Differential, Replace (F 23) Illustration Differential with ring gear (1)
 Remove, Disconnect Remove transmission - see operation "Transmission, Remove and Install (F 23)".
 Disassemble Disassemble transmission - see operation "Transmission, Seal Completely (F 23)". | 
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Remove, Disconnect When replacing the differential, the pressure collar adjustment and bearing pretension of the differential must be determined and adjusted if necessary. For this, the differential tapered roller bearings must be removed - see operation "Tapered Roller Bearing - Differential, Remove and Install (F 23)". The dimension of the shim (2) on the transmission casing side is determined first in the adjustment. This is used to adjust the pressure collar. Then the dimension of the shim (1) on the clutch housing side is determined. This is used to adjust the bearing pretension of the differential tapered roller bearings. For determination of the shims for the bearing pre-tension, the determination on the transmission side for adjustment of the pressure comb is always given priority. | 
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 Measure Determine dimension (I) (height clearance of ring gear to differential tapered roller bearing seat - transmission housing side) using a commercially available digital depth gauge (1) with a measuring range of at least 250 mm and graduation of 0.01 mm. Perform this measurement at three evenly-spaced measurement points on the ring gear and differential (arrows). Add the measured values and divide the sum by the number of measurements. This calculation is illustrated in the following table. | 
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Notice: The purpose of the following tables is to explain the pressure comb adjustment using an example calculation.
Measure The measurement values in the left-hand table serve as a calculation example for the evaluation of the measurement; to simplify the evaluation, you can enter your measurement results in the right-hand table (on the hard copy).
|
1st measurement |
For example |
15.02 mm |
+ |
|
1st measurement |
Your values |
mm |
+ |
|
2nd measurement |
|
15.06 mm |
|
|
2nd measurement |
|
mm |
+ |
|
3rd measurement |
|
15.05 mm |
|
|
3rd measurement |
|
mm |
= |
|
|
Total value |
45.13 mm |
:3= |
|
|
Total value |
mm |
:3= |
|
|
Mean value |
15.04 mm |
|
|
|
Mean value |
mm |
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This measurement is performed on the old differential with the old ring gear and subsequently, on the new differential. This can be performed with the new or old ring gear, depending on whether the ring gear must also be replaced. For removal and installation of differential ring gear - see operation "Ring Gear - Differential, Replace (F 23)". If, in the measurement, a value deviates from the other values of this measurement by more than 0.08 mm, the measurement must be repeated because a measurement error has occurred.
Measure Then the average for the old differential is subtracted from the average for the new differential. If the difference between the old and the new differential amounts to more than +0.02/-0.06 mm, the pressure collar must be adjusted. Table for example calculation of dimension difference:
|
Mean value |
New differential |
15.16 mm |
- |
|
Mean value |
Old differential |
15.04 mm |
= |
|
|
|
+ 0.12 mm |
± Difference |
Table for your dimension difference calculation:
|
Mean value |
New differential |
|
- |
|
Mean value |
Old differential |
|
= |
|
|
|
|
± Difference |
Measure If the difference is positive (+), then the shim (transmission casing side) (4) must be selected to be thicker by the same amount. If the difference is negative (-), then the shim (transmission casing side) (4) must be selected to be thinner by the same amount. If the shim (transmission casing side) (4) is thicker, the shim (clutch housing side) (1) must be selected to be thinner by the same amount. If the shim (transmission casing side) (4) is thinner, the shim (clutch housing side) (1) must be selected to be thicker by the same amount. In other words, the total thickness of the two shims remains the same. Corresponding shims can be obtained from the "Aftersales" division. The actual dimension for the shims (2) is determined using a micrometer (3) since the shims are not labelled. | 
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 Adjust A few examples for using the shims are listed in the table below.
|
Difference dimension |
Shim
(transmission casing side) |
Shim
(clutch housing side) |
|
- 0.25 mm |
Old |
|
0.90 mm |
New |
|
0.65 mm |
Old |
|
0.75 mm |
New |
|
1.00 mm |
|
+ 0.20 mm |
Old |
|
0.90 mm |
New |
|
1.10 mm |
Old |
|
0.75 mm |
New |
|
0.55 mm |
|
+ 0.13 mm |
Old |
|
0.90 mm |
New |
|
1.05 mm |
Old |
|
0.75 mm |
New |
|
0.60 mm |
|
+ 0.12 mm |
Old |
|
0.90 mm |
New |
|
1.00 mm |
Old |
|
0.75 mm |
New |
|
0.65 mm |
For the adjustment, the shims must be selected so that the smallest possible tolerance is achieved. Used shims can be re-used for subsequent adjustment operations, provided that they are not damaged. The shim (clutch housing side) is only altered in the subsequent adjustment of the bearing pretension for the differential regardless of the shim (transmission casing side).
