Drivetrain - Grinding or Wheel Bearing Noise When Accelerating
34, 37 Grinding or wheel bearing type noises from front when accelerating or at constant speed
34 13 13
2028650/2
January 15, 2013.
Supersedes Technical DIAGNOSIS AND REPAIR Group 34 number 12-08 dated February 21, 2012 for reasons listed below.
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Affected Vehicles
Condition
Customer states constant howling, droning, or scraping noises heard from the front of the vehicle when accelerating lightly.
Technical Background
The ball bearing for the left flange shaft spins in the gearbox housing because of a gap between the outer bearing ring and the support bracket. This
can result in grinding marks and swarf (Figure 1, Figure 2).
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Tip: The affected ball bearings are only fitted on the left side; therefore, the complaints do not occur on the right side.
Note:
After a removal of the bolts to check for this condition, the bolts must always be replaced by new parts (new part number: N 91208801).
Production Solution
Not applicable.
Service
Try to reproduce the customer complaint so that it can be clearly assigned to this TSB by removing the support bracket and checking for wear marks.
If wear marks are present as shown in Figure 1 or Figure 2 above, follow checks and repair instructions below:
On V6 and V8 engines:
1. Remove the gearbox according to the repair manual.
2. Loosen the support bracket of the left final drive (if necessary) and pull the left flange shaft out of the gearbox according to the repair manual,
taking care not to damage the shaft seal.
3. Proceed to Checks Section below.
On all models with 4 cylinder engines:
1. Remove the left drive shaft according to the repair manual.
2. Remove the brake caliper and hang caliper off to the side without stressing the brake hose.
3. Detach the suspension strut from the lower control arm, and the suspension strut from the sway arm link. (Loosen upper bolts for the strut if
needed to allow for more clearance).
4. If necessary for bearing housing clearance, remove the upper control arm bolt and allow bearing housing to swing out of the way.
5. Remove any shielding from the axle opening.
6. Pull the left flange shaft out of the gearbox (according to the repair manual) (Figure 3). Support the flange shaft through the lower opening on
the gearbox (service flap) to avoid damaging the oil seal between differential and gearbox housing (Figure 4).
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Note:
After a removal, the bolts must always be replaced by new parts (new part number: N 91208801).
7. After removing the flange shaft visually check the oil seal between differential and gearbox housing with a lamp through the lower gearbox
opening (service flap) for damage.
Note:
Remove bearing and bearing bracket from axle and discard. Use new bearing for measurements.
8. Proceed to Checks Section below.
Checks Section:
The following steps assist in determining how many shims must be fitted between bearing and gearbox housing to make the bearing extend out
from the case a minimum of 0.5mm to 0.8 mm (Figure 5).
Tip: Bearing in Figure 5 is only for demonstration purposes. Always measure using a new bearing.
Determine the number of shims to be fitted:
1. Use size 600 grit sandpaper to remove any corrosion or dirt on the gearbox flange surface.
Do not clean the bearing carrier.
2. Measure whether the gap between bearing and gearbox housing is flush or extended from case.
3. Use a straightedge on two different positions on the bearing and on the gearbox housing (this leads to four measuring positions) (Figure 6).
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4. Determine the value with a feeler gauge on four different points (Figure 7).
Tip: Bearing in Figure 7 is only for demonstration purposes. Always measure using new bearing.
5. After the measuring, calculate how many shims must be fitted between bearing housing and bearing. Each shim is 0.30 mm. Examples shown
above.
Note:
Although the bearing may extend from the case as shown, the distance may not be enough to hold the bearing tight. Measure as follows to
determine and correct.
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Reassembly:
1. Install new support bracket and bearing onto the shaft per repair manual, being sure the part number of the support bracket is pointing
outward.
Tip: When fitting the support bracket the part number must point to the outside.
2. Clean the flange shaft with a fluff-free cloth and slightly lube the shaft at the seal contact area using G 052128A1.
3. Install the shims and feed the shaft back through the opening of the lower gearbox side with appropriate support, taking care not to damage the
seal (Figure 10).
4. Be sure to replace the support bracket bolts.
Note:
Because the bearing turns, it may have taken material off of the bearing carrier in axial and radial directions. The resulting free play can be
ignored, as a turning of the outer bearing ring is prevented by the axial clamping force of the support bracket.
WARNING
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Warranty
Required Parts and Tools
Additional Information
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service
manuals for the latest information.
