Is the 7g gearbox really that bad?

[Mactech]

I've had 3 of the 5 speed Mercedes 'boxes and 4 of the 7g ones.
The 7g is superior in every respect in my opinion. I was really impressed with the clever way it got itself into the very right gear going up and down hills.
The boxes are matched to differnt engines by Mercedes and the petrol ones I have tried are all good.
The 7+ box I have spent an afternoon with in a new ML and it is an improvement again, but not quite as good overall as the new 8 speed boxes used in my BMW 5 series and the company car....

 

[BlackC55]

I am not a fan.

There is no need for 7 gears esp on a diesel

This month so far we have seen two blow up. No drive at all and a sump full of metal. The 5speed is a much more pleasant box to drive with IMO. One with 56k and the othe with 78k.

From a repair point of view they are much more expensive than the average 5speed to overhaul.

 

[V12]

Hi Olly, would you put that down to poorly maintained vehicles and lack of preventative maintenance or just simply weak mechanicals.

 

[st4]

I am not a fan.

There is no need for 7 gears esp on a diesel

This month so far we have seen two blow up. No drive at all and a sump full of metal. The 5speed is a much more pleasant box to drive with IMO. One with 56k and the othe with 78k.

From a repair point of view they are much more expensive than the average 5speed to overhaul.

The voice of reason.

7g is rubbish. I've sampled it from my car, to C320 and CLS350 and E500. All changed slowly and jerkily. All bar the petrol had a poor span of speed in 3rd gear meaning a 69mph change, just what you don't want pressing on or overtaking.

I've sampled vast amounts of 5g cars from 4pot diesels to V8 AMGs and all have been responsive, well spaced gearing wise and a joy to drive.

Olly and I are right, OP the rest are IMHO wrong.

 

[davidjpowell]

The voice of reason.

7g is rubbish. I've sampled it from my car, to C320 and CLS350 and E500. All changed slowly and jerkily. All bar the petrol had a poor span of speed in 3rd gear meaning a 69mph change, just what you don't want pressing on or overtaking.

I've sampled vast amounts of 5g cars from 4pot diesels to V8 AMGs and all have been responsive, well spaced gearing wise and a joy to drive.

Olly and I are right, OP the rest are IMHO wrong.

I like the gearbox. But had to have a replacement on a 40k C320 diesel. Not really cricket, and not something I have seen before or since.

Fortunately it was under warranty- as MB quoted the cost of the part at £3.5k.

ETA - what happens when the car is ten years old and blows it's box?

 

[Berkshire Rich]

The voice of reason.

7g is rubbish. I've sampled it from my car, to C320 and CLS350 and E500. All changed slowly and jerkily. All bar the petrol had a poor span of speed in 3rd gear meaning a 69mph change, just what you don't want pressing on or overtaking.

I've sampled vast amounts of 5g cars from 4pot diesels to V8 AMGs and all have been responsive, well spaced gearing wise and a joy to drive.

Olly and I are right, OP the rest are IMHO wrong.

It's a shame you have had bad experiences, but it's a bit rich to say, even in your opinion, that other people's positive experiences that they have posted on here are wrong!

 

[Troon]

it's a bit rich to say, even in your opinion, that other people's positive experiences that they have posted on here are wrong!

You must be new to the internet...

 

[bpsorrel]

Indeed. You'll learn soon enough that Steve's opinion is the only one that counts!

 

[Paul/]

There is no need for 7 gears esp on a diesel

The W219 CLS brochure had torque charts for several of the engine options, I was surprised to note that the 320cdi torque profile didn't have a proportionally broader peak than the petrols, so would seem to have a similar gearing need.

 

[Paul/]

The voice of reason.

7g is rubbish. I've sampled it from my car, to C320 and CLS350 and E500. All changed slowly and jerkily. All bar the petrol had a poor span of speed in 3rd gear meaning a 69mph change, just what you don't want pressing on or overtaking.

I've sampled vast amounts of 5g cars from 4pot diesels to V8 AMGs and all have been responsive, well spaced gearing wise and a joy to drive.

Olly and I are right, OP the rest are IMHO wrong.

Perhaps the explanation for this consistent opinion based on experience with multiple instances of each box, is down to a difference of preferred driving style between the naysayers and advocates of the 7g?

Which reinforces an earlier suggestion that the OP gets a good testdrive before deciding.

 

[Berkshire Rich]

You must be new to the internet...

Ah, he is one of those. Silly me

 

[st4]

Indeed. You'll learn soon enough that Steve's opinion is the only one that counts!

It's the only correct one anyway.

 

[st4]

I like the gearbox.

Fortunately it was under warranty- as MB quoted the cost of the part at £3.5k

ETA - what happens when the car is ten years old and blows it's box?

You pay the price of liking the box, which part price is £3500.

I must be odd in driving four 7g cars and finding all the shifts harsh but driving many 5gs and being impressed. A £20 sensor failure in a 5g is a valve body change at over £1000 in a 7g.

 

[st4]

Perhaps the explanation for this consistent opinion based on experience with multiple instances of each box, is down to a difference of preferred driving style between the naysayers and advocates of the 7g?

Which reinforces an earlier suggestion that the OP gets a good testdrive before deciding.

I drive mainly on rural A and B roads. Seldom in town and a bit on motorways. 7gs sole plus is the tall nature of top gear for economy but for proper driving it's pants. Indeed 5g 250cdi cars have quicker 0 to 60 times than the 7g plus cars. And that's important for pulling smartly out of junctions, spanning speed in gear for overtakes.

