ZMA-R - Front Disc Brake Service - xBhp.com : The Global Indian Biking Community

Old Fox · 02-01-2010, 11:19 AM

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 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.

srini · 02-02-2010, 01:15 AM

thanks for the detailed explanation.Tried it once earlier but got a lil messy.I have one query though.After we put the tire back in it's place,wont there be any aligment issues.I've always wondered about this,even though during the event of punctures,I did the same...

soumen.sam · 02-02-2010, 05:45 PM

Nice job man… but one thing would be good i.e. Silicone grease. Normal grease won’t last in the disc braking system due to high heat. So why silicone grease should be apply in all disc brake parts. Also where rubber parts are working/moving normal grease may affect them. I dont know how clearly but in those place like floating pins etc we must use non petroleum grease.

If you take a closer look in a newly assemble disc brake you can find that the grease are pure white. And you can feel that these are not normal grease. Thanks any way.

Old Fox · 02-03-2010, 12:39 PM

@srini: Mis-alignment is not a problem if the wheel-bearings are in order and the axle not warped. Though it is important to remember that if more force is needed while assembling than used suring dis-assembly, there there is a need to re-check the procedure as something might get damaged by that excessive force.

@soumen.sam: Silicone grease would be better no doubt but sourcing it in small packaging is a problem. And it is expensive to buy in larger quantity. The 'white' grease that you see is usually EP Ball-bearing grease (EP - Extreme Pressure) which is fine enough for the purpose.

soumen.sam · 02-04-2010, 03:03 PM

Exactly, even I was looking for some high temperature grease like Silicone grease or copper grease but unable to shootout. Somehow at last I got Silicone grease but that cost too much. But without the exact things its hard to servicing the disc brake assembles. Same story for thread lock. Any way

kain · 02-06-2010, 06:55 PM

Nice and professional explaination..

Before assembling the inner pad (which is near pistons). just push the pistons slightly inwards..Finally after assembling the caliper in disc, press the brakes for approx 10 times to set the clearance and rollback correctly..

If there is any sliding problem in calipers, it will accompanied by overheating of disc due to continuous dragging of pads

02-01-2010, 11:19 AM	#1 (permalink)
Old Fox Senior Member Join Date: Oct 2007 Location: Noida Posts: 412	ZMA-R - Front Disc Brake Service 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 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. __________________ I don't let my motorcycles interfere with my motorcycling... Last edited by Old Fox; 02-03-2010 at 12:42 PM.

02-02-2010, 01:15 AM	#2 (permalink)
srini confused biker Join Date: Jul 2009 Location: b'lore Posts: 868	thanks for the detailed explanation.Tried it once earlier but got a lil messy.I have one query though.After we put the tire back in it's place,wont there be any aligment issues.I've always wondered about this,even though during the event of punctures,I did the same... __________________ *as soon as i believe Im the best,Im not the best anymore...*

02-02-2010, 05:45 PM	#3 (permalink)
soumen.sam ROADS I love you.. Join Date: Sep 2008 Location: Kolkata Posts: 85	Nice job man… but one thing would be good i.e. Silicone grease. Normal grease won’t last in the disc braking system due to high heat. So why silicone grease should be apply in all disc brake parts. Also where rubber parts are working/moving normal grease may affect them. I dont know how clearly but in those place like floating pins etc we must use non petroleum grease. If you take a closer look in a newly assemble disc brake you can find that the grease are pure white. And you can feel that these are not normal grease. Thanks any way. __________________ Roads I love you..

02-03-2010, 12:39 PM	#4 (permalink)
Old Fox Senior Member Join Date: Oct 2007 Location: Noida Posts: 412	@srini: Mis-alignment is not a problem if the wheel-bearings are in order and the axle not warped. Though it is important to remember that if more force is needed while assembling than used suring dis-assembly, there there is a need to re-check the procedure as something might get damaged by that excessive force. @soumen.sam: Silicone grease would be better no doubt but sourcing it in small packaging is a problem. And it is expensive to buy in larger quantity. The 'white' grease that you see is usually EP Ball-bearing grease (EP - Extreme Pressure) which is fine enough for the purpose. __________________ I don't let my motorcycles interfere with my motorcycling... Last edited by Old Fox; 02-03-2010 at 12:42 PM.

02-04-2010, 03:03 PM	#5 (permalink)
soumen.sam ROADS I love you.. Join Date: Sep 2008 Location: Kolkata Posts: 85	@ Old Fox Exactly, even I was looking for some high temperature grease like Silicone grease or copper grease but unable to shootout. Somehow at last I got Silicone grease but that cost too much. But without the exact things its hard to servicing the disc brake assembles. Same story for thread lock. Any way __________________ Roads I love you.. Last edited by Old Fox; 02-04-2010 at 03:16 PM. Reason: Wheel-aligment issue removed. Need to keep this post focused on the disc brake service.

02-06-2010, 06:55 PM	#6 (permalink)
kain Junior Member Join Date: Jul 2009 Location: Chennai Posts: 29	Nice and professional explaination.. Before assembling the inner pad (which is near pistons). just push the pistons slightly inwards..Finally after assembling the caliper in disc, press the brakes for approx 10 times to set the clearance and rollback correctly.. If there is any sliding problem in calipers, it will accompanied by overheating of disc due to continuous dragging of pads __________________ Kain..Dont Just Drive, Feel it.. Last edited by Old Fox; 02-07-2010 at 12:01 PM. Reason: Two adjacent posts from same user merged.

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