SOLVED: DL501 0B5 S6 Surging and jerking issue, intermittent

[slowguy]

I did so much searching on this and never did find a straight-answer resolution. I have the DSG DL501 0B5 trans in the s6 and was very impressed with its lightning-quick shifting from day one although it had this issue that got progressively more noticeable as time went on. I never had a single code for the trans, but after tons of research I decided to change the fluid and filters couple of times, replace the mechatronics once, bought a custom dsg tune and still had the issue. It wasn't terrible just quite annoying to get the occasional jerk, shudder, or surge on startup or in gear at a standstill. I decided if I was going to pull the trans, I might as well go all-in and do everything. Not only did I purchase a transmission with less than half the mileage and 3 years newer, I decided to bight the bullet and have it completely gone trough and rebuilt to include the clutch. The clutch frictions in the new trans looked almost perfect which led me to believe the car was a "family car" but I still went ahead and put everything brand new. Out of pure curiosity, however, I will yank out the old clutch just for a good inspection to see what 550 or so hp does to the plates. I mean, why not?

I've been a part of this forum for many years and had many Audi projects. I shamefully admit I rarely initiate a post like this unless it's something I feel could really help someone else that was in my position.

The second I got the trans out of the car I spun the flywheel to see if I could hear or feel anything abnormal. I immediately noticed the clang of what sounds like broken springs in the Dual mass flywheel! How could I have not thought of that! It's so obvious and such a common issue with past dsg revisions. I replaced two of these in two diesel jetta's in the past. It was so obvious and so simple it upset me a little that I didn't realize this until the trans was out of the car and on the ground. It could have saved me so much pondering, research, and $$. At least everything is new now!

So...if any of you have surging, jerking, or shuddering at start, backing up, at a standstill in drive, or changing from forward to reverse, -and- you have no codes in the trans module (and I didn't even hear any typical clanging noise that most defective DMF's exhibit)...think about looking into replacing the DMF. I'm sure, now, it could have been done without completely dropping the trans. Although it's no easy procedure, you could just separate the trans from the block, pull the driver side axle, and probably slide it out.

[slowguy]

few pics of the new trans

[skiptowncat]

How did the old clutches look? What miles and any tune on the car?

[slowguy]

I only pulled out the DMF from the old transmission thus far and immediately realized it is defective. I am doing all the little things on the car before I get it out of the shop - focusing on that for the moment. Cleaning, leather treatment, stuff like that. I'll know soon. You need a special tool to pop out the clutch. Oh and it has 130k stage 2 + tune. I'm guessing around 500-550 hp? All I know is this is one of the quickest cars I've ever owned.

[goldenzrule]

Interesting. My car has always had a surging issue. When it is cold in the morning, and I drive out of the driveway, it will at first feel like you are applying brakes and then off the brakes and then on again until it warms up a little. It will also surge or "jump" a little when parking in the garage. Have almost hit the old shelving I used to have in there in front of the car a few times because of this.

[slowguy]

I won't know 100% until I drive the new trans but the DMF was 100% one of the issues. It was obviously internally damaged. I don't know what all the symptoms would include but surging, without a doubt, would be one of them with my limited knowledge of the operation of a DMF. The computer would sense the inconsistent speeds due to the fluctuation of a faulty output between the engine speed and trans speed and try to compensate until the dmf was all the way connected in one direction (either forward or backward). Not to mention how common this issue is in the VW world. Like I said, years ago, I replace two of these in two separate TDI cars. I only wish I would have thought of it before doing all the other repairs (like two oil/filter changes and a Mech swap out). The crap isn't cheap :)

[slowguy]

https://youtu.be/ckf5fWGi5TU

Pretty good explanation here. Break those springs and imagine the surging between the output of the engine and the input to the trans when the two are in sync (like changing direction, speed, or at a stop). Again, all depends how motivated I get and how much curiosity I continue to have about this but I may cut open the defective one just to take a peak at those broken springs and see how they are broken.

[bakes]

Would the clunky shift from first to second be a symptom of this as well? Whenever I go from a stop the first to second (when in D and not sport mode) is never smooth and clunky. I was under the impression this is just a common trait of the 7 speed transmission. When I start in Sport mode this is significantly reduced and almost gone. Thoughts?

[slowguy]

Honestly, I think any clunking could be a symptom of a bad DMF. Obviously the more mileage and the more power could accelerate the degradation of this component, but it is a common failure point - one I forgot about until I was able to actually spin it by hand. The one major downside is its location. You still need to separate the trans from the engine to access it. On the plus side, when compared to other components of the drive system, it's a cheaper part and very easy to change once you have access. I am excited to see the difference when I drive the car again. I've heard many stories about the roughness of a dsg but then I've also heard people say when it's operating properly it's silky smooth. I have my doubts but I can always be optimistic. I'll know soon enough.

[slowguy]

update to this; had to pull the trans a second time! The car drove very smooth and all the coding/programming/immo issues worked out with no codes....until there was one. Clutch slipping. Scratching my head for quite some time not know how a brand new clutch could slip. Broke down and pulled the trans, disassembled clutch only to figure out that the clutch kit they sell is a friction and plate short. These were for the s4 and s5 but the s6 has an extra one. So, 20 hours later, and three checks of the clutch, it's going back in. Good feelings this time!

[HolyHell]

update to this; had to pull the trans a second time! The car drove very smooth and all the coding/programming/immo issues worked out with no codes....until there was one. Clutch slipping. Scratching my head for quite some time not know how a brand new clutch could slip. Broke down and pulled the trans, disassembled clutch only to figure out that the clutch kit they sell is a friction and plate short. These were for the s4 and s5 but the s6 has an extra one. So, 20 hours later, and three checks of the clutch, it's going back in. Good feelings this time!

Update?

[978rs4]

Any update on this? I have a OB5 DSG in a B8 s4 that also has this surging and rpm fluctuation when cold first starting out going slow no fault codes passes all adaptations. And it goes away when warm. It also some times feels like your piping the clutch if you start out at maybe 1/2 throttle then spins the tires and rips. No clutch slipping.

[slowguy]

Yep. Old thread. Ran like a dream after I put in the required extra friction. Graduating to a little newer s8 plus tuned this weekend. Guess it’s back to a true auto trans.

- - - Updated - - -

Fyi I now have a spare trans and a freshly built clutch I’m listing soon

[VinnysS4]

update to this; had to pull the trans a second time! The car drove very smooth and all the coding/programming/immo issues worked out with no codes....until there was one. Clutch slipping. Scratching my head for quite some time not know how a brand new clutch could slip. Broke down and pulled the trans, disassembled clutch only to figure out that the clutch kit they sell is a friction and plate short. These were for the s4 and s5 but the s6 has an extra one. So, 20 hours later, and three checks of the clutch, it's going back in. Good feelings this time!

Have a question for ya. What did you end up doing with the clutches? Did you just add one of the old friction and steels to the pack? Im asking because I got my hands on my OEM clutches from my s6 and some new raybestos gpz clutches and the friction discs are identicle thickness but the steels are thinner on the s6 to accommodate the extra disks. The clutch packs measured out side by side(oem 13 disks vs raybestos 11 discs) are within a few thousands thickness of each other. Nearly identical.

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[AndrewF1]

Do you still have that S6 dl501 rebuilt trans?