The Bucking Audi - Transmission Digest

The Bucking Audi

The continuously variable transmission (CVT) used in Audi’s A4 and A6 vehicles, called the 01J or Multitronic, could show up in your shop with a bucking complaint. This style of CVT (see Figure 1) does not use a fluid coupling as a pass-through device for engine torque input. This means that when the vehicle is engaged or comes to a stop in gear, the forward or reverse clutch must slip. When the brake is released and the throttle is depressed, the clutch applies and the drive and driven pulleys begin to move in relation to each other to provide gear ratios.

The Bucking Audi 

Shift Pointers

Subject: Bucking complaint
Unit: Audi 01J (Multitronic) CVT
Essential Reading: Rebuilder, Diagnostician
Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor

Shift Pointers

  • Subject: Bucking complaint
  • Unit: Audi 01J (Multitronic) CVT
  • Essential Reading: Rebuilder, Diagnostician
  • Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor

The continuously variable transmission (CVT) used in Audi’s A4 and A6 vehicles, called the 01J or Multitronic, could show up in your shop with a bucking complaint. This style of CVT (see Figure 1) does not use a fluid coupling as a pass-through device for engine torque input. This means that when the vehicle is engaged or comes to a stop in gear, the forward or reverse clutch must slip. When the brake is released and the throttle is depressed, the clutch applies and the drive and driven pulleys begin to move in relation to each other to provide gear ratios.

A restricted cooling system can cause a bucking complaint during the application of the clutch and dissipate when it fully applies. In some instances, the driver might feel this shudder every few seconds at a steady cruise under 2,000 rpm in Tiptronic 4th gear but not at the same cruising speed in Tiptronic 3rd gear. Flushing the cooling system and replacing the transmission fluid and the external filter may eliminate the problem. The question you have to ask yourself is why the cooler and filter got restricted in the first place. It could be signs of a failing forward clutch (see Figure 2). Originally, there was an update that changed the forward-clutch stack-up from six friction plates to seven trapezoid-design friction plates. The part number for this repair kit was ZAW 398 001, installation of which was to be accompanied by a TCM re-flash using CD-ROM part number 8E0 906 961J. Now, you need a VIN and you receive the entire forward-clutch drum and planetary assembly as a set.

If a decision is made to flush the cooler and replace the fluid and external filter, you must perform the following procedures before and after the work.

  1. Inspect the transmission-fluid level though the check pipe at the bottom of the transmission. It has a 10mm allen-head plug (see Figure 3). If the transmission is full, some fluid should spill out. Fill with CVT fluid VAS 5162 as needed.
  2. Have all four wheels off the ground (a minimum of 8 inches) and check to see that each wheel rotates freely by hand.
  3. Observe the Tiptronic indicator and shift from 1st to top gear, accelerating moderately after each shift but never exceeding 35 mph.
  4. Shift the transmission back down to first gear.
  5. Carefully apply the brake until the wheels come to a stop.
  6. With the brake applied, place the transmission into reverse.
  7. Release the brake and moderately depress the accelerator to a reverse-gear speed of 12 mph.
  8. Carefully apply the brake until the wheels come to a stop.
  9. Return the selector lever to Drive and repeat steps 2 through 8 five more times.
  10. When finished, place the selector lever into park and turn off the vehicle.
  11. Change the transmission fluid. The drain plug is alongside the check plug and can be removed with Audi key number 3357. Fill the transmission through the check plug using a suitable fill device with CVT fluid VAS 5162 (4.5 to 5 liters).
  12. Repeat steps 2 through 9. Once you have finished, place the vehicle on the ground and road-test it.

There is also a transmission re-adapt procedure that you may need to perform. This should always be done anytime transmission work is performed or if the battery has been disconnected for any great length of time. This procedure follows:

  1. The transmission fluid must be at 145°F (65°C) or warmer before the procedure can be performed properly.
  2. Find a suitable road clear of traffic where you can drive the vehicle and stop several times.
  3. Place the selector lever into drive and drive forward at part load about 70 feet (20 meters), and then apply the brake and come to a complete stop. Continue to depress the brake pedal for about 10 more seconds with the selector lever still in Drive.
  4. Shift the selector lever into reverse with the brake pedal depressed.
  5. Release the brake and drive backward at part load about 70 feet (20 meters), then apply the brake and come to a complete stop. Continue to depress the brake pedal for about 10 more seconds with the selector lever still in Reverse.
  6. Repeat this procedure (alternating between drive and reverse) five times.

When fluid-change and adapt procedures are completed, the vehicle should engage the forward and reverse clutches without any shudder or bucking feeling. But if the bucking should continue or return soon after, chances are the clutches will need replacement.

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