DB8 / DB6 / DB4 Disc Brakes Digital Service Manual

SRAM Service

General Safety

Safety First!

We care about YOU. Please, always wear your safety glasses and protective gloves when servicing SRAM products. Protect yourself! Wear your safety gear!

Safety Precautions and Warnings

Safety Instructions

Always wear safety glasses and nitrile gloves when working with brake fluid.

Place an oil pan on the floor underneath the area where you will be working on the brake.

Use only SRAM Hydraulic Brake grease.

If the brake system has been contaminated with DOT fluid, the entire brake system including the lever and the caliper must be replaced. DOT brake fluid contamination will cause degradation of the seals used in the mineral oil system and the brakes will be unsafe to continue to use.

Used mineral brake oil must be recycled or disposed of in accordance to local, state, and federal regulations. Never pour used brake oil or fluid down a sewage or drainage system or into the ground or body of water.

Warning

CRASH HAZARD

Do not use DOT 4 or DOT 5.1 brake fluids. Use only Maxima Mineral brake oil with SRAM Mineral oil hydraulic brakes. Do not use any other oil or fluid; it will damage the system and make the brakes unsafe to use, which could lead to serious injury and/or death.

Do not allow any brake fluid to come in contact with the brake pads. If this occurs, the pads are contaminated and must be replaced.

Warning

Servicing your brakes removes all of the brake fluid from the system. You must bleed the brakes after you service the brake caliper and/or lever.

For brake bleed and brake hose shortening instructions, visit sram.com/service.

We recommend that you have your SRAM Brake components serviced by a qualified bicycle mechanic. Servicing SRAM components requires knowledge of bicycle mechanics as well as the special tools and lubricants/fluids used for service. SRAM brake systems need to be serviced periodically to optimize braking function. If brake fluid is leaking from any area of the brake there may be damage or wear and tear to the internal moving parts. If the system has been contaminated with the wrong fluid there may be damage to all rubber and plastic internal parts. If your brake was damaged in a crash there may be damage to the lever blade, pushrod, and housing assemblies. Inspect and replace these parts to restore proper brake function.

Visit sram.com/service for the latest SRAM Spare Parts catalog and technical information. For order information, please contact your local SRAM distributor or dealer.

Information contained in this publication is subject to change at any time without prior notice. Your product's appearance may differ from the pictures contained in this publication.

Part Preparation and Service Procedures

The following procedures should be performed throughout service, unless otherwise specified.

Clean the part with isopropyl alcohol and a clean, lint-free shop towel. Clean the sealing surface on the part and inspect it for scratches.

Replace the o-ring or seal with a new one from the service kit. Use your fingers, a cable tie or a pick to pierce and remove the old seal or o-ring.

Apply SRAM Hydraulic Brake grease or Maxima Mineral Brake oil to the new seal or o-ring when instructed.

Notice

Do not scratch any sealing surfaces when servicing the product. Scratches can cause leaks. Consult the spare parts catalog to replace the damaged part.

Tighten the part with a torque wrench to the torque value listed in the red bar. When using a crowfoot socket and torque wrench, install the crowfoot socket at 90 degrees to the torque wrench.

Model Code Identification

Product model code and specification details can be identified with the serial number on the product. Model codes can be used to identify the product type, series name, model name, and product version associated with the production model year. Product details can be used to identify spare parts, service kit, and lubricant compatibility.

Model Code example: DB - DB - 6 - A1

DB = Product Type - Disc Brake

DB = Platform/Series - DB

6 = Model - 6

A1 = Version - (A - first generation, 1 - first iteration)

To identify the model code, locate the serial number on the product and enter it into the Search by Model Name or Serial Number field at www.sram.com/service.

Warranty and Trademark

Consult sram.com/service whenever a separate manual is referenced in this document.

Read the full warranty policy for your components at sram.com/en/service/warranty.

For information about trademarks used in this manual, visit sram.com/website-terms-of-use.

Service Parts, Tools, and Supplies

Highly specialized tools and supplies are required for the replacement and maintenance of your SRAM components. We recommend that you have a qualified SRAM dealer work on your SRAM components.

Spare Parts

Consult the SRAM Spare Parts Catalog for Spare Part Kits.

