motor

is64fun · 10-03-2004, 09:26 AM

well i thought a lot but could not come up with an apropriate idea why mercedes used automatic transmission in slr. moreover, why did they used 5-speed isntead of 7-speed which is newer technology? any idea

and the second question: the f1 transmission in ferraris, do they faster than the manuel gearboxes like carrera gt or the smg2 in bmw? and is selespeed different form those???

TT · 10-03-2004, 09:31 AM

Well for the SLR.. it was developped not really yesterday, and 7 gears gearboxes are still pretty new. The E60 M5 got one but its development started after the SLR's.. and of course also Merc is working on their 7 speed box, but I guess they were not ready for the SLR.

As for Ferrari's F1 tranny or BMW's SMG2, they maybe spoil a bit the fun of a good H gate, but for sure you can't be that fast with a manual box

I'd still take the wooden manual stick of the CGT anyday even if I will be slower than a 150 milliseconds F1 thing

Buba81 · 10-03-2004, 09:40 AM

Originally Posted by is64fun

well i thought a lot but could not come up with an apropriate idea why mercedes used automatic transmission in slr. moreover, why did they used 5-speed isntead of 7-speed which is newer technology? any idea

and the second question: the f1 transmission in ferraris, do they faster than the manuel gearboxes like carrera gt or the smg2 in bmw? and is selespeed different form those???

As far as I know, and I'm sorry, because I can't deliver a link or proof of it, Mercedes will bring the 7 speed gearbox to the slr in the future...
But it has so much torque, the 5 gear speedshift does the job quite well... I mean, its not an ordinary 5 gear C-class automatic gearbox after all, this thing is really fast...

I actually don't know if the ferrari F1 Gearbox is faster tahn any of the others, but I think so... It's around 15 milliseconds in the most recent version... Again, no link for the proof, but a freind of mine owned a couple of Ferraris and also has a dealership (merc though

), so I guess he' quite well informed...
But, anyone, fell free to correct me...

Have a nice and sunny sunday°!

Buba

is64fun · 10-03-2004, 10:02 AM

you are right. i also know that it is not a normal 5-speed c-class gearbox. but they are in f1. so they should know how to make it. their teammate mclaren developped a gearbox for the f1 car with 2 clutch. they might also take this in consederation. meanwhile as i know in f2003 or in f2002 the time for gearchange was 0.017 sec

queit fast ha

is64fun · 10-03-2004, 10:12 AM

meanwhile thanks tt

Ford Capri 2.8i · 10-03-2004, 11:16 AM

I think simply that every big brand is making a lot of investment in this sort of gearboxes(and of course BMW, Merc and Ferrari are taking advantage of their formula 1 experience)....and i think that the future of the gearbox will be the gearbox with the 2 clutch similar to the VW group since it seems that its smooth, quick, the fuel consumption is not different from the manual gearbox.....we have just to wait for a little while in order to improve the 2 clutch gearbox making it as soft as the traditional automatic gearbox

mindgam3 · 10-03-2004, 11:24 AM

The main difference between the F1 and the road versions of semi automatics are that F1 boxes dont need to be concerned about smoothness and not as much durability, at least not to the same extent, they just need to ram it in gear the quickest way possible.

Even on the early 360 models, there have been many complaints of their F1 clutches going after 5k, especially when left in automatic mode. The semi technology is improving all the time though and I guess in about 5 years or so semi auto boxes will be even faster, alot more reliable and a lot more smooth. I wouldnt be suprised if semi auto boxes were offered in just about all cars in 10-15 years

Ford Capri 2.8i · 10-03-2004, 11:41 AM

Apart from the good text of mindgam.......just to say that the semiautomatic gearbox(its efficiency when changing the gears is obvious comparing it with the manual equivalent) is spreaded from a long time ago in every race car cathegory such as the rallying, the hill climb championship F3000, the touring cars, and even in some of the cheapest championships.....such as the renault clio cup, or the rallying citroen C2 challenge in France

Ford Capri 2.8i · 10-03-2004, 11:43 AM

i forgot saying...apart from the text of mindgam, i agree 100% of his statements apart from the contribution that i made in the text before

cooperluke · 10-03-2004, 11:58 AM

wooden manual stick of the CGT anyday

It's the only slightest detail I don't like in the Carrera GT!! I think it has nothing to do with the car!! It should be in carbon fiber, or titanium, or kevlar!!
Wood? It seems like the one from a Jaguar, or a Rover...

