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      07-10-2017, 02:13 PM   #155
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Quote:
Originally Posted by kyrix1st View Post
Not the case with the ZF6HP on 3.0si z4 (e85). It has a lock up clutch and overheat like shit on track. It would be more time efficient for you to run both smg and zf versions of e85 on track than to give you shaky statistics behind my desk.
As for the article, if you can direct me the mechanical difference between zf 6 speed and 8 speed other than the obvious I will bother to read that.

I was not implying that lock up clutch does not act similar or identical to clutch packed manuals or dct; anything with centripetal acceleration will have centrifugal force outwards the rotating mass, in this case damped flywheel by dampers and turbine (as it seems to be in alignment with shaft rotation from your picture) in torque converter which will also be damped by tranny fluids inside the turbine. I do admit the way I said it is solely thanks to tranny fluid, which obviously isn't. In MT cars however, we do adjust gear rattle in SM flywheel with heavier oil so you can't say drivetrain vibration has nothing to do with fluid; it lubricates the rotating components afterall.

I have to point out the fallacy in your google logic of DCT vs torque converter is that people who drive sports cars with DCT tend to be more sensitive and caring while people with traditional automatics just go to service shop rather than discuss online because forum chatting is more time consuming so google doesn't do justice in showing demographics. People with automatics don't drive like complete idiots as sports car owners do. Thats why they buy an automatic! Launch control in addition is peformed from standstill, and while thermal capacity may favor zf torque convs, you launch once off the start line and sustain the momentum at high speeds both to cool the car and drive fast. Why would you launch the car several times except for drag race? This car isn't built for that. Buy a challenger for that stuff.

I have said repeatedly that primary disappointment is lack of connection between the car and the driver in torque converters, not just the creep(which can be adjusted seen in X6M) but each gear change which lacks the "bang."
I haven't driven a car with the old ZF6HP transmission on a track so I only have your word that it "overheats like shit on track". I never had any issues with heavy trailer towing with my E60 and the ZF6HP however (and Norway isn't flat nor do we have long stretches of straight roads)...

Regardless, the ZF6HP is a old transmission design and I find it much more relevant that BMW uses the ZF8HP45 in the M235i Racing for long distance competitions, apparently without any overheating issues. After all, it's not like they are going to use the ZF6HP in the M5...

Here is ZF's introduction to the ZF8HP that also covers some of the advantages it has over the ZF6HP:

https://www.zf.com/global/media/en_d...nsmissions.pdf

As regards inertia (which is what I guess you are referring to) in the clutch/flywheel assembly compared to the inertia in a flexplate/torque converter you have to take into account the complete assemblies in both configurations.

A DCT car has a flywheel (double mass for the S55 engine) and the twin clutch assembly. Which added together weighs roughly (weight of flywheel from Realoem.com):
  • Flywheel: 8,1kg
  • DCT clutch: 13kg (weight of total clutch assembly, source ZF)
  • Total weight of rotating assembly: 21,1kg

An automatic transmission car with torque converter has the flexplate and torque converter assembly. Which added together weighs roughly (weight of flexplate from Realoem.com):
  • Flexplate: 2,01kg
  • Torque Converter: 17,4kg (complete assembly, source ZF)
  • Total weight of rotating assembly: 19,41kg

So, not a whole lot more of rotating mass and inertia between the two different systems. Yes, transmission fluid inside the converter also adds to the inertia of that system, I'll agree to that. But the systems aren't night and day apart in inertia, factor in all the other rotating masses and the percentage in weight difference becomes pretty small.

I'm not sure I follow you in the use of heavier oil in MT cars with single mass flywheels. Tremec transmissions for instance use Dexron III ATF, which is a fairly thin oil... Even my old Sierra Cosworth with a single mass flywheel and a Borg Warner (now Tremec) T5 transmission use ATF transmission oil. So, I don't really see how much of an impact on vibrations that thin layer of oil between the cogs really can have, when Tremec for instance insists on using thin ATF oil.


