Hello everyone. I've owned my 2006 E55 AMG Wagon for a little over a year now, and I plan on keeping the car long term. It's only around 80K miles or so, so I don't think it will have any issues keeping on trucking for quite a few more years. I just love the overall package the car offers, and don't see any modern vehicles that come close for money I would like to spend.

That said, I have one major peeve with the car. The transmission. Even when it shifted properly, it was sluggish and simply not very satisfying. Then it started acting up, and I have not been able to get it to behave properly since. Basically, it acts like a manual all of the time, refusing to freewheel anymore, and it has very odd lockup behavior in the lower gears when you accelerate. It also starts to slip noticeably during long drives. I changed out the conductor plate, replaced one of the solenoids that controls lock-up, and it still does the same. Had it in to the Mercedes dealership, and they claimed it was just slightly under-filled and actually fine after charging me $400. They also gave me a long lecture about how I shouldn't mess with their "extremely special and difficult" AMG transmission on my own, and that it was a miracle I hadn't grenaded the whole thing. I also despise the fact that there is no transmission dipstick, and I can't tell how much fluid is in the damn thing. I bought a universal dipstick and looked up the values I should be seeing in millimetres, and it measures WAY off that. Half way full it was already measuring over the supposed full mark, and now at the proper fill level according to the dealer, it's like 3 times the supposed required measurement. Someone should just make a normal dipstick for these as an aftermarket option.

All of this mess has made a crazy idea take root in my brain. What if? What if I just swapped this thing with a ZF 8HP-90?

You can pick up good examples of this transmission for quite cheap, they are an absolutely brilliant transmission if you have never experienced one. Feels like a Volkswagen DSG.

Now of course, it's not likely to be a one for one swap and off you go. The following are the issues I can personally foresee with such a project.

1. An adapter plate may be needed. Can't find solid information on this so far, but I have found adapter plates for mounting a BMW N54/55 transmission (BMW uses the 8HP on that engine) to a M113K. I think it's probably possible, but would need more research to figure it out.
2. Probably would need a custom/modified drive shaft of some variety, as I doubt the overall length of the two transmissions is identical, though I can't find any dimensions info on either so far.
3. Would likely need to adapt the trans mounts somehow.
4. Would need a controller for the new transmission. Lots of good options there for the 8HP. Not 100% sure about integration with factory controls though.

From there, there would be a good bit of work integrating everything, but nothing that isn't possible in my estimation. Anyone have any thoughts on my crazy idea?

 

I think you may have bought the engine oil dipstick? The 167-169 mm full mark (if that's what you're referring to) is for engine oil. The transmission dipstick just has 2 sets of high/low marks, 1 for 40 degrees and 1 for 80 degrees.

I'm not sure about the ZF, but the M113k has been mated to a 722.9, so that's an improvement in terms of shift times

 

The ZF8HP only handles torque up to about 500 ft-lbs. Maximum torque. A properly running 55 engine will rip it to pieces in a couple months. Those internals can't handle it. It's a jerky transmission when it's cold, and ZF is notoriously unreliable when it comes to design.

There's no universal millimeter reading on the transmission dipstick TOOL. It's marked 25c, and 80c and you measure it when it's hot only at 80c or slightly above (in park), with the engine running, after you row it through the gears. You can pull the transmission temperature off DAS, or point a thermal tool at the pan itself. I use DAS.

Sounds to me like you completely hosed your transmission valve body. If you don't know what you're doing in terms of something basic like measuring ATF level in a transmission without a dipstick, then you do not have the requisite general experience necessary to start installing replacement conductor plates or screwing with the valve body. 722.643 transmissions are very sensitive to fluid level, and need to be measured correctly before you **** with anything internal.

 

I'm not a fan of the 722.9, but I think it would handle the power better than the ZF8HP.

 

I bought a generic all purpose one graduated in millimeters and looked up the measurements on this site. Don't remember what they were exactly, but I measured it out and marked it off with a sharpy on the dipstick.

 

The ZF 8HP-90 is the stock transmission in the 840 HP, 770 lb/ft of torque Dodge Demon. Those have a reputation for blowing up their differentials, but the transmissions are holding up fine. I have no doubt it would handle the power as well as, if not likely better than the 722.9.

 

Condescend much?

