Wheel conversions for 1986-1987

Discussion in '1st & 2nd Generation 1983-1989' started by adam_in_48060, May 8, 2007.

  1. JasonWW

    JasonWW New Member

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    Come on, that's virtually impossible. Wouldn't that defy basic physics? The only way that the 2 sections could bind simultaneously is if the closer pitch section used a larger diameter wire and I'm pretty sure it doesn't.

    Where did your info come from?
     
  2. JamieDaugherty

    JamieDaugherty New Member

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    It is quite easy in fact. Just do the math and you will see. All you need is two springs stacked together that reach solid height at the same load. Not at all difficult.

    I've been in the suspension business for almost 15 years - my info comes from actual measurements and analysis of stock parts.
     
  3. JasonWW

    JasonWW New Member

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    I'm sorry, I wasn't refering to 2 different springs, I was refering to a single spring of the same diameter wire it's full length being wound with 2 different spacing lengths between the coils. In other words a progressive rate spring or "dual rate" spring.

    [​IMG]

    I'm sure you know how progressive springs work, but for everyone else wondering, I'll explain it in detail.

    Imagine the above pictured spring is 24" long. The tightly wound section at the bottom is 6" long and the upper portion is 18" long.

    As this spring is compressed, the spacing between the coils shrinks at a constant rate due to the wire diameter and coil diameter being the same (like 1mm per every inch of spring compressed, just for examples sake). Now the coils at the bottom are going to run out of space and will bind up well before the upper coils do. At this point in the springs compression we will call these lower bound up coils "dead coils" because they are no longer functioning as a spring. They are functioning more like a spacer. Now the coils left over that are still able to compress (the "live coils") are now only 18" long which means the rate has just increased by approximately 25%. So from 0.49kg/mm to 0.61kg/mm more or less.

    Now at what point in the bikes suspension travel that this change in rate occurs is harder to determine. The weight of the bike and the amount of preload are big factors, but if I had to hazard a guess I say within the first 1/5 to 1/4 of total suspension travel.

    Now if you wanted to design a spring that looked like a progressive but functioned like a linear rate, you would have to start with a wire that had 2 different thicknesses. You would wind the tighter coils at the bottom with the thicker wire and then the rest of the coils with the thinner wire. This way as the spring compresses the spacing between the coils will shrink at differing rates. The upper portions gap would shrink at 1mm per inch of spring compression while the lower would shrink at 1/3mm. That way, the upper 3/4 of the spring would coil bind at the same time as the lower 1/4 of the spring. It's possible to do, but I've never seen it done, nor do I know of any benefits of doing it. Two big reasons not to do it is the cost of a dual thickness wire and it's longevity. Could 2 thicknesses of wire be welded together, wound and then heat treated and actually last over time? Hard to say.

    Although I've never actually measured the wire thickness on the stock springs, I'm pretty sure it is all wound from the same diameter wire.
     
  4. JamieDaugherty

    JamieDaugherty New Member

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    The stock springs are wound with two different pitches but are not progressive rate. Measure them and do the math, you will see what I mean.

    A progressive rate spring is like two differnt springs (of the same OD and wire diameter) stacked together. It is very easy to make fork springs this way without being progressive rate. You have way over complicated this!

    Stock Honda/Showa fork springs are not progressive rate!
     
    Last edited: May 11, 2013
  5. JasonWW

    JasonWW New Member

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    I thought I simplified it. :redface:
     
  6. 577nitroexpress

    577nitroexpress New Member

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    Hi, I posted a photo of my F2 front rim being machined down ~6mm on each mounting point. Its not hard, and any decent machine shop can do it. It IS the easiest and fasted way to do the wheel swap. You do not have to remove the front forks or any of the other crap with it. CBR600 F2 forks are not cartridge forks, so you still have to invest in emulators to make them work (decent). A fork brace and emulators on the stock forks will be more than enough performance for any street rider. If after these mods and upgraded rear shock, you are exceeding the capabilities of the suspension, 1, your gonna' die in a horrific accident on the road, 2, you should be a professional road racer for Honda, 3, buy a better and newer bike. IMHO of course!

    577nitro-
     
  7. 577nitroexpress

    577nitroexpress New Member

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    Use the old racer trick and put a zip tie around the fork tube. Slide it to the bottom and ride, the tie will slide up as the fork compresses, measure the amount of travel from the slider to the tie.

    I measured the old 18" and the new 17" rim's(with tires mounted), I measured the actual size as mounted on the rim. I put a 160 on my F2 rear rim, which seems to be just about right.
     
