Shimano_XTR_M975_usermanual_bleedprocedure Shimano XTR M975 Usermanual Bleedprocedure

User Manual: Shimano_XTR_M975_usermanual_bleedprocedure

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Technical Service Instructions

SI-0037A-001

8. If the brake lever is then operated, air bubbles in the system will rise up

through the port into the reservoir tank. Once the bubbles stop appearing,
depress the brake lever as far as it will go.
The normal condition is for the lever to be stiff at this point.

Adding mineral oil and bleeding air
Lever operation

■ Adding oil and bleeding air at the reservoir tank
1. With the spacer for bleeding (yellow) still attached to the calipers, place the bicycle into a bicycle
stand or similar as shown in the illustration.

Loose

< BL-M975/M775 > Set so that the brake lever is

parallel to the ground, and then
remove the reservoir tank cover.

Diaphragm

Slightly stiff

Stiff

9. Fill the reservoir tank with oil and then replace the reservoir tank cover. Fill the reservoir tank to

overflowing with oil while replacing the cover to ensure that no air bubbles remain inside the
reservoir tank. In addition, be careful not to get any oil on parts such as the rotor and brake pads.

Brake lever
should be parallel
to ground

Tightening torque:
0.3 - 0.5 N·m {2.7 - 4.4 in. lbs.}
Hose
Calipers

Reservoir tank

< ST-M975/M775 >

Turn the lever unit so that the top of the reservoir tank is parallel to the
ground, and then remove the reservoir tank cover.

10. Return the brake lever to its original position.
Note:

Reservoir tank
Diaphragm

Reservoir tank

Note : When reassembling, set the
diaphragm so that it is aligned at the
same angle as the base of the
reservoir tank.

2. Set a 7mm socket wrench in place, attach a bag to the tube,

Diaphragm

Do not use brake fluid fillers, as they can cause small bubbles of air to form, and such bubbles
can cause severe drops in braking performance.

Base of reservoir tank

■ Adding oil and bleeding air at the caliper using a syringe
(including Shimano bleeding kit)
Socket wrench
(7mm)

Bleed nipple

1. Place the reservoir tank so that it is parallel to the ground,
and then remove the reservoir tank cover.
(Refer to step 1 in "Adding oil and bleeding air at the
reservoir tank")

and then place the tube onto the bleed nipple as shown in
the illustration.

2. Attach a 7 mm socket wrench, and fill the syringe with oil
3. Loosen the bleed nipple by 1/8th of a turn to open it, and

Tube

then pour oil into the reservoir tank. Gently operate the
brake lever while doing this to help prime the system with
the oil.

Bag

and connect a hose to the bleed nipple. Then loosen the
bleed nipple by 1/8 of a turn to open it. Push the plunger of
the syringe to add oil. The oil will start coming out from the
reservoir tank. Continue adding oil until there is no more air
mixed in with the oil that is coming out. (If using the Shimano bleeding tool, be sure to read the
service instructions for the Shimano bleeding tool.)

3. Once air stops coming out, temporarily close the bleed nipple. (If the Shimano bleeding tool has
been installed to the brake lever at this time, remove the Shimano bleeding tool.)

4. Oil will come out periodically from the bleed nipple about every 5 minutes.
5. After a little while, the oil and air will flow naturally from the bleed nipple into the tube. In this way it

will be possible to easily extract the greater part of the air remaining inside the brake system.
It may help to shake the hose gently or to tap the reservoir tank or caliper gently with a screwdriver
or move the position of the caliper at this time.

Do not continually squeeze and release the lever at this point.
If this is not observed, air bubbles may remain mixed in with the oil inside
the caliper, and it will take longer to bleed the air. (If the lever is
continually squeezed and released, drain out all of the oil and then add oil
again.)

4. Connect the oil bottle to the bleed nipple, and then loosen the bleed nipple. After a little while, the

Bleed nipple

oil and air will flow naturally from the bleed nipple into the tube of the oil bottle. In this way it will be
possible to easily extract the greater part of the air remaining inside the brake system.
It may help to shake the hose gently or to tap the reservoir tank or caliper gently with a screwdriver
or move the position of the caliper at this time.
Bleed nipple

Tube

Bag

The oil level in the reservoir
tank will drop at this time, so
be sure to keep adding oil to
maintain the oil level so that
air is not drawn in through
the port (so that air does not
enter through the port).

Oil bottle

6. Once air stops coming out from the bleed nipple, temporarily tighten the bleed nipple.
7. With the brake lever depressed, open and close the bleed nipple in rapid succession (for
approximately 0.5 seconds each time) to release any air bubbles
which may be in the calipers. Repeat this procedure about 2 to 3
times.
Then tighten the bleed nipple again.