As regards my Google search examples. Try Googling "DSG overheating" and see if your theory about people driving sports cars are more "sensitive and caring"... DSG is the VAG workhorse transmission in cars like Skoda Octavia, VW Golf, Seat Leon, Audi A3 etc... VAG has had a lot of issues with their DSG transmissions, overheating being just one of them. And it seems even owners of lowly base models take to the internet and post in forums about these issues... So have to disagree with your "logic" about who posts online about issues with their car. It's not just the caring and sensitive sports car owners


BTW, AMG's MCT transmission is an automatic transmission with a wet start up clutch assembly instead of a torque converter (just like the ZF HCC) and before that AMG's used to have pure automatic transmissions. Audi has the ZF 8-speed in the RS6/7, Jaguar has the ZF 8-speed in their R-models and the much lauded Alfa Romeo Giulia Quadrofoglio also has the ZF 8-speed, of which Top Gear said:

Quote:
The 8-speed ZF is brilliant – the shifts are double-clutch instant, hit home the moment you ask for them, and the big paddles are good to use despite being column-mounted. Plenty of other firms use this gearbox, but as far as sporting applications go, I like it here better than anywhere else.
Also seem like Motor Trend thought the ZF8 is a "great transmission" in the Alfa:




So in your opinion these cars aren't bought by people who loves driving and "drive like idiots"? I mean, since they have bough a car with an automatic...
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      07-10-2017, 02:44 PM   #156
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Quote:
Originally Posted by Boss330 View Post
I haven't driven a car with the old ZF6HP transmission on a track so I only have your word that it "overheats like shit on track". I never had any issues with heavy trailer towing with my E60 and the ZF6HP however (and Norway isn't flat nor do we have long stretches of straight roads)...

Regardless, the ZF6HP is a old transmission design and I find it much more relevant that BMW uses the ZF8HP45 in the M235i Racing for long distance competitions, apparently without any overheating issues. After all, it's not like they are going to use the ZF6HP in the M5...
The thing is ZF torque converters rarely let you go over 7000 rpm (hates it over 6500rpm redline) and you will definitely feel the lack of high rev in corners similar to Hatzenbach or even Pflanzgarten.

Quote:
Originally Posted by Boss330 View Post
I'm not sure I follow you in the use of heavier oil in MT cars with single mass flywheels. Tremec transmissions for instance use Dexron III ATF, which is a fairly thin oil... Even my old Sierra Cosworth with a single mass flywheel and a Borg Warner (now Tremec) T5 transmission use ATF transmission oil. So, I don't really see how much of an impact on vibrations that thin layer of oil between the cogs really can have, when Tremec for instance insists on using thin ATF oil.
Depends on the setup and number of gears. You use SMF+sprung pressure plate in a 5 speed it would make little to no noise because it is damped. In a 6 speed (particularly getrag) it makes a pretty loud rattle even with sprung pressure plate, so we dampen it a little bit using the thicker oil. When the tranny gets hot, the rattle comes back because the oil thins out, but after some cool down, it doesn't make the rattling noise.


Quote:
Originally Posted by Boss330 View Post
As regards my Google search examples. Try Googling "DSG overheating" and see if your theory about people driving sports cars are more "sensitive and caring"... DSG is the VAG workhorse transmission in cars like Skoda Octavia, VW Golf, Seat Leon, Audi A3 etc... VAG has had a lot of issues with their DSG transmissions, overheating being just one of them. And it seems even owners of lowly base models take to the internet and post in forums about these issues... So have to disagree with your "logic" about who posts online about issues with their car. It's not just the caring and sensitive sports car owners
All those cars you mentioned are "hot hatch" segments and people who opt for DSG for its performance. You seem to be trying to divert attention to DCT overheating, but would a transmission(unless it is faulty) regardless of being DCT or torque converter overheat under normal use? Likely not. Where would it overheat? Fast mountain roads or track, and usually so when the driver doesn't quite know how to manage cooling cycles. You live in Europe so you should have been to nurburgring nordschleife. Ask a guy there whether he would drive an automatic over MT or DCT. Here there's a lot of E92 DCTs at the track but I haven't heard a single one complaining about transmission overheating.

I still stand on my two reasons I mentioned previously on why a transmission would overheat, and torque converter up until very recently has been the lesser being. I see that bumper aeros are also slightly different for M235i racing, and I assume that air duct path is also different. I wish I had the actual data to clarify the superiority of high end DCT vs high end torque converter other than the shifting speed and weight but I haven't digged in yet.

Quote:
Originally Posted by Boss330 View Post
So in your opinion these cars aren't bought by people who loves driving and "drive like idiots"? I mean, since they have bough a car with an automatic...
Never said ZF isn't a great transmission. My father happens to own '13 XFR(8 speed) and shifts are generally fast but you don't have that mechanical clunking feel of DCT. ZF is a very good transmission for comfort. Since your brought up journalism I would also comment on how Chris Harris (the current Top Gear host) thinks about these cars:



Where he mentions this about F12 M6.

