Repairing Rear Wheel Bearing Housing Thread

Information 

All tasks required during thread repairs must be done manually.

Use cutting oil for thread repairs.

• Do not use a power drill.
• Do not use an impact bolter.
• Do not use tools to secure the drilling template. Tighten fastening screw by hand.

Overview of tools: > VAS 6627A - Brake Calliper Repair Set 

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Overview of tools: Time-Sert basic set

Overview of tools: > VAS 6627/8 - Thread Repair Kit, M12 x 1.5 

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Overview of tools: Time-Sert additional set

Information 

The wheel bearing housing can remain installed during thread repairs.

• The numbers shown in the illustration have the same end numbers as in the tool sets. 
• For clarity, some of the repair steps are shown on the removed wheel bearing housing. 

1. > VAS 6627A/10 - Drilling template  must be fitted on the intact thread using a fastening screw -2-  . You will be working on the other side with the defective thread.

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   Fitting drilling template

2. Drill out the defective thread.
   1. 2.1 Drill out installation sequence for the thread.

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      Tools for drilling out thread

      1	Drill bit, > VAS 6627/8 - Thread Repair Kit, M12 x 1.5
      4	Guide sleeve, M12, internal diameter: 12.25 mm; > VAS 6627A - Brake Calliper Repair Set
      6	Threading die holder, > VAS 6627A - Brake Calliper Repair Set

   2. 2.2 Fit guide sleeve into > VAS 6627A/10 - Drilling template  . Drill out the thread as far as the stop using the threading die holder and drill bit.
   3. 2.3 > VAS 6627A/10 - Drilling template  must now be removed. Carefully blow the chips out of the bore hole. Wear protective goggles.
3. Countersink the bore hole.
   1. 3.1 Using the seat miller, countersink the bore until it is sufficiently deep to allow the stop of the seat miller to sit on the wheel bearing housing (as far as the stop). -2- 

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      Countersinking bore hole

   2. 3.2 Bore hole countersunk. -A- 

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      Bore hole countersunk

   3. 3.3 Check the countersink depth of the bore hole

      Fit the M12 threaded bush into the bore hole against the screw-in direction. -5- 

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      Checking countersink depth

   4. 3.4 The collar of the M12 threaded bush must be sitting in the recess up to the first thread. -5- 

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   Checking countersink depth as far as the first thread

4. > VAS 6627A/10 - Drilling template  must be fitted using a fastening screw -2-  .

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   Fitting drilling template

5. Cut thread.
   1. 5.1 Cut installation sequence for the thread.

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      Tools for thread

      1	> VAS 6627A/10 - Drilling template
      3	Tap, > VAS 6627/8 - Thread Repair Kit, M12 x 1.5
      5	Guide sleeve, M12, internal diameter: 10 mm; > VAS 6627A - Brake Calliper Repair Set
      6	Threading die holder, > VAS 6627A - Brake Calliper Repair Set

   2. 5.2 Oil the tap. -3- 

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      Oiling the tap

   3. 5.3 Insert the tap into the drilling template. The guide sleeve is projecting slightly out of the drilling template. But it has made contact. The guide sleeve will drop during the cutting process using the threading die holder.

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      Inserting the tap

      1	> VAS 6627A/10 - Drilling template
      3	Tap, > VAS 6627/8 - Thread Repair Kit, M12 x 1.5
      5	Guide sleeve, M12, internal diameter: 10 mm; > VAS 6627A - Brake Calliper Repair Set

   4. 5.4 Carefully cut the thread as far as the end of the bore hole (as far as the stop) using the tap.

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   Cutting the tap as far as the stop (1)

   1	> VAS 6627A/10 - Drilling template
   5	Guide sleeve, M12, internal diameter: 10 mm; > VAS 6627A - Brake Calliper Repair Set
   6	Threading die holder, > VAS 6627A - Brake Calliper Repair Set

6. Re-mill the bore hole.

   Information 

   Mill in/countersink the bore hole.

   • The collar of the threaded bush must be at least 0.2 mm below the contact surface of the wheel bearing housing in the bore hole. 
   • The collar of the threaded bush must not be projecting out. 
   1. 6.1 Using the seat miller, countersink the bore again until it is sufficiently deep to allow the stop of the seat miller to sit on the wheel bearing housing (as far as the stop). -2- 

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      Countersinking bore hole again

   2. 6.2 Carefully cut the thread again as far as the end of the bore hole (as far as the stop) using the tap. This removes the remaining milling burrs. The tap must screw out without catching!
   3. 6.3 Check again to make sure that the collar of the threaded bush has disappeared in the recess. If it has not disappeared, repeat the milling process! -5- 

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   Checking countersink depth as far as the first thread

7. Clean the thread (using brake cleaner for example).
8. Insert the M12 threaded bush.
   1. 8.1 Screw in the M12 threaded bush as far as possible by hand.
   2. 8.2 Only oil the screw-in tool! Screw in the screw-in tool as far as possible by hand. Continue screwing until the threaded bush is sitting slightly deeper in the bore hole on the wheel bearing housing.

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      Screwing in threaded bush

   3. 8.3 Then, screw the threaded bush in further using the threading die holder and the screw-in tool. -4- 

      Information 

      Mill in/countersink the bore hole.

      • The collar of the threaded bush must be at least 0.2 mm below the contact surface of the wheel bearing housing in the bore hole. 
      • The collar of the threaded bush must not be projecting out. 
   4. 8.4 Once the M12 threaded bush is screwed in so that it is sitting slightly deeper in the bore hole on the wheel bearing housing, you will feel the increased resistance. Continue screwing carefully until there is less resistance again.
   5. 8.5 The screw-in tool must screw out without catching. -4- 
9. Check that the M12 threaded bush is seated correctly.
   WARNING: Threaded bush sticking out of wheel bearing housing. 

   • Brake calliper can become loose. 

     → The contact surface of the brake calliper must be flush with the contact surface of the wheel bearing housing.

     → The brake calliper must not be supported on the threaded bush.

     → There must be NO gap between the brake calliper and wheel bearing housing.

   1. 9.1 The M12 threaded bush -5-  is inserted at the correct position if the collar of the M12 threaded bush is below the contact surface of the brake calliper -A-  ! The M12 threaded bush must not be projecting out.

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      Threaded bush fitted at the correct position, at least 0.2 mm deeper in the bore hole

   2. 9.2 The M12 threaded bush is at the correct position if it is sitting slightly deeper in the bore hole. -arrows- 
10. Clean the thread with brake cleaner after you have completed the repair work. The thread must be free of grease and chips.