The oil level in the reservoir
tank will drop at this time, so
be sure to keep adding oil to
maintain the oil level so that
air is not drawn in through
the port (so that air does not
enter through the port).

5. Carry out steps 6 to 10 in "Adding oil and bleeding air at the reservoir tank".

One Holland, Irvine, California 92618, U.S.A. Phone: +1-949-951-5003

Tightening torque:
4 - 6 N·m {35 - 53 in. lbs.}

Industrieweg 24, 8071 CT Nunspeet, The Netherlands Phone: +31-341-272222

3-77 Oimatsu-cho, Sakai-ku, Sakai-shi, Osaka 590-8577, Japan

Please note: specifications are subject to change for improvement without notice. (English) © Mar. 2007 by Shimano Inc. XBC IZM Printed in Japan.

XTR Brake Lever

BL-M975

For Disc Brake

For Right Hand

2

4

1

5
3

For Left Hand
7

8
6

4
5

2

9

1

3

7

8

SHIMANO
CODE NO.
Y-8U0 98010
Y-8U0 98080
Y-8U0 24000
Y-8SZ 07000
Y-8U0 98020
Y-8U0 98030
Y-8U0 98040
Y-8U0 98050
Y-6AU 98090

DESCRIPTION
Lid Unit
Lid
Diaphragm
Lever Axle Fixing Bolt
Lever Axle
Lever Unit
Lever Member
Adjust Boss & Boss Spacer
Clamp Bolt (M8 x 16) & Washer

A : Same parts.
B : Parts are usable, but differ in materirals, appearance, finish, size, etc.
Absence of mark indicates non-interchangeability.

-M
9
ST

-M
9
ST

ITEM
NO.
1
* 2
3
4
5
6
7
8
9

66

9

75

6

INTERCHANGEABILITY

A

A

A
0808-2612A

SI-8E50C-004-00

General Safety Information

< BL-M975 >

WARNING
• The 203 mm and 180 mm rotors provide a higher braking force than the 160 mm rotors. Make
sure that you have a complete feel for the braking characteristics before using the brakes.
• Please use extra caution to keep your fingers away from the rotating disc
brake rotor during installing or servicing the wheel. The rotor is sharp enough
to inflict severe injury to your fingers if caught within the openings of moving
rotor.
• The calipers and rotor will become hot when the brakes are operated, so do not touch them
while riding or immediately after dismounting from the bicycle, otherwise you may get burned.
Check that the brake components have cooled down sufficiently before attempting to adjust the
brakes.
• The required braking distance will be longer during wet weather.
Reduce your speed and apply the brakes early and gently.
• If the road surface is wet, the tires will skid more easily. If the tires skid, you may fall off the
bicycle. To avoid this, reduce your speed and apply the brakes early and gently.
• Always make sure that the front and rear brakes are working correctly before you ride the
bicycle.
• Be careful not to allow any oil or grease to get onto the rotor and brake pads, otherwise the
brakes may not work correctly.
• If any oil or grease do get on the pads, you should replace the pads. If any
oil or grease gets on the rotor, you should clean the rotor. If this is not done,
the brakes may not work correctly.
• Before riding the bicycle, check that the pad thicknesses are 0.5 mm or
more.
• Vapor lock may occur if the brakes are applied continuously. To relieve this
condition, momentarily release the lever.
Vapor lock is a phenomenon in which the oil inside the brake system becomes heated,
which causes any water or air bubbles inside the brake system to expand. This can then
result in a sudden increase in the brake lever stroke.
• Use only genuine Shimano mineral oil. If other types of oil are used, it may cause problems
with brake operation, and cause the system to be unuseable.
• Be sure to use only oil from a freshly-opened container, and do not re-use oil which has been
drained from the bleed nipple. Old oil or already-used oil may contain water which could cause
vapor lock in the brake system.
• Be careful not to let water or air bubbles to get into the brake system, otherwise vapor lock may
occur. Be particularly careful when removing the cover of the reservoir tank.
• If cutting the brake hose in order to adjust the length of the hose, or when changing over the
brake hose from left to right or vice versa, be sure to bleed the air from the hose by carrying
out steps (5), (8) to (10) given in “Adding mineral oil and bleeding air” in the Service
Instructions.
• When turning the bicycle upside down or on its side the brake system may have some air
bubbles inside the reservoir tank which are still there when the reservoir tank cover is replaced,
or which accumulate in various parts of the brake system when it is used for long periods. The
M975 disc brake system is not designed to be turned upside down. If the bicycle is turned
upside down or on its side, the air bubbles inside the reservoir tank may move in the direction
of the calipers. If the bicycle is ridden in this condition, there is the danger that the brakes may
not operate and a serious accident could occur.
If the bicycle has been turned upside down or on its side, be sure to operate the brake lever a
few times to check that the brakes operate normally before riding the bicycle. If the brakes do
not operate normally, adjust them by the following procedure.

