[Mirv]

Is it the speedo cable you're referring to shown it this picture?
View attachment 2431983

This is attached by a single 10mm bolt. But the bolt has to be removed completely because it fits into a slot within the speedo cable.
View attachment 2431985

Once this bolt is completely removed then the speedo cable on mine was released with a gentle pull. Half the plastic end on mine had broken off and remained in position and had to be fetched out.
View attachment 2431987

This is what the end of the speedo cable should look like.
View attachment 2431989

If this is not the "big cable" you're talking about could you post up a photo. There's nothing else that I can think it would be.

It's not the spedo cable and I did solve the problem with the help of another member. The cable in question had a locking tab in front of where the cable plugged into the transmission. It required a 1/4 turn to release the cable.

 

[CaptainSLC]

Ok, it's been a while but I've now got my full kit of parts to replace all the bits that were found to need attention while I was removing the transmission.

First job is to replace the front an rear seals of the transmission. There wasn't an obvious problem but it's certainly worth while with the transmission out.

Starting with the rear seal the fist challenge is to remove the slotted nut that holds the 3 legged flange. Not only is this nut torqued down pretty tight but it is also peened to the shaft.

The special tool to remove this nut is expensive and hard to get so I bought a 30mm deep socket and modified it to fit the slots in the nut. In hindsight perhaps a 12 point socket would have been a better bet and my modified tool seemed a bit light duty for the task.

With the transmission on the floor I drilled a couple of holes in a long bar to match with two of the flange holes so that this bar could be used to hold the flange still while I heaved on the nut. With the help of a breaker bar the nut finally moved - evidently the modified socket was up to the task after all.

And here is the result. The nut is still in good shape and the splines look good. The seal was pretty brittle and was a bit of mission to get out. So far so good.

 

[CaptainSLC]

The supplied seal was made by Corteco. No problems with that, they seem to make a pretty good product.

Wherever possible I like to make jigs to put seals in. It's a bit pedantic but it pays dividends when seals go in first time. This jig was turned out of wood. The outer diameter is about the same size as the the seal housing so that when it is fully pressed home the seal should line up with the face of the housing. The larger of the inside diameters just clears the raised lip on the seal and the inside hole slips neatly over the end of the output shaft to provide a guide keeping the whole jig straight.

The seal is placed loosely on the seal recess

The jig is placed over it and the seal tapped into place. The guide hole worked perfectly and the seal went in without any catching. The real payback for the jig would be if you had to do this with the transmission still in the car.

And here is the result...

 

[CaptainSLC]

The intention was to replace the rear nut with a generic replacement but a trawl of the local transmission parts suppliers turned up nothing. Without fail they all correctly identified the nut as being from the rear of a 722 transmission but no-one had a replacement. The consensus was to re-use the slotted nut with a bit of locktite - so that's what I did. Very glad I made the tool to fit it - if I'd chiseled it out I would have been stuffed.

The seal was lubed up with a bit of ATF, and the flange inserted.

The nut was smeared with thread lock and torqued up to 118Nm (12kpm). Again, the fabricated tool was up to the task.

Job done! The next exciting installment will be the front seal and o-ring.

 

[nobby]

Very nice work.

 

[Jyuma]

Good job.

 

[CaptainSLC]

Transmission Front Seals

Thanks for following everyone! For the more observant you may have noticed that this is not the same transmission that I removed. When I first bought my '73 SLC the transmission was significantly overfilled (40mm above full) and the ATF was a "medium" brown and smelt pretty bad (however, it shifted ok). After replacing the ATF and filter and filling to the correct level it worked fine - except - for the first kilometer after cold it would slip badly. After that everything was completely fine. I tried some Lucas Transmission Fix, but it didn't. It has always been a nagging problem and in anticipation I bought a the second hand transmission from a '77 SLC that I was assured worked fine (we'll see). The ATF was nice and clean and smelt fine so I think it is worth a try. However, I digress...

We now delve "where angles fear to tread" into the realm of the front seals. The front seal is relatively straight forward but the o-ring behind the front pump cover requires the front of the transmission to be removed.

