Does the rear brake caliper piston go back "all the way" ?

[maz20]

I was trying to change my worn rear brake pads yesterday with the KMG Rear Brake Pads (PAD174) (

Amazon.com: KMG Brake Pad (PAD174 Non-Metallic Organic NAO (EBC FA174 Equivalent)): Automotive

WWW.AMAZON.COM

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Buy KMG Brake Pad (PAD174 Non-Metallic Organic NAO (EBC FA174 Equivalent)): Pads - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

, super cheap just $10/pair!)

 

The FZ-07 comes stock with a Nissin rear caliper, but the new pads were "too thick" to fit over my rear rotor! After opening up my rear brake line, I tried everything, from the screwdriver-between-pads technique to using a thick heavy rod to push the rear caliper piston back into the caliper--and that rear caliper piston always sticks out a little bit (couple of millimeters) from the caliper. 

 

Is that by design? Is it truly impossible to push the rear piston back far enough so it becomes truly "flush" with the outer caliper surface? (Not trying to break the rear caliper or piston!)

 

If so, what is the proper/recommended way to sand down the new pad material to fit my rotor?

[mossrider]

Just now, maz20 said:

I was trying to change my worn rear brake pads yesterday with the KMG Rear Brake Pads (PAD174) (

Amazon.com: KMG Brake Pad (PAD174 Non-Metallic Organic NAO (EBC FA174 Equivalent)): Automotive

WWW.AMAZON.COM

---

Buy KMG Brake Pad (PAD174 Non-Metallic Organic NAO (EBC FA174 Equivalent)): Pads - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

, super cheap just $10/pair!)

 

The FZ-07 comes stock with a Nissin rear caliper, but the new pads were "too thick" to fit over my rear rotor! After opening up my rear brake line, I tried everything, from the screwdriver-between-pads technique to using a thick heavy rod to push the rear caliper piston back into the caliper--and that rear caliper piston always sticks out a little bit (couple of millimeters) from the caliper. 

 

Is that by design? Is it truly impossible to push the rear piston back far enough so it becomes truly "flush" with the outer caliper surface? (Not trying to break the rear caliper or piston!)

 

If so, what is the proper/recommended way to sand down the new pad material to fit my rotor?

Either you have the wrong/defective pads or you have something wonky/incorrect with your caliper.

The pads should fit easily in place without any fiddling, sanding or monkey business. 

 

I would double check my work, the caliper and the pads. Call the manufacturer and check on the part number. There's something amiss here. This should be a 5 minute job, no sanding, grinding, filing or fitting.

[maz20]

Thank you for the prompt response!!

 

According to the manufacturer, I have right part. It fits perfectly into my shims, has the exact shape of the usual OEM brake pads, and everything seems just as it should be. It's also listed as "EBC FA174 equivalent", and those EBC FA174 pads (which I was using prior to these new KMG pads) fit without any issues at all.

 

But, it's impossible to fit them in over the brake rotor. The gap  between the pads inside the caliper is too small (by a few mm) to fit my rotor inside : (

 

And I'm starting to think this caliper piston wasn't mean to go "all the way" in (i.e., be flush with the caliper itself)--it just stops a few mm sticking out of the caliper!

[mossrider]

Just now, maz20 said:

Well, according to the manufacturer I have right part. It fits perfectly into my shims, has the exact shape of the usual OEM brake pads, and everything seems just as it should be.

 

But, it's impossible to fit them in over the brake rotor. The gap  between the pads inside the caliper is too small (by a few mm) to fit my rotor inside : (

 

And I'm starting to think this caliper piston wasn't mean to go "all the way" in--it just stops a few mm sticking out of the caliper

That piston looks fine. Your pads must be too thick, wrong pads, poor quality control, incorrect part number or whatever.

They should drop in the caliper and the caliper should plop right over the disc.

I wouldn't file or grind shet, send them back.

[maz20]

Ahh, I see--I'm guessing it's just the pads are too thick (Thickness can be a good thing, but not in case where they can't fit over the rear rotor!)

 

Not sure if necessarily poor quality control though, selling brake pads as "equivalent" (and pretty much identical) to EBC FA-174 but just only with more pad material (though, I would say they definitely did not test them on an FZ-07 rear caliper! Probably the other "174-compatible" calipers, on other bikes, happen to be just a smidge wider instead!)

[Beemer]

Did you try a large "C" clamp to squeeze it in? I've had luck in the past using them for that but in this case it looks like it might very well be a case of the wrong pads as mossrider said.

[mjh937]

Personally I would not go cheap on brake pads. I guess if the rear ones fall it is not too bad (better than the front failing anyway), but why not spend the extra $20 on quality ones.  I will never skimp on brakes or tires, they are just too important to my safety. 

[peteinpa]

I haven't done brakes on the FZ07 yet but my last 3 Hondas had Nissin brakes. The piston should go all the way in. By your pic., it's not all the way in. Try pumping the piston back out a bit then open the bleeder and squeeze it back in.

 

forgot to add...did you clean the piston before shoving it back in? Clean it with a cloth soaked with brake fluid, no brake cleaner or carb. cleaner etc.

 

Just looked at the brakes on Amazon, arent the OEM pads sintered? You never downgrade your pad material. Get sintered pads.