"Difference here is the powertrain. The powertrain is just absolutely extraordinary, because it is aggressive and you have to get up and use all of it; then this car comes alive, and it comes alive in a way that the others I'm afraid can't match."

Which sums up the characteristics of DCT: sustainable at high rpm, rev happy, fast and aggressive.
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      07-10-2017, 11:22 PM   #157
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Boss330 thanks for the detailed information about the ZF, it's going to be an amazing transmission to experience.
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      07-11-2017, 11:57 AM   #158
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Quote:
Originally Posted by kyrix1st View Post
The thing is ZF torque converters rarely let you go over 7000 rpm (hates it over 6500rpm redline) and you will definitely feel the lack of high rev in corners similar to Hatzenbach or even Pflanzgarten.



Depends on the setup and number of gears. You use SMF+sprung pressure plate in a 5 speed it would make little to no noise because it is damped. In a 6 speed (particularly getrag) it makes a pretty loud rattle even with sprung pressure plate, so we dampen it a little bit using the thicker oil. When the tranny gets hot, the rattle comes back because the oil thins out, but after some cool down, it doesn't make the rattling noise.




All those cars you mentioned are "hot hatch" segments and people who opt for DSG for its performance. You seem to be trying to divert attention to DCT overheating, but would a transmission(unless it is faulty) regardless of being DCT or torque converter overheat under normal use? Likely not. Where would it overheat? Fast mountain roads or track, and usually so when the driver doesn't quite know how to manage cooling cycles. You live in Europe so you should have been to nurburgring nordschleife. Ask a guy there whether he would drive an automatic over MT or DCT. Here there's a lot of E92 DCTs at the track but I haven't heard a single one complaining about transmission overheating.

I still stand on my two reasons I mentioned previously on why a transmission would overheat, and torque converter up until very recently has been the lesser being. I see that bumper aeros are also slightly different for M235i racing, and I assume that air duct path is also different. I wish I had the actual data to clarify the superiority of high end DCT vs high end torque converter other than the shifting speed and weight but I haven't digged in yet.



Never said ZF isn't a great transmission. My father happens to own '13 XFR(8 speed) and shifts are generally fast but you don't have that mechanical clunking feel of DCT. ZF is a very good transmission for comfort. Since your brought up journalism I would also comment on how Chris Harris (the current Top Gear host) thinks about these cars:



Where he mentions this about F12 M6.

"Difference here is the powertrain. The powertrain is just absolutely extraordinary, because it is aggressive and you have to get up and use all of it; then this car comes alive, and it comes alive in a way that the others I'm afraid can't match."

Which sums up the characteristics of DCT: sustainable at high rpm, rev happy, fast and aggressive.
Just want to clarify that I also consider the DCT/PDK versions of double clutch transmissions to be the current gold standard. My point here is that the more aggressive ZF8HP transmissions are getting closer to the DCT and that automatic transmission, as proven by the latest GM/Ford auto, can offer just as quick shifts as the PDK. In my opinion it's just as irrelevant to talk about the old ZF6HP in this context as it is to use the GM TH350 from a 1978 Chevrolet Suburban as a reference to explain how a modern automatic transmission can perform.

I don't think that we have yet seen a ZF8HP that is as good as the DCT, even though the Alfa Romeo Giulia Quadrifoglio version seem to come pretty close, with fast and hard upshifts as well as aggressive rev matching on downshifting.

I have just tried to clear up some of the obvious misconceptions about how shifting, the torque converter and lock up works in a modern automatic trans.

I'm also worried about the apparent rpm limit in the ZF8HP. And if the rev counter video I shared is accurate, then it seems shift points have changed from roughly 7200rpm to between 6300-6700 rpm. That is a further deviation from the "high rpm M engine" philosophy if proven to be the case...


BTW, you do know that VAG offer the DSG in Polo, Touran, Tiguan, Sharan, Transporter/Multivan cars and that the models I referred to was just a random selection of models. Also, I wouldn't consider a 1,6l diesel Golf a "hot hatch" just because it's a Golf... (even though it seems you do ).

I have been to the Nürburgring quite a few times (once so far this year) and since no M-cars have had a automatic transmission it's not really a realistic proposition you make. However, a lot of AMG's, M235i's, Audi RS models, Jaguar F-type R's etc run around the Nürburgring with their 7- or 8-speed automatic transmissions without any problems. As well as a lot of ordinary BMW Gmbh models for instance.

