Wheel conversions for 1986-1987

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

  1. JamieDaugherty

    JamieDaugherty Active Member

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    You can double check, but I believe the amount that needs to be machined from each rotor mounting surface is 6mm. The net result is the rotors should have the spacing as your VFR's stock wheel.
     
  2. 577nitroexpress

    577nitroexpress New Member

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    yes 6mm per side, just did it this weekend.

    577
     
  3. JasonWW

    JasonWW Member

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    Will the 87-88 CBR1000F "Hurricane" rear rims bolt on?

    They have larger diameter rotors, but the mounting bolts look the same as the VFR rims, so the smaller VFR rotor might bolt onto the CBR rim and require no mods to the caliper mount.
     
  4. 577nitroexpress

    577nitroexpress New Member

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    Yeah but they are friggin ugly. Go for the F2 wheels, its the easiest by far and well documented. I am keeping my stock front forks and upgrading the springs and installing emulators along with a fork brace. 99% of street riders would find this more than good enough. I having Jamie send me his kit for the rear, which is easy peasy to install and hassle free.

    Who is the bloke that did the single sided conversion, and is it documented?

    577.
     
  5. fredsncoma

    fredsncoma Member

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    Who is the bloke that did the single sided conversion, and is it documented?

    577.[/QUOTE]

    That bloke is Toecutter and yes there is a thread. I think it is SSSA conversion
     
  6. 577nitroexpress

    577nitroexpress New Member

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    So do I need to send you my sprocket carrier to be milled for the rear wheel kit for my 1986 VFR700 I ordered?
     
  7. JamieDaugherty

    JamieDaugherty Active Member

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    No, you do not.
     
  8. JamieDaugherty

    JamieDaugherty Active Member

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    While some people have stuffed 120 tires on the Hurricane fronts, they aren't wide enough to handle that tire safely. They are 3.0in wide and a 3.5in wide is what is needed for a 120/70 tire.

    My opinion is that Hurricane wheels aren't a good choice because you don't really get much of a performance gain, if any.
     
  9. JasonWW

    JasonWW Member

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    Can we get a moderator to add more info to the very first post?

    Under the F2 front wheel swap it needs to be metioned that the stock spacer and the speedo drive unit needs to be machined down in addition to the rotor mounts (which is 6mm on each side) .

    Under the use of the Hurricane front wheel it needs to be mentioned that you can mount a 110/80/17 Radial tire for a nice upgrade.

    After some research I found the Hurricane front rims to be 2.5" wide, not 3". In addition, there is one Radial tire that will fit it a 110-80ZR-17. It is the Avon Azaro. This combo should make a big improvement over the stock wheels and Bias ply tires. Hurricane owners have swapped to these radial front tires and reported many improvements.

    The down side of the Hurricane swap is that there is only one Radial tire choice, the rest are bias ply. Doing the F2 front swap give you the wider 3.5 wheel and many dozens of tire choices.
     
    Last edited: Mar 18, 2013
  10. 577nitroexpress

    577nitroexpress New Member

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    I'm re-posting this over here, for greater visibility.

    I've spent some time applying all of that math I learned years ago and here is what I've come up with for ride height adjustments and the F2 wheel swap.

    Here are my findings:
    Decreasing the wheelbase, increases the affect the changes make to rake a trail.
    At the stock wheelbase of 1477mm the decrease in ~15mm ride height change is 0.5818595284 increase in degrees change to the rake. <<< Corrected.
    Raising the rear 24mm << 10mm increase in shock length, decreases the rake by 0.9309265768 - 0.5818595284 degrees = .3491 overall decrease in rake. << Corrected.

    Decreasing the front fork 5mm decreases the wheelbase by about 2mm.
    You could decrease the wheelbase by 5mm in the rear and increase the effect the front has even more.
    Total ride height is down about .5 inch at the seat, which also reduces the center of gravity (CG), which in theory should reduce transition time and effort from lean to lean.
    This method has another benefit, the stock swing arm is designed for a 10.5" shock length, the rising rate ratio is for that length shock, increasing the length increases swing arm travel and causes strain on the counter shaft bearings.
    This is caused by the chain being too taught at max tension during normal movement around the arc. To solve you must loosen the chain more than recommended and risk a thrown chain.
    As you can see I've put some math behind this, and have hopefully shown a different point of view. I have to admit, the bike looks sexy with the arse end up high though.

