KTM Duke 390 Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
65 Posts
Discussion Starter · #1 ·
Hi guys,

It's time to upgrade the brake pads on the Duke from Organic to Sintered (2017 and before) or changing to new sintered pads (2017 and newer).

I, however came into an issue during reinstalling. The brake piston are out too much to compensate for the wear of the old pads and I am now unable to install the newer pads with thicker pad material. Not enough clearance by about 1-2mm i say.

I tried to push the piston in but am unable to do so without any tools.

The solution I found is to get a c-clamp and lay the old pads across the piston and push them back in, but i've read on other forums that doing so would force old brake fluid with contaminants and water pass the seals and into the ABS unit which could cause problems down the road.

Others have suggested to loosen the bleed nipple and it would be easier to push the pistons in and clamp the brake hose to prevent fluid forcing back up the lines.

So, what's the right way?
 

·
Registered
Joined
·
700 Posts
The system is designed for brake fluid to move in and out of the calliper as the pads move in and out. As you push fluid out of the calliper the fluid in the line will flow back into the master cylinder. This will not force anything past the seals in the ABS unit. You may find it easier to loosen the top of the master cylinder.
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #3 ·
The system is designed for brake fluid to move in and out of the calliper as the pads move in and out. As you push fluid out of the calliper the fluid in the line will flow back into the master cylinder. This will not force anything past the seals in the ABS unit. You may find it easier to loosen the top of the master cylinder.
hey @Mirius

Which part are you referring to regarding the master cyclinder?
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #5 ·
Depends if you are talking front or back.
The front. Is it the part when the brake hose connects to the banjo bolt on the master cyclinder? Crack it loose abit and I'll be able to push the pistons in?


Dealers did the brake service and change of brake fluid 1000KM ago. so fluids are still new and fresh. I've deglazed the rotors already with scotchbrite pads. I just haven't been able to push the piston in😅
 

·
Registered
Joined
·
700 Posts
The front. Is it the part when the brake hose connects to the banjo bolt on the master cyclinder? Crack it loose abit and I'll be able to push the pistons in?


Dealers did the brake service and change of brake fluid 1000KM ago. so fluids are still new and fresh. I've deglazed the rotors already with scotchbrite pads. I just haven't been able to push the piston in
The master cylinder is the box attached to your front brake lever that contains the fluid. Do not crack open the banjo bolts because doing so can introduce air into the system. Removing the lid of the master cylinder reservoir will ensure that you are not fighting air pressure inside the master cylinder. It will also allow you to check that fluid doesn’t overflow as you push the pads back. This happens when an idiot tops up the master cylinder because the fluid level drops as the pads wear (it’s only necessary to top up if you have replaced the front brake master cylinder with one that has too small a reservoir). If this has happened then forcing the pads back with a c clamp could damage seals in the abs pump because you will put more pressure into the system than it was designed to handle.

It’s quite common to need to use a tool to push the pads back in. But this is also a sign you may need to overhaul the calliper and replace the seals.
 

·
Registered
Joined
·
65 Posts
Discussion Starter · #7 ·
The master cylinder is the box attached to your front brake lever that contains the fluid. Do not crack open the banjo bolts because doing so can introduce air into the system. Removing the lid of the master cylinder reservoir will ensure that you are not fighting air pressure inside the master cylinder. It will also allow you to check that fluid doesn’t overflow as you push the pads back. This happens when an idiot tops up the master cylinder because the fluid level drops as the pads wear (it’s only necessary to top up if you have replaced the front brake master cylinder with one that has too small a reservoir). If this has happened then forcing the pads back with a c clamp could damage seals in the abs pump because you will put more pressure into the system than it was designed to handle.

It’s quite common to need to use a tool to push the pads back in. But this is also a sign you may need to overhaul the calliper and replace the seals.
ahhhh, just the cap eh. All right, i'll give it a shot. thanks!
 

·
Registered
Joined
·
7 Posts
Might be a good idea to go ahead and flush the fluid and replace while you're doing pads. You can get a pack of cheap syringes on amazon to suck some fluid out of the reservoir (the part with the cap next to the lever). If fluid was added after the pads wore, you will push fluid out of the reservoir (brake fluid eats paint by the way, so make sure an wash off any spills on paint with soapy water), which is why some suggested to open the bleed nipple and push the pistons back in.

As Mirus said, you don't want to get air in the system, but at the same time brake fluid has a limited life and should be changed every couple of year (more often if you track the bike or are hard on the brakes)
 

·
Registered
Joined
·
700 Posts
Opening the bleed nipple and pushing the pads back in doesn’t serve any purpose. If the fluid needs changing then the whole system needs flushing through. If it doesn’t need changing the losing fluid out if the bleed nipple means topping up with new fluid and you don’t really have a good measure of how much to add - you’ve just created more work for no gain.
 
1 - 9 of 9 Posts
Top