Fork mods

Discussion in 'Mechanics Garage' started by PaulAmico, May 2, 2003.

  1. PaulAmico

    PaulAmico New Member

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    New to the list here...

    I have a '93 VFR750F with Penske rear shock (brilliant) and Race Tech-ed front. I'm ok with the Race Tech stuff, but still disappointed with my rebound damping - the front forks seem to pogo a bit too much for my liking. Has anyone had any success with swapping the VFR forks with some other front end? Will later model years fit up to the early 90s? Are they any better? I may also want to get a little more sporting stance and get different clip ons. Has anyone had success with this either?

    Thanks.
    Paul
     
  2. waldrm

    waldrm New Member

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    Have you tried 10 weight oil to replace the stock watery fork oil?
     
  3. PaulAmico

    PaulAmico New Member

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    The oil isn't stock anymore. When I had it Race Tech-ed, the guys at the shop replaced it. However, I'm not sure what weight is in there right now, so I should change it. It's a long story about why I don't know, maybe one I'll tell sometime, but it has to do with a crash, insurance money, and the wrong size front tire.

    I do know a bit about suspension and the effects of using different oil weights, because of this experience, and because I have taken a couple workshops from a local racer about suspension. I was wondering more specifically if anyone has tried to fit up their VFR with some different forks (eg 929 or SuperHawk) to replace the old pushrod forks with more modifiable or adjustable forks off of another bike.

    Wouldn't it be as simple as measuring the length of the fork tubes and trying to find a different front end with the same length? To reiterate, I'm looking for total adjustability without dismantling the fork or having to drain and replace oil.

    Thanks,
    Paul in CA (but soon to be in KY)
     
  4. Elvie

    Elvie New Member

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    Here you are Paul. If you know a bit about suspension then see if you can wrap your head around this. I was reading an old bike test with the VFR FS vs ZX9R Ninja E1 and the ninja uses usd 41mm forks, 6 pot calipers, 320mm discs on a similiar 17 inch rim with similiar 120/70/17 rubber and I'm just thinking that maybe the front end of the ninja could slide into the VFR yokes. By comparison my FV uses standard cartridge forks, 296mm discs and sliding calipers and I can't imagine your FP being much different. You'd have to take measurements of fork length I guess and get the forks resprung (although the ninja is only 8kg heavier) but there is a pretty serious front end upgrade there if it all works out. I'm not that mechanically minded but, like yourself, have ventured into uprating the viffers front end. Failing that I believe the forks from the Firestorm slot straight in.

    Hope this helps some. Let me know what you think. Dont' want to be the only raving lunatic :D

    Elvie
     
  5. afterburn

    afterburn New Member

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    VTR100F forks should fit, but a often done mod is to use the CBR600F3 dampers in the VFR forks. They fit and add damping adjustments.
     
  6. waldrm

    waldrm New Member

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  7. PaulAmico

    PaulAmico New Member

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    Hey thanks for all of that. I was out of pocket for a week or so moving my family and all of my possessions to Louisville, KY from the Bay Area.

    I'll look into all of this and see what's what. I'm also going to try to do some low cost stuff to see what I can do to improve the ride to my liking. You know, new house, new job, new life and all...
     
  8. GlobeStomper

    GlobeStomper New Member

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    Greetings

    New to the site here.... ::)

    I just picked up a 1994 VFR that was exposed to some bad salt air, and as a result gained some bad corrosion on some surfaces. In particular, the fork stanchions.

    So a replacement is in order, and I'm thinking of a swap to a CBR fork or something similar...just like Paul.

    I'll take some measurements and see how things go...

    Any tips appreciated!!

    Cheers
     
  9. Guest

    Guest Guest

    I have a 2000 mod with a penske 8760 rear shock.I recently had .95kg springs and ohlins valving fitted in the forks.previously it had .9kg springs with thicker oil and stock valving.If stock suspension is 1/10 the thicker oil and heavier spring would be 3/10 and the current setup 8.5/10 from what i hear racetech would be around 6/10.It has transformed the bike at least as much as the rear shock.I can now feel the front tyre very early into the corner encouraging faster,later turn in.If you are unhappy with the rebound just get your suspension guy to shim up the preload on the rebound stack or to change the valving.
     
  10. SAFE-T

    SAFE-T New Member

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    Re: Fork mods

    Pretty old thread, but here's my .02

    There are several forks you can use on the VFR:

    1. CBR 929/954
    2. RC51
    3. VTR1000
    4. F4/F4i
    5. R1

    All require the following additional parts:
    * triple clamps (use CBR 929/954 or RC51)
    * clipons (50mm for 1, 2 and 5; 43 mm for 3 and 4)
    * brake lines
    * master cylinder (use CBR600F4/F4i)
    * calipers (use Nissin calipers on Honda forks - 1 to 4 are the same)
    * fender (1 and 2 use CBR929; all others use matching fender for that bike )
    * axle (1, 2 and 5 are 25mm; 3 and 4 are probably the same 20mm as the VFR's)
    * wheel spacers

    1 and 2 also require a matching wheel, or 320 mm Ducati rotors and 25 mm wheel bearings for your VFR wheel. AFAIK, Ducati rotors do not fit on the 90-93 VFR front wheel. 3 to 5 can use the stock VFR wheel.

    The Honda ignition is a universal fit for all other Honda top triple clamps. Which means if you use the R1 forks, you still have to get Honda triple clamps. Honda calipers will not fit on the R1 fork, but the monoblock Yamaha calipers are better anyway (R6 and R1 are identical, but R6 units are more plentiful and therefore cheaper).