Every post I've ever read about the innards of automatic transmissions reinforces attention to cleanliness. So I'll be doing my best using lint free wipes and covering everything wherever possible to minimise contamination.

In preparation the transmission needs to be stood on it's end. An easy way to achieve this is to drill a 16mm hole into a scrap board about 30mm thick. The hole is a nice fit onto the output shaft and the transmission balances nicely on this board.

First task is to remove the 11 bolts (13mm socket) that hold the front bell housing to the main transmission case. Once the bolts have been removed the transmission front can be removed with a little persuasion with a soft mallet.

The ring gear and the input shaft are held in place by the front seal and come out with the pump housing in the transmission front. The ring gear and input shaft should then be pulled out and put somewhere nice and clean :thumbsup:

 

[CaptainSLC]

Remove the 4 bolts that hold the pump housing. Note that there are some shims between the ring gear and the front bearing. Remove these and put them somewhere safe.

The pump housing will be held in a recess by the o-ring. Put a bit of padding under the pump housing and use a punch to push it out of the recess.

Here is the pump housing removed and the recess that it came out of.

 

[CaptainSLC]

The o-ring can now be replaced. Sure enough, the old o-ring was stiff and inflexible so it was a problem waiting to happen. Well worth replacing.

The front seal wasn't looking all that great either. This will be replaced with a "dph" seal. Haven't used a seal from this supplier before but they seem to get good reviews.

Very easy to fit the new seal with the pump housing out of the transmission. Inserted using a press - job done.

 

[CaptainSLC]

The pump housing can now be replaced into its recess and bolted down, re-using the wave spring washers. These bolts need to be torqued down to 20Nm (2kpm).

The front housing gasket has to be replaced. This was a much more difficult than I expected - it didn't take too long to realise that the gasket was well and truly baked on and there was a risk of damaging the mating surface if I scraped too hard. So I purchased some gasket remover (never had to use this before) and it acts like paint stripper on steroids :eek a real bubbling brew. The directions say to spray it on, leave it for 10 minutes and start scraping. Well, it took 5 applications to work my way through the gasket. Of course it was a real mission to try and keep any residue out of the clean transmission innards.

 

[CaptainSLC]

Place the ring gear and input shaft into the transmission body and lubricate the front seal and the mating surface on the input shaft with ATF to allow the seal to slip on easily.

Don't forget to replace the shims between the ring gear and the input bearing.

One side of the gasket is lightly coated in Permatex aviation gasket sealer, the gasket placed onto the transmission body and the other side of the gasket lightly coated.

Slide the front housing onto the input shaft and bolt the housing to the transmission body. I've used threadlock on these bolts - just in case. The bolts must be torqued up to 13Nm (1.3kpm)

That's it!

Please remember, I'm an enthusiastic amateur. I do my homework, but let me know if I'm doing anything wrong - I won't be offended and we don't want any "fake knowledge" on the forum :angel

 

[Nate Y]

Great thread. Increasing the knowledge on these transmissions is a service to all of us.

 

[azizamro]

dear hchaugli
my car is 500SL 1985
signals and hazard was working but i removed old stereo with amplifier it was missconnected to the wiring harness so since i removed the stereo with amplifier and its wires the hazard and signals r / l not working any more i tried my best to solved it but i dont have any chart or map of wiring diagrams for the indicator and hazard so please can you help me of that problem and if you could guide me to provide owner and workshop maintenanc manuals thank for your help
sencerly
aziz amro

 

[Ruindr]

@azizamro, welcome to the forum

Please start a new thread on a new topic. If you want to tag a specific member, use @ before the username.

 

[CaptainSLC]

Ok, I'm back and have the time to complete the process of getting the transmission back into the car - sorry for the break in transmission.

Still a couple of maintenance things to do.

It is worth changing the transmission fluid filter while the transmission is out and empty of ATF. I'm using a Mann filter which seems to be a reasonable compromise between quality and cost. The kit also includes a pan gasket.

