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The problem
The brake lever felt hard, lever travel felt sort of rough which made brake feather and trail braking rather devoid of proper feedback. The brakes squeaked even when the wheel was turned by hand.
The diagnosis
The ZMA has floating callipers and the calliper pins need cleaning and greasing at times, especially during the monsoon. Due to accumulated dust, moisture contamination and possibly traces of rust, the calliper does not float freely on the pins. This affects both brake application and brake release.
Precautions
#The disc pads will need to be pried apart a little to allow the disc to get between them when you mount the wheel. Push through the axle (Do not hammer it in if it sticks. There must be some mis-alignment between the various holes for it to get stuck. If it came out easily, it should go in easily too)
#Wash the bike, at least the area you will be working on, to avoid getting unnecessarily dirty/oily hands into places that get damaged by the dirt/oil. (I did not do it but you can be wiser than that
)
## MAKE SURE NO ONE PRESSES THE FRONT BRAKE LEVER WHEN YOU HAVE REMOVED THE FRONT WHEEL. THE PISTONS GET PUSHED THROUGH WHEN THERE IS NO RESISTANCE TO THEIR MOVEMENT AND GETTING THEM BACK IN ENTAILS A LOT OF UNNECESSARY WORK.
# When using the emery paper on the pads, do not rub the emery on the pads. Instead, place the emery on a flat surface and gently slide the pads face down on it. The point is to rub off the top glazing without taking out any miles out of their use.
Tools needed
see pic below
Procedure
Step 1
Remove the Axle nut with a 19mm spanner, using the 14mm spanner to hold the head end of the axle to prevent it from rotating.
Step 2
Pull out the axle while supporting the wheel
Step 3
Roll the wheel out, sliding the bottom end side-ways a bit to clear the fender. Make sure you don't touch the disc surface with your fingers. Skin oil or other greasiness could affect braking later.
Step 4
Below is a detail-labeled picture of the disc brake.
Step 5
Unscrew the disc pad pin caps using the flat head screwdriver. Use a driver with a blade that is large enough to fit well into the slot and allows you to apply proper force without slipping and damaging the slot.
Step 6
Beneath the caps, the allen heads of the pad retaining pins become visible
Step 7
Use the 4mm Allen Key to unscrew the retaining pins
Step 8
And pull the pins out
Step 9
The disc pads now hang loose. And you can clearly see the wear-limit grooves. These pads on my bike have another 5000 odd kms left in them considering my riding habits
Step 10
Remove the pads, clean their sides and back with the wire brush and rub the face with emery paper
Step 11
Now you can clearly see the calliper pistons and the pad springs. DO NOT clean any of the parts around the pistons with petrol or kerosene or diesel or any other solvent. You will end up damaging the seals within. A mild soap solution and a soft tooth brush will do the job well enough
Step 12
Grab hold of the calliper body and pull it outwards. (The direction is indicated by the red arrow in the pic below). Small rubber boots similar to their larger cousins on front fork tubes, cover the floating pins. Just pulling firmly and smoothly will allow a clean dis-engage of their sealing lip and the calliper body will slide off as shown
Wipe the pins with a clean cloth, apply new grease (preferably EP - Extreme Pressure type) and reassemble the unit going backwards over the procedure of dis-assembling it.
Step 13
Put in the disc pads starting with the inner one and pushing the retaining pins partially through it
The brake lever felt hard, lever travel felt sort of rough which made brake feather and trail braking rather devoid of proper feedback. The brakes squeaked even when the wheel was turned by hand.
The diagnosis
The ZMA has floating callipers and the calliper pins need cleaning and greasing at times, especially during the monsoon. Due to accumulated dust, moisture contamination and possibly traces of rust, the calliper does not float freely on the pins. This affects both brake application and brake release.
