Breakpad wear

[DeepBlueRider]

During my latest bike checkup I've noticed strange wear pattern on my brake pads. As you can see on picture, inside brake pad is almost two times thinner than the outside. I've checked caliper on the other side and it have more even wear there.

Couple months ago I've disassembled both calipers, clean and check pistons and seals.

Is this sign of problems or just usual wear ?

Sorry for strange photo look - I was enhancing it to show wear not win world press photo

View attachment 49014

 

[trepetti]

I think that is unusual. My guess would be that the outside pistons are not getting the same fluid pressure as the inside ones. And I would think that means diminished braking force.

 

[norcalwelder]

Check the pins that the caliper floats on. If they are rusty or binding up, the caliper will not center like it should and the pads will wear unevenly. Some brake grease on the pins does wonders!

 

[yamihoe]

Check to see if the piston are sticking.... It couldn't hurt to put some fresh dot4 thru all the lines as well (bleed them)
I usually spray my calipers with brake cleaner every time I line my chain, it seems to keep them a tad bit freer.

 

[Tailgate]

Funny, because I just changed out my front disc pads because, just like with you, an inner pad was more worn than its opposing outside pad. Once I took it apart, I realized that replacing pads wasn't still really necessary but I replaced them anyway. I, too, was thinking that it was some hardware issue. (It's probably a slightly sticking piston?) but with the new pads, no worry. To do a claliper overhaul the rubber seals alone are $80.00 so, nah, I'll think about doing that another time...Brakes fine just like before. It's still curious why one side of the pads would wear much quicker. Geesh, I don't ride but a few times in the rain, bought brand new. I was even thinking about trying to file a extended warranty claim re the premature pad wear but I can jujst imagine extended warranty dept balking at that! I say, unless you want to take apart, replace caliper seals, just replace pads and ride). Well, if you decide to overhaul caliper, then, I imagine one has to wait maybe 10,000 miles before even determining that the premature wear "problem" is fixed.

 

[DeepBlueRider]

Check the pins that the caliper floats on. If they are rusty or binding up, the caliper will not center like it should and the pads will wear unevenly. Some brake grease on the pins does wonders!

2008 Caliper is single block. Caliper doesn't float on pins. There is only one pin (#22 on pic). I was thinking about lubing it with copper based brake grease but I didn't feel comfortable with lose grease being so close to brake pads.

View attachment 49019

 

[DeepBlueRider]

Check to see if the piston are sticking.... It couldn't hurt to put some fresh dot4 thru all the lines as well (bleed them)
I usually spray my calipers with brake cleaner every time I line my chain, it seems to keep them a tad bit freer.

Pistons don't seems to be sticking. I've cleaned them couple months ago during switching to SS lines so I also had to replace brake fluid

 

[DeepBlueRider]

I say, unless you want to take apart, replace caliper seals, just replace pads and ride.

I thought the same. I don't believe it happened lately - probably I just haven't noticed it earlier. Keeping that in mind - I've put over 15k miles on that calipers so probably changing pads will be good enough

BUT...

I just can't stand not knowing why it's happening

 

[TownsendsFJR1300]

As posted above, that's NOT A FLOATING caliper(its solid bolted to the fork). The pistons come out as needed and take up any space. There is NO FLOATING PIN IN the S2 bikes, (the front S1 bikes, yes, as its a two piston caliper). Besides a good cleaning, Yamaha recommends to REPLACE the BRAKE SEALS every TWO YEARS.

In real life, I've found you can usually get 4-5 years out of the seals.

Also, when pulling the lever (presurizing the system), its NOT GOING TO apply more pressure to one side than the other.

What is happening is the brake caliper seals are hardening up, sticking and NOT RELEASING the piston(s) causing the pads to stay partially applied, thus causing the un-even wear.

A good cleaning and new seals will solve your issues.

I suspect you have a fair amount of drag on the front wheel (when lifted) when on the centerstand and ft wheel lifted due to the brakes dragging. Bfore I replaced my seals, I was getting approx 3/4 a turn(free spin, by hand). With the new seals, I currently get 4-4.5 free spins with the same amount of force (as the pistons, with fresh rubber seals, NOW retract as they should). **It should be noted that I regularly use my air compressor and blow dust and debris out from the calipers/disc's every month or so, it helps keep crap from building up.

BTW, they do make high temp brake grease. Actually Yamaha provides a small pink packet of grease with the new seals.

I've re-assembled with and without grease. I personally prefer NO grease as the grease tends to attract road crap. A little, and I mean a little, on the seals when installing the pistons back in is ok, be stingy with it..

 

[DeepBlueRider]

A good cleaning and new seals will solve your issues.

I didn't realize old seals might be an issue. When I was inspecting seals they seemed fine but I will try to replace them then. I will let you guys know if that helped.

 

[TownsendsFJR1300]

I didn't realize old seals might be an issue. When I was inspecting seals they seemed fine but I will try to replace them then. I will let you guys know if that helped.

When I changed mine out, I compared the old next to the new ones. I could NOT see or feel any difference. The rubber just hardens up with time/wear and tear, doesn't flex, and causes the pistons to stick.

