Monday 11th June 2012

PH Blog: shifting expectations

The Ferrari 458 and Merc SLS share the same gearbox, so why do they behave so differently? Harris knows...

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Bernd Maylander is a very amusing chap who is also a very handy racing driver - he won the N24 in 2000. You will probably know him best as the poor soul who tries to wrestle the F1 safety car around a circuit ahead of two-dozen single-seaters with rapidly reducing temperatures, pressures and levels of patience. I sat opposite him at dinner a few months back - but that is of no interest.

SLS GT promises faster shifting

In the context of Monday's Mercedes SLS GT announcement, one area of conversation now seems particularly apposite - we were discussing the SLS. He was talking about the car, the way it handles, his technical input and driving the knackers off it. As someone who covered 10,000 glorious miles in an SLS last year, I was asking him about the gearbox. Because that really was the only downside to an otherwise spectacular machine, the point being why was it so slow to shift?

To recap, the SLS uses Getrag's Powershift DCT 7DCL750 transmission. That's a long way to say it has a dual-clutch 'box with seven forward gears capable of handling 750Nm of torque. I first drove it in a Ferrari California and it was one of the few things I liked about the car: smooth in automatic mode, barely perceptible in manual, but still retaining just the right slug of ker-thump to let the driver know something was happening. Best of all, you pulled either lever and the shift was instantaneous - you thought, it changed gear.

California and 458 share SLS's Getrag gearbox

Six months later I was sitting in an SLS for the first time wondering what was going on. The same Powershift DCT 7DCL750 transmission had the most irritating delay on manual shifts. It felt almost reluctant to change gears, there was a much longer pause between pulling a paddle and the cogs changing. I phoned a car-testing mate. "Was it like this for you?" Yes, was the reply.

Even more surprisingly, the Getrag 7DCL750 is also used in the Ferrari 458, possibly the best deployment of dual-clutch technology ever seen in a sports-car, so intuitive and fast you wonder if the gearbox ECU is actually hard-wired into the driver's cranium.

Now I didn't quote gearbox designation codes at Herr Maylander (I didn't know them at the time) but I did ask him why effectively the same gearbox felt so different, and rather slow-witted in a Mercedes. He said it was simply a matter of calibration. AMG knew the capabilities of the transmission, but when it used the fastest response and shift-speeds, it couldn't pass the company's powertrain reliability tests, so it had to alter the calibration accordingly.

Gearbox failures not unknown on 458s

This piqued my interest, so I did a little digging on the web of truth and justice. Turns out the first Ferrari Californias did have some issues. And if you Google "Ferrari California gearbox failure / problems" or "Ferrari 458 gearbox failure / problems", you'll find of owners of both cars who have had issues and replacement gearboxes. It has to be said that almost all of them appear to have been treated very well by Ferrari.

Search for "Mercedes SLS gearbox failure / problems" and there isn't a single thread detailing such an incident.

Now this might just confirm that Ferrari owners are more active online than SLS owners, but if there were similar problems with AMG's version of the transmission, it's probably safe to say at least one owner would have made some serious noise about it. Maybe this blog will surface such an incident?

Mercedes has erred on caution with durability

What I find fascinating is the different approaches of two carmakers to the same mechanical hardware. Honestly, there were times when I was driving the SLS in manual mode, especially when I was lapping the 'ring, that if someone had offered me a dose of Ferrari 458 shift behaviour with the outside chance of a whoopsie, I'd have leapt at the opportunity because even though I worked around the slow shifts, it was a glaring downside to an otherwise compelling dynamic package.

Of course I don't have Ferrari's view on this - nor do I have anything official from AMG. Viewed objectively, and taking into account owner profiles and brand expectations, it was impossible for Ferrari to deliver the 458 with the same gearbox calibration as the SLS. The media would have lynched it for being slow and rubbish. It had to give customers and journos the full-experience and deal with any downsides. In being both a Merc and GT car, the gullwing just about carried off its protective gearbox mapping, but it was a close call.

The hardware is the same - it's all in the tuning

Bernd had a few things to say about other applications of the Getrag dual-clutch, but it's probably not fair to quote them here. What he did say was that I would soon get the chance to drive an SLS with a much faster gearshift, and that it was a real improvement. That car is the SLS GT.

