mgfan

I'm very annoyed now, after just over 1000 miles the gearbox on my C300 hybrid has developed a very annoying fault. For some reason the change from 1st to 2nd is now a hard jolt rather then a smooth change, a bit like just dumping the clutch in a manual. None of the other gears seem to be affected and it does it regardless of whether its on diesel or electric drive so definitely looking like a gearbox failure.

Is this a common problem or could it be something unique to the hybrid box?

It's booked in on Tuesday which is annoying because other then this the car has been flawless and I really love it.

Glyn M Ruck

They need to put the car on a Star, Check all the change pressures & reset all adaptions. They will probably also reflash the software on the TCU. These are software controlled transmissions & you probably just have a glitch. I doubt the issue is mechanical but until fault diagnosis is done with a Star we won't know. 1st to 2nd issues are always most noticeable because of the large ratio change. 1st gear is a very low ratio.

Glyn M Ruck

BTW ~ When you brake hard coming up to a stop do you get a jolt on the downchange? This was the biggest gripe with the 722.9 Plus. The latest software brings the car to a halt in second gear & then selects 1st for takeoff. This software change made a big difference to customer perceived smoothness of operation. Once again the very large ratio change.

mgfan

No, the down change is fine as are all the other gears it's just 1 > 2 which is a problem.

Glyn M Ruck

OK ~ then you have one of the latest software versions where the car stops in 2nd gear. Probably only needs the first to second clutch pressure corrected to allow controlled slip before lock up. I would certainly not worry about it until the dealer has had it on a Star.

EDIT: I presume when you select comfort mode on the transmission so that the car pulls away in 2nd gear unless over 75% of throttle is used this does not happen?

Glyn M Ruck

They might now call Comfort mode Eco mode. Sorry I don't have a 205 to check. We have 2 in the family but none at my home.

Glyn M Ruck

Another consideration. Sorry but no one on this board knows the hybrids well yet. Some diesels ~ higher torque models always pulled away in 1st. I don't know what they have programmed for the hybrid. Diesel & electric motor = low RPM high torque availability. It might not pull away in second like standard gasoline cars in Comfort/Eco mode. Ask the dealer.

Glyn M Ruck

Reason for high torque fast rise diesels not starting in second gear like gasoline models was that torque exceeded the transmissions torque capacity for second gear without the car rolling already. This would accelerate wear on the 2nd gear planetary gear set.

mgfan

Mine seems to pull away in 1st most of the time. I supposed with mine you've got the torque from the diesel engine combined with the boost from the electric.

mgfan

It was indeed a software 'glitch'. Not entirely happy with the explanation as they don't seem to know what cause the glitch however after being recalibrated the gear change is now smoother then ever.

It was also my first experience of MB service and I must say it was exemplary. Took the car in at 10am and was off in a loan car within 10 minutes and mine was then ready to collect having been fixed an valeted by 4pm. The only downside was the loan car which was a 64 plate B200 and was awful, even my 13 year old MG ZT was a nicer drive however thankfully I didn't have to drive it very much.

Glyn M Ruck

There are so many influences that can corrupt the software that they would be guessing. Just be thankful that Microsoft did not write the software. Then you would have frequent issues.

Pleased it's sorted.

Glyn M Ruck

Another point. This is one of the advantages of going to your dealer for services. Benz makes frequent software updates until a vehicle becomes mature. At service the dealer will always connect a Star to check whether your car requires any software updates. It's not like your home computer that has a permanent & reliable internet connection for software updates, patches, repairs & service packs.

MB205

I have this exact same issue on my C300 hybrid. 1st to 2nd is really poor like you describe, the other changes from 2nd to 3rd etc aren't too bad but sometimes jolt.

The downchanges from 2nd to 1st and 3rd to 2nd can sometimes be really bad too.

Got the car booked into Mercedes this Friday so hopefully the software glitch you mentioned will fix it. Have to say I'm not overly impressed with this gearbox at all, it's quite slow to respond and the manual mode isn't really manual at all, changes up and down for you and automatically goes back to auto after a couple of minutes - isn't it about time Merc switched to double clutch transmissions anyway?

Glyn M Ruck

A DCT is in the wings for those that want it. Not sure when it will launch. At the moment confined to the A Class.

ManiacGT

Given how jerky the standard auto box is (and this in 2015!) a DCT would be a welcome addition. My BMW DCT is six years old and you can't even feel it shift, you can only tell by the exhaust note. The S205 by comparison feels like someone taps the brakes every time it shifts. Its the least impressive part of the car for me.. not a very nice auto box at all.