Edit: To be clear, the car started this behavior out of the blue one day in the middle of an hour long drive. This was less than a month after a complete dealer service (previous owner was a Mercedes employee and had one last service hooked up as a favor) There was no leak from the transmission, so I did a little research and found the known issue with the conductor plate. Took a look at what was involved, and it is a very straight-forward job. The job itself was quite easy, if a bit messy from the dripping fluid, but it did not affect the problem at all. I was not super worried about the fill level issue with the generic dipstick because I measured the fluid I removed, and put an equal amount of new fluid back in. Something in the measuring how-to I read here is definitely off though. Took the car to the dealer for an evaluation when the issue remained unchanged, and they stated the transmission was "slightly underfilled", but there was no change in behavior after they claimed it was topped up.

I'm no master mechanic, but I've been doing my own work for years with no issues. To be clear, I have no intent to do all of the work involved if I did decide to try this. I know I could manage everything except the drive shaft modification and transmission mount fabrication with a little help from a friend, but I think I would probably be better off paying someone for the whole job, minus the transmission controller integration most likely, as I find that challenge interesting. Don't have a place to leave an immobile car sitting around while I work on it at the moment, as my garage is underground down a ramp, and would prefer to have the car back quickly, as I don't like to drive my other car in bad weather if I can avoid it.

It's also worth pointing out that there are literally hundreds of thousands of ZF 8HP tranmissions out there in the world, and problems have been largely non-existant from what I can find. Only problems I found reported where when someone modified their car beyond the capabilities of the particular model of 8HP. One guy had 750 WHP on a 8HP-70 for example, which is the one that is limited to 500 Lb/ft and blew up one of the clutches I believe. Not ZF's fault in that case.

 

The ZF 8 is a top-tier transmission and Mercedes could only wish they could make something as good and versatile as it.

Adapting it to something as worthless as the 55K? That's a dead mission if I've ever seen one.

 

Worthless is in the eyes of the beholder. I love this car, just wish it had a better transmission. Would rather spend 5-10 K on making it better, that a lot more on another car I won't like as well.

 

Triple or quadruple that number

 

You can buy a new 8HP for $4K, and a good used one for less than a grand. Hell, you might be able to get one for like $75 at a salvage yard if you are lucky. A few hundred for a drive shaft modification, and the rest is just labor hours for the swap and transmission mount fabrication, which I am guessing would run a few grand.

 

certainly no wiz here, but this kinda thing used to just be mechanical... machine an adapter and your good to go..... today you have to modify the computers for the tranny and the engine to talk to each other, this is where your cost could skyrocket.... my .03


EDIT:

The motor ECU has been cracked since we have tuners out there offering tunes... dunno if the Tranny ecu has been cracked ?

 

There are stand-alone transmission controllers that work with the 8HP and a lot of other transmissions out there. They can integrate with paddle shifters and various electronic shift levers. You have to do a bit of the programming yourself, but I personally find that an interesting, and potentially quite rewarding challenge as you can tune the shift speed and quality to your preferences, as well as create several presets such as a sport mode with fast shifts, and a comfort mode with more relaxed shifts.

 

feeshta- most of these cats think the 722.6 is an advantage LOL. I'm not joking. Do some searching...this setup has been discussed previously.

 

The 722.6 is the best you can have on this car albeit it’s not a great shifter when it comes to shifting speed. It’s robust though and used in various AMGs.

The transmission reinforcement by MKB or Renntech is what you should be doing. This coupled with a transmission tune makes the car feel more solid and shifts much better.

I’ve driven 3 cars by MKB with the reinforced transmission and 2.82 gearing with the transmission tune. All I can say is that it is the best upgrade that can be done on this platform but not common and discussed much over here. The shifts are quick and you can really feel the difference, feels so much better. This also raises the transmission tolerance and higher torque limits.

Renntech sells this upgrade if you want it in the US else you can get in touch with MKB for the upgrade along with 2.82 and transmission tune.

Rather than messing with the idea of putting a different transmission and figuring out on getting it to work, money and time can be saves by this upgrade. This should cost about USD 3380 from Renntech and EUR 2680 from MKB for the transmission reinforcement and tune.

Renntech requires the car in their HQ for this upgrade, MKB you can get the parts and get it done with a reputed transmission garage.

 

The MCT might be a slightly more realistic option and should bolt right up, at least to the later production M113K.

 

MKB ? Link?

