Fork service ?

Discussion in '7th Generation 2010-Present' started by glory racing, Jul 2, 2013.

  1. glory racing

    glory racing New Member

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    At 16k I need to replace the fork oil. While I am in there I might as well install heavier springs. Anyone 'been there done that' and have specific info? (stock spring rate, replacement springs, vendors, etc.)



    Thanx,

    Mark
     
  2. squirrelman

    squirrelman Member

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    Fork spring changes need to be based upon your weight (with gear) and riding style and getting the right sag numbers.
     
  3. lshark

    lshark New Member

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  4. Dangerous Dave

    Dangerous Dave New Member

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    If I remember correctly, Ohlins offers 1.0 and 1.1 kg springs. I went with the 1.0 because I'm a fairly light guy (160 lbs without gear). Whatever the stockers are rated at is a moot point because they're total crap. Unless your day job is thoroughbred jockey, you won't get the sag right with the stock springs. For me the Ohlins springs were a massive improvement. $140 well spent from Spiegler Performance.
     
  5. glory racing

    glory racing New Member

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    Just ordered a Penske 8983 for the rear. It appears you have to remove all of the Tupperware to install...WTH!

    Regarding the front, I am thinking I will just replace the oil and install 1.2 springs and call it good.
     
  6. Dangerous Dave

    Dangerous Dave New Member

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    You can't just pull the bolt out of the upper shock mount unfortunately. Lord knows I tried. You take the tank off and there's a big stud and nut which are the upper shock mount. You pull the shock out with the mount, swap the mount to the new shock and reinstall. Not as bad as it sounds, as long as you don't spend a couple hours like I did trying to avoid it.

    That's a pretty stout spring. Are you a pretty stout boy??
     
  7. glory racing

    glory racing New Member

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    I tip the scales at around 190 but the VFR is the 2 up machine. She also insists that the side cases and tank bag is always full! Are you thinking a 1.1
    might be sufficient?

    If solo I ride the fz1.
     
  8. glory racing

    glory racing New Member

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    Fork springs for the vfr1200 is easier said than done. The only thing I could find was a Hyperpro progressive and 1 and 1.1 from Ohlins. Didn't want progressive and the Ohlins are backordered and must come from Sweden...3 weeks! Finally found Sonic Springs and we are going to create a spacer that will work with the VFR internals. Hopefully I will have a good report next week.
     
  9. Dangerous Dave

    Dangerous Dave New Member

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    Any news yet?
     
  10. glory racing

    glory racing New Member

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    I fabed the spacer, installed the 1.1 springs and replaced the oil at the stock standards of 5 weight at 160mm. Free sag is now at 25mm. Much better! But there is still an issue. Not sure why but the preload adjusters do not affect sag levels! Zero preload = 25mm Full preload = 25mm ??? Gonna pull them back apart and see if I can figure out why no change.
     
  11. JamieDaugherty

    JamieDaugherty New Member

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    A couple of things to point out:

    - With aftermarket springs you always have to cut new spacers. I have a detailed How TO on my site for this here -> http://www.daughertymotorsports.com/howto/Forks/forkspringsfuild.html

    - Stock springs are NOT progressive rate as many people think. They are wound with two different pitches but each section reaches solid height at the same load so there is no progression of rate. They do this to make the springs damp out any harmonics that could be transmitted to the rider through the bars. I've never felt that with aftermarket springs so I don't understand why it is important.

    - Doing springs alone is at best a net zero gain. At first it might feel better because the support is improved. The down side is you exaggerate two of the biggest problems with the stock front end: excessive high speed compression and lack of rebound. The additional spring rate makes both of those worse resulting in decreased performance. That said, springs are a step towards a proper setup but it should not be considered the end solution.

    - Changing fluid weight is a bad thing for similar reasons to above. Folks will often "go with heavier fluid" during a spring upgrade. Please do not do this! In fact, with most bike, the VFR included, it is best to go with 5w fluid which is lighter than stock. Nothing is going to make the forks well, it is only a revalve that will do that.

    I hope this helps!
     
  12. glory racing

    glory racing New Member

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    Thanx for your post and the info.

    I realize that revalving would be ideal but right now time and money suggest otherwise for me. This winter I can probably have them revalved. Are you suggesting that I should just leave the forks with the original springs for now even though it is substantially undersprung? My research showed the VFR 1200 fork fluid to be 5 weight. Am I wrong again? What could be causing the rebound adjusters to have no affect?
     
  13. JamieDaugherty

    JamieDaugherty New Member

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    Bear in mind that suspension setup factors both the springs and the valving. When you say "undersprung" please understand that is relative to a certain damping characteristic. The equation that describes the response of a damped harmonic oscillating system requires input for both the spring rate and the damping force (at a given suspension velocity). Ideal spring rates have been sorted out decades ago but many people do not understand how the damping must match in order for everything to work as it should.