The last M-car I drove was the F80 M3 CP with DCT and I also love how hard it shifts and the near instant gear changes, that makes the driving experience that bit more "special". AFAIK there isn't any technical reasons they can't achieve the same with an automatic transmission, especially with the HCC wet start clutch system instead of the torque converter. And it seems that the ZF8HP in the Alfa allready comes pretty close to the DCT.

Fingers crossed that the M5 will have a transmission that delivers!

Last edited by Boss330; 07-11-2017 at 12:07 PM..
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      07-17-2017, 09:47 PM   #159
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Quote:
Originally Posted by kyrix1st View Post
6ms in a roughly 1cm travel distance of clutch engagement is very possible. Do the math and you get the horizontal velocity of 1.67 meters per second, which is 1/455th of a bullet travel speed (760m/s.) And electric transfer switch what? Speed of light is 3.72E5 times the speed of bullet.

By this transmission, do you mean ZF8HP? I've never owned one with it, but I've driven 120d, M135i, Audi RS7 (pre-facelift). I didn't say I dislike it, I just think it doesn't quite fit the M character. ZF could be fast, but you can't argue you don't feel as connected as that of SMG or DCT. Downshifts never feel as firm.

Other ones I've driven (haven't owned them all except E60 for brief period) E60 M5, F82 M4, F10 M5, Cayenne (tiptronic) and Panamera S. PDK feels faster than the current Getrag DCT in the M.

Thinking of getting a low mileage E63 coupe/F87 (two very different cars I know) in the coming months but torque converter is unlikely to be on my priority list for the enthusiastic driving. Overheats way too quickly and goes into limp mode; sucks for prolonged high rpm (>7000) driving. Ever noticed how ZF doesn't like you shifting at the redline? Their limit is 7500rpm before shit starts breaking down
I don't need to calculate the order of magnitude (the maths). The 6ms figure you keep mentioning is simply incorrect. ZF do not even quote such a time in their restricted technical papers. The electrical portion of the mechatronics takes time to process and travel to the mechanical interfaces. Additionally a multi-transmission gearbox does not perform a normal gear change in sequential order (PDK 7DT, and DCT are 2 transmissions, not 1). A 1-2 change is considered a Transmission A to Transmission B shift. Only when a shift on the same Transmission occurs is it possible to be considered a normal gear change (i.e. On DCT, 5th to 7th would qualify as they are on the same input clutch, same input shaft, same sub-transmission, same dog clutch, and same output shaft). I do know of a VAG DSG Transmission that used the 7ms number in publications, however it is misleading and only represents the duration when ZERO torque is transmitted during an overlapping shift process on a transverse DSG with TWO output shafts.

There are multiple versions of the ZF 8HP, and I asked specifically to see if you've driven the 2nd Generation (ZF 8HPTU) which incorporates many significant design and operating characteristic improvements. None of the cars you've listed have it. For BMW AG Products only certain vehicles with Sport Automatic Option have the GA8HP50, GA8HP75, GM8HP75 and GA8HP95 (one exception is Rolls Royce Ghost V Specification with the GA8HP90 which is a TU variant). That 3rd one is unique (note the M designation for M GmbH). It utilizes a different torque converter that does not unlock except when stationary, though comfort shifts have some slip included. The G12 Alpina B7 and G30 M550i share the same GA8HP75 with modified torque converter rated at 800nm but with RPM limitations on peak torque from below 3000rpm and above 5000rpm on the B7 and below 1800rpm on the M550ix. The M760LiX and Rolls Royce Ghost based Black Badge Variants use the GA8HP95 rated for the full 1000nm from 1200rpm to 6500rpm. Unfortunately with up to 900nm currently available at 1500rpm (this will be increased soon to 1000nm), launch control must occur with 2nd gear active to prevent damage to the Axle to body mounting points.

The Max Speed on torque converters is an "issue" if a very high redline is needed. At 7200rpm input speed, the impeller vanes are near supersonic, causing bubbles to form in the fluid. At 7400rpm, these bubbles implode and vaporize at 7500rpm causing complete TC Stall and physical damage. I've personally gone head to head with engineers from ZF and multiple Auto Manufacturers over this issue (coined the term ZF Honk which earned me the nickname Keyser Söze of the Automotive World). My F90 will mark the 45th BMW Group vehicle I've acquired via personal means and additionally, it, along with equipment and features the F90 introduces, will be incorporated into BMW Security Vehicles and the Security Driver Training Program which I have been an instructor at for 2 decades.

