Darkside death wobble

Discussion in 'Victory Cross Country' started by USMCXC, May 19, 2017.

  1. USMCXC

    USMCXC Member

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    Okay, don't need opinions on Darkside. This is the second time I'm riding Darkside. I've got a 21-inch in a front, rear end dropped almost two inches. Last time I rode Darkside I had an 18 inch tire on a front and I believe it was before I lowered it. Anybody have a similar setup and have issues with death wobble. I am running ride at 40psi and it can get squirrelly at any speed but generally happens under hard acceleration and above 75mph. If I can't narrow it down I'm fling back to Avon venom. Thanks in advance.
     
  2. kaitiff

    kaitiff Well-Known Member

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    Need to know which tire you're running both front and back. The type of tires can have a huge effect on what pressure you should be running.. from what I've seen on the Darkside forum I would spitball and say you've got too much pressure in that rear tire. Also, when you change the geometry of a bike by lowering/raising front or rear it can have an effect on the handling. Did you rake the front end when you put the 21" on? Have you checked the matrix on the Darkside forum for what other's are running similar to your setup?
     
  3. Half_Crazy

    Half_Crazy Well-Known Member

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    Things that may help...
    Check the steering head 'fall away' or tension on the bearings. Too loose or too tight will make strange things happen.
    Make certain the rear wheel is centered and aligned. If it is steering the bike even slightly by being out of alignment, under acceleration it will want to wobble side-to-side (cycle of steer/correct, steer/correct over and over) and the faster you go the worse it gets.

    Could have something to do with the combination of radial and bias tires too, causing a harmonic through the chassis. It could also be incompatibility between the tread pattern of the front and rear tires.

    Just thinking out loud...
     
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  4. kaitiff

    kaitiff Well-Known Member

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    Well tone it down some man.. you're making too much sense and it's distracting. hehe
     
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  5. USMCXC

    USMCXC Member

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    Ok, thanks for the input gents. I did not rake the front end when I went to a 21" tire. I don't believe it would be the steering bearings because I just took off an Avon rear that I had on for about 10,000 miles and I never had this issue. I'm running a 165/55R16 Extensa HP on the rear and the front is the Avon venomX 21". What PSI are you thinking I should run it with? I've read several darkside posts and most guys say they're running there's around 40. I imagine it's a possibility that the dynamics between the front 21 and rear darkside might be an issue since I didn't put a rake kit on when I went up from an 18" front wheel.
     
  6. USMCXC

    USMCXC Member

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    What matrix are you taking about? I don't think I've ever seen it.
     
  7. Pauljp

    Pauljp Well-Known Member

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    I run 33psi on my Darkside tire. Mind you my aerodynamics is stock.
    If you lowered the rear and raised the front it changes the dynamics a lot.
    You say you rode this way with the Avon and never had a problem? Then maybe you are going to have to give up the Darkside.
     
  8. kaitiff

    kaitiff Well-Known Member

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    Gotta work on your google-fu my friend... I literally went to google and typed in 'Darkside tire matrix'.. first hit link..

    Darkside Tire Info Center

    Also, if you haven't done so check out this forum...
    Riding on the Darkside
     
  9. vision_nut

    vision_nut Moderator Staff Member Moderator

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    I would say raise the back end up to stock. Wobble comes from rear for the most part.
    Its the cheapest solution
     
  10. Half_Crazy

    Half_Crazy Well-Known Member

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    It handled fine with a motorcycle tire... now it handles like sh!t with the darkside... but you want to keep the darkside? Hokaaaay....

    Ya think?

    Lowering a bike that far, well, you are just castrating the thing to be honest. 1st, the rear fender, bags, pipes, etc are awfully close to the ground and things WILL get damaged. 2nd, suspension travel is a good thing and lack thereof is a bad thing... not all roads are smooth and a nice big dip or hump could earn you a helicopter ride to the trauma center. I see this a lot with lowered bikes on Sandgates Road. There's a bad dip on the inside of a turn and the shop has one insurance job after another... people crashing on that dip... slammed bikes have to be ridden carefully. You can ride your bike carefully if you like, I'm not having any.

    I know you don't want darkside opinions, but dude, if the car tire is making the bike dangerous to ride, maybe you should consider removing it. Just sayin'.
     
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  11. primethious

    primethious Well-Known Member

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    Between raising the front and lowering the back the bikes geometry is way off.
    The head bearings need to be checked.
    I love Darkside , but it may be the straw in this case, or it could be the 21 without rake, or it could be lack of rear suspension. Find what your willing to live without and make that change.
     
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  12. Half_Crazy

    Half_Crazy Well-Known Member

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    Shouldn't need rake until you go to a 23" front wheel. I know people with air-ride front and rear who have to air up the rear FIRST. If they air up the front first it will damage the rear fender (hits the ground).

    13882185_1166400343422242_4748171946034614919_n.jpg

    13906746_1166395730089370_8714421891556032112_n.jpg
     
    Last edited: May 20, 2017
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  13. catfish40

    catfish40 Member

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    I was getting a wobble above 85 on some roads. I'm running double darkside with stock diameter wheels & not lowered. General on the back & Pirelli on the front. I dropped the pressure to 36F & 38R & it seemed much better. I was at 40 & 41. I have only put 270 miles on it since making the change so I'm still experimenting with pressure. I think that the main problem was to much pressure in the front tire. My theory is that since my front is a wider rear tire, I needed to lower the pressure to get more of the tire on the road. might be right or might be wrong, just my opinion.
     
  14. Half_Crazy

    Half_Crazy Well-Known Member

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    Simple question: What makes any of this desirable? Why would I want to induce wobbles and instability on my motorcycle just to have a rear tire on the front backwards and a car tire out back? What is the end goal here?

    Seriously, I'm curious...
     
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  15. catfish40

    catfish40 Member

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    For me it was mostly curiosity. I've been riding all kinds of bikes for over 40 years. I have some friends that ride darkside on gold wings & they get thru the twisted pretty good so I thought that I would try it. Wasn't expecting the wobble but now that I have that lined out I'm liking it. When I put cams pcv & filter on my bike I wasn't that thrilled with them either since it ran pretty good before I did it. Once I had KMC tune it I'm very happy. Some things just take time to dial them in. I like the way the dark side tires look too, especially the wider tire on the front. When I wear these tires out I'm not sure what I will put on but I figure at least I tried it.
     
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