560SEC 722.3 transmission rebuilt

I’ve known the automatic transmission in my 560SEC was weak for a few years now.    It was exhibiting a lot of the symptoms of wear that these 722.3 transmissions do when they are wearing.   When it was cold, there was a lot of resistance in reverse.  It would also occasionally bang into a lower gear or shift erratically.   Once it warmed up, it was a lot better,  the feel of the transmission was not close to the 722.3 in my 560SEL or the one in my 300TE.    While it didn’t leak normally, if I didn’t use the car for about a month, it would dump about a litre of ATF on the ground in protest.

I didn’t really like driving it in reverse with that resistance.  I used to make sure I parked the car so I didn’t need to reverse it when cold.   This wasn’t a long term solution.   I am planning to drive the car to Melbourne later this year, so I didn’t want the transmission to fail on me on the trip.   In addition, was worried about damaging things further driving it this way.   At this point I thought it was time to have the 722.3 transmission rebuilt.

This was not a job I wanted to take on myself, so one of the mechanics I use arranged to take the car over to a specialist he uses for these transmissions.    I got the car back earlier this week and its nice to have it shifting so nicely and to have reverse again.

When having a 722.3 transmission rebuilt, its possible to just have it resealed, or actually go through the whole thing.   As my issues were deeper than just leaks, I wanted it done properly.   The labour to remove, tear down, re-assemble and re-install the transmission is the lions share of the job, and I didn’t want to have to do this any time soon.  I also asked them to replace the rear main seal while the transmission was out.

The rebuilder left the old parts for me to examine.  I’m not especially knowledgeable about the inner workings of these transmissions, so I wasn’t familiar with all the parts that were replaced, but it was interesting to see the major ones.

From what I understand, the picture above shows the friction discs.  The set at the top is for the reverse clutch pack and the bottom ones are for the front and rear clutch packs (note there are two different sizes).

As expected, the reverse friction discs are far more worn than the others.   It’s good to see that while they were worn, they were not down to metal.

The front (left) and rear (right) bands were also replaced as part of the rebuild.   Like the friction discs, there is clearly wear, but they don’t seem badly damaged.

There were also other misc parts replaced, such as the vacuum modulator and various larger seals.   I’m not sure what the springs and components in the bottom right are for.

Looking at this last photo, it is pretty clear why these transmissions are always leaking.   There are a huge number of o-rings.   Not all of them are for externally sealing the transmission, but plenty are.   There are also these large seals, which I think are for the valve body.  The torque converter was sent away to be rebuilt, so I don’t have any parts to look at for it.

I’ve only driven the car a short distance since having the 722.3 transmission rebuilt.   So far, I’m quite happy.    I’m going to drive the car to Canberra in a couple of weeks as a bit of a trial for the longer trip to Melbourne.   I did a similar thing with my 450SLC before driving it to Adelaide, and the longer drive identified a number of things I was pleased to sort out.

My 300TE had its 722.3 transmission rebuilt not long before my purchase.  Looking at the invoice, there were a lot of the same problems.   Worn reverse clutch discs, and B1 band.   These seem like the standard 722.3 issues.