When the rumors first began about the F90 switching to the 8HP75, I answered a post in this forum that a TC was no-go unless the powerband was "neutered". Although this is one way of looking at it, compared to DCT, there is no calibrated torque reduction for the sake of the transmission or driving dynamics above 7km/h. It was the best choice for the F90. M DCT was a Getrag Manual Gearbox (it was to be the 7 Speed Manual that was patented) with Borg Warner Mechatronics and Clutch Pack just as ZF 7DT is also the basis of the ZF 7MT.

Engine redline will be 7000rpm with fuel cutoff at 7200rpm to prevent possible TC Vane overspeed. Unlike the M550i, in certain operating modes it does not shift early. Overheating won't be an issue for the vast majority of track venues.

ZF 8DT would be a handicap IMO (a DCT F90 Prototype I drove wasn't quite as good overall). In the ICE only version, Max torque is 750nm in AWD mode, Switchable 100% rear 2wd is not possible (and would have further torque restrictions), and it wastes space. Without the Electric Assist, the bell housing is essentially empty.



Quote:
Originally Posted by kyrix1st View Post
It's funny because I mentioned VLN on my previous thread; they are likely using upgraded transmission cooler with bigger fans. Also, the car can't really be compared since it is less powered and much lighter than M5 so there is less strain.

I think it would depend on which ZF tranny they are running; the one with 1000Nm torque limit should have much higher threshold whereas 750Nm one will run very close.

If you like the floating carpet feel, ZF is the right choice. I don't think it's right for M, it should be more dynamic. There will never be half the aggressiveness of mechanical "banging" in torque converters since it absorbs all that shock by tranny fluid.
The M235iR (2015 version with HCC) is the basis for the most aggressive Manual Mode Shift Setting. It performs them in 40ms and the "bang" has been tuned in on the F90. The torque limit will be 850-900nm across the full powerband. That said, with Drivelogic in Automatic Sport+ (D3) and MDM 4wd Sport+ Active, the shifts are the fastest and most pronounced (this is internally referred to at ZF as Supersport Mode). In more relaxed modes it does behave like a sporty TC Auto, but that's where DCT fell short. I also feel that it's better than DCT at 8/10 and up.


Quote:
Originally Posted by Boss330 View Post
Did you bother to read the ZF document on double clutch, torque converter and the new HCC?

Again, the lock up in a torque converter is a mechanical coupling just like the clutch on a DCT or single clutch manual transmission! The "fluid coupling" part of the torque converter is only used for start and stop. After that the lock up clutches mechanically locks the connection between the crank and the input shaft of the transmission.

Again, if you had read the ZF document you would have seen that the lock up system also employs a "twin torsional damper", to create the same effect a dual mass flywheel does, since gearshifts are done with the torque converter locked up! So to repeat once again, the fluid coupling is only used for takeoff, after that lock up is employed and vibrations are taken up by the torsional damping system (since the torque converter now is in a mechanically locked state).

A 270mm dual clutch pack weighs 13kg
A 270mm torque converter weighs between 17,4 and 18,8kg

So, yes a torque converter is roughly 5kg heavier than a DCT clutch pack

I'm not sure if you don't want to understand how the lock up system works or if you just want to argue

Look at these drawings that explains how the torque converter and lock up clutch works. Notice that the torsional damper is connected to the lock up clutch, not the torque converter. That is because the power transfer during driving goes through the lock up clutch and the damper takes up vibrations during shifting and on/off throttle situations etc.
The MW250's are installed in the 8HP75 (which is what the F90 transmission is based on). It will have a TC which doesn't appear in that brochure.

Quote:
Originally Posted by mundo74 View Post
dont care how sophisticated the ZF is, it just sounds bad to say your m5 has an automatic transmission. doesn't sounds special one bit. after all buying these types of cars are mostly emotional and not rational.
Automated = Automatic legally from now on. FWIW, the F06/10/12/13/80/82/83/87 with DCT have S205A - Automatic Transmission hidden in the VCDS Data. The F90 has a new CIP module that incorporates all vehicle dynamics, drivetrain, connecteddrive, Radar, Nav, and Camera Systems. It's quite emotional and sophisticated.

