micabobo

Hey all,
I recently got a 2018 A4 (6-speed manual) and pretty much immediately noticed that there is a dragging/jittering/vibration noise and feeling coming from the rear of the car when accelerating from a stop and as well in low-speed turns.
I did some investigation and found the well-known TSB regarding the Quattro Ultra AWD clutch fluid. The car is a CPO vehicle from an Audi dealership, but I am lead to believe that it was previously a lease vehicle.
I do not think that TSB was ever acted upon and the vehicle has ~68000 miles on it.
The situation seems to present itself then the AWD control system engages the AWD clutch as well as the clutch pack in the rear differential.
On the highway, the AWD clutch is disengaged and the aforementioned vibration is absent. I monitored the AWD actuator solenoid currents with my Autel and saw that the clutches engage when the solenoids have no current flowing through them (clutches are normally-engaged).
During cruising, the solenoids have ~2.1 A going through them and the clutches disengage.

Since the vibration is coming from the rear of the car, I am lead to believe that the rear differential clutch pack is beyond saving (I checked the differential fluid and it must have been serviced recently due to its cleanliness and it dripping out of the fill port).
However, the AWD clutch most likely has never been touched in the entire history of the vehicle (I assume the previous owners basically treated the car like a rental car).

Anyway, I am scheduled to drop the car off at the dealership tomorrow under warranty and hope that the rear differential can be replaced and possibly the AWD clutch. I would like the "clock to be reset" so my major task from now on is sustainment work (maintenance).

I have heard that these are the major issue items for cars equipped with the Quattro Ultra system (if left without routine servicing).

UPDATE: Vibration issue solved by implementing the center clutch TSB that Audi had issued a few years back regarding vehicles equipped with the Quattro Ultra system. Center clutch is operating properly and has strong engagement.

micabobo

Also, anyone else who has encountered Quattro Ultra problems, please share them. I want to know that I will be potentially walking into.

georgeee

Thanks for sharing, I'm interested in how this pans out, if yours was an isolated incident or not since I (and everyone now actually) have the quattro ultra as well.
I just got the car so can't vouch or complain about it yet, I'm around the 1k miles area now.

black.cat

My 2018 6MT had the same symptoms in the TSB. But Audi made the case with my warranty company to replace the entire rear diff. It was a $5.5K job and I only had to pay a $250 freight fee. It drives good as new now.

as I understand, they have to replace the rear diff clutch fluids, put 80 miles on it and change the fluid again before testing another 80 miles. It’s a whole process and not covered by Audi Care. It’s billed as a recommended maintenance for any Quattro W/ultra with the issues in the TSB.

LightningTruck

Couple things about the Quattro Ultra clutch unit (hangs off the back of the transmission):
It only holds 400ml of fluid, very little.
There is no recommended service interval for the Quattro Ultra clutch unit.
Audi care would have nothing to do with it, that only covers scheduled maintenance.
If you have it CHANGE THE FLUID ASAP.
Let me know if you need a picture of the unit.
.

micabobo

Oh yes, I have seen the unit on the transmission. I had it at my friend's shop the day I picked it up to take a look underneath the car and familiarize myself with the layout and overall structure of the car. I used to drive an 03 330xi (6MT) so this is quite the jump.
I marked the bolts with a grease pen as a pre-emptive measure in the event the audi dealership claims they changed the rear differential but end up not doing so.

I plan to change out the AWD clutch fluid as soon as possible. Do you think that given 68k miles, the unit is fried?

SMac770

There's two different active assemblies in "quattro ultra". There's the type 0CJ or type 0CX AWD clutch assembly on the tail end of the type 0CJ or type 0CX transmission (leave it to Audi to reuse type codes for two different groups of devices). And then there's the type 0B0 rear diff with the integrated dog clutch. Both are controlled by the J492 AWD control module mounted to the AWD clutch housing. There's a lot of TSBs for the quattro ultra components, but not sure what is software update vs control module swap vs AWD clutch swap vs rear diff swap. As mentioned, neither physical assembly has any scheduled service action. Any interaction with them would be a broke/repair task.

AWD clutch type 0CX (6MT) - https://www.ilcats.ru/audi/?function...30&language=en
AWD clutch type 0CJ (DCT) - https://www.ilcats.ru/audi/?function...95&language=en
type 0B0 rear diff - https://www.ilcats.ru/audi/?function...24&language=en

micabobo

From my own observations, I am leaning on the rear differential's dog clutch being shot as the vibrations are coming from the rear of the vehicle. If the AWD clutch (0CX in my case) is bad, the vibrations should be coming from the middle of the car.
Either way, I hope the dealership warranty would replace either (if not both) of the components. That way, I can make sure to be on top of the maintenance intervals for those components.

micabobo

I will keep you posted.

a2oc

2018 A5 6MT with 50k, so far so good. Did ask the dealer to change the oil on the quattro and rear diff as preventative maintenance at 40k. Audi say those oils are lifetime fluid with no service interval, so it is kinda hard even for the them to find those fluid.