S4 8-speed question
#41
AudiWorld Super User
The ZF8 was introduced to replace the ZF6 as a means for increased efficiency and mileage while supporting large input torque loads. Considering the range of vehicles/brands that get this transmission (Dodge trucks, MB, BMW and Audi vehicles, etc), it makes more financial sense to buy a transmission from a company that specialize in trannies vs trying to re-invent that wheel.
#42
AudiWorld Super User
As I said in post #25, the C7 A6 and A7 using the 3.0TFSI engine used the DL501 dual sequential S tronic transmission in most of the world. Including my A7. Only North America used the ZF8HP with the supercharged 3.0TFSI, because it was smoother, which apparently better suits drivers from North America who are more used to torque converter transmissions. Saying this, I am not sure what transmission was being used in China.
Now, this is all very clear to me, but I wanted to be very sure that I wasn’t misinterpreting some kind of Audi-speak naming system. So I called Udo Rügheimer, Audi Germany’s head of communication for product, technology, and innovation.
“It is a conventional planetary transmission,” Rügheimer confirmed over the phone. He clarified that the hanging point was torque; the new S4 has too much of it for their existing dual-clutch transmission to handle.
My next question was if it might be possible that there would be a dual-clutch in the S4’s future. I didn’t write down his exact turn of phrase, but Rügheimer happily explained that high torque is simply one of many engineering considerations in a car. It is perfectly possible to build a dual-clutch that can handle it. He pointed to the 2016 Audi R8, which has a new dual-clutch that manages just fine.
“It is a conventional planetary transmission,” Rügheimer confirmed over the phone. He clarified that the hanging point was torque; the new S4 has too much of it for their existing dual-clutch transmission to handle.
My next question was if it might be possible that there would be a dual-clutch in the S4’s future. I didn’t write down his exact turn of phrase, but Rügheimer happily explained that high torque is simply one of many engineering considerations in a car. It is perfectly possible to build a dual-clutch that can handle it. He pointed to the 2016 Audi R8, which has a new dual-clutch that manages just fine.
https://jalopnik.com/the-new-audi-s4...sio-1730778195
It has nothing to do with "unable to handle the torque", and everything to do with "unable to handle the torque in a pleasant manner". The ex-head of BMW M Division more transparently cited this as the reason M Division are progressively moving away from dual sequential transmissions to torque converters.
And I doubt if moving to a ZF8HP was done for cost savings. It is only used where the torque ceiling and quattro drivetrain render use of an S tronic unsuitable.
I believe that the DSG is developed by Borg Warner and licensed by VAG, so it isn't like Audi is designing it from the ground up on its own. Additionally, Audi is already using a DSG for the A4/A5 and switched from the ZF8 to a DSG for the 2019 A6/A7. Regardless, the ZF8 has proven to be a reliable, robust transmission, so its inclusion in the S4 and S5 doesn't both me.
#43
This information was relayed by Audi reps to nearly every reviewer when the S4 and S5 were introduced. I even watched an S4 review on Youtube that had an interview with an AoA product planner who explicitly stated that the ZF8 was chosen over a DSG for its low-speed smoothness and because the new 3.0T had too much torque for existing DSGs.
However, I agree that the most likely reason is that Audi wanted to limit R&D and/or manufacturing expenses.
#44
AudiWorld Super User
#46
AudiWorld Super User
#47
AudiWorld Super User
Only expense for Audi on the ZF would be mapping for shift pressures on the gear changes to change the driver experience. All software, almost zero risk stuff. If the ZF was so expensive, and cheaper for OEM's do their own, my BMW 340 wouldn't have the same ZF8 AT as my Audi SQ5. The days of mfr's doing 100% proprietary designs are gone since it really makes no sense. Let transmission experts build transmissions. Let brake experts design brakes. My SQ5 has the same memory seat controls as my BMW 340 as well.
#48
You said it takes no R&D. Not that it takes less R&D. And just because there is a ZF 8 speed doesn't mean it's an off the shelf transmission for every car. Even between applications (example S5 to RS 5) there are differences in the gears and torque converter.
#49
AudiWorld Super User
That amount of R&D is almost negligible though. Audi (or whatever brand) would just spec what their gear spacing and converter engagement RPM is. There isn't a series of prototype, destructive testing, new molds, prototype, etc which is expensive.
#50
AudiWorld Super User
You can't dispute my overall point, so you're resorting to pedantry to win the argument. You still haven't addressed which option is lower overall cost for Audi and implied that the ZF8 is more expensive than developing a new DSG for the platform. Do you stand by that argument?