Disappointed with the F8X DCT specs

[Sedan_Clan]

Originally Posted by CanAutM3

Not sure I follow you. E46 and E60 both had SMG (single clutch automated manual). DCT was first introduced on the E9X.

But I agree. I also was a 20 MT driver before I got my DCT E92 and totally love the DCT. This is a big reason for my disappointment with the DCT specs on F8X.

I misread your initial post, so disregard it. That's what I get for only half reading before posting. You'll love the MT.

[CanAutM3]

Originally Posted by Sedan_Clan

Actually the E46 M3 had SMG II, which was a dual clutch transmission like DCT.

Pretty sure it was not. All SMGs were single clutch units. SMG I on the E36 M3, SMG II on the E46 M3 and SMG III on the E6X M5/6. Dual clutch was introduced with DCT (Dual Clutch Transmission)

[Sedan_Clan]

Originally Posted by CanAutM3

Pretty sure it was not. All SMGs were single clutch units. SMG I on the E36 M3, SMG II on the E46 M3 and SMG III on the E6X M5/6. Dual clutch was introduced with DCT (Dual Clutch Transmission)

I edited it. I misread your initial post.

[elitex]

Originally Posted by CanAutM3

Pretty sure it was not. All SMGs were single clutch units. SMG I on the E36 M3, SMG II on the E46 M3 and SMG III on the E6X M5/6. Dual clutch was introduced with DCT (Dual Clutch Transmission)

Wow so much misinformation on this forum. I agree with you on this one.

[bmwluvr24]

Originally Posted by CanAutM3

Not sure I follow you. E46 and E60 both had SMG (single clutch automated manual). DCT was first introduced on the E9X.

But I agree. I also was a 20 MT driver before I got my DCT E92 and totally love the DCT. This is a big reason for my disappointment with the DCT specs on F8X.

There was DCT available on the later E60 M5. I just test drove one at Carmax.

[CanAutM3]

Originally Posted by phishhead24

There was DCT available on the later E60 M5. I just test drove one at Carmax.

Nope. Somebody fooled you

[elitex]

Originally Posted by phishhead24

There was DCT available on the later E60 M5. I just test drove one at Carmax.

wow, another one. carmax lied to you.

[bmwluvr24]

Originally Posted by CanAutM3

Nope. Somebody fooled you

You are right........the stick looks identical, but it was actually SMG III. My bad.

[bmwluvr24]

Originally Posted by elitex

wow, another one. carmax lied to you.

They didn't know anything to be honest. I just thought it was DCT because it looks the same in the car. It was a 2006 and was flawless shifting. I had to read up just now to realize that I put my foot in my mouth. Sorry fellas.

[Tonymiabmw]

Originally Posted by CanAutM3

I am realistic. The ///M division did design (at least provide the design specs of) the DCT on the E9X specifically for the S65, and thus resulted in a great powertrain combo. Yes, I do understand the costs involved in development and this is why I am saying they went cheap with the DCT. As posted earlier, I believe they had limited budget to work with on the F8X and decided to invest on the 6MT this time around.

Shifting at redline from 1st to 2nd brings the revs down to 4100RPM, well below the start of the power plateau at 5500RPM. Same for the 2nd to 3rd shift that brings the revs down to 5000RPM. This is not optimal for max acceleration performance.

Now, short shifting at the end of the power plateau at 7300RPM, the 4th to 5th shift brings the revs to 5700RPM (above the start of the power plateau). With a delimited car, the 5th to 6th shift would bring the revs to 6200RPM (700RPM above the start of the power plateau). Further, why do I need 3 gears that cannot reach top speed on a performance oriented car?

There was plenty of room to better optimize the ratios for the S55. It is my opinion that BMW decided that the DCT developed for the S63Tu was "good enough" for the F8X.

this make no sense the gear ratios are not to far off from the E9x in respects to the f80s power band


e90
1st 4.780 44
2nd 2.933 71 5200
3rd 2.153 97 6200
4th 1.678 124 6500
5th 1.390 150 6900
6th 1.203 173 7300
7th 1.000 208 7000
The engine produces 414 bhp at 8300 RPM
peak torque of 295 lb·ft (400 N·m) at 3900 rpm

Being that the F80 has A lower redline in 7600rpm and all of its horsepower was at 8300prm on the e9x and it having a 8400rpm redline. I don't get your logic behind the Ratio being off? If anything it should be just about right like the E9x being that the f80 creates all its torque in the mid RPM range

[elitex]

Originally Posted by phishhead24

They didn't know anything to be honest. I just thought it was DCT because it looks the same in the car. It was a 2006 and was flawless shifting. I had to read up just now to realize that I put my foot in my mouth. Sorry fellas.

no issues, I actually like single clutch when you're hammering it. Puttering around town is very annoying on SMG.