  8. artee

    artee New Member

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    I think you will find tha the 94 f2 forks are cartridge.
    Being in the UK, I used the 88/89 vfr750 rc24 triples (straight swap) to convert my 700's front end with 94 f2 cartridge forks.
    CBR600 spacer on the opposite side to the speedo drive et voila job done. Later vfr clip ons are used.
    [​IMG]
    [​IMG]
    94 f2 forks

    Roger
     
  9. RG07

    RG07 New Member

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    Where did you get that exhaust? The bike looks great. I am into a project...I want it to look as good as this...I have an 09 GSXR600 complete front end off my raace bike I wanted to use...the rear I am still undecided on...Thanks
     
  10. artee

    artee New Member

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    Who's exhaust?

    Roger
     
  11. Captain 80s

    Captain 80s New Member

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    Looking for a definitive list or parts and specs for fitting F2 rear rim using the F2 caliper bracket (drilling to mount brake stay arm as done earlier in this thread) to an 86 VFR.

    Which spacers to use and what sizes do they need to be machined to?

    I know this has been discussed to death, but I've read everything and I'm getting a bunch of mixed info. Some of it from using a cut and welded VFR bracket and some from using the F2 bracket. Perhaps they are the same width, but still would like some spacer dimensions.

    Anybody have the complete story?

    Thanks!
    Mike.
     
  12. JamieDaugherty

    JamieDaugherty New Member

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    Mike - not to worry, I offer kits for all forms of swap. For the most efficient install I offer a version that comes with a brand new machined caliper bracket. That's the cleanest way to make the swap.

    Don't forget that no matter what the stay arm needs machined. That is included with my kits as well. Just an FYI!
     
  13. Captain 80s

    Captain 80s New Member

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    Cool. I guess I'll cool my jets and and we'll do a package when I send the fox shock for modification.
     
  14. Rune

    Rune New Member

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    First, thanks for a great forum!

    My bike is a vfr750f from 86. I have bought a Kawasaki zx9r ninja to use as donor bike. Im planning to use fork, rims and brakes... Does someone have experience with this kind of swap? Ok donor bike? Any advice?
    donor.jpg

    Br
    Rune
    Norway
     
  15. JasonWW

    JasonWW New Member

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    I have a Kawasaki ZX7 front end so I could brobably help.
    What year ZX9 do you have?
    Have you measured the fork lengths, yet?
    Have you measured the steering stem diameters and length?

    Your probably going to use the zx9 triple trees with the Honda steering stem, although I used the Kawi stem after lengthening it.

    Our VFR's have long forks and long stems so make sure your ride height will be okay. Mine is a bit lower in the front, but that helps to reduce trail which is usually needed with these swaps.
     
    Last edited: Jan 11, 2015
  16. JamieDaugherty

    JamieDaugherty New Member

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    Probably you will run into a lot of headaches only because you are trying to mix and brands. If you choose Honda wheels and Showa suspension things will be a lot more straightforward. You will find that Honda designed motorcycles very consisently. If you choose a CBR600F2 instead you will already be halfway there. If you decide to stick with the ZX9R be prepared for many more custom parts, some head scratching, and fabrication at every turn.

    Just my advice!
     
  17. JasonWW

    JasonWW New Member

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    Nah, people have GSXR front ends on these bikes as well. Remember that all front ends have the same basic parts. The only custom parts you might need, assuming the fork legs are long enough, will be in the steering stem area. You'll probably have a Kawi key for ignition and a Honda key for gas filler. You'll need to remember not to order Honda brake pads down the line. :)

    Stick with the Honda switches and master cylinders.

    Front end swaps are time consuming and complicated no matter the brand or model, but their worth it.
     
  18. keny

    keny New Member

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    I had a ZX9R fork for a time on my 1987 RC24, when I still had it (reget selling it mutch!)
    Yes, steering stem from the Rc24, needs some spacer made if I recall right. For brakes as ignition lock, I used stock VFR parts, but I say you need a bigger MC for the brakes, as the ZX9R callipers need that. The stock is just to small and makes the level pull to long. The ZX9R odo drive works whit the vfr clocks, just needs a cabet that fits bothe ends, just cant recall what bikes odo cabel I did use.
    Trail is way to long whit this setup, a real problem. I had lower 110/70 front tire to help it a bit. In the end I did put the stock fork back.
    I guess the F2 has a front end geometry more close to the VFR so a reason why it works and is more common.
     
  19. Rune

    Rune New Member

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    Thanks for responds.

    Reason for the swap, is to get a "upside down" fork and 17" rims. The donor bike I have in mind has this, Kawasaki zx9r year 1997, similar to attached image.
    Have not received the donor bike jet, no measures, will update when I have...
     
  20. JasonWW

    JasonWW New Member

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    I'm going to suggest you start a new thread in this section so we can discuss your bike specifically. Then we can get into all the details with you.
     
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