[maz20]

On 3/1/2019 at 6:06 AM, Beemer said:

Did you try a large "C" clamp to squeeze it in? I've had luck in the past using them for that but in this case it looks like it might very well be a case of the wrong pads as mossrider said.

I tried a couple of things, even pushing the piston in with the blunt handle of a hammer and putting some weight on it too. Don't want to break it : (( ( C-clamp sounds like overkill for this kind of simple operation)

 

On 3/1/2019 at 8:08 AM, mjh937 said:

Personally I would not go cheap on brake pads. I guess if the rear ones fall it is not too bad (better than the front failing anyway), but why not spend the extra $20 on quality ones.  I will never skimp on brakes or tires, they are just too important to my safety. 

I have KMG brake pads in the front too, and they both fit and brake perfectly without any issues, even for full-organic (well, I don't also ride that aggressively either! And, my suspension isn't even dialed in (requires a proper upgrade) for that more optimal braking either!)

 

On 3/1/2019 at 2:29 PM, peteinpa said:

I haven't done brakes on the FZ07 yet but my last 3 Hondas had Nissin brakes. The piston should go all the way in. By your pic., it's not all the way in. Try pumping the piston back out a bit then open the bleeder and squeeze it back in.

Interesting, not sure if Nissin might do something different on the motorcycle rear calipers. My other KMG brake pads fit just fine in the front : ) I opened the brake lines at the reservoir initially, and it only went back as far as my pics show. No further even after opening the bleeders too

 

On 3/1/2019 at 2:29 PM, peteinpa said:

forgot to add...did you clean the piston before shoving it back in? Clean it with a cloth soaked with brake fluid, no brake cleaner or carb. cleaner etc.

I never took any caliper apart for a brake pad swap, but will give it a try! At the very least, I'll see whatever interference there really is to the piston going all the way back, and get the internals cleaned out too^^

 

On 3/1/2019 at 2:29 PM, peteinpa said:

Just looked at the brakes on Amazon, arent the OEM pads sintered? You never downgrade your pad material. Get sintered pads.

Never knew if OEM was sintered or not, actually. A long time ago I called my dealer about that too, they didn't know either. I generally go full organic (zero sintering) because I ride mostly in often stop-and-go city traffic, and can be heavy/often on the brakes at times -- so, I figured with all that kind of riding may as well make it easier on the rotors. Didn't know about the whole "downgrading" thing, why is that?

 

 

 

 

 

[sunblock]

https://www.youtube.com/watch?v=QPd5IfdBklA

[peteinpa]

Don't take a caliper apart! just clean the piston while its extended before shoving it in.

 

most (all?) brake pads today are sintered. by going to organic you drop two steps passing semi metalic. your cutting your stopping power way down.

[Beemer]

8 hours ago, maz20 said:

I tried a couple of things, even pushing the piston in with the blunt handle of a hammer and putting some weight on it too. Don't want to break it : (( ( C-clamp sounds like overkill for this kind of simple operation)

 

I have KMG brake pads in the front too, and they both fit and brake perfectly without any issues, even for full-organic (well, I don't also ride that aggressively either! And, my suspension isn't even dialed in (requires a proper upgrade) for that more optimal braking either!)

 

Interesting, not sure if Nissin might do something different on the motorcycle rear calipers. My other KMG brake pads fit just fine in the front : ) I opened the brake lines at the reservoir initially, and it only went back as far as my pics show. No further even after opening the bleeders too

 

I never took any caliper apart for a brake pad swap, but will give it a try! At the very least, I'll see whatever interference there really is to the piston going all the way back, and get the internals cleaned out too^^

 

Never knew if OEM was sintered or not, actually. A long time ago I called my dealer about that too, they didn't know either. I generally go full organic (zero sintering) because I ride mostly in often stop-and-go city traffic, and can be heavy/often on the brakes at times -- so, I figured with all that kind of riding may as well make it easier on the rotors. Didn't know about the whole "downgrading" thing, why is that?

 

 

 

 

 

It's very similar to your hammer method, it's just pushing in on it, only it's gentler/more precise and more effective. You can slip a block of wood in between to protect it. Your call. 

[sansnombre]

I haven't replaced the pads on the FZ yet, but on many autos over the years. My exp says that the piston should be able to go all the way in, further than yours is showing. I've had this happen before and no amount of force will get it back in.

 

The way I've found that allows the piston to go all the way in, is to slightly open the bleeder valve while pushing on the piston. This allows a small amount of fluid to exit the caliper and allow the piston to be pushed in further. You MUST close the valve/nut while the brake fluid is flowing and you;re maintaining pressure on the piston, or else you can introduce air into the system. Basically, push firmly on the piston, crack open the valve, the piston will move, close the valve, release the force on the piston.

 

In theory, the fluid should be able to be pushed back through the lines into the reservoir and allow the piston to fully recede, but sometimes it doesn't work that way.

 

I've had this work many times, but never on this bike. But the signs/symptoms seem to be the same as I'm seeing in your post. Good luck.

[mossrider]

Have you checked that the reservoir is not over full since pushing back the piston? Take the cap off and check, also a good time to flush the system and replace the fluid (it's cheap) and rebleed the system.