Personally, I can't wait. It's as necessary as the extra 20hp is unnecessary. And it will still be my favourite sub-£200k supercoupe.

Chris

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Harris versus the SLS's gearbox on the Nordschleife

 

 

[bobalog]

Very interesting article.

I wonder if the extra torque in the Merc is also a contributing factor?

[British Beef]

Sounds like Ferrari have made the decision to sacrficie durability and reliability for that last % of performance, whereas Mercedes have intorduced a slightly larger safety margin to give the transmission an easier life, making it more reliable.

As more of a super GT from mercedes this nod towards longevity and reliability makes sense, where as the all conquering 458 puts outright performance 1st, which is fair enough in my opinion.

I do wonder how modern day Ferraris would stand up to being driven every day, how long would that gearbox survive & what is the cost of a replacement, as you never see high mileage ones?

[rohrl]

Could an SLS owner get someone like DMS to rewrite the gearbox software so it's more similar to the Ferrari settings?

[TheRoadWarrior]

It's interesting that the same box performs so differently in 2 vehicles but it's a good example of the automotive industry approach and also evidence of the difference calibration and tuning can make to the experience of driving a car.

There's loads of examples where different manufacturers(Or even within one company) use effectively the same hardware yet the actual experience of using the respective products is almost the polar opposite from each other.

Just goes to show how important the details are, people often think that you have to change lots of components or uprate things massively to change the feel of a car, often thats just not the case

[George H]

I liked the gearbox in the SLS I tested, but that was on the road and not on the track. This was compared to the TT2 gearbox in my DB9 though, was a lot quicker than that when in manual mode.

[300bhp/ton]

British Beef said:

Sounds like Ferrari have made the decision to sacrficie durability and reliability for that last % of performance, whereas Mercedes have intorduced a slightly larger safety margin to give the transmission an easier life, making it more reliable.

As more of a super GT from mercedes this nod towards longevity and reliability makes sense, where as the all conquering 458 puts outright performance 1st, which is fair enough in my opinion.

I do wonder how modern day Ferraris would stand up to being driven every day, how long would that gearbox survive & what is the cost of a replacement, as you never see high mileage ones?

I guess the other worry is, in a few years time when a 458 is the price of a current 355, how many owners at that level will want to/be able to fork out for new gearboxes if they actually "drive" the car?

[Bash Brannigan]

If the SLS GT has an improved shift does this mean that they've sorted the source of failure, and so can presumably retrofit the solution, or that they've decided that it doesn't need to pass their reliability tests?

[TheRoadWarrior]

Bash Brannigan said:

If the SLS GT has an improved shift does this mean that they've sorted the source of failure, and so can presumably retrofit the solution, or that they've decided that it doesn't need to pass their reliability tests?

They wont have revised down the acceptable life of the component(Gearbox) unless it's a limited volume run, so if the shift is better and this isn't a special edition I would expect they've found some way around the original concern- either tuning or a hardware modification.

[LaurasOtherHalf]

this is the most interesting front page item i've read on pistonheads for months, well done chris exactly the type of story pistonheads should be bringing to the fore.

now, porsches water-cooled reliabilty issues please

[Speed_Demon]

Very interesting. Enjoyed this.

Kind of shows how different priorities are between companies, and the difference that can make.

[Numeric]

You also may find that Merc always account for the high mileage user? They probably have visions of an SLS hitting 200k miles+, where Ferrari are likely surprised if one of their cars gets to 50k in 10 years.

So your margin for failure can be much bigger (lower?) with the 458 as you predict first that it won't go that far and also that in a lot of instances when seeing its occasional use it won't be driven close to its limits.

So Merc have worked with the supplier to devise a better box for the GT while original owners can motor on with confidence that 50k miles a year is not going to kill the car.

Mind you - one thing I do know about cars is something else is just waiting to drop off instead :-))

[slipstream 1985]

LaurasOtherHalf said:

this is the most interesting front page item i've read on pistonheads for months, well done chris exactly the type of story pistonheads should be bringing to the fore.

now, porsches water-cooled reliabilty issues please

agreed i like little snip bits of info like this. its useless pub drivel to drive non car people mad but us lot love to talk about and hear.