 

https://www.mkb-tuning.de/en/product...&prod_gruppe=3

You can contact them for the pricing. The pricing I mentioned in my previous post was from the price list I’d received a few years back.

 

That might be worth looking into. MKB is located a couple hours from me. I live in Frankfurt, Germany, and they are down near Stuttgart. The most offensive part of the behavior of this transmission is the extremely sluggish shift times, followed by the weird engine braking it has currently. Oddly, I never mind that in manual cars, I guess because I can always just depress the clutch or go to neutral when I just want to coast, but in the Merc, something sounds wrong when you are chugging down a hill against the resistance of the transmission for some reason. It just feels wrong.

Not really sure I would want to change the gearing, as I don't really have an issue with how the car is geared now. 5th gear is a very nicely chosen autobahn cruise gear, and I don't think I would want to lower that ratio.

 

You’re located in Germany and I believe you’ll be in good hands with MKB. This is a upgrade that will be worthy rather than just rebuilding or replacing the transmission. Keep us posted if you are planning on this upgrade.

 

Two things:

1. If you used a generic graduated dipstick, it won't work. The Mercedes conductor plate has a positive stop built in to it so the tip of the dipstick is just below the valve body; it never goes down to the bottom of the pan. (Interestingly, the Mopar conductor plate does not have the stop; it relies on the handle at the other end being fully inserted for correct positioning)

2. If you are serious about the 8HP, contact Russel Drake at Sound German Automotive. He knows both transmissions in-and-out and has developed programming for both.

 

I wrote an inquiry to MKB, and their response is pasted below. Seems they believe the gearbox itself is shot, which would be rather disappointing given the 722.6's vaunted reputation for durability. Honestly the gearbox's supposed durability was one of the reasons I chose this car over several others, including a C63 AMG wagon, so it's rather irritating to have it fail less than 6 months into my ownership. I can't know for sure how the previous 2 owners drove the car, but I do know that the car was routinely maintained by Mercedes for the majority of it's lifetime, as the second owner, who owned the car from 2008-early 2019 was a Mercedes Benz employee who took advantage of their employee maintenance program, which is quite generous here in Germany. For example, he had one of the front air struts replaced a couple years back, for less than $400.

For reference, 3,300 Euro is currently a bit less than $3,700, and I don't have to pay the 19% VAT (Value Added Tax ) because I am an American.

Anyone have any thoughts on whether MKB is correct in their assessment that the clutches are worn out?


Dear Mr. Fish,


thank you very much for your friendly inquiry and your interest in our products.


We know the problem you describe. It is the worn clutch discs in the different clutch packages of the automatic transmission that cause the slippage.

In this case, we recommend an overhaul and simultaneous reinforcement of the gearbox.

This means that all wear components in the gearbox are renewed and at the same time the gearbox is additionally reinforced,

so that an additional load is possible. We use the gearbox reinforcements for our increase of performance and are very satisfied with them.

The costs for this are incl. installation of the gearbox from the vehicle approx. 3300 € + VAT. Alternatively, you can also send us the gearbox to the workshop.



If you are interested in this modification, we will be happy to provide you with a detailed offer.

Please don’t hesitate to contact us for further information or assistance.



Best regards,



Petros Avramidis

Technical Management



MKB Motorenbau GmbH

Otto-Hahn Str. 2

71364 Winnenden

Germany

 

Since you live close by, I guess you should take your car there for it to be assessed. If you were planning on the reinforcement, I guess the additional cost won’t increase by much. The transmission is going to be completely ripped apart for the reinforcement, saving on labor cost. You can have the rebuilt transmission and a much stronger one. I strongly recommend you visit them, they are experts. Maybe they work out a reasonable quote for you when you’re there.

 

I swappwd trans zf8hp70 to my cls 55 amg trans is stering by tcu turbo lamik controler
if You wanna know something more about this send me po on Facebook
Rafał Płaszczyca Katowice
mór write to my on Instagram Raalph_p

 

I stumbled upon this old thread and I'd be curious to hear what the end of this story was.
Also I am absolutely amazed how non-constructive most of the useless post were that the original poster of the question received and how polite he remained and explained everything. Kudos!
I absolutely agree that the 8HP would be a major upgrade upon the old five speed.

So? If there is any update on this, I'd like to hear about it.

Best regard, Tadek