Safety and Protection Supplies

Safety Glasses

Nitrile Gloves

Apron

Shop Towels

Oil Pan

Lubricants and Fluids

Maxima Mineral Brake Oil

Hydraulic Brake Grease

Threadlock

Medium-compound strength threadlocker

Isopropyl Alcohol

Bicycle Tools

Brake Hose Cutter

Bleed Block

Pad Spacer

Mineral Oil Syringes

Bicycle Repair Stand

Common Tools

Plastic Mallet

Digital Calipers

Socket Wrench

Torque Wrench

Open End Wrench

8 mm

Crowfoot

8 mm

Sockets

9 mm

Hex Wrenches

2.5, 4, 5 mm

Hex Bit Socket

2.5 mm

TORX Wrenches

T8, T10, T25

TORX Bit Sockets

T10, T25

Needle Nose Pliers

Plier with Soft Jaws

Pick (non-metallic)

Internal Retaining Ring Pliers

Exploded View - Caliper

DB8/DB6/DB4

1. Pad Retention Bolt	8. Brake Pad (2)	15. Pad Spacer
2. Caliper Body Bolt (2)	9. Pad H-Spring	16. Bleed Block (X-Large)
3. Outboard Caliper Body	10. Caliper Body Seal (2)	17. Hose
4. Caliper Piston 16 mm (2)	11. Inboard Caliper Body	18. Compression Nut
5. Caliper Piston 15 mm (2)	12. E-Clip	19. Hose Barb
6. Piston Seal 16 mm (2)	13. Bleed Port Plug	20. Compression Fitting
7. Piston Seal 15 mm (2)	14. O-ring

Caliper Service - DB8/DB6/DB4

Warning

CRASH HAZARD

If the brake system has been contaminated with DOT fluid, the entire brake system including the lever and the caliper must be replaced. DOT brake fluid contamination will cause degradation of the seals used in the mineral oil system and the brakes will be unsafe to continue to use.

Notice

Caliper service is only required if the pistons are damaged.

If the calipers are operating normally, they do not require disassembly and service. Clean the calipers and install the brake pads.

Notice

The brake caliper must be serviced before the brake lever. The lever must be connected to the caliper and the brakes must still have fluid in them in order to advance the pistons and service the caliper. Once the lever has been disconnected and the fluid is drained it is not possible to advance the pistons.

Brake Pad Removal

1

Clamp the bicycle into a bicycle work stand and remove the wheel.

2

Remove the caliper bolts and lever clamp bolt.

3

Remove the E-clip from the pad retention bolt.

4

Remove the pad retention bolt from the caliper.

5

Remove the brake pads and pad H-spring from the caliper.

Notice

If the brake pad thickness is less than 3 mm then replace the pads.

Piston Removal

Notice

The brake caliper must be serviced before the brake lever. The lever must be connected to the caliper and the brakes must still have fluid in them in order to advance the pistons and service the caliper. Once the lever has been disconnected and the fluid is drained it is not possible to advance the pistons.

1

Install the pad retention bolt.

Insert the pad spacer so that it snaps into place.

2

Squeeze the brake lever to advance the pistons until they contact the pad spacer. Make sure the pistons are advancing evenly. You may need to use a tire lever to hold back any pistons that advance more than other pistons; this will allow the other pistons to advance.

3

Remove the compression nut and hose.

Remove the pad spacer.

4

Loosen the two caliper body bolts. Remove the caliper body bolts and set aside.

5

Separate the caliper body halves.

Use your fingers or pliers with soft jaws to remove the pistons from each caliper body half.

6

Use a cable tie or plastic pick to remove the piston seals from the four piston bores.

Warning

CRASH HAZARD

Use a cable tie or plastic pick. Do not scratch the seal gland. Scratches could cause fluid to leak when the brake is applied, which will contaminate the brake pads. Oil on brake pads could lead to a brake failure which may result in serious injury or death.

7

Remove the caliper body seals.

Clean the caliper body halves and piston bores.

8

Remove the bleed screw from the caliper.

Piston Installation

1

Apply a small amount of SRAM Hydraulic Brake grease to the o-ring. Install a new o-ring on the bleed screw.

Install the bleed screw into the caliper.

2

Apply Maxima Mineral Brake Oil to the new caliper seals and install the new caliper seals into each caliper piston bore according to their diameter.

Notice

Do not apply grease to the caliper piston seals. Grease on the seals will reduce the clearance between the pads and rotors when the brake is released resulting in low pad rollback.

3

Inspect the caliper pistons for damage and replace the pistons if damaged.

Apply a small amount of Maxima Mineral Brake oil to the circumference of each piston.