That is why I don't buy one!!

CSedl87 · 10-03-2004, 12:44 PM

The wood is from one of their race cars (I forget which one) that won Le mans. Back in the 60s/70s they didn't have use of CF or Kevlar, so the only way they could save weight was with balsa wood (which the shifter is made of), and Fiberglass. So it's an ode to it's predicessors.

ZfrkS62 · 10-03-2004, 01:06 PM

mindgam3 pretty much hit the nail on the head.

BMW's SMGII has proven itself to be nicer on the clutch than the 6spd. And the SMGIII that is coming in the M5 should have even smoother shifts than what the M3 has when in programs S1-2 or in the automated modes. Even the next version that comes on the regular cars should have a smoother transition. As i've said in the other posts, (Leaked numbers on E55 vs M5) BMW will probably be replacing the automatic transmissions with the SMG in all their cars except the 7 series. Just as soon as they get the shift quality smooth enough.

As the article that is linked in the M5board.com meets Chris Bangle, said. Optimal shiting at 8300RPM manually will not be consistent. That is where the SMG takes up the slack.

As for the automatic over the manual in SLR. I asked one of the Mercedes techs I work with, why Mercedes didn't put a manual behind that engine, he said it's because they don't have one that is strong enough to handle the power of the engine. this doesn't surprise me since Mercedes hasn't had a manual transmission in the US since who knows when.

sentra_dude · 10-03-2004, 01:52 PM

Originally Posted by ZfrkS62

mindgam3 pretty much hit the nail on the head.

BMW's SMGII has proven itself to be nicer on the clutch than the 6spd. And the SMGIII that is coming in the M5 should have even smoother shifts than what the M3 has when in programs S1-2 or in the automated modes. Even the next version that comes on the regular cars should have a smoother transition. As i've said in the other posts, (Leaked numbers on E55 vs M5) BMW will probably be replacing the automatic transmissions with the SMG in all their cars except the 7 series. Just as soon as they get the shift quality smooth enough.

As the article that is linked in the M5board.com meets Chris Bangle, said. Optimal shiting at 8300RPM manually will not be consistent. That is where the SMG takes up the slack.

As for the automatic over the manual in SLR. I asked one of the Mercedes techs I work with, why Mercedes didn't put a manual behind that engine, he said it's because they don't have one that is strong enough to handle the power of the engine. this doesn't surprise me since Mercedes hasn't had a manual transmission in the US since who knows when.

Don't forget about the little C-Class and the base model SLK...both are available with real three pedal manual transmissions.

ZfrkS62 · 10-03-2004, 02:53 PM

i think i remember him mentioning something about the C class but i haven't seen an SLK with a manual. If they're out there than ok, but as i think i've established thus far, i'm not a Mercedes fan

Wutputt · 10-03-2004, 03:08 PM

Originally Posted by TT

Well for the SLR.. it was developped not really yesterday, and 7 gears gearboxes are still pretty new. The E60 M5 got one but its development started after the SLR's.. and of course also Merc is working on their 7 speed box, but I guess they were not ready for the SLR.

Isn't the easiest explanation the fact that Mercedes' current 7G-Tronic auto transmission can only safely handle 700 Nm of torque and the SLR has 780 Nm of torque? And Mercedes had made a special reinforced 5-speed auto transmission (for their very ‘torqueful’ AMG-engines) that can handle 1000 Nm of torque.

So I think it was more a budget case:
Make a reinforced version of their brand new 7G-tronic transmission which would cost a lot of money to develop or use a transmission that can handle all the torque of the SLR and that is already available.