sakimano

anyone felt like their DSG clutch(es) were slipping?

I just watched Primetime's videos of his runs at the strip today, and two times, it sounded like his clutch was slipping

help me understand DSG - from what I remember, there are 2 clutches...one to handle the odd-to-even shift (i.e. 1-2, 3-4, 5-6) and one to handle the even to odd shifts (2-3, 4-5)...and presumably one of those handles the reverse shift too.

When you watch this video, it sounds like on his 2-3 shift the clutch slips.

http://www.youtube.com/watch?v=DjicvRlBrqA


and on this video it sounds like when he keeps pushing after the finish line, his 4-5 shift slips. The 2-3 shift sounds like its ok...might slip a tiny bit.

http://www.youtube.com/watch?v=NmLxLTHDxLo


What do you guys think? Would sure explain great 60' times but the car losing a little bit the rest of the way down the track.

PsYkHoTiK

There is a "hesitation" sometimes.

It's like that even on APR's video:

<iframe width="560" height="349" src="http://www.youtube.com/embed/DRM-N-kfIDY" frameborder="0" allowfullscreen></iframe>

Which is why there is some good interest in a "DSG" tune.

I can't remember if the launch control capable 2011 S4s have this issue or not though...

Brandonb

The only time I've noticed any "slipping" on WOT shifts on my 2011 DSG is when I forget to turn off traction control before a run. The car senses some wheel slip right after some shifts and retards the throttle for a second.

blackhawk878

I would consider that "normal" factory operation for a 2010 anyway. Mine does the same thing which is why I have a good amount of interest in a DSG tune, like Psykhotik said. There is an S4 currently being tested for a TCU tune here in Phoenix(Tempe), hopefully something will come of it soon.

Link to the thread on AZ: http://www.audizine.com/forum/showth...eed-a-Test-Car

Sandy S

Does not sound like a slip to me. The engine rpm would go up on a slip and it goes down slightly. Looks like it just took a little bit for the engine to catchup with the initial torque requirement of the higher gear.

primetime

Sak, The clutches are not slipping... the only hesitation is at about 4,000rpm after the initial launch, which the car has done since day one and I believe all DSG S4's do... At least the 3 that I have driven did...

I pulled all of the tranny fields from vagcom yesterday and will do some logging once I figure out what is what... More concerned as to why my trap is off by 2+MPH... Since the logs to APR so will see what they say... Was making 13.4 psi but my IAT's were a little high... Will try again this weekend... Gonna buy some rims this week... My anchors weigh 58lbs and the setup I think I will be getting should be about 48-49lbs so that will help... later Ron

NWS4Guy

Agree, sounds more like an engine hiccup, if it were slippage the revs would defnitely climb a lot.

RE: DSG functionality

There are 2 clutches and 2 drive shafts, the outter one is hollow and the second shaft is inside the other one. One shaft (and corresponding clutch for that shaft) holds even gears, 2, 4, 6 and R, the other shaft has odd gears - 1, 3, 5, 7.

The TCU (Transmission control unit) talks to the ECU to manage shifts, it can tell the ECU to rev the engine to x,xxx RPMs and hold it there so the appropriate gear can be selected and the clutch released, so that the engine and gear and spinning at the exact same speed with no clutch slippage for downshifts. For upshifts it asks the ECU to retard timing so revs drop as fast as possible to rev match as well.

The clutch packs are wet clutches, in an very specific ATF suspension that cools the clutches as well as helps them function. The only time the clutches slip is in R and 1, to allow the car to start moving, from there on, all shifts are (supposed to be) perfectly matched, since the DSG can tell the speed of the engine and shafts to match them perfectly when shifting.

81bear

Sorry to thread jack but can't let you get away with hiding this mid sentence and not elaborating.

primetime

Yeah, after cleaning and weighing the stockers I decided it is time to cut some weight and get some wheels... I am leaning towards one of the BBS wheels... Working with a few folks on pricing and availability at this point... Cutting weight of the wheels will be huge and probably net me more than most other mods at this point... I really do like the look of the stock wheels but they just weigh too damn much... On top of that I got the Dunlop Sport Maxx tires which according to tirerack are about 4 lbs more than the PS2's... I am hoping to get a 19x8.5(23-25 lbs) wheel with a ET of 35 and run a 245x35x19 Conti Extreme DW(21 lbs) assuming the weights are accurate this would net me between 12 - 14 lbs per corner... That will be very noticeable... I do want to sort the trap speed issue out before making changes and then add the wheels... I will buy when I find the right deal since I am not that pressed but would like to do it this week... I'll post pics and impressions once I get whatever I decide to go with... later Ron

NWS4Guy

Swap out the stock rotors for something else, also not very spendy unless you went for the entire BBK, you can save another 5 per front wheel swapping out rotors. Like the wheels, that will remove unsprung and rotating mass.