Glyn M Ruck

Don't despair. The 722.9 in my CLK is fantastic after numerous software updates. The 722.9 Plus software is not mature yet. This is the joy of software controlled transmissions. Benz can frankly make it how you like it. They take feedback from their customer base & steadily react to major gripes with software updates. Just make sure that the updates get done when you service the car. You are not stuck with what you don't like at present.

Some driving readjustment is also required with these transmissions. They take so many parameters into account compared with an old hydraulically operated with vacuum override fixed change pattern transmission.

You need to drive more deliberately with them & you will get on with one another far better. No sudden throttle input. Don't accelerate hard & then immediately stomp on the brakes. If you want 50% throttle then do that and leave the rest to the transmission. No yo-yoing of the throttle pedal. It confuses the TCU. Don't stomp the throttle pedal to the floor. Accelerate progressively. When you stomp the pedal to the floor it causes the MAF to hunt & delays transmission adaption. It will slow down take off. Etc. I have always felt that for people that are stuck in the past & want their transmission stuck in the past & far less efficient, Benz should add a button that just switches in a standard Map. Then people that yearn for the old US slush box feel can have it. The 722.9 Plus is vastly more efficient that BMW's ZF sourced 8 speed. You just have to dyno the two makes to see the high losses in the BMW transmission.

Be prepared to change old bad driving habits & have all software updates done & you will be pleasantly rewarded.

EDIT: There should be no shift shock & jerking at all. The 7 speed was originally criticised for being too slurey and soft on ratio change.

There is also no doubt that this transmission is happier behind the larger engines than the 4 bangers.

ManiacGT

I drive the car entirely differently to the BMW. I've experimented with numerous styles to try and understand it better, softly and aggressively or even trying to predict the shift to lift off and avoid the issue, but that's quite difficult. Heavy ish throttle seems the best, or hardly any throttle at all. Anywhere between that is jerkyville.

D2 to D3 is awful when cold, akin as mentioned to dabbing the brakes. When it shifts D2 to D3, revs rush higher like its not matched the revs properly for the change and when the clutch engages there's then momentary engine braking, making it rev up before it settles. D2 to D3 seems to be the most jerky and others have agreed on my other post here about it. Once the car is warmed up its fine, but for the first 10-15 minutes its annoying. The other gears, shifting up or down are still felt but nowhere like D2 to D3.

Glyn M Ruck

Even when the car is at high idle, open loop fully enriched at cold start it should hold lower gears for longer to heat the Cats but should not jerk other than possibly when you select drive & it's very cold. Make them reflash your software at next service. There should never be any flare of RPM on gear change either.

megaoctane

I have the same issues with mine. D2 to D3 - very bad when cold. Not so bad when warm. And while cold D4 to D5.
I often just drive in Comfort mode - and the car switches to 1st gear only when fully halt. Else it keeps 2nd gear.
Had my car in at the dealer and workshop 8 times.
Does anybody know if new software has been released the last month?

mgfan

Mine is very smooth in all gears now, certainly smoother then when I first got it.
Got to agree with the manual change though, the paddles fitted to mine are the biggest waste of time ever. It'll only actually change if it agrees with your choice of gear and even then if you don't change up or down before the car thinks you should it'll just do it anyway.........most pointless manual EVER!!!!!!

r1155

Well, mine is in today to get the gearbox looked at, exactly the same problem at around 1000 miles, very lumpy change 1st to 2nd and 3rd back to 2nd. Dealer booked it in straight away within 2 days. will update progress later on.

r1155

Been in, good for about 2 days, now just as bad, will have to take it back I suppose.

ManchesterMan

Evening / Morning All

First post here, take it easy on me! I own a W205 C220 AMG Line Auto. Ever since day one the gearbox has been nowhere near as smooth as it was on my previous car (W204 C220).

Quite often it will hold onto low gears for far too long, generally 1st and 2nd. It's really noticeable, sometimes it revs to around 2300-2500 rpm before it changes! It's driving me mad as apart from this problem I absolutely love this car.

I've noticed that it seems to be worse and do it much more often if i've been driving the car for a long period of time?

Thoughts?

MB205

Just an update on my issues. Took the car in last week and got it back after a software update. The gearbox is so much better now. 1st to 2nd is now by far the quickest change of the lot and I've not had a single jerky gear change since the update.

I had a CLA220 on loan with a DCT gearbox and when I got the C Class back, although the changes aren't quite as quick, it's definitely a massive improvement and I didn't feel like the single clutch transmission in the C was a real downgrade.

MB205

Okay looks like I spoke too soon. The gearbox has gone back to the way it was with the extremely poor shift from 1st to 2nd and the others being slower than usual and clunking on the downshift. Noticed this Monday last week. Traffic updates are also intermittent. Back to the dealer...