 

[Paul/]

I drive mainly on rural A and B roads. Seldom in town and a bit on motorways. 7gs sole plus is the tall nature of top gear for economy but for proper driving it's pants. Indeed 5g 250cdi cars have quicker 0 to 60 times than the 7g plus cars. And that's important for pulling smartly out of junctions, spanning speed in gear for overtakes.

Apparently 5th on 7g (not sure about 7g+) has identical gearing to 4th on 5g, and 6th on 7g is almost identical to 5th on 5g, so that's all consistent with your points.

On the other hand, according to the MB Training Manual for the 7g:

- Shorter computer reaction time by 0.1 second
- Downshifts shortened by up to 0.2 second
- Coasting downshifts shortened by 0.4 – 2.5 seconds
- 60 to 120kph acceleration times shortened by 23 - 28%
(depending on model)​

• Fuel consumption reduced by up to 4%

(I assume that those are all in comparison with 5g)

None of this alters the fact that for your driving, you clearly find the 7g slower than the 5g.
But I still recommend the OP tries it to see if it suits him OK.

(meant to add- my own mileage is a few Mway runs otherwise mainly suburban 40 limit stuff, some B road at national limit- not much stop go in any of it)

 

[st4]

Apparently 5th on 7g (not sure about 7g+) has identical gearing to 4th on 5g, and 6th on 7g is almost identical to 5th on 5g, so that's all consistent with your points.

On the other hand, according to the MB Training Manual for the 7g:

- Shorter computer reaction time by 0.1 second
- Downshifts shortened by up to 0.2 second
- Coasting downshifts shortened by 0.4 – 2.5 seconds
- 60 to 120kph acceleration times shortened by 23 - 28%
(depending on model)
• Fuel consumption reduced by up to 4%

(I assume that those are all in comparison with 5g)

None of this alters the fact that for your driving, you clearly find the 7g slower than the 5g.
But I still recommend the OP tries it to see if it suits him OK.

6th is taller than the 5g I've had on my own C and E220. Iirc the 212 220 5g was matched more like the 6th in 7g in 5th gear.

7g cars to fit in the transmission tunnels designed for 5g cars go without sprag clutches so roll back on hills. Every 7g I drove would roll back on steep hills. MB rather than redesign the transmission casing and therefore transmission tunnels decided to make 7g fit into 5g casing. They should have waited to introduce 7g on cars designed to take it and engineer it properly, not quickly.

 

[Mr E]

I drive mainly on rural A and B roads. Seldom in town and a bit on motorways. 7gs sole plus is the tall nature of top gear for economy but for proper driving it's pants. Indeed 5g 250cdi cars have quicker 0 to 60 times than the 7g plus cars. And that's important for pulling smartly out of junctions, spanning speed in gear for overtakes.

So do I.

It kicks down quicker, and shifts down two gears in one go, so overtaking is generally quicker. Mrs E, who hates autos with a vengeance, likes it so much that she takes mine when I'm working at home - something she has only ever done under protest in the past.

I've also had Master E peering over my shoulder - he's doing the Level 3 course at the mo and is covering auto gearboxes in some depth. He thought from the MB tech literature that the 7g box came in one size only. Also, he says, the sprag clutches are included in an auto box to smooth downshifts - the 7g does away with them as the electronics are supposed to synch the changes better. This would explain why the clunky shift 2>1 (which is the most difficult to manage in terms of torque transfer) can be improved by a software update, as it would modify the timing of the various operations during the shift. Stopping the car rolling back is a happy by-product of having a sprag clutch in the box, but is not the feature it is included in the design for.

IMHO there is nothing better than a 7-speed E250CDi for all-round performance along the highways and byways of Sussex

 

[Mr E]

7g cars to fit in the transmission tunnels designed for 5g cars go without sprag clutches so roll back on hills. Every 7g I drove would roll back on steep hills. MB rather than redesign the transmission casing and therefore transmission tunnels decided to make 7g fit into 5g casing. They should have waited to introduce 7g on cars designed to take it and engineer it properly, not quickly.

Wasn't the 7g (722.9) introduced in 2003? That means it has been around for 9 years, so surely the latest cars in the line-up are all designed around it?

No 7g has a sprag clutch - never designed to have it from the outset - as the bits and bobs are designed to change gear without the backlash that the sprag clutch smooths out.

Do you have any documentation that backs up your assertion about the size of casing, etc? Master E would like to see that and include in his course documentation.

 

[st4]

Wasn't the 7g (722.9) introduced in 2003? That means it has been around for 9 years, so surely the latest cars in the line-up are all designed around it?

No 7g has a sprag clutch - never designed to have it from the outset - as the bits and bobs are designed to change gear without the backlash that the sprag clutch smooths out.

Do you have any documentation that backs up your assertion about the size of casing, etc? Master E would like to see that and include in his course documentation.

Try the big PDF file that's linked to the thread in the technical section under 7g. I'm on my iPhone app so doing a link to its tricky.

Clearly however from numerous documented issues with harsh down changes that MBs electronics don't work as well as the conventional sprag clutch.

It's also common sense. A 7g has two more gears, it needs more space and if it had a bigger casing it wouldn't fit within a transmission tunnel designed for a smaller 5g box. remove sprag clutch and hey presto 7 goes into 5...

Bar the W164 and W218 all MBs have been available with both transmissions. Why, because they fit into the same casing which fits into the same space in the transmission tunnel. As it were the W218 is 212 based which was sold with the vastly superior 5g box.

 

[BenzedUP]

.
A £20 sensor failure in a 5g is a valve body change at over £1000 in a 7g.

My friend might of just got ripped off by MB dealer then, he had to change his valve body on his 04 C32AMG, it was a speed sensor I believe (car would stick in gear, won't shift up or down) but they said they don't sell these on their own so he spent £700 with MB to get that replaced, his car is 5G AMG Speedshift.