push too hard if you have not yet fitted the tail cone section as the back of the rear sun and planet assembly will rub on the centre casing...

...by tightening the nut on the output shaft; this shaft should be correctly positioned between the position of the bearing race in the tail cone section and the length of the tail cone section when it is fixed to the centre casing...

...BUT...

...be aware that not all of the gear set at this stage is longitudinally held in place – you can pull it out leaving the output shaft in place.

The main points to remember at this stage in the game is that the longitudinal position of the gear set is dependent on:-

1. The wear in the ball bearing race in the tail cone section.

2. The correct “tightness” of the nut on the output shaft.

3. The correct “tightness” of the bolts holding the tail cone section to the centre casing.

4. The correct assembly of the gear set fitting into the rear sun and planet assembly – make sure you've fitted it correctly – that the sun and planet gears are properly engaged – and that you've got the delicate bearing races fitted in an undamaged state.

5. The thickness of the gasket between the main casing and the tail cone section – which also means the condition of the mating surfaces between the two casings.

6. Finally – just to be really pedantic – the physical length of the casings and the yoke. If for some obscure reason these dimensions are at fault – good luck to you! You'll have to be pretty inventive with some shims to make it work.

Stretch · #34 09-09-2011, 05:06 AM

If you haven't already done so, flip the transmission vertically so that the tail cone section and the output shaft are pointing downwards. Hold the transmission securely – I used a Black and Decker type workmate (foldable work bench) for this.

You should be able to – with care – spin the gear set slowly. Listen out for any signs that the rear sun and planet system is scraping against the rear wall of the centre casing. If this is happening there is mostly likely something wrong with the pair of bearings in tail cone section or the thickness of the gasket between the centre casing and the tail cone section (see above). You need to fix this before you go any further.

Fit the input shaft to the gear set...

...and fit the cap on the input shaft. Secure these three screws with Loctite.

The gear set clearance is measured by measuring the distance “a” from the bearing in the front bell house casing to the casing mating surface with the gasket fitted.

Next you measure distance “b” which is from the mating surface of the casing to the position in the input shaft cap where the bearing on the front bell house casing will sit.

The clearance “c” is found by subtracting “a” from “b” (c=b-a). This clearance is adjusted by the removal or addition of shims so that there is a free space of 0.4mm to 0.5 mm

Once you are certain that the gear set clearance is correct fit the front bell house casing and torque the securing bolts as specified in the table above. You can now place the transmission in a horizontal position if you wish.

Stretch · #35 09-09-2011, 05:07 AM

As for all assembly work ensure that the pistons and the cylinder holes in the casing are clean.

Replace the seals on the pistons. Note that the position of the seals are positioned in such a way as to make it harder to fit them!

Lubricate seals and pistons prior to fitting with clean ATF. As before for the stiffer sprung brake band pistons (such as the B3) use of a clamping mechanism will help with installation.

Fit piston and piston cover simultaneously – not one and then the other. If necessary use the home-made yoghurt pot shims to help the seals go in nicely. Here's a picture of the B2 piston with its metal spring ring (which should be changed).

Do not use excessive force to put the brake band pistons into place. Do not let the sealing rings become pinched or wrapped round the wrong way. If you have trouble installing the brake band pistons the answer is probably going to be more lubrication. If necessary consider using grease.

When you've got the brake band pistons fitted with the caps in place push the caps further into the casing so that you can fit the retaining clips.

Stretch · #36 09-09-2011, 05:07 AM

The B1 and B2 brake bands are adjusted by adding different lengths of “torpedo” shaped bullets between the static stays and the lugs on the brake band. They are apparently available in 22mm to 26mm lengths in 1mm increments.

This is how you measure the brake band play. First attach a strip of masking tape to the surfaces of the B1 and B2 brake band drums and mark the positions of the ends of the brake bands when they are in their relaxed position.

Next apply compressed air to the ports in the main casing that normally would be connected to the valve body. By applying compressed air (be careful – don't over cook it!) to these ports you simulate hydraulic pressure. If the brake bands do not move you need to check whether you have fitted the brake band pistons correctly – see if you snagged a seal.

Here are photographs of the ports.

Apply compressed air pressure to the actuation side of each brake band piston and mark the new position of the brake band on the masking tape. Once done you can remove the tape and measure the distances each brake band travels. The values you measure should be between 3mm and 4 mm.

Stretch · #37 09-09-2011, 05:08 AM

To adjust the B3 (reverse) brake band the process is a little different. I still advocate checking the with compressed air whether the brake band piston works and moves freely however.

To adjust this brake band you simply have to tighten the adjusting screw (that pushes against the static stay side of the B3 brake band actuating mechanism) to 0.5 mkp (4.9Nm) and then back off the adjusting screw by 1 and ¾ turns and then tighten the lock nut. To gain sufficient access to the adjusting screw and its lock nut it is best to remove the kick down solenoid.

Prior to moving the adjusting screw it is necessary to remove this screw – clean it up – and refit with fresh sealing compound. My adjusting screw looks like it has had an unfortunate time in a previous life. I decided to leave well alone as there was hardly any wear on the reverse brake band when I removed it.

