ssaa77

Hey guys - did a search on this and couldn't find anything. I noticed that when I accelerate from a stop, the car hesitates as if there's a more traditional automatic tranny gear shift. I thought that was odd, so I shifted into manual and noticed that it occurs even if I hold the gear in M1.

Only happens in first gear and from a stop. Anyone have this problem? I bought the car used and had the 15k mile check up done, so I don't know if this was something that's always happened or after the check up.

Any insight would be appreciated!

superswiss

By hesitation, do you mean that you get on the throttle, but there's a slight delay until the car starts moving?

If so, that is completely normal. Given that the transmission is a computer operated manual transmission, the clutch is disengaged when you are stopped. Then once you give it enough throttle, the computer engages the clutch and the car starts moving. The speed at which the computer engages the clutch depends on how aggressive you stump on the throttle.

Same happens in a manual transmission car. The driver first gives some throttle and then starts to engage the clutch. The slight difference is that the DSG has forward creep programmed in, so it starts engaging the clutch shortly after you release the brakes and automatically gives it enough throttle so the engine doesn't stall, but you only feel that creep come in if you get off the brakes w/o getting on the throttle.

ssaa77

Thx for the help. The car has started moving already before this happens. It really just feels like a typical automatic transmission changing from 1st to 2nd gear. It's very odd. Almost a hiccup while accelerating in 1st.

superswiss

That was going to be my next question. This is also perfectly normal. What you are experiencing is the clutch going from slip to full grab. At that point the clutch experiences a sudden change in friction, which causes a jolt in the drivetrain. A similar thing happens with modern torque converters when they lock and the coupling goes from fluid to fixed mechanical. This happens in a traditional manual transmission as well. How pronounced it is depends on how tight the drivetrain is. If the drivetrain has a lot of play you may not feel it as much. The RS5 is a performance car, so the drivetrain is pretty tight.

I'm not sure if you've ever driven a manual, but what you have to do is smooth out this transition by progressively applying more throttle as the clutch engages. It's a bit more intuitive with a manual transmission as you push in the throttle and let out the clutch pedal at the same time. In this car you gonna have to fine tune your senses and feel what the clutch is doing and operate the throttle accordingly.

ssaa77

Interesting. Will try it out. I get your explanation on manual transmissions, but never had this happen before on two different b8 s4s with stronic and a gtr.

superswiss

I can't comment on the GTR, but the S-tronic in the RS5 is a hardware and software tuned version of the S-tronic in the S4. It has faster hydraulics for example and is known to shift more aggressively. What mode are you in? Sport mode in the RS5 is really not meant for daily driving. It's meant for the track. I only get this hesitation in Sport auto or manual with light or moderate throttle. If I take off aggressively from a stop it doesn't happen. In D auto and manual I don't really get this hesitation. The clutch takeup in the RS5 in Sport mode is more aggressive than in the S4.

antoff

thanks for your detailed explanation superswiss!!! Sounds like engineer man talks!!

I am experience same "lag", but when drive select is on D comfort mode. Lets say on a stoplight when green comes I step on pedal little aggressive and first RPMs goes high and at around 3300 in a second clutch engages and car starts moving..

superswiss

What you are describing is a deliberate 1-2 comfort shift. I get that, too. The first gear is very short and the transmission just executes the 1-2 shift as comfortable as possible in comfort mode.

PhilNotHill

OP:

I believe this video answers your question. For the Audi S-Tronic dual clutch transmission, when the car is in Park the computer has no idea whether you are going to go forwards or backwards so it preselects Reverse and 2nd gear. Why? Because second grear is on the same shaft as Reverse. So if you go forward it takes about a second to downshift to first.

the video also describes how to accelerate from first and downshift.

Does this answer your question?

superswiss

Neat video, thanks for sharing. Explains things very well. Minor correction in your comment above. It preselects Reverse and 2nd, because Reverse and 1st are on the same shaft (not 2nd). Probably just a typo.