[The Pits]

The 355 I had gained 140kg of weight in the nose between the early cars and the pile of garbage that I bought. Of course totally unreported because the press only drove the early cars. Given Ferrari claimed 350bhp for the engine (almost believeable) and an extra 30bhp from the exhaust (totally unbelieveable), the extra weight really hampered performance and handling. Which is of course a complete disgrace as the price went up during it's production run, but not the power, not even by 1bhp to compensate.

I wouldn't be surprised at all if the press 458s had a more extreme gearbox setting and the customer cars have a worse, but more reliable set up. However typical ferrari mileages are so tiny they could easily get away with a compromise over longevity. In either event it's totally unacceptable for the SLS to have a sub-optimal gearchange, if nothing else for the eye-watering amount Mercedes are charging for it (doubly so given essentially the same engine is available in a C63). Trouble is with flappy paddles is, just like other high tech devices, computers or phones or camers, they go out of date so quickly. All this just so douchebags who can't change gear can pose in London? What a shame, supercars are being ruined and the infinitely more involving manual gearbox is all but over.

[jimbobsimmonds]

TheRoadWarrior said:

Just goes to show how important the details are, people often think that you have to change lots of components or uprate things massively to change the feel of a car, often thats just not the case

Yes, I was shocked at the difference between 2 S60s. Only difference was a stiffer rear ARB on one. Huge difference; the big swede actually turned in!

[George H]

The Pits said:

What a shame, supercars are being ruined and the infinitely more involving manual gearbox is all but over.

How does making a car less involving ruin it?

Automated manual gearboxes with paddleshift make it far, far more desirable for me than a manual gearbox.

[jimbobsimmonds]

George H said:

How does making a car less involving ruin it?

Automated manual gearboxes with paddleshift make it far, far more desirable for me than a manual gearbox.

You can't make a Fast and the Furious film with paddleshifts can you?

also, my only experience of paddle shifting is with a Fabia VRS and, although not in the same league as the above, it was not a positive one. I couldn't put my finger on what I didn't like abput it, partly because it wouldn't go down when I wanted it too coming up to a roundabout (not far off, half a second maybe, but still...). All I know is the salesman for Skoda was a real petrolhead, to the extent he slagged off his product; I explained that the VRS wasn't powerful enough for what I wanted and my problem with the gearchanges and that the brakes were a bit st when pressing on and he off the record agreed. Tried to sell me his mates Focus ST instead

[900T-R]

jimbobsimmonds said:

Yes, I was shocked at the difference between 2 S60s. Only difference was a stiffer rear ARB on one. Huge difference; the big swede actually turned in!

I achieved a similar thing on a classic Saab 900 by only using the rear ARB of the factory upgrade package (lifted from another car, of course). It pulled off the resulting lift-oversteer antics rather better than a 205 GTI thanks to its longer (but still rather short for a large car) wheelbase.

Indeed, I am often left wondering at the sledgehammer approach of aftermarket modifiers (both private persons and companies) - it's almost like they haven't quite figured out which weak spots of the original car to address, and took a scattergun approach instead. (Of course, 'demo/show' cars also exist to show off as much of a company's portfolio as possible which tends to compromise the effort in itself; a few notable exceptions notwithstanding).

[Jontee12]

Just signed up because I felt compelled to tell Chris 'monkey' Harris that lap had me sat catching flys. Such a sick video, thank you Chris for being so bloody mental! Hopefully see you in the car park one day? I reckon riding shotgun on a lap like that would make the taxi feel like a First bus to town! Keep up the fantastic work!

[kambites]

Interesting article, and one which I think sums up the approach of the two manufacturers rather well.

Presumably there will be after-market tuners modifying the SLS to make the gearbox behave more like the Ferrari, for those who are less worried about reliability.

[900T-R]

George H said:

How does making a car less involving ruin it?

Because unless you're a racing driver, sports cars are all about involvement? If it's just about going from A-B as quickly as possible, there are more efficient options (but none remotely as interesting as an experience)...