Cross Drilled Rotor Resurfacing For Vehicles Beyond Warranty/Program Coverage (SI B34 09 20)

Publication date: 2020-11-30
Reference number: SI B34 09 20

CROSS DRILLED ROTOR RESURFACING FOR VEHICLES BEYOND WARRANTY/PROGRAM COVERAGE

TECHNICAL SERVICE BULLETIN

Reference Number(s): SI B34 09 20, Date of Issue: November 30, 2020

BMW:	All models with standard compound, cross-drilled brake rotors

INFORMATION

Cross-drilled rotor (aka disc) resurfacing may now be performed as a customer pay option only, using the BMW approved on-car brake lathes.

Approved brake lathes:

BMW AutoComp TM Elite On-Car Brake Lathe manufactured by Hunter Engineering Company.

BMW Brake Lathe Package with 1250 Cutting Head and updated gearbox kit, SIB 34 04 20 , (or with G2X Electronics) manufactured by Pro Cut International LTD LLC.

When an axle's brake disc/rotor measured thicknesses are still above the minimum specification, the procedure of resurfacing the brake discs/rotors has been implemented as an alternative to their replacement.

If the measured brake disc/rotor thicknesses are:

Above the minimum thickness specification (stamped on the rotor, or from the ISTA "Brake Replacement" repair instruction/Technical Data) PLUS 0.5 mm;

Then the brake discs/rotors on that axle can be resurfaced using a BMW approved on-car brake lathe.

It is recommended to make one pass and remove 0.125 mm from the inner and outer friction surface (total 0.250 mm) of the brake disc/rotor.

Approximate resurfacing time is roughly 20 minutes per axle (10 minutes per rotor).

In some cases, an additional pass may be necessary to achieve an acceptable friction surface for the new brake pads.

NOTE: "Trailing marks" may be visible from the cross-drilled holes after resurfacing. They are the small dark spots adjacent to some of the existing vent hole drillings.
The trailing marks a purely visual and do not affect the braking performance

The customer should be made aware that the trailing marks will become more visible with brake applications and will eventually disappear with normal driving.

PARTS INFORMATION

Obtain and confirm the part numbers for your specific vehicle by entering the chassis number in either ETK or AIR which takes into account specific equipment and/or options.

Part Number	Description	Quantity
Refer to ETK	Front brake pads (Set)	1
Refer to ETK	Rear brake pads (Set)	1
Refer to ETK	Brake pad paste	Per axle as needed.

WARRANTY INFORMATION

This Service Information bulletin provides technical and repair-related information.

QUESTIONS REGARDING THIS BULLETIN

Technical inquiries	Submit feedback at the top of this bulletin
Warranty inquiries	Submit an IDS ticket to the Warranty Department or use the chat available in the Warranty Documentation Portal
Parts inquiries	Submit an IDS ticket to the Parts Department