■ Burn-in period
• Disc brakes have a burn-in period, and the braking force will gradually increase
as the burn-in period progresses. Make sure that you are aware of any such
increases in braking force when using the brakes during the burn-in period. The
same thing will happen when the brake pads or rotor are replaced.

When installing the components to carbon frame/handle bar surfaces, verify with the
manufacturer of the carbon frame/parts for their recommendation on tightening torque in order to
prevent over tightening that can cause damage to the carbon material and/or under tightening
that can cause lack of fixing strength for the components.

■ Installation of the hose
< For left lever >
BL-M975

Refer to the Service Instructions for the SM-BH59 brake hose (SI8H20) for details on installing the hose.
Do not let the hose become twisted when installing. Make sure that
the calipers and levers are in the positions shown in the
illustrations.

The following tools are needed to assemble this product.
Usage location

Tool
TL-LR15
Allen key 4 mm

Gently depress the brake lever several times and wait for the bubbles to return to the
reservoir tank. It is recommended that you then remove the reservoir tank cover and fill the
reservoir tank with mineral oil until no bubbles remain.
If the brakes still operate sluggishly, bleed the air from the brake system.
(Refer to "Adding the mineral oil and bleeding air".)

Caliper fixing bolt

Allen key 5 mm

Adapter (post type) fixing bolt

Allen key 5 mm

Brake pad fixing shaft

Flat-tipped screwdriver

Reservoir tank cover

Phillips screwdriver #1

Cable supporter

Phillips screwdriver #2

Brake hose fixing bolt

8 mm wrench

Bleed nipple

Socket wrench 7 mm

Start with two 0.5 mm thick shims, and use the
0.2 mm shims for fine tuning. tighten the calipers,
and check that the calipers and the rotor do not
interfere with each other. Next, the caliper fixing
bolts do not contact the rotor.

5. Install the new brake pads, and then

install the pad spacers (red). Make
sure that you do not forget to install the
snap rings at this time also.

Spacer for bleeding

Tightening torque:
0.2 - 0.4 N·m {1.8 - 3.5 in. lbs.}

Brake pads

Snap ring
Shim
0.2 mm

0.5 mm

Pad spacer (red)

6. Depress the brake lever several times to check that the operation becomes stiff.
7. Check that the rotor and the brake pads do not touch each other, and then check the oil

Snap ring

■ Adjustment when the pistons are not operating correctly

Lace the spokes as shown in Figure 1 below for the left side of the front wheel
(the side where the rotor is installed), and the left and right sides of the rear
wheel, and as shown in Figure 2 below for the right side of the front wheel.
Rotating
direction of
wheel

Front left

Rear left Rear right

level (adding more oil if required). After doing this, replace the reservoir tank cover.

Tightening torque:
0.2 - 0.4 N·m {1.8 - 3.5 in. lbs.}

Check that the spokes have been laced as shown in the illustration.
A radial assembly cannot be used.

Shim
(0.5mm, 0.2mm)

Front right

Calipers

While wearing protective gloves, apply
a force to the calipers to turn it in a
counterclockwise direction. While
doing this, tighten the fixing bolts.

ST-M975 / BL-M975

Rotor

SM-RT97

Hose

SM-BH59

1. Remove the wheel and the brake pads.
Clean the pistons and surrounding area, and remove the reservoir tank cover.
from the reservoir tank at this time.

3. Install the brake pads and the pad spacers (red).
4. Depress the brake lever as far as it will go, and then operate it several more times so

Frame
mounting boss

that the two pistons all move to their initial positions.

Rotor

5. Remove the pad spacers, install the wheel, and then check that there is no interference
between rotor and the calipers. If they are touching, adjust using shims.

Fig. 2

6. After checking the oil level, replace the reservoir tank cover.
Tightening torque:
6 - 8 N·m {53 - 69 in. lbs.}

■ Installation of the rotor
(SM-RT97)
SM-RT97L (203mm)
SM-RT97M (180mm)
SM-RT97 (160mm)
SM-RT97SS (140mm)

Secure the two bolts with a length of wire as shown
in the illustration in order to prevent the bolts from
coming loose.

