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Originally Posted by Boss330
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
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.
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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
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
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.