    I would agree your fork springs should be changed. My experiences are that many people see this as a solution when it is not. In fact, it causes as many problems (more, usually) than is solves, as described in my post above.

    The stock fluid is the SS stuff, which is no good. Make sure to use the Honda Pro Oils 5w, Spectro 85/150, or something similar. Again, fluid is not a tuning tool so so not expect major improvements from it.
     
  14. JamieDaugherty

    JamieDaugherty New Member

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    Your weight alone calculates to over 1.1kg/mm, so I would suggest either 1.15kg/mm or 1.20kg/mm. The 1.15 rate can be had by running a 1.1 on one fork and a 1.2 in the other. I can supply you with a mixed set like that, I don't of anyone else who will do that.
     
  15. glory racing

    glory racing New Member

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    The bike is bottoming out! Regardless of damping, is it the spring that resolves this issue? The way I understand it (or don't understand it) the spring supports the weight and the amount of movement while the damping regulates the speed. If you have any quality suggested reading on how suspensions work I will certainly read it. Then maybe I can quit asking all these dang questions and start providing some answers instead.

    Thanx for the spring suggestion. Another suspension 'expert' who does suspension for a living as well says He uses the 1.2 for goldwings and the like. The 1.2 might be to stiff and may cause me to lose the front end. Would it be true that If the bike is bottoming with a 1.1 spring, a stiffer spring is needed?

    Again, any thoughts on why the preload adjusters do not change the sag numbers?
     
  16. JamieDaugherty

    JamieDaugherty New Member

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    No, the spring supports the weight but the valving controls the MOTION of the suspension. If you are having problems with the bike when the suspension is moving it is almost always with the damping. I do not know of any books that accurately describe this unless they are technical level that require an Engineering degree to understand, sorry. I've yet to find a user-level book that has anything worthwhile inside.

    I believe those forks use long top-out springs, that's why your measured sag doesn't change. Remember: your spring preload adjustment only changes the ride height. That is true for all motorcycles. For your bike you will need to get proper springs with the correct internal preload in order to have good sag.
     
  17. lear 31a

    lear 31a New Member

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    I am considering trading my 6th Gen in for a '10 7th gen or a BMW 1200GS.
    This talk of swapping suspension out at 16k is scaring me some.
     
  18. Dangerous Dave

    Dangerous Dave New Member

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    Are you bouncing the front end, letting it settle and then measuring, then raising it, letting it settle and re-measuring, just to make sure you don't have a big stiction problem since reassembly? [/run-on-sentence] :biggrin:


    That's just crazy talk! I changed my suspension at 3k. :rolleyes:

    To Jamie: I know that in theory everything you say is correct, but theory never really tells the whole story. I've also read online comments from suspension tuners about the damping rates being all wrong in the VFR12. I too simply couldn't afford to do it all at once, having just bought shock, tires, and springs. I can definitively say that the addition of the Ohlins springs in otherwise stock forks made a dramatic improvement. I'm a retired racer, and while I make no claims about ever being the fastest guy out there, I do like to corner aggressively. I don't know what rate the stock springs were *supposed* to be, or what the hell Honda was thinking when they put them in there. But I can tell you that with my narrow 160 lb ass aboard and preload adjusters cranked to the limit, I could not get the static sag below 42 mm. Hopefully we can agree that's way too much. After having the 1.1 kg Ohlins springs installed by Spiegler Performance (I carried in the forks) and putting the front end back on the bike, I actually could NOT reinstall the rear wheel until I backed off the preload adjusters. That's how "saggy" the stock springs were. The Ohlins springs were a welcome addition, and dialing in a few clicks more rebound now has the front end feeling pretty acceptable to me. It is afterall my commuter, not a track bike. I had a blast flogging it down at Deal's Gap a couple weeks ago, with and without the wife on the back. Would it likely be better with some revalving? Probably. But I'm not the least disappointed with the improvements made thus far. Reavalving will probably have to wait for next year's budget. For now, I'm pretty pleased with what the bike has become, and I was one of its biggest naysayers when I first got it.
    Just my $.02
     
  19. glory racing

    glory racing New Member

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    Thanx for the suggestion but not stiction. Sorry but I do not have an answer yet as I did not tear into them again today. The big brown truck showed up with the Penske so I installed it instead. I wasn't expecting it so soon. Gonna check/set sag in the morning a go for a ride.
     
  20. glory racing

    glory racing New Member

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    Thanx to the Penske purchase, right now I am in the same boat of only being able to afford fork springs/fresh oil at this time. Total cost was only $93. If it does not ride like I think it should I will have Jamie revalve over winter.

    Speaking of Jamie, he was kind enough to give me a call this morning and discuss fork 'suspension' for 21 minutes. He certainly did not have to invest his time to 'teach' me stuff. There are not a lot of service people who would have been so considerate and giving. Thanx Jamie.
     
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