Assuming you dont race/track your C8, would a torque converter be a better option over the DCT. Im assuming the DCT may be better on gas but you guys who know chime in.. Thanks

 

A torque converter would be smoother in stop & go traffic, and be cheaper/simpler to build & maintain. That's about where the advantages end. An automatic world class sports car deserves a DCT.

 

Thanks K, so a follow up question: what would the advantage(s) be of the DCT IF not tracking or racing the car, if any?

 

8 speed ZF on my '21 M4 Competition was fantastic. As close as you could get to a DCT. That being said, the DCT does seem quicker at both up and down shifts. It is not as smooth at cruising speeds, however. Doesn't really bother me. Replacement cost would be a huge difference, however. That is where the TC has a big advantage. All in all, the DCT is the right way to go on a high performance car. Disadvantages are really minor.

 

Quicker shifts and better MPG with less driveline loss.

 

Come on....it's not even close. The DCT is far superior in a performance car.

 

You can easily find out by driving an auto C7 back to back with a C8. You will find a big difference.

 

I think this is a cutaway of the C7 8 speed transmission. It's soooooo much simpler!

 

As for smoothness - I have an F150 with the twin turbocharged V6 and 10 speed automatic. In the normal drive mode it is smooth - shifts are often imperceptible. But I think the C8 Tour mode and automatic shift is almost as smooth. I would not pick one over the other on the basis of smoothness. In sport shift mode - the F150 shifts are a bit more snappy, and upshift and downshifts are more aggressive. And, like the C8, it will recognize slowing down and downshift for engine braking - and also to maintain speed gong down hill. Again, while it is smooth, I think the C8 is too.

If there is an advantage to the TC type transmission, to me, it would just be that GM has been making them for a long time, and likely to be extremely reliable. I'm not saying the DCT is not - but it is GM/TREMECs first attempt. My 66 Pontiac TurboHydramatic probably has well over 100000 miles - its never been touched. Its probably smoother than the C8 and the F150. But I don't think a DCT is inherently less reliable, at least from a mechanical perspective.

I think there was a Turboglidede that essentially use three individual drive turbines, each connected to a different ratio inside the gearbox. "shifting" happened via sequential engagement of the turbines - it was smooth, seamless, and horribly inefficient. I'm not sure it was simple either. But in a way, it sounds like a DCT (or a triple clutch transmission) shifting between gears via clutch (in this case hydraulic clutch) action doesn't it? It also had a variable pitch stator.

 

Agree on this. I was wondering if you didn't race or track car, is it worth it vs the TC. So the DCT should be put in all cars?

 

I said "in a performance car". A truck or big sedan can have a torque converter auto....but not my performance car.

 

I understand so we agree on the performance cars/DCT. Is there ANY reason to put DCTs in regular cars if they are so good?... or too costly, not efficient, problematic, etc....