[Defect] 790 R (2019) Front Brake Failure

Discussion in 'Parallel World (790/890)' started by OhDuh, Feb 3, 2020.

  1. OhDuh

    OhDuh Adventurer

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    Hi guys,

    just wanted to inform you about an issue we had in another forum and which occured again now.

    So over the month esspecially with 2k km twisties in like 10 days I had a moving brake point. But not the usual heating related thing.
    So in one moment I had a lot of freeplay, next curve it was very little almost braking by itself and then just before a hairpin the break point was so much in that it barely braked. Pretty scary. Got it checked out, break fluid was fine and almost no air in there. Didn't get a whole lot better but I couldn't really reproduce it.
    At one stage I was overtaking a car and then it increasingly breaked harder and harder by itself until the front abs had to take over. My rotors even turned slightly blue.

    It got towed and brought to the dealer. They replaced the handlebars brake cylinder (if it is called like that). Ktm actually wanted to only send a repair kit but the dealer wanted new parts which I appreciated. Didn't get new rotors though. Since then brake point of the leaver is always at the same spot now I'm rebuilding confidence slowly but steadily.

    This occured to 3 or 4 poeple now. Latest guy crashed into crash barrier / guard rail at the highway exit because it didn't brake. Luckily there were just small bruises and scratches.

    For me it was a process getting worse over time, for the last guy it was more of an immediate thing. I've got a video attached with a lot of freeplay even though I didn't change the lever position. Next time it was like really hard and engaging nonstop by itself.



    https://photos.app.goo.gl/DLeEVbhWi33BqhJz5
    #1
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  2. tshansen

    tshansen Been here awhile

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    Thank you, i had my rotors changed just before the season ended... my brake reservoar is getting a new lid next month, little bit of leakage. If the new lid and rubber gasket wont seal it, i will get a new one. Thank you for this info, i did not know. Will keep an eye out for any future problems with the brake
    #2
  3. braaap!

    braaap! Long timer Supporter

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    That’s very freaky in a bad way!.. Keen to hear the cause?
    #3
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  4. OhDuh

    OhDuh Adventurer

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    They didn't know. It is weird cause if you flick the brake lever it was all normal again or maybe even hard to pull in again. If you slowly pulled it in, the master cylinder kind of got stuck and the lever had lots of freeplay. Let it flick and the lever sits there without freeplay. So something inside the master cylinder was definitely faulty. Unfortunately I couldn't pinpoint the issue any further.

    @tshansen I was told that a little leakage is common due to air expansion and compression with different weather conditions. I wouldn't worry too much. There are little openings in the lid to avoid high pressure. But with the master cylinder I got a new reservoir including new seal and lid and it didnt leak anymore. So take my dealers info with a grain of salt.

    Offtopic: what happens with your second Draumr XL and maybe the fjol? Are you keeping them, selling them or maybe doing a giveaway (to step up the influencer game on youtube)? I'd be the first to drive up to Norway to go camping with you :D :beer
    #4
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  5. a.c.e.

    a.c.e. U Mud, Bro?

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    OT but... tell me the date :wink:
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  6. tshansen

    tshansen Been here awhile

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    Hahaha... First i need to try out all the equipment thorough, then i will do a giveaway. I'm a firm believer of giving back when something is given to me. So there will be some cool stuff this season, but i can't share all the details yet :p Now i have equipment for people to borrow if they want to try it out before deciding :-)
    #6
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  7. floalex

    floalex Adventurer

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    One of the failures was unfortunately me.

    Looks like a pure German problem so far.
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  8. Jarrett2

    Jarrett2 Been here awhile

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    I noticed the other day on a ride that the front brake was really hitting hard when going slow, but came on soft as I was coming into a corner at high speed.

    It required me to get on the back brake which I rarely ever need to do on other bikes.

    Any chance that's a precursor for this deal?
    #8
  9. OhDuh

    OhDuh Adventurer

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    It might be. It's really hard to objectively investigate this. I was feeling paranoid and couldn't really show the dealer my issue. As said it took me a few thousand k to go from being noticeable to the "you gonna die in the next curve" stage.

    Keep a close eye on this and if you are thinking that something is wrong, don't blame it on you becoming crazy but rather the bike going lethal.
    #9
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  10. floalex

    floalex Adventurer

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    Until the occurrence yesterday my bike run a bit over 8.500km.
    #10
  11. 990s

    990s Adventurer

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    I have this same issue with moving brake point. This with several centimeters, and very worrying. I have not lost any brake power, yet. But this it is not good. It is hard to show to the dealer, because this is not always the same, even not every day.

    BTW I,m from Norway
    #11
  12. OhDuh

    OhDuh Adventurer

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    Try taking videos whenever it seems off and send / show that your dealer. Maybe also send them a link to this thread
    #12
  13. ramirin

    ramirin Ready to push

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    Have you guys noticed difference in braking on different drive modes? I was thinking could it be because of lean angle sensitive abs system which should be disabled in offroad(?) mode - or maybe something being wrong with this system.

    Brake cylinder itself is pretty simple piece with not too many moving parts..
    #13
  14. OhDuh

    OhDuh Adventurer

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    Not really. I got my brake fluid changed and it still occurred. Only replacing helped. Since the behavior was affected by how the lever was used I 'd rule your idea out. Bike was standing still and turned off.
    Pulling the lever and sliding off so it snapped back made it hard to pull. Slowly pulling kept it in. I tried lubricating the lever hinge with graphite spray, but you hardly get in there without disassembling.

    The issue has to be pretty bad already to be able to reproduce it in the way I described above
    #14
  15. ramirin

    ramirin Ready to push

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    That is surely a failed cylinder.
    #15
  16. [Art]

    [Art] Been here awhile

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    Angle system is disabled in Offroad and rally ride mode.
    Front ABS will be less intrusive in Offroad mode.

    So yes, there are differences in braking depending on the configuration of the riding aids.
    See the FAQ for details.
    #16
  17. OhDuh

    OhDuh Adventurer

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    That would surprise me. Do you have any sources? Try driving a curve with 60 mph. Even with very little lean angle the tc interferes at lvl9. Drive on a muddy spot or wet grass and tc9 will let you spin your rear tyre while upright

    Might be speed dependent but I think not solely
    #17
  18. 990s

    990s Adventurer

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    Well i might change the master cylinder anyway, since i,m thinking of changing to single disc front: (Thanks to you Ramirin !)

    This one has adjustable level action, looks sexy, and i like powerful front brakes. The external fluid reservoir may be vulnerable thoug..
    https://www.brembo.com/en/bike/sporting-use/master-cylinders
    #18
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  19. [Art]

    [Art] Been here awhile

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    Source: Go to the ktm website, open the 790 page, select sofware&electronic. Explore from there and you’ll find the following quotes.

    “By selecting 'offroad ABS', the ABS function is deactivated on the rear wheel, while the front wheel ABS intervention is reduced and lean-angle sensor data is ignored

    “Offroad ride mode is not lean-angle sensitive, meaning that traction control does not intervene when a rider uses a berm, sand dune or rut to lean into a turn.”
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  20. [Art]

    [Art] Been here awhile

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    Maybe, just maybe, the rally mode only disables the angle sensor once you’re under a certain tc level? I guess that’s possible…
    #20
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