This is not the same transmission that was removed. I'm taking this opportunity to replace it with a donor. The previous transmission was slipping a bit when cold and the ATF had that nasty burnt smell even after replacing the fluid. This transmission seems fine. The ATF is nice and clear and doesn't smell burnt.

The filter is easily removed via two screws and spacers.

When replacing the filter make sure that the tube is a snug fit into the body. There is a cork seal on the end of the tube which I soak in ATF before assembling.

The pan gasket is a tight fit and has a tendency to slip off. I had this with genuine gaskets as well so I don't think it is a Mann thing. They just seem to be a tad too small and I've had a gasket slip off on me before resulting in an immediate leak when refilling with ATF - very messy so I've been very careful ever since. Then the pan bolts need to be torqued up to 7 Nm.

 

[CaptainSLC]

Next, the torque converter needs to be re-installed. But I believe it is worth putting a litre of ATF into the converter before installation so that ATF will circulate quicker on first start up. I'm not sure if this is entirely necessary, but it can't hurt. Sorry for the spillage, it's a bit tricky pouring and photographing at the same time.

With the transmission still upright the torque converter can be carefully lowered into place. It is really important that the torque converter be correctly seated. Rotate the torque converter back and forward a couple of times and it should clunk into place.

This is close to what the level should be on the torque converter. From memory I think it even dropped a couple more millimeters after this shot was taken. There is a plastic plug that can then be installed. This plug is meant to stop the torque converter from falling out when the transmission is returned to the horizontal (my original 1973 transmission did not have this plug).

Not wanting to rely on the plastic plug I also put a ratchet strap across the torque converter to hold it in place during installation - it can be easily removed at the last moment. Note that there are three hex screws holding the ring gear to the torque converter. These will mate into holes in the flex plate on installation. It is worth lining one of these screws up with the plastic plug (note, it needs to be rotated into alignment on the photo) so that it can be mated with the flex plate during installation (care also needs to be taken in getting the flex plate lined up - but that comes later).

 

[CaptainSLC]

One final job on the transmission is to service the vacuum actuator. The cap of the actuator can be removed by clamping the spring clip together and pulling the cap outwards. Sorry for the fuzzy photo, but you get the idea.

Inside the cap is an O-ring that should be replaced. It's a 15mm ID, 2mm cross section (unfortunately not the 2.5mm cross section supplied in most metric kits). I lightly greased the O-ring with vaseline before installing.

After replacing the cap I tested the actuator with a hand vacuum pump and it held a vacuum well. It doesn't prove the operation of the actuator but at least nothing is leaking.

 

[CaptainSLC]

Rear Main Seal

It's not part of the transmission, but the rear main seal is the reason for the removal. There is no doubt that it has seen better days.
There are conflicting procedures on how to replace the rear main seal. The Haynes manual recommends removing the Intermediate Flange from the block and then removing the Rear End Cover. Really? I don't think I'm missing anything here - I've taken the path of least resistance. A self tapper into the seal and claw hammer easily removed the seal.

The surface of the rear journal was a bit discoloured but otherwise in pretty good condition. There was no wear line that I could detect.

The replacement seal that I have ordered is a "repair" seal which has different offset of the seal lip so that it rubs on a different section of the journal. In my case there is no wear so it's not important. You can see the difference in profile in the photos below.

 

[CaptainSLC]

Rear Main Seal (Continued)

It may be overkill but I turned up a wooden drift to make sure the seal went in straight and to the correct depth. This replaces the special Mercedes tool for the job. The main feature is a center spigot to guide the drift centrally.

The seal is lubricated with engine oil and placed in position. The drift was then used to drive the seal in.

Job done.

 

[CaptainSLC]

Bush replacement

Some more maintenance to do before replacing the transmission. All the bushes on the linkages were shot so they were all replaced.
There are two bushes on the gear select linkage. They are a pretty tight fit. The bush was greased then I used a combination of socket and bolt to pull it into place.

There is a smaller bush on the Control Pressure Lever. The same technique was used to install this.