Quote:
Originally Posted by kyrix1st View Post
Not the case with the ZF6HP on 3.0si z4 (e85). It has a lock up clutch and overheat like shit on track. It would be more time efficient for you to run both smg and zf versions of e85 on track than to give you shaky statistics behind my desk.
As for the article, if you can direct me the mechanical difference between zf 6 speed and 8 speed other than the obvious I will bother to read that.

I was not implying that lock up clutch does not act similar or identical to clutch packed manuals or dct; anything with centripetal acceleration will have centrifugal force outwards the rotating mass, in this case damped flywheel by dampers and turbine (as it seems to be in alignment with shaft rotation from your picture) in torque converter which will also be damped by tranny fluids inside the turbine. I do admit the way I said it is solely thanks to tranny fluid, which obviously isn't. In MT cars however, we do adjust gear rattle in SM flywheel with heavier oil so you can't say drivetrain vibration has nothing to do with fluid; it lubricates the rotating components afterall.

I have to point out the fallacy in your google logic of DCT vs torque converter is that people who drive sports cars with DCT tend to be more sensitive and caring while people with traditional automatics just go to service shop rather than discuss online because forum chatting is more time consuming so google doesn't do justice in showing demographics. People with automatics don't drive like complete idiots as sports car owners do. Thats why they buy an automatic! Launch control in addition is peformed from standstill, and while thermal capacity may favor zf torque convs, you launch once off the start line and sustain the momentum at high speeds both to cool the car and drive fast. Why would you launch the car several times except for drag race? This car isn't built for that. Buy a challenger for that stuff.

I have said repeatedly that primary disappointment is lack of connection between the car and the driver in torque converters, not just the creep(which can be adjusted seen in X6M) but each gear change which lacks the "bang."
Comparing the worst of the BMW Spec ZF6HP to a significantly modernized drivetrain system you've never experienced....

Quote:
Originally Posted by mundo74 View Post
You need to send this to those poor idiots at Porsche, Lamborghini And Ferrari. They need to read this memo.
Porsche had no choice. The 8HP won't fit in the new MSP platform with Electric Assist. No other transmission will be offered on that platform due to these manufacturing constraints. Lamborghini and Ferrari will have the 8HP in at least 2 models.

Quote:
Originally Posted by Boss330 View Post
I didn't think AMG used the ZF HCC since AMG/MB makes their own transmissions, but that what they use is similar to the ZF HCC...

And thanks for the info on the newer M235i Racing using the HCC instead of the torque converter.

Do you have a source that verifies that the F90 M5 won't use the HCC?
Daimler assemble their own transmissions in-house from components they make as well as source from ZF, Getrag, GKN, and Aisin. HCC is the MCT Startup Clutch. It isn't a torque converter. It is lighter and in its own way more "sporty". In more relaxed driving though, it sacrifices abrasive wear, builds up significant heat, and is overall more prone to faults and maintenance.

Van Meel already confirmed the TC in the F90 (and GM8HP75) transmission. The TC is a combination between the ZF Active Launch Torque converter and HCC. My time behind the wheel recently has not produced any complaints worth mentioning. I go way back with him and the promises have been kept with the F90.

Quote:
Originally Posted by kyrix1st View Post
The thing is ZF torque converters rarely let you go over 7000 rpm (hates it over 6500rpm redline) and you will definitely feel the lack of high rev in corners similar to Hatzenbach or even Pflanzgarten.

I still stand on my two reasons I mentioned previously on why a transmission would overheat, and torque converter up until very recently has been the lesser being. I see that bumper aeros are also slightly different for M235i racing, and I assume that air duct path is also different. I wish I had the actual data to clarify the superiority of high end DCT vs high end torque converter other than the shifting speed and weight but I haven't digged in yet.

Never said ZF isn't a great transmission. My father happens to own '13 XFR(8 speed) and shifts are generally fast but you don't have that mechanical clunking feel of DCT. ZF is a very good transmission for comfort. Since your brought up journalism I would also comment on how Chris Harris (the current Top Gear host) thinks about these cars:



Where he mentions this about F12 M6.

"Difference here is the powertrain. The powertrain is just absolutely extraordinary, because it is aggressive and you have to get up and use all of it; then this car comes alive, and it comes alive in a way that the others I'm afraid can't match."

Which sums up the characteristics of DCT: sustainable at high rpm, rev happy, fast and aggressive.
Tech finally allows the TC to show its capabilities. As far as overheating, just because a TC locks, doesn't mean they all operate the same way. The E85 isn't always fully locked, as it has to follow fairly rigid programming logic. More often than not it's slipping to protect the more costly bits. Without a cooler, yes it heated up.