Once installed, the "free spin": went from approx .5 - .75 rotations to 4-4.5 full rotations

 

[DeepBlueRider]

While ordering seals I've noticed upper and lower pistons have different part number (link)

I don't recall any diffrence between upper and lower piston when I was checking it last time. Does anyone knows what is the difference and how to identify pistons (part number on piston maybe ?) ?

 

[dpaul007]

I believe the upper and lower pistons on each caliper are different diameters, hence requiring different sized rings.

 

[dxh24]

Something isn't returning to where it's supposed to. Causing uneven wear. Seals or lube probably all you nred

 

[TownsendsFJR1300]

I believe the upper and lower pistons on each caliper are different diameters, hence requiring different sized rings.

+1 on the above.

Each caliper has 4 pistons, ONE CALIPER has TWO of a larger size than the other 2. The larger pistons, are maybe 1/4" (as I recall) larger then the smaller ones.

I don't think you'd be able to re-assemble if you mixed them up. There should be a part on the inside of the pistons, but just putting a tape measure next to them, it'd be pretty obvious..

Installing the seals, as they do sit tight in the bore, takes a little fiangling.

 

[DeepBlueRider]

So I've finally got seals. One strange thing kit comes with red grease in plastic bag (like ketchup in McDonalds . Anyone if and how to use it ? I've always though brake fluid will be enough lubrication for seals.

 

[greg]

So I've finally got seals. One strange thing kit comes with red grease in plastic bag (like ketchup in McDonalds . Anyone if and how to use it ? I've always though brake fluid will be enough lubrication for seals.

apply it to the inside of the seals where it contacts the piston, and also rub some on the outside of the piston before you push it in.

the grease is vital IMO, and will help prevent dirt ingress, corrosion, and the pistons from sticking, and from the seals drying out.

it's safe to use with brake fluid and rubber, and it will not melt and contaminate the pads

 

[TownsendsFJR1300]

apply it to the inside of the seals where it contacts the piston, and also rub some on the outside of the piston before you push it in.

the grease is vital IMO, and will help prevent dirt ingress, corrosion, and the pistons from sticking, and from the seals drying out.

it's safe to use with brake fluid and rubber, and it will not melt and contaminate the pads

Use it sparingly and just enough as it will attract dirt/grime anywhere past the outside dust seals.

Years ago, I cleaned mine(didn't replace) and greased the seals (brake specific grease-Permatex). Worked better for about 9 months then the pistons started hanging up again.

Cleaned them again, installed NEW seals WITHOUT the grease, just brake fluid for the lubricant installing the pistons. So far its been about 2 years and I'm still getting about 4 "free spins" by hand on the front wheel.

IMHO, installing the seals dry may allow the seals to grab the pistons (better than with grease) and flex, letting the pistons retract and come out (the seals actually pulling the pistons back in once hydralic pressure is released).

I do, with the air compressor, maybe once a month, give a quick shot of air inbetween the calipers and rotors and blow out all the excess dust. You'd be surprised the small cloud of dust that comes out. Just a little less crap to gum up later..

Unfortunatly Yamaha doesn't note where to put the grease.

 

[DeepBlueRider]

Thanks for clarification guys. I will go without grease then as so far I was always using only brakefluid and it worked fine.

I think retracting pistons might be caliper related. When I was rebuilding my wife's ER6N I've soaked seals and pistons in brake fluid. After assembly it was pulling but pistons like champ ! On FZ6 I don't see that dramatic effect.

Let me rephrase my thanks again. I greatly appreciate all the help I'm getting from forum members. It's one of the best forums I'm lurking around. Posts are helpful and insightful. I would like to contribute more but I realize my knowledge about motorcycles is limited and I don't want to confuse other members especially when there is a lot people here with much more experience.

I'm talking too much - Anyway I just wanted to say thank you to all of you.

 

[DeepBlueRider]

So I've did rebuild yesterday. Long story short Scott - You should stop giving people advice to rebuild their calipers My bike stopped slowing down when off-throttle after rebuild First turn was kind of scary as I've approached it normally but bike just flew over it I was not able to get 4 after rebuild but I came to something like 2.5 - 3 (from 0.75-1). So there is huge improvement. Why it's not full 4 revs ? I don't know. Maybe my brakepads are different (causing little more drag than others) or maybe rotor is little wrapped (riding longer time with dragging pads could cause it, although I don't feel pumping on lever when braking).

Back to work - It was kind of pain in ass. When it comes to working on bike I'm very careful and pedantic so I might overdid in some places. Also fact 08 FZ6 have monoblock calipers makes it tight to work on as you can't separate them any way.

While getting first piston is easy then removing second is harder as you have to block passage somehow. If you do it with your hand you can hurt yourself. I couldn't find any better way so instead pushing out with compressed air I've used high pressure bicycle pump.

I had problem with removing old seals without destroying them. I've tried tooth pick, kind of plastic rod. Nothing worked. I had to grab my wood carving chisel set, punch into rubber and pry it out (making sure chisel won't touch anything else as it have all sides sharp like razor.

I've lubed seals and pistons with brake fluid and put it on.

It wasn't hard, but tedious and making sure everything works as it should and there was no mistakes took time.

Now I have to only re-bleed brakes as brake lever is much softer than it was before but it might be also related to pistons moving back to caliper body requiring more lever travel to put pads in touch with rotor. Braking power is very good just travel and feedback feels different.

Again Thank you everybody for guiding me through this adventure