■ Mineral oil replacement
It is recommended that you replace the oil inside the reservoir tank if it becomes severely
discolored.

For post type (BR-M975P)

Attach a tube with a bag to the bleed nipple, and then open the bleed nipple and drain out
the oil. You can operate the brake lever at this time to help the oil to drain out. After
draining the fluid, pour in fresh brake fluid while referring to "Adding the mineral oil and
bleeding air". Use only genuine Shimano mineral oil.
Dispose of the waste oil according to proper country and/or state disposal regulations.

Rotor fixing
lock ring
Wire

* The RT97SS (140 mm) rotor is
for rear use only.

TL-LR15

Bolt

Tightening torque:
40 - 50 N·m {350 - 435 in. lbs.}
Wire

Be sure to read the service instructions for the “Adding mineral oil and
bleeding air” in conjunction with these service instructions.

Secure the brake lever as shown in the
illustration.
Bolt 1

Brake lever Tightening torque:
6 - 8 N·m {53 - 69 in. lbs.}

Bolt 2

If bolt 1 tries to loosen (turn in the counterclockwise direction), force is applied
via the wire to turn bolt 2 in the tightening direction (clockwise). However, bolt
2 cannot turn any further in the tightening direction.
Accordingly, this prevents bolt 1 from turning in the loosening direction
because it is also connected via the wire.
If either one of the bolts tries to loosen, this causes a force to be applied to the
other bolt to turn it in the tightening direction. In other words, this system
prevents the bolts from loosening.

This service instruction explains how to use and maintain the Shimano bicycle parts which
have been used on your new bicycle.
For any questions regarding your bicycle or other matters which are not related to
Shimano parts, please contact the place of purchase or the bicycle manufacturer.

One Holland, Irvine, California 92618, U.S.A. Phone: +1-949-951-5003

Cable Supporter

SM-HANG

Mineral Oil

SM-DB-OIL

Brake pad unit

The caliper mechanism includes two pistons. If these pistons do not operate properly or if
they protrude unevenly, or if the brake pads remain in contact with the rotor, adjust the
pistons by the following procedure.

2. Push the piston back in straight, without bending it. Note that some oil may overflow

(For Cross-Country)

Brake Lever

Piston

go, while being careful not to twist it.
(Note that some oil may overflow from
the reservoir tank at this time.)

Disc Brake System

BR-M975

1. Remove the wheel from the frame, and remove the

4. Push the piston back in as far as it will

■ Installation of the brake lever
< ST-M975 >

Caliper

Brake pads

step (1) in "Adding mineral oil".

• M07Ti brake pads are designed to reduce the amount of noise which is
generated between the pads and the rotor when the brakes are operated. A
longer running-in period is required for this type of pad compared to M06Ti pads.

In order to realize the best performance, we recommend that the following
combination be used.

If oil adheres to the brake pads after oil is added, or if
the brake pads are worn down to a thickness of 0.5 mm,
or if the brake pad presser springs are interfering with
the rotor, replace the brake pads.

3. Remove the reservoir tank cover while referring to the
< For right lever >

■ Wheel spoke lacing

Fig. 1

SI-8E50C-004

the pistons gradually move outward to automatically adjust the clearance between
the rotor and the brake pads. Therefore, you need to push the pistons back to
their original positions when replacing the brake pads.

2. Clean the pistons and surrounding area.

ST-M975

* For the HB-M975, the
right side of the front
wheel can be a radial
spoke type.

Technical Service Instructions

Note: The M975 brake system is designed so that as the brake pads become worn,

brake pads as shown in the illustration.

• Remove the spacer for bleeding (yellow), and then set the
wheel which has the rotor onto the frame.
• Install the brake pads.

Installation

Brake lever fixing bolt

■ Handling the mineral oil
• Use safety glasses when handling, and avoid contact with eyes. Contact with eyes may result in
irritation.
In the event of eye contact, flush with fresh water and seek medical assistance immediately.
• Use gloves when handling. Contact with skin may cause a rash and discomfort.
In the event of skin contact, wash well with soap and water.
• Inhalation of oil mist or vapors may cause nausea. Cover nose and mouth with a respirator type
mask and use in a well ventilated area.
If mist or vapor is inhaled, go immediately to an area with fresh air. Cover up with a blanket.
Stay warm and stable and seek professional medical advice.
• Do not drink. May cause vomiting or diarrhea.
• Keep out of reach of children.
• Do not cut, heat, weld or pressurize the oil container, as this may cause explosion or fire.
• Disposal of Used Oil : Follow local county and/or state codes for disposal. Use care when
preparing oil for disposal.
• Directions : Keep the container sealed to prevent foreign objects and moisture from getting
inside, and store it in a cool, dark area away from direct sunlight or heat.