Notice: The next measurement is carried out on the old and new differential (2) without differential tapered roller bearing and without ring gear. However, the dimension for the shim (transmission casing side) that has already been determined must also be taken into account; this dimension must be given highest priority for adjustment operations on the differential and must not be altered in the subsequent adjustment.
Measure Measure dimensions I, II and III using a commercially available digital depth gauge (1) with a measuring range of at least 250 mm and graduation of 0.01 mm. Dimensions II and III are subtracted from dimension I. This calculation is illustrated in the following table. This derived dimension IV corresponds to the distance between the seats of the differential tapered roller bearings. | 
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Notice: The purpose of the following tables is to explain the pressure comb adjustment using an example calculation.
Measure The measurement values in the left-hand table serve as a calculation example for the evaluation of the measurement; to simplify the evaluation, you can enter your measurement results in the right-hand table (on the hard copy).
|
Dimension I |
210.25 mm |
- |
|
Dimension I |
mm |
- |
|
Dimension II |
18.25 mm |
- |
|
Dimension II |
mm |
- |
|
Dimension III |
18.30 mm |
= |
|
Dimension III |
mm |
= |
|
Dimension IV |
173.70 mm |
|
|
Dimension IV |
mm |
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Measure This measurement is made at three measurement points distributed uniformly over the differential. The calculated values for dimension IV are added and divided by the number of measurements. This method of calculation is illustrated clearly in the table below.
|
|
For example |
|
|
|
|
Your values |
|
|
|
1st measurement |
Dimension IV |
90.02 mm |
+ |
|
1st measurement |
Dimension IV |
mm |
+ |
|
2nd measurement |
Dimension IV |
90.06 mm |
+ |
|
2nd measurement |
Dimension IV |
mm |
+ |
|
3rd measurement |
Dimension IV |
90.05 mm |
= |
|
3rd measurement |
Dimension IV |
mm |
= |
|
|
Total value |
270.13 mm |
:3= |
|
|
Total value |
mm |
:3= |
|
|
Mean value |
90.04 mm |
|
|
|
Mean value |
mm |
|
This measurement is then carried out in the same manner on the new differential. If the difference in height between the old and the new differential amounts to more than ± 0.04 mm, the differential bearing pretension must be adjusted. If the difference in height is less than ± 0.04 mm, the adjustment of the differential bearing pretension is retained. Only the dimension of the shim (clutch housing side) is adapted to the dimension of the shim (transmission casing side); this is described in the table below.
Adjust
|
Shim (transmission casing side) old |
Shim (clutch housing side) old |
|
Shim (transmission casing side) new |
Shim (clutch housing side) new |
|
0.90 mm |
1.10 mm |
|
1.00 mm |
1.00 mm |
|
1.25 mm |
0.75 mm |
|
1.10 mm |
0.90 mm |
The total thickness of the two shims remains the same as long as the height of the differential (dimension IV) does not change or the deviation remains less than ± 0.04 mm. The determination of the shims for the adjustment of the differential bearing pretension is described in the table below. Notice: The total dimension of shims + height of differential (dimension IV) = remains the same at ± 0.04 mm for new and old differential. The adjustment has been made correctly if the differential and shim assemblies have the same dimension with the new differential as with the old differential.
Adjust If dimension IV for the new differential is larger than dimension IV of the old differential, the shim (clutch housing side) is thinner by the difference of dimension IV. If the new differential is shorter than the old differential, the shim (clutch housing side) is thicker by the difference of the dimension (IV). In doing so, the previously determined dimension of the shim (transmission casing side) must not be altered. A few examples for using the shims are listed in the table below.
|
Dimension IV (old) |
Shim (clutch housing side) old |
Dimension IV (new) |
Shim (clutch housing side) new |
|
90.10 mm |
0.75 mm |
90.03 mm |
0.80 mm |
|
90.07 mm |
0.85 mm |
90.15 mm |
0.75 mm |
|
90.21 mm |
0.90 mm |
90.08 mm |
1.05 mm |
The smallest possible tolerance is desirable for the adjustment. In doing so, the shim (transmission casing side) must not be altered, since the pressure collar adjustment has already been made.
Notice: When replacing the differential and re-using the old inner races for the differential tapered roller bearing (2 and 3), these must be reinstalled - see operation "Tapered Roller Bearing - Differential, Remove and Install (F 23)". When using new inner races for the differential tapered roller bearing, the outer races for the differential tapered roller bearing (1 and 4) must also be replaced - see operation "Tapered Roller Bearing - Differential, Remove and Install (F 23)". Install differential ring gear - see operation "Ring Gear - Differential, Replace (F 23)". | 
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 Assemble Assemble transmission - see operation "Transmission, Seal Completely (F 23)".
 Install, Connect Install transmission - see operation "Transmission, Remove and Install (F 23)".
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