Disappointed with the F8X DCT specs

[CanAutM3]

Originally Posted by catpat8000

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

Although I am having second thoughts, I will still likely end up with a DCT. I am just more and more pissed about how it got compromised compared to the 6MT

I guess this thread is me venting , I need a couch

[E36toF30]

Originally Posted by CanAutM3

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

You're assuming both cars exited the corner before the straight at the same speed, which they very well may not have. I agree that the faster shifts contributed too though. Again, it's pretty much impossible to get all the potential out of a manual transmission car on a track unless you're a professional (even just in terms of acceleration).

Originally Posted by CanAutM3

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.

Your certainty may be misplaced. There is simply no way to know for sure until people actually get to drive the new cars. Also, if the F8X 6MT and DCT are at all close on a track, that probably speaks more to the flexible powerband of the S55 (making the manual easier to drive since being in the optimal gear is less important) than a failing of the DCT.

[Carl L]

Amazing that three frequent posters in this thread alone have been exposed as not knowing the difference between SMG and DCT.

[CanAutM3]

Originally Posted by E36toF30

You're assuming both cars exited the corner before the straight at the same speed.

The corner before the back straight is a long double apex 180degree turn. I was right up his butt trough the entire turn more than once. So yes, exit speed was very similar (as I mentioned, we were running the same wheels and tires).

[Tonymiabmw]

Originally Posted by Carl L

Amazing that three frequent posters in this thread alone have been exposed as not knowing the difference between SMG and DCT.

I know the difference just haven't had a car with SMG in 4 year and didn't really think about it until it was brought up.

[Carl L]

Originally Posted by Tacoma

Also, I don't really buy the "too much traffic" excuse for not getting the manual. I've been driving manuals for 20 years in heavy Toronto traffic which is worst than Miami, and have never said to myself... geez, I wish I had an auto in this traffic. Never.

Good for you. I grew up driving manuals but when I moved to a huge city I became sick of the constant plunging of my left leg. The arrival of DCT was a huge boon as it fills the gap for the many former stick drivers who are in this camp but find regular autos too disconnected.

[bmwluvr24]

Originally Posted by Carl L

Amazing that three frequent posters in this thread alone have been exposed as not knowing the difference between SMG and DCT.

Very true. I couldn't tell the difference at all. The E60 M5 I drove felt very similar, shifting wise, to my friends E92 M3. I do still feel dumb for saying it was DCT, but I only figured out it was SMG III by reading up. Oh well.......shit happens.

[Tonymiabmw]

Originally Posted by phishhead24

Very true. I couldn't tell the difference at all. The E60 M5 I drove felt very similar, shifting wise, to my friends E92 M3. I do still feel dumb for saying it was DCT, but I only figured that out by reading up. Oh well.......shit happens.

I was trying to say SMG in M5 was not bad at all, E46 was crap I agree E60 SMG was very good but had a driving curve to it.

[bmwluvr24]

Originally Posted by Tonymiabmw

I was trying to say SMG in M5 was not bad at all, E46 was crap I agree E60 SMG was very good but had a driving curve to it.

Yeah I read where you corrected your statement. Hey man, we all make mistakes. Just ask gee-m-w, he hasn't gotten more than 25% of his posts right from the get go, so no worries!

[Carl L]

Originally Posted by phishhead24

Very true. I couldn't tell the difference at all. The E60 M5 I drove felt very similar, shifting wise, to my friends E92 M3. I do still feel dumb for saying it was DCT, but I only figured that out by reading up. Oh well.......shit happens.

All good bud, and props for admitting it rather than BSing. Sold my M5 as SMGIII was so undriveable in auto and it became the wife's daily...and she can only drive in auto mode despite my efforts. Great fun in manual mode at WOT though, like thunder.

[CanAutM3]

Originally Posted by Tonymiabmw

I was trying to say SMG in M5 was not bad at all, E46 was crap I agree E60 SMG was very good but had a driving curve to it.

The SMG III in the E6X M5/6 was specifically designed as an SMG. The odd shift patterns of the 7 speeds would have been impossible to use as a standard MT. It was much less of a compromise compared the the SMG I and II that were standard 6MTs with servos added.

