I have recently done an ATF change with the latest .14 fluid, on my .6 transmission in my late 2006 CLK ( a strange combo., I know) and shift quality is improved, but I fancy test driving a few other CLKs and E W211 classes, in particular those with some larger Diesel engines, like the 320 cdi, and some petrol 320s. However at the Mercedes Approved, the manufacture dates; result in the 722.9 transmission, and I just want to know how the .9 compares with the 722.6, assuming they're both reasonably healthy transmissions...

Will I be able to notice any behavioural differences in shift quality? Or purely just different shift points.

Ben

 

There are many things better about the .9 over the .6, the most obvious being two extra forward gears to give you better gas mileage. First gear is also lower in the .9 so you get more torque to the wheels for start-off. You also get a second (higher) reverse gear. This might be beneficial if you drive in snow. Another thing is that the .9 can downshift by two gears at one. For example, if you are in 6th and hammer it, it can skip 5th and go straight to 4th, then skip 3rd and go straight to 2nd. This improves response in "spirited" driving. Another difference is in the electronic control. The ToushShift + and - functions are slightly different. When you tap down, instead of just going from "D" to "4", the TCU tries to anticipate what you want. If you are tapping down and accelerating, it assumes you want a good hearty downshift so it will choose a lower gear, so not just "D" to "6". Depending upon how aggressively you are accelerating when you tap down, it might go to the lowest gear possible, given road speed. In other words, it tends to be a bit "smarter" interpreting your inputs.

The physical internals are about the same except for the additional 3 gears. In fact, many of the internal parts are interchangeable. Some not so good things are in additional complexity. The TCU is now located inside the transmission as part of the conductor plate. It is now also a part fo the DAS (Drive Authorization System). This makes it more expensive to replace in terms of labor, because you must drop the transmission pan and remove the valve body, instead of just pulling back the floor carpeting in the passenger footwell. Also, since it's part of DAS, only a dealer can code a new TCU and it must be a factory-fresh virgin part. Of course this is not an issue if it never fails, but the problem is, they are prone to fail in early 722.9s - i.e. those built prior to 2008. There have also been issues with the fluid pump failing and the torque converters failing in the earlier versions. Finally, the refill and level check process is more complex. There is no dipstick - not even a dip tube to insert a dipstick or pour fluid into. Instead, fluid is pumped in through the drain plug ont he pan, and the level is checked by the overflow rate through the drain plug.

I like the 722.9 much better than the .6, but I'd advise getting a newer model - one built in 2008 or later.

 

I'm pretty sure my 2005 has a .9

Just crossed the 25K mark tonight, still hoping I never hear about "conductor plates" and "turbine input improper" issues. I wish it had paddle shifters, the response from hitting the gearshift left or right is laughably slow.

All of the electronic gizmos give it great fuel economy on the road, but really take a bite of of throttle response once moving. I have to say that my '68 SS396 or even '79 T/A had more of an "alive" feeling, despite the fact that CLK500 would leave either one for dead in 1/4 mile. Giving it some gas at 30 MPH results in all sorts of electro-mechanical fiddle faddling to keep emissions in range, but takes all the fun out. When you goose it you sometimes need power NOW, not in 2-3 seconds when everything else gets lined up.

But getting 27-29 MPG on freeway whilst doing 80 MPH is amazing. Neither of the 7 litre beasts of the past got over 15 MPG.

 

I would do a reset on the shift adapts. and while its relearning drive it a little aggressive

 

MY2005 CLK500 will have the 722.9 7-speed. Paddle shifters would not make a difference - they do the exact same thing as tapping the TouchShift left and right. The "reset" procedure Gixxerbo mentions might help, but it's not a transmission reset - it just re-synchronizes the accelerator to the throttle:

1. Make sure everything in the car is turned off and closed.
2. Turn the key to position 2 so all the dash lights are illuminated.
3. Press the accelerator fully to the floor, depressing the "kick-down" button.
4. Hold he pedal for 5 seconds and continue to hold it down.
5. Turn the ignition switch back one click to position 1.
6. Release the accelerator pedal, but leave the key in position 1.
7. Sit quietly and wait for about two minutes - do NOT open or turn anything on.
8. Listen for a "click" or "ping" noise form the dash.
9. Start the engine and drive the car for at least five minutes.

 

Thank you for the awesome comparison in its entity Rudeney! Much appreciated.

I quoted the part above to let everyone know (you probably know that already) that the 722.6 TCU did receive an update at some time which allows it to downshift to the next available gear based on the conditions and driver input rather than having to sequentially go from D to 4 to 3 etc....

If I know I'm in 3rd yet displaying D and tap - as I'm acceleraring, the instrument cluster will go from D to 2 and the 2nd gear will engage rather than going from D to 4 to 3 to 2 like my 2003 CLK used to do.

My current car is a Euro-spec 2005 CLK 320.