Precautions
#The disc pads will need to be pried apart a little to allow the disc to get between them when you mount the wheel. Push through the axle (Do not hammer it in if it sticks. There must be some mis-alignment between the various holes for it to get stuck. If it came out easily, it should go in easily too)
#Wash the bike, at least the area you will be working on, to avoid getting unnecessarily dirty/oily hands into places that get damaged by the dirt/oil. (I did not do it but you can be wiser than that
)## MAKE SURE NO ONE PRESSES THE FRONT BRAKE LEVER WHEN YOU HAVE REMOVED THE FRONT WHEEL. THE PISTONS GET PUSHED THROUGH WHEN THERE IS NO RESISTANCE TO THEIR MOVEMENT AND GETTING THEM BACK IN ENTAILS A LOT OF UNNECESSARY WORK.
# When using the emery paper on the pads, do not rub the emery on the pads. Instead, place the emery on a flat surface and gently slide the pads face down on it. The point is to rub off the top glazing without taking out any miles out of their use.
Tools needed
see pic below
Procedure
Step 1
Remove the Axle nut with a 19mm spanner, using the 14mm spanner to hold the head end of the axle to prevent it from rotating.
Step 2
Pull out the axle while supporting the wheel
Step 3
Roll the wheel out, sliding the bottom end side-ways a bit to clear the fender. Make sure you don't touch the disc surface with your fingers. Skin oil or other greasiness could affect braking later.
Step 4
Below is a detail-labeled picture of the disc brake.
Step 5
Unscrew the disc pad pin caps using the flat head screwdriver. Use a driver with a blade that is large enough to fit well into the slot and allows you to apply proper force without slipping and damaging the slot.
Step 6
Beneath the caps, the allen heads of the pad retaining pins become visible
Step 7
Use the 4mm Allen Key to unscrew the retaining pins
Step 8
And pull the pins out
Step 9
The disc pads now hang loose. And you can clearly see the wear-limit grooves. These pads on my bike have another 5000 odd kms left in them considering my riding habits
Step 10
Remove the pads, clean their sides and back with the wire brush and rub the face with emery paper
Step 11
Now you can clearly see the calliper pistons and the pad springs. DO NOT clean any of the parts around the pistons with petrol or kerosene or diesel or any other solvent. You will end up damaging the seals within. A mild soap solution and a soft tooth brush will do the job well enough
Step 12
Grab hold of the calliper body and pull it outwards. (The direction is indicated by the red arrow in the pic below). Small rubber boots similar to their larger cousins on front fork tubes, cover the floating pins. Just pulling firmly and smoothly will allow a clean dis-engage of their sealing lip and the calliper body will slide off as shown
Wipe the pins with a clean cloth, apply new grease (preferably EP - Extreme Pressure type) and reassemble the unit going backwards over the procedure of dis-assembling it.
Step 13
Put in the disc pads starting with the inner one and pushing the retaining pins partially through it
The outer pad has a locating slot on top that engages with a protruding pin on the calliper body. Screw in the retaining pins with the allen key making sure you tighten them properly and screw in the pin caps.
With the disc pads in place, re-mount the wheel, reversing the dis-assembly procedure for it. Once the wheel is in place and the axle nuts tightened, turn the wheel and squeeze the brake lever a few times and feel it going hard from near the beginning of its travel. With the brake released, the pads might make a slight 'hissing' sound as they barely graze the disc while the wheel turns. This is normal and expected of bikes with some appreciable mileage on them specially as the calliper piston seals go a trifle limp with usage and are unable to withdraw the pistons all the way back on release of the lever. Nothing critical about this.
Footnote: It is good to do this service once in some 2-3 months depending on your usage. Rains, off-roading and beach-riding will make the brakes demand such service more frequently.
With the disc pads in place, re-mount the wheel, reversing the dis-assembly procedure for it. Once the wheel is in place and the axle nuts tightened, turn the wheel and squeeze the brake lever a few times and feel it going hard from near the beginning of its travel. With the brake released, the pads might make a slight 'hissing' sound as they barely graze the disc while the wheel turns. This is normal and expected of bikes with some appreciable mileage on them specially as the calliper piston seals go a trifle limp with usage and are unable to withdraw the pistons all the way back on release of the lever. Nothing critical about this.
Footnote: It is good to do this service once in some 2-3 months depending on your usage. Rains, off-roading and beach-riding will make the brakes demand such service more frequently.
. I hope my experience can add some value to this thread.
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