Maintenance
■ Brake pad replacement

■ Installation of the calipers (BR-M975)
and securing the hose.

Rotor fixing lock ring

CAUTION

Operate the brake lever several times and check whether the brakes operate normally or
not. Also check that there are no oil leaks visible.

Brake lever Tightening torque:
6 - 8 N·m {53 - 69 in. lbs.}

Note

• The 203 mm and 180 mm rotors have a larger diameter than the 160 mm and
140 mm rotors for cross-country bicycles, and so the flexing of these rotors is
greater. As a result, they will interfere with the brake pads.
• If the brake caliper mounting boss and the dropout are not parallel, the rotor and
caliper may touch.
• When the bicycle wheel has been removed, it is recommended that pad spacers
should be installed. The pad spacers will prevent the piston from coming out if
the brake lever is depressed while the wheel is removed.
• If the brake lever is depressed without the pad spacers installed, the pistons will
protrude further than is normal. Use a flat-tipped screwdriver or similar tool to
push back the brake pads, while being careful not to damage the surfaces of the
brake pads. (If the brake pads are not installed, push the pistons straight back
in, while being careful not to damage them.)
If it is difficult to push the brake pads or pistons back, remove the reservoir tank
cover and then try again. (Note that some oil may overflow from the reservoir
tank at this time.)
• Use isopropyl alcohol, soapy water or a dry cloth when carrying out cleaning
and maintenance of the brake system. Do not use commercially-available brake
cleansers or silencing agents, as they can cause damage to parts such as
seals.
• Do not remove the pistons when disassembling the calipers.
• If the rotor is worn, cracked or warped, it should be replaced.
• Parts are not guaranteed against natural wear or deterioration resulting from
normal use.
• For maximum performance we highly recommend Shimano lubricants and
maintenance products.

< C-shaped guide > < Usual type of cable stopper >

Tightening torque:
0.3 - 0.5 N·m {2.7 - 4.4 in. lbs.}

■ When cleaning with a compressor
• If disassembling the caliper body to clean the internal parts using a compressor,
note that moisture from the compressed air may remain on the caliper
components. Let the caliper components dry sufficiently before reassembling the
calipers.

< If brake operation is sluggish when the lever is depressed >

• If fluid leaks occur, immediately stop using the brakes and carry out the appropriate repairs. If
you continue riding the bicycle while fluid is leaking, there is the danger that the brakes may
suddenly stop working.
• If the quick release lever is on the same side as the rotor, there is the danger that it may
interfere with the rotor, so check that it does not interfere.
• It is important to completely understand the operation of your bicycle's brake system. Improper
use of your bicycle's brake system may result in a loss of control or an accident, which could
lead to severe injury. Because each bicycle may handle differently, be sure to learn the proper
braking technique (including brake lever pressure and bicycle control characteristics) and
operation of your bicycle. This can be done by consulting your professional bicycle dealer and
the bicycle's owners manual, and by practicing your riding and braking technique.
• Shimano disc brake systems are not compatible with tandem bicycles. Because tandem
bicycles have a high overall weight, the load on the brake system increases during brake
operation. If hydraulic disc brakes are used with tandem bicycles, the oil temperature will
become too high and vapor locks or ruptures in the brake hoses may occur, and this will cause
the brakes to fail.
• Obtain and read the service instructions carefully prior to installing the parts. Loose, worn
or damaged parts may cause the bicycle to fall over and serious injury may occur as a result.
We strongly recommend only using genuine Shimano replacement parts.
• Read these Technical Service Instructions carefully, and keep them in a safe place for later
reference.

For C-shaped guides and the usual
type of cable stoppers, use the
special Shimano cable supporter
(sold separately) to secure as
shown in the illustration.

Secure the brake lever as shown in the illustration. (Check that the
brake lever does not interfere with the shifting lever during
operation. Refer to the Service Instructions for the shifting lever also.
Some types might require the shifting lever to be installed first, due
to the position of the shifting lever fixing bolts.)

Industrieweg 24, 8071 CT Nunspeet, The Netherlands Phone: +31-341-272222

3-77 Oimatsu-cho, Sakai-ku, Sakai-shi, Osaka 590-8577, Japan

Resin Pads

M07Ti

* Service Instructions in further languages are available at :
http://techdocs.shimano.com

Metal Pads

M06Ti

Please note: specifications are subject to change for improvement without notice. (English)
© Nov. 2009 by Shimano Inc. XBC IZM Printed in Japan.



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