 

Thanks for that info on the 722.6 update. And it doesn't surprise me. I know there have been many TCU software updates. For example, the original 722.6 TouchShift code would not automatically upshift at redline - it would just drop RPMs by about 200 and "stay there" until the driver shifted. Also, on the 722.9, they made a change so that it does not downshift to 1st until you come to a complete stop. This was done to eliminate a clunk/jerk when coming to a stop.

 

I agree this may help, what i was referring to in Star or a good scanner you can reset the shift adapts of the transmission.

 

Yes, if you have SDS, resetting the driver-adaptive learning of the TUC is recommended. In fact, I would go through the whole adaptive learning process with SDS to set my own shift points.

 

Thanks for the replies guys. So what do you feel about the shift quality? Between the .6 and .9, how does the smoothness and speed of the shifts compare? Both when using tiptronic, and when the gearbox shifts automatically.

Sometimes in my .6 when I manually shift down or up, I can feel a bit of a jolt. I put this down to differences in transmission and prop shaft revs when there will be a significant difference in transmission speed when I force it, but don't know whether the .9 could compensate for this better.

 

The .6 transmission also determines the correct downshift gear. Frankly, with the torque curve of the M113 engine, the five-speed is a great setup.

 

I think the 722.9 shift more smoothly, but it's likely due to a smaller difference between gear ratios. When "slamming it" and using the TouchShift, the .9 is more responsive. Just my opinion.

 

Yeah, we discussed that there was a TCU software update for that. The .6's I've owned did not do that. The TouchShift just acted like using a PRNDL321 shifter "manually".

I think in terms of performance and fuel economy, more gears will always be better. I mean, we're seeing 9-speed ATs now. How long before we'll get 12 speeds? Actually, CVT is a good options, except most are horribly implemented. We had an Audi A6 with a CVT and it wasn't bad at all *IF* using the "manual" mode. With that, it used pre-set ratios to give it the appearance of a 6-speed. Gear changes came instantly. I've never really understood why CVTs aren't implemented this way. The whole thing where they either keep the engine at lowest RPMs or redline is ridiculous, IMHO.

 

CVt's reliability is a major issue, so many manufacturers are having trouble with them lasting. Parts arent available for allot of them so they are just throw away units.

 

Yeah, I've heard tales of CVT failure issue, but Nissan keeps using them on a good number of their cars. And I'll bet these problems can be overcome with some engineering expertise. I mean, it's 2016 and we have self driving cars. Can't we make a good transmission?

 

For cars with little engines that need to stay on a narrow torque band for power I can see a use of CVT. It doesn't make sense for MB cars with big engines that have flat torque curves. When Nissan puts CVT in the GTR I'll believe its usefulness with high horsepower engines. Personally, I'm not a fan of CVT - I like hearing the engine shift, and shifting it when I want. It's a big part of the aesthetics of the car.

 

Nissan uses the CVT mated to their 300hp 3.5l V6 engine. I like shifting, too. I'm just saying that a CVT is a much simpler device than a traditional planetary gear transmission and it can shift much more quickly and without a loss of power during shifts. Not only that, the shift points can be programmed with a virtually unlimited range. If someone could develop a reliable CVT, with the right programming to emulate a traditional discrete gear unit, they'd have a winner. For example, how many times have you hammered it to pass a car, but your speed was too fast to go to 3rd, so you got 4th instead and that didn't give you quite the torque you wanted? With a properly configured CVT, the TCU could select a gear ratio between "3rd" and "4th" to give you maximum torque. Now, just hold that ratio and step-upshift instead of "motor boating" and you'd have my vote!

 

I had a 2009 Nissan Rogue, recently sold for a 2016 Audi Q5. The Rogue CVT was great. Smooth and positive. It had paddle shifters to emulate the semi0auto trans, but I almost never used them. The engine wasn't powerful, but I could haul decent loads with it.

 

Have CVT on 2012 Nissan Quest. My wife hates it. Very poor acceleration and A LOT of revving involved.

 

Didn't you test drive it before you bought it?

 

We did. Not on a highway though. On 25 mph street. First brand new car and a lot of emotions were involved. Plus I had no idea about existence of such trans.
My wife loves her Quest a lot because of styling. She felt in love with it. She says that is the most beautiful van on market. Still enjoys it. With crappy tranny though..

 

Rodney, i understand your points, and it may be great for some people. To me it reminds of a slipping clutch in a manual transmission. As to downshifts, 3rd gear in my CLK is all I ever need for passing and the AMG's downshift to third is measured in miliseconds. Again I think the CVT is more appropriate in a lower horsepower car when the engine needs to stay in a certain torque band to provide decent power.

It's interesting that none of the gas powered Infinity models use CVT transmissions, all use 7 speed adaptive automatic transmissions.

 

Can I just ask What gearbox does my 2004 clk w209 270 cdi have, or how to find out? I'm guesting a 722.6.

 

722.6

722.9 introduced from 2005. Although my Reg. December 2006 has a 722.6, built in summer 2006.

 

Every W209 CLK55 AMG (even the 2006) uses 722.6

Every non-AMG W209 up to 2005 uses 722.9. The exception is with the 2005 CLK320, which uses the 722.6.