The Range Rover I'm using for DD is a test vehicle and has Drivetrain (except for the diesel power plant) more similar to the F90 than most current BMW's, but feels 100% Range Rover, easily copes with the daily torture tests, and only has shown one issue that can only be solved by the driver. It's about the programming now. It's what makes the F90 more special than its predecessors.

Quote:
Originally Posted by Bowser330 View Post
Boss330 thanks for the detailed information about the ZF, it's going to be an amazing transmission to experience.
The CAR will be an amazing experience. There's still much to be revealed including a couple of features and functions I'm quite proud of.

Quote:
Originally Posted by Boss330 View Post
it seems that the ZF8HP in the Alfa allready comes pretty close to the DCT.

Fingers crossed that the M5 will have a transmission that delivers!
The Giulia Quadrifoglio didn't skip on tradition and go with the 8HPTU instead of a DCT Transaxle for costs

There will be complaints, praises, and then those who actually get it. They'll be the ones out driving an amazing feat of engineering full of soul rather than googling DCT vs Slushbox and being internet experts.

Last edited by lemetier; 07-18-2017 at 06:13 AM..
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      07-18-2017, 12:55 AM   #160
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Originally Posted by lemetier View Post

There will be complaints, praises, and then those who actually get it. They'll be the ones out driving an amazing feat of engineering full of soul rather than googling DCT vs Slushbox and being internet experts.
While I'll admit I'm still a bit concerned about the amount of weight on the front axle and the change to a TC Auto, I've got to say Liam, that is about one of the best posts I've ever read! You're awesome.

Something you may know about, I've read mention of the 19" setup being a square 275/40r19 setup and the 20" setup being 275/35r20 up front with either 285/35r20 or 295/35r20 rear. Can you confirm?
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      07-18-2017, 11:58 AM   #161
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Quote:
Originally Posted by brad850csi View Post
Quote:
Originally Posted by lemetier View Post

There will be complaints, praises, and then those who actually get it. They'll be the ones out driving an amazing feat of engineering full of soul rather than googling DCT vs Slushbox and being internet experts.
While I'll admit I'm still a bit concerned about the amount of weight on the front axle and the change to a TC Auto, I've got to say Liam, that is about one of the best posts I've ever read! You're awesome.

Something you may know about, I've read mention of the 19" setup being a square 275/40r19 setup and the 20" setup being 275/35r20 up front with either 285/35r20 or 295/35r20 rear. Can you confirm?
Very kind of you sir. I really appreciate the positive reaction.

DIN weight and the distribution aren't an issue. Both are improved compared to the F10. The new Central Intelligence Module should also be reason not to balk over the transmission. Not only has the available data from ConnectedDrive been improved, data from PDC Radar, ACC Radar, 3D Pulse LIDAR, 3D Stereo Cameras, rear, side, and front Radar (depending on options installed) is fed into the system making it extremely difficult to put the car in a situation where the drivetrain cannot adapt.

As for the tires, don't be surprised if there are several different combinations depending on equipment. The specs can be changed by the driver in iDrive (including out of range customer fitted combinations).
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      07-18-2017, 06:28 PM   #162
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an autobox does not in an M belong. dont care how "as good" it is. Porsche spent a boatload of money to develop a new pdk knowing the 8hp was around. ill enjoy my dct until I eventually get a car that has no transmission.
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      07-19-2017, 12:37 AM   #163
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Quote:
Originally Posted by lemetier View Post
Quote:
Originally Posted by brad850csi View Post
Quote:
Originally Posted by lemetier View Post

There will be complaints, praises, and then those who actually get it. They'll be the ones out driving an amazing feat of engineering full of soul rather than googling DCT vs Slushbox and being internet experts.
While I'll admit I'm still a bit concerned about the amount of weight on the front axle and the change to a TC Auto, I've got to say Liam, that is about one of the best posts I've ever read! You're awesome.

Something you may know about, I've read mention of the 19" setup being a square 275/40r19 setup and the 20" setup being 275/35r20 up front with either 285/35r20 or 295/35r20 rear. Can you confirm?
Very kind of you sir. I really appreciate the positive reaction.