[Carl L]

Originally Posted by Tonymiabmw

I was trying to say SMG in M5 was not bad at all, E46 was crap I agree E60 SMG was very good but had a driving curve to it.

Ah, so just leaves Sedan Clan then

While much better than the second iteration, SMGIII was quickly outdated once DCT hit the mainstream and it remained the weakest link of a fabulous car in my opinion.

[Tonymiabmw]

Originally Posted by CanAutM3

The SMG III in the E6X M5/6 was specifically designed as an SMG. The odd shift patterns of the 7 speeds would have been impossible to use as a standard MT. It was much less of a compromise compared the the SMG I and II that were standard 6MTs with servos added.

Your very informative learning a lot thanks.

Wow third is 2.153 on E90 DCT vs 1.701 on F80 but wouldn't that be the case with the E90 to keep rpm higher because of such a high power band?

[CanAutM3]

Originally Posted by Tonymiabmw

Your very informative learning a lot thanks.

Wow third is 2.153 on E90 DCT vs 1.701 on F80 but wouldn't that be the case with the E90 to keep rpm higher because of such a high power band?

You also need to factor in final drive, which lessens the difference:

6.791 for the E9X and 5.869 for the F8X.

[Tonymiabmw]

Originally Posted by CanAutM3

You also need to factor in final drive, which lessens the difference:

6.791 for the E9X and 5.869 for the F8X

So gear x Finaldrive = Overall drive right?

[CanAutM3]

Originally Posted by Tonymiabmw

So gear x Finaldrive = Overall drive right?

Yes

[Tonymiabmw]

Originally Posted by CanAutM3

Yes

So how do you calculate RPM from Gear ratio?

[Kadema]

CanAutM3, if revs are brought down to 4100 in 2nd and 5000 in 3rd, I'm pretty sure that doesn't hurt performance at all, because torque at the wheels will still be high enough to cause wheelspin. Same with M5/6. The short lower gears must have other reasons than performance even for F1x M cars. See my point with parking maneuvers.

Also, in higher gears, you will be forced to slightly short shift due to drivetrain losses and their interaction with air drag, so the tighter gearing makes sense. I'm sure you won't be noticeable faster if you'd change gear spacing any other way.

I didn't notice that the new DCT is even heavier. They really focused on the MT. Anyway, I still think DCT and FI engine fits better.

[CanAutM3]

Originally Posted by Tonymiabmw

So how do you calculate RPM from Gear ratio?

I guess you mean to ask how you correlate road speed and RPM using gear ratios?

Like so:

V = (RPM * (WD*25.4 + TW*AR*2/100)xPi*60) / (GR*FD*1000000)

V = Road speed in km/h (divide by 1.609 to get mph)
RPM = engine speed in RPM (duh)
WD = Wheel diameter in inches
TW = Tire width in mm
AR = Aspect ration in %
Pi = 3.1416
GR = Gear ratio
FD = Final drive

This remains an approximation because tire specified dimensions are not exact. But this calculation is still pretty close.

[Tonymiabmw]

Originally Posted by CanAutM3

I guess you mean to ask how you correlate road speed and RPM using gear ratios?

Like so:

V = (RPM * (WD*25.4 + TW*AR*2/100)xPi*60) / (GR*FD*1000000)

V = Road speed in km/h (divide by 1.609 to get mph)
RPM = RPM (duh)
WD = Wheel diameter in inches
TW = Tire width in mm
AR = Aspect ration in %
Pi = 3.1416
GR = Gear ratio
FD = Final drive

Thanks

[Sedan_Clan]

Originally Posted by Carl L

Amazing that three frequent posters in this thread alone have been exposed as not knowing the difference between SMG and DCT.

Actually I did, but I misread his post. Embarrassing I know. That's what I get.

I thought he was saying that the units in the previous cars were automatic and didn't actually have clutches. Then I started thinking about the DCT and that's where I got all wrapped up. Trying to post here when I should be writing tickets is the problem.

I'm not off until 0500.

[Tonymiabmw]

Originally Posted by Tonymiabmw

Thanks

AR=the height of the tire, from the bead to the top of the tread right?