LI42 10-P-064899

Juddering/shuddering at the front axle brakes
Topic number
LI42.10-P-064899
Version
7
Function group
42.10 Service brake
Date
08-16-2017
Validity
All vehicles of model series 222/217 without AMG
Reason for change
Remedy updated
Reason for block
Complaint:
Juddering/shuddering of the brakes at the front axle brake can be felt when braking normally.
Validity for cold juddering:
Cold juddering occurs when braking normally at any speed and is identifiable as pulsation of the brake pedal.
As opposed to cold juddering, thermal juddering only occurs when braking sharply at high speeds.
This document is not valid for juddering related to heat.
Cause:
Grinding of a thickness error into the brake disk.
Possible causes:
- Different torque due to improper tightening of the wheel threaded connection
- Wheel contact surface damaged or soiled
- Imbalance at the wheel
- Wheel suspension or steering parts damaged
Remedy:
Always check the components of the wheel assembly:
1. Check operational condition of disk brake and brakepads (see attachment AP42.10-P-4256EW), particularly sliding
elements.
2. Check the wheel for imbalance (including vertical runout if possible) and, if necessary, rebalance.
3. Ensure operational condition of wheel suspension and steering parts.
4. Check wheel hub contact surface for damage and cleanliness.
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5. If none of the components mentioned above are visibly or measurably damaged, then carry out the following repairs:
5.1 Replace brake disks with appropriate A-object number and Index 39.
Note:
- Please observe "Note on processing, transporting and storing compound brake disk" (AH42.10- P-9406-12LF, see
attachment)!
- Note that brake disks with Index 39 are extensively validated and filtered out in production.
They are subject to carefully selected quality criteria and only an extremely limited amount are available.
Therefore, please remember that the brake disk with Index 39 may only be used in the described problem instance
and not for any repairs of worn parts.
5.2 Replace brakepads.
6. Install wheels as follows:
Note:
- An impact wrench must NOT be used for assembly!
6.1 Clean, check and protect the wheel threaded connection components from corrosion before assembly (see attachment AR40.10-P-1100-02A).
6.2 Mount wheel bolts crosswise by hand with max. 20 Nm (see picture in attachment "Wheel threaded connection
tightening sequence").
6.3 First tighten wheel bolts crosswise with a torque wrench up to max. 70 Nm (see picture in attachment "Wheel
threaded connection tightening sequence").
6.4 Lower vehicle until the tires are prevented from spinning.
6.5 Tighten wheel bolts crosswise with a torque wrench to the prescribed vehicle-specific tightening torque (see picture in attachment "Wheel threaded connection tightening sequence").
6.6 Lower vehicle completely.
6.7 Retorque wheel bolts with vehicle-specific prescribed tightening torque.
Attachments
File
Description
Anzugreihenfolge Radverschraubung.jpg
Wheel bolts are to be tightened in the 1-2-3-4-5 sequence
shown in the picture
Symptoms
Chassis/suspension / Brake system / Service brake / Function / Vibrates/shudders
Parts
Attachments
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File
Description
AH42.10-P-9406-12LF.pdf
Notes on handling, transport and storage of composite
brake disks.
AR40.10-P-1100-02A.pdf
Clean/check/corrosion protect wheel bolting components.
AP42.10-P-4256EW.pdf
Assess condition of brake disks.
Operation numbers/damage codes
Op. no.
Operation text
Time
Damage
code
40-1590
REMOVE/INSTALL WHEELS (2)
42101 H4
42-2706
REMOVE/INSTALL BRAKE PADS OF
FRONT AXLE, REPLACE IF NECESSARY (WHEELS REMOVED)
42101 H4
42-2731
REMOVE/INSTALL BRAKE DISKS OF
FRONT AXLE, REPLACE IF NECESSARY (BRAKE PADS REMOVED)
42101 H4
Note
Attachments
Anzugreihenfolge Radverschraubung.jpg:
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