Wondering if anyone else noticed that when using manual downshifting and braking into a corner the A8 often changes the engine's braking effort that I find disconcerting. It feels as if the transmission shifts into a higher gear during hard braking, lessening the engine's braking effects, yet the engine RPMs remain the same, indicating no actual downshift.

So, what is happening and how to eliminate that "up-shift" sensation during braking?

 

are you talking about how it rev matches? it's getting ready to accelerate out of the corner....you could always push the brake pedal to slow down....?

 

No, that is not what I am trying to describe.

I am under moderate-to-hard braking, approaching a corner, say in 3rd gear, pulling about 5000 RPMs. As I am hard on the brake with the RPMs dropping according to my loss of speed, I would suddenly feel the considerable lessening in the engine braking. The feeling is, as if the transmission just shifted from 3rd into 4th, yet the engine RPMs on the tach are the same as they were before the apparent shift.

To put it an other way; it feels like a decoupling of the transmission from the engine and the feeling that you lost the braking power of the engine while the sensation is that I am approaching the corner NOT in gear but, in Neutral. I have only 1200 miles on the car but, this happened to me at least a dozen times while braking into corners.

 

probably the torque converter unlocking. would have to retune the transmission to keep it locked.

 

Interested to hear if this is normal--as one would think the A8 would engine-braking similar to a manual, while in full manual mode.

ax- will you be using the car for Solo? I'm leaning towards the A8 (for upcoming Z06) due to better gearing, but want the manual feel/control--or it may be no dice.

 

it still has a torque converter. will never work like a manual.

 

GTB - While I had competed in Solo for years and on track with SCCA for decades, this Stingray is for street enjoyment only. Still, it is very unexpected to feel the car suddenly lose engine braking as I am in the process of braking into a corner. It could also lead to a loss of control as during the cornering process any changes in the braking dynamics could upset the car and spin it.

Like I said, it feels as if suddenly the tranny shifted into Neutral but, that is not the case as the acceleration picks up without delay when pressing the go-pedal out of the corner.

This is somewhat similar to two Chrysler products I had for my company vehicles, a T&C van and a Pacifica. With those cars there was engine braking up to about 3000 RPMs but, when exceeding it the engine braking ceased to exist. Coming steep downhill I had to watch to make sure I kept the RPMs below 3K, othewise the car felt like it shifted into Neutral and just ran away. The engine RPMs revved up with the increased speed, indicating that the engine-to-drivewheel coupling was still there. That was the chief reason these cars required new brake pads and rotors every 15K miles in hilly areas. The dealers pretended not to know what I was talking about when I complained. Chrysler fixed it in the newest generation T&C transmissions.

My C7 is different as it seems to have engine braking at, say 5000 RPM, just to loose it during the braking process as the RPMs drop. Since I am not familiar with the torque converter lockup/release operation I will defer to the dealer.

Thanks for any suggestions, however.

 

Reading the Owner's Manual I'm wondering if the base model has these different Trans Shift Modes? The manual says, "if equipped". Copied from the manual:

"Trans Shift Mode (if equipped) Normal Normal Normal Sport Track"

I know that I can select those different modes in my car but, not sure if the Transmission Shift Mode is part of the selection. I've been driving the car mostly in the Touring (Default) mode. Perhaps the Sport or Track mode will have different Torque Converter lockup and release settings?

 

Yes, there are different TCC, shift point, shift pressure, throttle response, etc tables for different modes.

 

Thanks, Higgs, I will be testing those modes for TCC operation.