    Also, wanted to add that I calculated the exact final drive delta with the swap and found that using the stock front sprocket (16T) and the CBR600 rear of 43T with the 17" wheels there is a rotation loss of .008%. So if you normally cruise at 6000RPM for the same speed you'll be at 6048rpm
     
    Last edited: May 8, 2013
  11. JasonWW

    JasonWW Member

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    I did some quick measurements on my 86 while the front end is off and its supported by an engine puller crane. Using a tape measure and a protractor with a plumb bob I found that lowering the front ride height (not fork length) 3/4" (19mm) changes the rake 1 degree which reduces the trail 6mm. Reduced trail means lighter steering and less stability.

    So it really drives home how the soft stock front springs hugely effect the bikes feel under braking or decelerating. I know my bike dives 3"-4" under braking. Assuming that the front dives 3" and the rear stays the same, you lose 4 degrees of rake and 38mm of trail. That's huge! Plus I know the back end does lift which makes the rake even steeper reducing trail even more.
    I'm pretty sure that's why everybody that swaps in firmer front springs reports a big improvement in handling. It makes perfect sense to me.
     
    Last edited: Jun 3, 2013
  12. JamieDaugherty

    JamieDaugherty Active Member

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    You might want to run those numbers again. A 1477mm wheelbase motorcycle with an increase of 15mm of rear ride height results in a decrease in rake of 0.58 degrees. This is a change that is noticeable.
     
  13. 577nitroexpress

    577nitroexpress New Member

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    I corrected post, your right .58 degree, cheap shit calculator did arcsin incorrectly, f*ckme!:mad:.
     
  14. 577nitroexpress

    577nitroexpress New Member

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    I never could get the plum level or protractor squire. I guess springs a matter of taste and riding style, I would rather have soft springs and emulators/cartridge forks with real rebound and compression dampening than just stiff springs. Also, I believe the heavier springs are for the fork swap not the stock forks, which I retained. IMHO which has been know to be full of shit of late. But live and learn.
     
  15. JasonWW

    JasonWW Member

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    The stock 86/87 VFR700's have front springs in the .55-.60 range (I think it's kilograms per millimeter) which everyone says is correct, if you weigh 90lbs. :redface: I've read that lots of folks swap to .90-.95 springs which is more appropriate for a 180lb-190lb or so person. I thought this was fairly common knowledge on this forum. Maybe Jamie can confirm or deny.

    Anyway, I have stock springs in my bike and I'm around 190 and they are way too soft. Using the zip tie on fork leg trick I see I'm bottoming out every time I use the front brakes lightly. Just normal bumps seem to bottom it out too.

    I know you can adjust rebound by changing fork oil viscosity and emulators can let you dial in the compression. To get the most from the stock front end the consensus is to run emulators as well as firmer springs. If your fairly light weight then just emulators might do the trick. :wink: You can always change to a stiffer spring later if you feel the need.
     
  16. 577nitroexpress

    577nitroexpress New Member

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    I'm in the 170 pound range, I haven't experienced any issues with the forks springs, they haven't bottomed, and aren't too harsh. I guess I'm in the average range they designed it for.

    I remeasured with a yard stick and square three times, the old rim/tire and the new one, and still get ~.714" Delta in radius and ~.50" at the seat. This about what I get with the bike upright square from the axe to ground as well.

    Using squares and levels I was able to physically measure the rake with the 5mm drop and its bang on 27 degrees, maybe a FCH over, my eyes aren't that good anymore. I'm happy with it, if I raise it it goes to 27.7 or so.
     
    Last edited: May 9, 2013
  17. JasonWW

    JasonWW Member

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    How did you determine you aren't bottoming out in front?
    Is this a reply to the other thread about rear tire heights?

    You can go to tire company websites and look at the tire specs for different sizes and they usually show diameter.

    What are the 2 rear tire sizes your measuring?
     
  18. JamieDaugherty

    JamieDaugherty Active Member

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    The stock springs are good for a -200lb rider. That's right, if you could somehow be pulling up on the bike while riding with 200lb of force that would be good. That means for everyone the springs are incredibly soft. Here are some details:

    Stock rate = 0.49kg/mm
    Rate for 170lb rider = 1.0kg/mm
    Rate for 190lb rider = 1.05kg/mm

    I hope this helps!
     
  19. JasonWW

    JasonWW Member

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    That .49 spring rate must be the softer part of the progressive spring. I bet once that section coil binds, the rate goes up. To what, I don't know.
     
  20. JamieDaugherty

    JamieDaugherty Active Member

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    The stock springs are often considered progressive - THEY ARE NOT. There are two distinct wind pitches but each get to solid at the same time so there is no progression of rate. This was done to reduce NVH (noise, vibration, harshness) because a spring design like this has no resonant frequency.

    FYI
     
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