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2014 brake pads: do old brake pads = poor performance.

422 Views 18 Replies 4 Participants Last post by  rich46
So I have been out on the 2014 Duke a few times. Changed all the fluids bled the brake system no air. What I am finding is I seem to have to death grip for a quick stop and the performance is still poor with crap feel. I am beginning to think the pad compound had changed and is not as efficient. Is this a thing or should I be posting in LoonyToons.
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So I have been out on the 2014 Duke a few times. Changed all the fluids bled the brake system no air. What I am finding is I seem to have to death grip for a quick stop and the performance is still poor with crap feel. I am beginning to think the pad compound had changed and is not as efficient. Is this a thing or should I be posting in LoonyToons.
Hi Zombi, You didn't give us a ton of information like how long the bike was sitting, was there crap in the fluid when you bled the system etc. If the pads look normal (not new just like old pads) then as long as they don't have brake fluid, fork oil or the like from a leaking seal I suspect that your problem is not the pads. Contaminated fluid and/or just sitting will often cause the pistons to stick in either the calipers or mastercylinder. What I would do is flush your system (both front and rear) with alcohol (not 70% or 80% but 99% alcohol not the stuff you get from the local drug store but pure ) and then bleed the system two times with brake fluid. Try that and see if you get better lever and pedal feel. If that still leaves you with trouble then you may need to rebuild the system. This is an easy task but do take the system apart before ordering your kits as you may need to replace caliper pistons (most mastercylinder kits come with a piston and seals) as most often these are steel and corrode. Also remember that if the bores are scored then you'll need to replace the calipers/master. I get my stuff from a firm called Brakecrafters as they have a good stock and fast turn around time. Also do use good brake fluid like Motul 660/660 or AP 550 not some DOT 4 from your local discount auto parts store. There's a huge difference and the cost is well worth the results.

One last thing to not forget brake fluid is hydroscopic. It absorbs water like crazy so at the very least add some plastic wrap top the container top if you have some left over. Myself when I'm done with the last brake bleed I throw away what's left. Again have fun brake systems are for the most part simple and an easy repair.

Rich
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A little more info:
Bike is just hit the 4000 mile mark. It gets used only sporadically throughout the summer months.
Bike has been on Motul 5.1 received fluid from freshly opened 5.1 bottle.
When I did the fluid I just sucked the old from the masters and than pulled clean through top to bottom.
System has shown no leaking from brake system or forks, rotors are clean and basically like new.
Masters clean no signs of leaking no crud move smoothly with no signs of resistance.
This is an ABS bike, I might try to disable the ABS unit and see if it feels better.

Fluids that came out looked nice and clean.
I had a 4 pot mono bloc brake seize up on 2 pistons on the same side and that made for very poor brakes, but it was obvious on dismantle with one pad worn and the other side far less worn. Your problem if not obvious on inspecting the pad wear sounds like an ABS issue.
On second inspection "Post ride with poor braking and feel", findings (Pad contamination) were an almost imperceivable film fluid on the caliper + back of pads. I cant tell where there is a leak but there is just the slightest wetness in the brake dust. Pistons move nicely. I will purchase some new pads and a seal kit and start over.
Is it a bad fork seal?
That was my first thought but it is brake fluid too thin for the fork fluid. Forks show no signs of leaking.

I was planning on doing the fork seals and bushings as the chrome on the WP forks shows excessive wear. Might just have to do everything at once.

I did have a weird inspection experience where a piece of paper was found in my Euro high beam button causing my headlight to not work causing it fail on the inspection.
Knowing the light has never failed previously, I inspected the shit in the parking lot and found the paper in the switch and like magic the light worked just like it always had.
Got my sticker and left. Now I am wondering if this fluid was from that visit also.

Come to think of it I had a fluid contamination issue on a Honda that same shop did a recall service on, along with some other damage I found on the bike at return to me. I got the psychically damaged parts replaced but they refused to replace the soaked pads. I did them on my own.

I am thinking I will clean everything up and pressure the system up a bunch and see if there really is a leak.
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Sand them down an reseat (y) if that doesn't work pads are trash
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Found this, sounds like this could possibly be my issue. except my pistons move.
"Duke 690 with spongy unimpressive Brembo front brake. Pads, rotors and bleeding did nothing to remedy issue. Cause was a single sticky/melted (not sure if it is chemical or thermal degradation) inner caliper piston seal (there are 8 seals, 2 per piston). The melted seal adhered to the piston creating a "spring" retracting the piston into the bore between braking events causing fluid to return to the master cylinder. The perceived sponginess was the piston moving only against the "spring" until the gap between the caliper piston and the brake pad was filled."
A little more info:
Bike is just hit the 4000 mile mark. It gets used only sporadically throughout the summer months.
Bike has been on Motul 5.1 received fluid from freshly opened 5.1 bottle.
When I did the fluid I just sucked the old from the masters and than pulled clean through top to bottom.
System has shown no leaking from brake system or forks, rotors are clean and basically like new.
Masters clean no signs of leaking no crud move smoothly with no signs of resistance.
This is an ABS bike, I might try to disable the ABS unit and see if it feels better.

