Measuring backlash
WARNING: This page is about a different car, the 2008 Audi A4, 2007 Audi A4, 2006 Audi A4, and 2005 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.
- Install pinion shaft with shims "S3 " and "S4 ".
- Install differential with ring gear: S1 is installed on cover side, S2 in transmission housing.
- Install cover for final drive and tighten bolts to 20 Nm.
- Insert ring gear adjusting tool VW521/4 and VW521/12.
- Turn differential 5 turns in both directions so that the taper roller bearings seat properly.
- Secure universal dial gauge bracket VW 387 to housing.
- Install dial gauge with dial gauge extension VW382/10 (6mm flat).
- Adjust measuring lever VW388 to distance "a" = 73mm (for 182 mm dia. ring gear).
- Measure play between teeth faces (backlash) as follows:
- Turn ring gear until it makes contact with the face of one tooth (end of backlash travel).
- Preload dial gauge to 2 mm and set to "0".
- Turn back ring gear until it makes contact with opposite tooth face (backlash).
- Take backlash reading and write down measured value.
- Turn ring gear through 90° and repeat measurements another 3 times.
NOTE:
- If the pinion shaft rotates during the measurements, counter-hold pinion shaft to make sure that the measured value of the backlash is correct.
Determining average backlash
- Add the four measured values together and divide by four.
| Example: | ||
| 1st measured value | 0.28 mm | |
| + | 2nd measured value | 0.30 mm |
| + | 3rd measured value | 0.30 mm |
| + | 4th measured value | 0.28 mm |
| = | Sum of measured values | 1.16 mm |
- Result: the average backlash is 1.16 mm : 4 = 0.29 mm
NOTE:
- If the individual measurements differ from each other by more than 0.06 mm, the installation of the ring gear or the final drive gear set itself is not correct. Check installation; replace final drive gear set if necessary.