DIN weight and the distribution aren't an issue. Both are improved compared to the F10. The new Central Intelligence Module should also be reason not to balk over the transmission. Not only has the available data from ConnectedDrive been improved, data from PDC Radar, ACC Radar, 3D Pulse LIDAR, 3D Stereo Cameras, rear, side, and front Radar (depending on options installed) is fed into the system making it extremely difficult to put the car in a situation where the drivetrain cannot adapt.

As for the tires, don't be surprised if there are several different combinations depending on equipment. The specs can be changed by the driver in iDrive (including out of range customer fitted combinations).
Judging by this, the full complement of automation will be available. This makes me, and my tech nerdiness, very happy.
Thank you very much for your insight. Like I've mentioned previously, I was very unsure what to think of an automatic transmission. However, I'm convinced that M division has properly done their homework.
I think the biggest storyline of this new M5 will be the Central Intelligence Module, and what it's capabilities are. I wonder if it employs fibre optics to ensure fast data transfer rates.
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      07-19-2017, 06:50 AM   #164
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Quote:
Originally Posted by lemetier View Post
The Range Rover I'm using for DD is a test vehicle and has Drivetrain (except for the diesel power plant) more similar to the F90 than most current BMW's, but feels 100% Range Rover, easily copes with the daily torture tests, and only has shown one issue that can only be solved by the driver. It's about the programming now. It's what makes the F90 more special than its predecessors.
Range Rover 5.0 SC would be the only transmission mechanically identical to XFR and XFR-S; ZF in Vogue is possibly the smoothest TC out there and is nowhere as sporty as a Jag (with ZF8HP) in general. I don't know which one Jag falls in, but I sure hope not it's in the same range as X6M.

How can a torque converter reproduce mechanical banging that is the result of engaging and disengaging pressure plates from dual clutches? If you are referring to exhaust "farts" apparently seen in F90 video, that is the same joke used in RS7.

I do recognize that use of higher thermal capacity materials/layouts to dissipate heat could be well engineered to produce good results, but it seems
rather than using higher thermal capacity materials ZF decided to direct oil flow so that higher thermal capacity is achieved. This is cost effective engineering, I'll give you that.

My question is, why not make it so that less heat is produced so it doesn't work the cooler so hard in the first place? That's less weight for less heat (Q=mCdT.) If most of the DCT bellhousing is empty as you say and ZF8HP weighs 91kg compared to DCT of 78kg, advantage of DCT is or MT is in lighter rotating mass.

Good info on ZF transmissions otherwise, efficient programming is always welcome regardless of its mechanical base; it's been a decade since Lexus focused on traction control programming rather than building a rigid chassis to cut down production cost and BMW seems to be following its predecessor albeit in different category.
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      07-22-2017, 07:52 PM   #165
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Quote:
Originally Posted by kyrix1st View Post
Range Rover 5.0 SC would be the only transmission mechanically identical to XFR and XFR-S; ZF in Vogue is possibly the smoothest TC out there and is nowhere as sporty as a Jag (with ZF8HP) in general. I don't know which one Jag falls in, but I sure hope not it's in the same range as X6M.

How can a torque converter reproduce mechanical banging that is the result of engaging and disengaging pressure plates from dual clutches? If you are referring to exhaust "farts" apparently seen in F90 video, that is the same joke used in RS7.

I do recognize that use of higher thermal capacity materials/layouts to dissipate heat could be well engineered to produce good results, but it seems
rather than using higher thermal capacity materials ZF decided to direct oil flow so that higher thermal capacity is achieved. This is cost effective engineering, I'll give you that.

My question is, why not make it so that less heat is produced so it doesn't work the cooler so hard in the first place? That's less weight for less heat (Q=mCdT.) If most of the DCT bellhousing is empty as you say and ZF8HP weighs 91kg compared to DCT of 78kg, advantage of DCT is or MT is in lighter rotating mass.

Good info on ZF transmissions otherwise, efficient programming is always welcome regardless of its mechanical base; it's been a decade since Lexus focused on traction control programming rather than building a rigid chassis to cut down production cost and BMW seems to be following its predecessor albeit in different category.
All Vogues from 9/13 on use the 8HPTU; the XFR and X5/6M also use the same transmission.

The "mechanical banging" isn't from the torque converter. It's from Transmission Brake Set B in gears 1-5 and only with the most aggressive settings active.

The torque converter design and functions in this application produces the least heat and least mechanical wear while providing the widest range of shift types and shift quality.

Might want to check the weight of 8DT75x vs 8HP75x (including the transfer box) WITH oil cooler and fluid included. The unit with the weight advantage isnt the one you suggest.
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