    Many parts on the CBR929/954 and RC51 are interchangeable - for instance, I have an RC51 lower triple and CBR929 upper triple on my '99VFR800 holding a set of RC51 Ohlins forks, a CBR954 fender and calipers with CBR600F4 master cylinder and an OEM Ducati Marchesini 5-spoke wheel with 320 mm Brembo 'Snowflake' rotors . This is just how it worked out for me, but in my experience CBR parts are typically cheaper.

    There are probably other forks you could use, such as GSXR and ZX6R (636) and although I considered them I have not seen anyone else use them nor have I spent anywhere near as much time measuring them as I did the five options I already listed. Of the four inverted forks I gave the most consideration to (CBR929/954, RC51 and R1) the CBR's were the shortest followed by the RC51's and then the R1's which were the longest.

    If you do go with the GSXR/ZX forks, I do know the Tokico radial calipers are the same. My guess is the GSXR tubes would be an OK fit in the Honda triples, but I'm not sure about the 636. Some bikes have funny sized pieces, like the R6's 22mm wheel bearings so you are on your own if you go this route. At the same time you are more than welcome to blaze a trail for others to follow... ;)

    IMHO, I can't imagine why someone would want to go to all the trouble to just to put a DIFFERENT set of regular forks on a VFR. Inverted forks are not more expensive than regular forks, and in some cases they are cheaper. If I had a VFR800 with LBS and wanted to upgrade my forks for cheap, here are your options from least to most expensive:

    a. RaceTech springs
    b. Traxxion springs
    c. RaceTech springs and compression valves
    d. Traxxion springs and RaceTech compression valves
    e. Traxxion springs and compression valves
    f. RaceTech springs, compression and rebound valves
    g. professional revalving and respringing of OEM units
    h. Traxxion springs, compression and rebound valves
    i. professional revalving and respringing of OEM units with CBR600 internals (only on VFR800 - F3 for 5th generation, F4 for 6th generation) This is my favorite
    j. Traxxion springs, compression and rebound valves
    k. Traxxion springs, compression and rebound valves with CBR600 internals

    Your other option, if you have a 98-01 VFR is to get a set of forks and clipons from an '02 or newer model which was generally regarded to have better suspension up front. No need to mess with the LBS, and you could sell your 5th generation forks and clipons for the same price as it cost to buy the 6th generation units.

    Whatever forks you decide to use you will most likely have to change something. The 98-01 R1 has the closest fork spring rate to the VFR's stock springs - all the others are either lighter or heavier. Heavier is probably OK since most tuners suggest more robust springs anyway, but I think you would be in for a rough ride (literally) with lighter springs. With the exception of perhaps Ohlins, all these other OEM forks will benefit from revalving or the installation of RaceTech/Traxxion fork bits.

    If you wanted to, you also have the option of making your VFR look more (or less) racy with your choice of brake/clutch master cylinders. The RC51 uses a remote (inboard) reservoir which you can substitute for the VFR's, leaving you with the choice of CBR929/954 and RC51 front brake master cylinder to make a matching pair.

    The 98-01 VFR's have black clutch/brake MC's so the CBR600F4/F4i is nearly identical. AFAIK 90-97 VFR's have gunmetal grey MC's so you either live with the difference, swap both out or starting painting/polishing to match.

    If you happen to have a 98-04 VFR800 you also have to deal with the linked brakes. Luckily they are not too difficult to disconnect but you still need about 6-10 hours to remove and replace bodywork and LBS parts, plus time to bleed your brake system afterwards. If you have an ABS VFR, you are blazing a trail to another planet :D

    Anyhow, this is my story. My mechanic and machinist think I'm on the highway to hell with this entire project, but at least there's some good scenery along the way.

    I am also working on a kit that allows you to use single-nut wheels on VFR800's. Feel free to zing me your email address if you want to be on my mailing list this fall.

    Cheers !
     
  11. day004

    day004 New Member

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    I think you should just RE-TUNE the forks you have.
    My forks have been RaceTeched and they are as perfect as you can get a non-adjusteable fork to get. If you send them back to RT be sure to give them all your specs, ie weight, one up or two up, accessories, and most important how hard you ride. Having given them all this info they tuned my forks incredibly well.
    Perhaps your local dealer can log into RT,s site to get the proper shim stack info...
    Dave
     
  12. Guest

    Guest Guest

    Thank you for the details on converting the front end Safe-T. Any chance you have more to offer or does anyone have info or websites that can explain how to do it better/more? I have only been able to find pits and peices on how to do it or saw pics of the job after it was done. I may start a hunt for a RC or like front end for my 97. If I can find one dirt cheap...some day I would consider it, even know I had my forks redone all ready by Traxxion Dynamics
    http://www.traxxion.com/about.shtml
    With the F3 tops and my original VFR bottoms.
     
  13. SAFE-T

    SAFE-T New Member

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    What more do you want to know, Joe Foe?
     
  14. Guest

    Guest Guest

    LOL Not sure in all honesty. Pictures say a thousand words though.
     
  15. waldrm

    waldrm New Member

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    I have a '93 VFR with an early ('93-'95) CBR900RR front end fitted. Much improvement, an aggressive look , and lower bar height. Nice thing is that the stock VFR wheel works with this setup with no mods.
     
  16. Bubba800

    Bubba800 New Member

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    SAFE-T, I'd like to see some photos of you VFR, if possible.
     
  17. Guest

    Guest Guest

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