[CanAutM3]

Originally Posted by Tonymiabmw

this make no sense the gear ratios are not to far off from the E9x in respects to the f80s power band


e90
1st 4.780 44
2nd 2.933 71 5200
3rd 2.153 97 6200
4th 1.678 124 6500
5th 1.390 150 6900
6th 1.203 173 7300
7th 1.000 208 7000
The engine produces 414 bhp at 8300 RPM
peak torque of 295 lb·ft (400 N·m) at 3900 rpm

Being that the F80 has A lower redline in 7600rpm and all of its horsepower was at 8300prm on the e9x and it having a 8400rpm redline. I don't get your logic behind the Ratio being off? If anything it should be just about right like the E9x being that the f80 creates all its torque in the mid RPM range

Actually they are quite off vs the E9X:

Max speed in gear:
F8X E9X
1st 36 44
2nd 67 71
3rd 102 97
4th 136 124
5th 174 150
6th 206 173
7th 259 208

1st and 2nd gears are much shorter, while gears 3 and up are longer and longer.

[Tonymiabmw]

Originally Posted by CanAutM3

Actually they are quite off vs the E9X:

Max speed in gear:
F8X E9X
1st 36 44
2nd 67 71
3rd 102 97
4th 136 124
5th 174 150
6th 206 173
7th 259 208

1st and 2nd gears are much shorter, while gears 3 and up are longer and longer.

Acceleration is all about torque. One way to accelerate more quickly is to multiply the torque at low speeds to help move the vehicle forward. Being that the ratios are shorter makes sense since this car does produce a lot more torque than the E90 at lower RPM. What the point in have wide ratio if all your going to do Is burn the tires off?

[E36toF30]

Originally Posted by CanAutM3

One of my track buddies has '11 ZCP 6MT M3. We are both running the same wheels and tires at the track. On more than one occasion, while playing around together, I was able to pull a clean pass on him on the back straight at LCMT (90-135mph), that is significant. When he is behind me, I just pull away and he can't keep up despite the draft. I've had similar experiences playing with other 6MT M3s. As much as I would like to say that I am the better driver , I attribute this advantage to the transmission .

No offense, but your post did nothing to diminish what Jonas said about Car and Driver's M3 6MT/DCT acceleration results. They found them to be nearly identical. Whereas on the F10 M5, the DCT is .3 seconds quicker to 60 (again, based on C&D testing).

I agree with you that the reason you're faster on the track than your friend with the 6MT is probably because of the DCT. Not having to manually shift makes it a lot easier to concentrate on other aspects of driving on a track. That difference comes through even though the two transmissions perform very similarly in acceleration testing. Considering that the F8X DCT probably will be faster than the F8X 6MT in acceleration testing (based on BMW's 0-60 quotes, F10 M5 tests, and the fact that the F30 335i is noticeably faster with its "slushbox" than 6MT), I'd say there's good reason to believe the DCT will be faster on a track as well, perhaps even to a greater extent than it is in the E9X.

[Tonymiabmw]

Originally Posted by CanAutM3

Actually they are quite off vs the E9X:

Max speed in gear:
F8X E9X
1st 36 44
2nd 67 71
3rd 102 97
4th 136 124
5th 174 150
6th 206 173
7th 259 208

1st and 2nd gears are much shorter, while gears 3 and up are longer and longer.

plus The E9X M3 LSD gearing depends on which transmission/clutch spec your car has - 6MT or the DCT. The manual transmission cars have a relatively short 3.85 gear ratio on manual transmission cars. The DCT comes with a taller 3.15 gear set to make up for the different transmission ratios and the additional 7th gear.
I don't think the Rear LSD ratio for the F80 is published but I bet the manual and DCT are different on the F80
So LSD ratio and Power band wise I doubt BMW got this wrong.