Install the pistons into each half of the caliper body according to their diameter.

Notice

Use only Maxima Mineral Brake oil. Do not apply grease to the caliper piston seals or pistons. Grease on the seals or piston will reduce the clearance between the pads and rotors when the brake is released resulting in low pad rollback.

4

Spray isopropyl alcohol on the caliper halves and both of your gloves, and clean them with a shop towel.

5

Apply a small amount of SRAM Hydraulic Brake grease to the new caliper body seals and install them onto the outboard caliper half.

6

Align the caliper body halves and thread each body bolt into the caliper.

Warning

New body bolts come with Loctite Blue 242 applied. If you re-use the body bolts, then you must apply new Loctite Blue 242 or equivalent to the bottom 5 mm of the body bolt threads. Failure to apply Loctite or equivalent could result in the bolts coming loose and cause a crash.

7

Tighten the caliper body bolts to the specified torque.

8

Insert the bleed block into the caliper.

Install the pad retention bolt.

Warning

You must bleed your brakes before reinstalling the brake pads.

Hose Installation

Warning

All SRAM brakes that use a compression fitting and hose barb must use a new SJ (Stealth-a-majig) hose barb and a new, red SJ compression fitting upon reassembly.

The factory may have installed a non-red SJ compression fitting, which functioned properly prior to disconnection. Upon reconnection, you must install a new SJ hose barb and a new, red SJ compression fitting.

Brake hoses assembled with non-Stealth-a-majig hose barbs and compression fittings will not function.

1

Cut the hose at the caliper end to remove the used barb and compression fitting.

2

Apply SRAM Hydraulic Brake grease to the hose barb threads.

Thread the hose barb into the hose until it is flush with the end of the hose.

Notice

Do not overtighten the hose barb. Overtightening may cause damage to the hose liner.

3

Thread the compression fitting over the hose barb, counter-clockwise, until it is flush or slightly lower than the hose barb.

The compression fitting is reverse threaded.

Apply SRAM Hydraulic Brake grease to the outside of the compression fitting and the threads of the compression nut.

4

Install the compression fitting and hose into the caliper.

Tighten the compression nut.

5

Spray isopropyl alcohol on the caliper and clean it with a shop towel.

Warning

Servicing your brakes removes all of the brake fluid from the system. You must bleed the brakes after you service the brake caliper and/or lever.

For brake bleed and brake hose shortening instructions, visit sram.com/service.

Exploded View - Lever

DB8

1. Reservoir Bolts	8. Hose Barb	15a. Piston Assembly - Standard
2. Reservoir Cap	9. Compression Fitting	15b. Piston Assembly - Stealth-a-majig
3. Bladder	10. Bleed Port Screw (2)	16. Washer
4. Lever Body	11. Bleed Port Screw O-Ring (2)	17. Snap Ring
5. Hose	12. Lever Pivot Pin	18. Pivot Clip
6. Hose Boot	13. Lever Pivot Bushings (2)	19. Lever Bias Spring
7. Compression Nut	14. Lever Pivot Hole	20. Lever Assembly

Lever Service - DB8

Hose Removal

1

Pull the hose boot off the compression nut and slide it down the hose.

2

Remove the hose compression nut.

Pull the brake hose and compression fitting from the brake lever body.

3

Pour the brake fluid into an oil pan.

Squeeze the lever blade to pump out the excess brake fluid from inside the lever body.

Lever Blade Removal

1

Place the lever pivot on top of a 9 mm socket. Gently tap a 4 mm hex wrench with a plastic mallet to remove the lever pivot pin from the lever body.

Set the pivot pin aside.

2

Remove the lever blade assembly from the lever body.

The lever assembly will separate into three pieces when removed from the lever body: lever bias spring, pivot clip, and blade assembly.

3

Remove the pivot bushings.

Reservoir Cap and Bladder Removal

1

Remove the reservoir cap bolts.

Remove the reservoir cap and bladder.

2

Pour any remaining brake oil into an oil pan.

Spray isopropyl alcohol on the lever and reservoir and clean them with a shop towel.

3

Separate the bladder from the reservoir cap. Spray isopropyl alcohol on the bladder and the reservoir cap and clean them with a shop towel.

Notice

All components must be completely dry before reinstalling them. Moisture residue from cleaning the bladder can leak out of the bladder as it dries, which can be misinterpreted as a system leak.

4

Remove the bleed screw from each side of the lever body.