Fluids that came out looked nice and clean.
Zombi, As you seem to have done your maintance almost exactly as I would have done considering the bikes age and miles. By the way congrats on doing the up-keep as it should be taken care of. There was one thing , after re-reading your post that I neglected to mention. Mite you have over-filled the reservoirs. ( an error that I have made and am familiar with ) Over-filling will give the controls a rather wooden feel and if extreme causes the brakes to not release. Just another thought before you start pulling things apart..:unsure:
Zombi, As you seem to have done your maintance almost exactly as I would have done considering the bikes age and miles. By the way congrats on doing the up-keep as it should be taken care of. There was one thing , after re-reading your post that I neglected to mention. Mite you have over-filled the reservoirs. ( an error that I have made and am familiar with ) Over-filling will give the controls a rather wooden feel and if extreme causes the brakes to not release. Just another thought before you start pulling things apart..:unsure:
LOL I know exactly what you are talking about. I had overfilled my 92 GSXR 750 brake system once. It had Brembo Iron rotors of the day. Once the system heated up the overfilling caused the brakes to slowly lock on full to the point the bike would not move. That is always a fun mistake. FYI: there was clearly fluid on the pad, hardly any but it was there.
Found this, sounds like this could possibly be my issue. except my pistons move.
"Duke 690 with spongy unimpressive Brembo front brake. Pads, rotors and bleeding did nothing to remedy issue. Cause was a single sticky/melted (not sure if it is chemical or thermal degradation) inner caliper piston seal (there are 8 seals, 2 per piston). The melted seal adhered to the piston creating a "spring" retracting the piston into the bore between braking events causing fluid to return to the master cylinder. The perceived sponginess was the piston moving only against the "spring" until the gap between the caliper piston and the brake pad was filled."
Zombie, I just read your last post. The seals would need to get pretty damn hot to melt as they are at the hot end of the caliper piston under normal operation. In saying this brake fluid is fairly caustic so I would not think that this would cause the seals to fail as they are exsposed to this all the time. Of the two seals which one was the worst ? The inner seal is the fluid seal while the outer one is what we call the dust seal. The outer one is there to keep crap out but may seal somewhat. Some calipers will not allow you to get the seals in the wrong grove but the Brembos are kind of close. Could the seals have gotten switched during assembly ? It does have me wondering what caused your troubles because if the seals did stick to the pistons then I'd think that it would not take much to destroy them as the are pulled from the groves. LOL all things considered you have done everything right so are now stuck with an overhaul. Cheers Mate
Zombie, I just read your last post. The seals would need to get pretty damn hot to melt as they are at the hot end of the caliper piston under normal operation. In saying this brake fluid is fairly caustic so I would not think that this would cause the seals to fail as they are exsposed to this all the time. Of the two seals which one was the worst ? The inner seal is the fluid seal while the outer one is what we call the dust seal. The outer one is there to keep crap out but may seal somewhat. Some calipers will not allow you to get the seals in the wrong grove but the Brembos are kind of close. Could the seals have gotten switched during assembly ? It does have me wondering what caused your troubles because if the seals did stick to the pistons then I'd think that it would not take much to destroy them as the are pulled from the groves. LOL all things considered you have done everything right so are now stuck with an overhaul. Cheers Mate
We will see when i tear into it. I have yet to find definitive seals for this caliper for this bike/year. I put a feeler out to a parts supplier and hopefully will hear back and get the caliper parts, pads, with the fork rebuild kit. Hopefully this can just be the end of it.
We will see when i tear into it. I have yet to find definitive seals for this caliper for this bike/year. I put a feeler out to a parts supplier and hopefully will hear back and get the caliper parts, pads, with the fork rebuild kit. Hopefully this can just be the end of it.
Zombie, If what you have is a four pot caliper then most likely it will be a 30/34 piston kit some times it can be a large 40 mm but most are 30.34. Just measure the Diameter of the bores and it sometimes helps to measure the distance center to center of the mounting boss. Brembo just doesn't make that many calipers for production bikes. Again try Brakcrafters. You can e-mail them with what info you have and they'll get back to you if they have questions
Zombie, If what you have is a four pot caliper then most likely it will be a 30/34 piston kit some times it can be a large 40 mm but most are 30.34. Just measure the Diameter of the bores and it sometimes helps to measure the distance center to center of the mounting boss. Brembo just doesn't make that many calipers for production bikes. Again try Brakcrafters. You can e-mail them with what info you have and they'll get back to you if they have questions
I suspect you are correct with the 30/34 kit. This would be the way as you get the pistons/seals for the same price that KTM sells the seals for. Brakecrafters has nothing but pads on their site for the bike.

I have a good bearing/hydraulics shop and just may hit them up to get the seals. They usually can pull something off the shelf.
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Cleaned everything up sanded the pads. HUGE!!! Improvement. Still not like new but no leaks so far.
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Zombi, You did the right things. Disc brakes are not as easily compromised as old fashion drum brakes. Mostly because they are designed to function out in the rain and road grime but a little TLC goes a long way.
Did you also hit the rotors with a wee rub down with emery cloth or sand paper ? Not too much, just enough to brake any glazing that might be evident. I use a small hard pad to wrap the emery cloth around so as to not put low spots or places I missed by using my fingers. I also wipe everything off with alcohol (99%) or acetone to make sure I keep any oils off the surfaces until the disc's and the pads become friends. A very light glaze :giggle:would have caused the brakes to not feel the same as they did before.
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