[CanAutM3]

Originally Posted by Tonymiabmw

Acceleration is all about torque. One way to accelerate more quickly is to multiply the torque at low speeds to help move the vehicle forward. Being that the ratios are shorter makes sense since this car does produce a lot more torque than the E90 at lower RPM. What the point in have wide ratio if all your going to do Is burn the tires off?

It is actually the other way around. The shorter gears on the F8X even further increase the greater torque produced by the S55. At WOT, it will impossible to put the power down in 1st gear. This is why I am guessing they are using a shorter 1st gear for when the S55 is operating at small throttle openings (not much boost hence not much torque).

With the relatively light weight of the F8X compared to the F1X, I don't think the F8X needs such a short first gear. The one on the 6MT is probably better suited.

[CanAutM3]

Originally Posted by Tonymiabmw

plus The E9X M3 LSD gearing depends on which transmission/clutch spec your car has - 6MT or the DCT. The manual transmission cars have a relatively short 3.85 gear ratio on manual transmission cars. The DCT comes with a taller 3.15 gear set to make up for the different transmission ratios and the additional 7th gear.
I don't think the Rear LSD ratio for the F80 is published but I bet the manual and DCT are different on the F80
So LSD ratio and Power band wise I doubt BMW got this wrong.

According to the published specs, the F8X DCT and 6MT have the same FD ratio (what you call the LSD).

[catpat8000]

Originally Posted by CanAutM3

Actually they are quite off vs the E9X:

Max speed in gear:
F8X E9X
1st 36 44
2nd 67 71
3rd 102 97
4th 136 124
5th 174 150
6th 206 173
7th 259 208

1st and 2nd gears are much shorter, while gears 3 and up are longer and longer.

OK, you finally convinced me. I'm going to get the manual and spend the $2900 I saved not buying the DCT on.... Carbon Ceramic Brakes!

Pat

[Tonymiabmw]

Originally Posted by CanAutM3

According to the published specs, the F8X DCT and 6MT have the same FD ratio (what you call the LSD).

Final Drive Ratio doesn't mean there Diff Ratio is the same. Given that their Final Drive Ratio is the same (manual and DCT) and the Overall gearing is diffent the diff in the DCT would have to have a different ratio from the Manual.

[Tonymiabmw]

Final Drive is that is the mathematical compilation of all gear ratios from the transmission, transfer-case, and the differential/final drive.

[CanAutM3]

Originally Posted by E36toF30

I agree with you that the reason you're faster on the track than your friend with the 6MT is probably because of the DCT. Not having to manually shift makes it a lot easier to concentrate on other aspects of driving on a track. That difference comes through even though the two transmissions perform very similarly in acceleration testing.

We are talking two relatively experienced trackers accelerating down a back straight. Concentration has nothing to do with it .

In my example, the DCT has the advantage due the much faster shifts times and slight gearing advantage.

Originally Posted by E36toF30

Considering that the F8X DCT probably will be faster than the F8X 6MT in acceleration testing (based on BMW's 0-60 quotes, F10 M5 tests, and the fact that the F30 335i is noticeably faster with its "slushbox" than 6MT), I'd say there's good reason to believe the DCT will be faster on a track as well, perhaps even to a greater extent than it is in the E9X.

This is also what I am hoping. However, as I posted in my OP, BMW published numbers indicate no advantage of the DCT from 100km/h to 200km/h (both 6MT and DCT quoted at 9.3s). DCT is also quoted as being slower from 80-120km/h in 5th. Is it only a marketing smoke screen? Or is it really the extra weight and increased losses of the DCT negating the benefits of the faster shifts?

I'd say that there is still a good chance that the DCT F8X will be faster that the 6MT on a track. But it will certainly be to a lesser extent than it was with the E9X.

[CanAutM3]

Originally Posted by Tonymiabmw

Final Drive Ratio doesn't mean there Diff Ratio is the same. Given that their Final Drive Ratio is the same (manual and DCT) and the Overall gearing is diffent the diff in the DCT would have to have a different ratio from the Manual.

Originally Posted by Tonymiabmw

Final Drive is that is the mathematical compilation of all gear ratios from the transmission, transfer-case, and the differential/final drive.

I think you have your terms confused. "Final drive" is the ratio of the differential. "Overall gear ratio" is the gear ratio of a given gear multiplied by the final drive.