EDIT: Here's some information from rs899 about the B3 (reverse) brake band adjusting screw

Quote:

Originally Posted by rs899

... The reverse (B3) ... has a habit of backing out and making one think one's transmission is in need of serious repair when it isn't. As for how the adjuster looks - I think they all have that look. I think I read somewhere that they snapped off the adjusting lugs at the factory or some such thing.

Here are some pictures of the kick down solenoid (just in case they are useful)...

...from this thread:-

722.118 kickdown solenoid condition - advice req'd (probably OK though!)

Stretch · #38 09-09-2011, 05:08 AM

I can understand why lots of people fear this part of the transmission. It does seem very complicated and it is full of many little parts. But no guts no glory – take it to bits and clean it up!

When I took my transmission apart I found quite a clean transmission. I have now seen much dirtier ones. Even so a layer of grime was to be found throughout the whole of my “clean” valve body. I'm happy that I took the time to take it to bits, clean it up, and get it all back together again.

Warning – the majority of the good advice that you'll find on this forum is to NEVER EVER take your valve body to bits. So when it all goes wrong and the bits fly past your ears...

...don't take it out on your partner, the dog, the cat, the children...

...remember you are the fool who has made this terrible mistake! It is nobody's fault but your own.

To help you remedy the silly mistake you've just made here are some photographs of the valve body in bits – and where they all go. If you want to reduce the chance of spreading the internal parts of the valve body everywhere remember to keep pressure on each plate (or layer) of the valve body as you take it apart.

Here are two enlargements of the photograph above

I've done my best to put names to the parts that you'll find in the upper parts of the valve body – the bits that are furthest away from where the filter goes.

These bits are specific to a 722.118 valve body – this valve body has MORE BITS than a typical 722.1XX valve body. I plan to be taking a 722.120 valve body to bits in the near future. When I do I'll post up some more photographs showing the differences.

The following bits positioned “between the plates” are shown in the following photographs. From information in the ATSG manual these parts seem to be common to all 722.1 transmissions.

And you'll find these bits in the upper reaches...

All I did to my valve body was to dismantle clean and reassemble with new gaskets. The parts all seemed to me to be in good condition.

Stretch · #39 09-09-2011, 05:08 AM

When you are ready to fit the valve body, place the plastic separator on top of the gear set.

Make sure that the connecting pipes and rubber seals between the gear set and the valve body are seated correctly and then fit the valve body and torque the fixing bolts as specified above. Fit the filter.

I left fitting the input shaft seal till last. I had several different ones in my seal kit so I checked to make sure I had got the correct one by comparing it with the diameter of the shaft on the torque converter.

I cleaned out the torque converter by rinsing it with petrol (well actually I used something else called “wash petrol” that I haven't seen in any other country) whilst slowly turning the rotor shaft.

Fit the torque converter and the plastic holding bolt to stop it from falling out.

Don't forget to stake the output shaft nut when you are sure you've finished assembling the transmission.

Well that's it really – apart from some trivial bits and bobs I've left out in a pathetic attempt at brevity. I apologise for the length of this DIY – but in my defence it is a monster subject.

Here's a picture of the done deal.

Please note – I have purposefully left out fitting and adjusting the vacuum dash pot as I consider this to be more related to adjustment than to rebuilding. Different subject. I'm done.

rs899 · #40 09-09-2011, 06:36 AM

This is great even without the pictures. I hope it keeps many classic MBs on the road that would have otherwise turned into Chinese crap ( that we don't need anyway)

layback40 · #41 09-09-2011, 08:54 AM

This must be up there with the best trans write ups on PP !!

A definite for a wikki I think.

vstech · #42 09-09-2011, 10:57 AM

Quote:

Originally Posted by layback40

This must be up there with the best trans write ups on PP !!

A definite for a wikki I think.

yeah, me and webmaster are CHOMPING at the bit to upload this to the wikki when it's finished!

rs899 · #43 09-09-2011, 11:16 AM

I've got a wee gripe. A bit hard to tell with the lack of pictures, but can we see the torque converter and the mating pump gear? It would be useful when you pick through the 722.3 to illustrate and compare the two assemblies to see how MB tried to fix the earlier weak 722.1 torque converter by making the ears wider ( and making the driven tabs smaller in the pump).

This is a common failure mode with these trannies as well as the reverse band adjustment backing out. Just think those common issues need some discussion....

Rick

Marvelicious · #44 09-09-2011, 01:05 PM

Take all the time you need with the pics! You sir, are the man!

Stretch · #45 09-11-2011, 01:46 PM

Quote:

Originally Posted by rs899

I've got a wee gripe. A bit hard to tell with the lack of pictures, but can we see the torque converter and the mating pump gear? It would be useful when you pick through the 722.3 to illustrate and compare the two assemblies to see how MB tried to fix the earlier weak 722.1 torque converter by making the ears wider ( and making the driven tabs smaller in the pump).

This is a common failure mode with these trannies as well as the reverse band adjustment backing out. Just think those common issues need some discussion....

Rick

Hi Rick,

I've got some pictures and a bit of text in post #5

722.118 Automatic transmission rebuild (Monster DIY)

Is there anything else I should add?