SUSPENDERS

Discussion in '5th Generation 1998-2001' started by NIBBLER, Jan 12, 2020.

  1. NIBBLER

    NIBBLER New Member

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    Now I have your attention. I am changing my front fork internals and the fork bottoms to Firestorm Items. The stanchions remain VFR800 Fi1. In another thread on this site it’s stated that these internals and fork bottoms slip straight into the VFR’s stanchions. Thus, you should also gain the Firestorms compression damping functionality. However the part numbers are different on the schematics and there appears to be a small hole in the bottom of the VFR’s stanchion near the bottom bush which the Firestorm doesn’t have. Can anybody tell me if the absence of a hole is to allow the compression damping functionality on the Firestorm? If not what is its purpose and why doesn’t the Firestorm have it? Also stanchion lengths and internal diameters are listed as different. The diameter difference suggests that the fork caps are not interchangeable? Images at the bottom of the page...

    VFR Stanchion specs:-

    Outer Diameter: 41 mm
    Inner Diameter: 36.3 mm
    Length: 628 mm
    Top Connection: Internal Thread
    Bottom Connection: No thread
    Thread: M37 x 1.0

    VTR Stanchion specs:-

    Outside diameter: 41 mm
    Inside diameter: 36 mm
    Length: 633 mm
    top connection: threaded
    Bottom no thread
    Thread: 37 x 1.0
    Colour: Chrome

    VFR Schematic:-
    upload_2020-1-12_11-54-35.png
    VTR Schematic:-
    upload_2020-1-12_11-55-22.png

    Thanks
     
  2. Darth Vader

    Darth Vader New Member

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    I think the chrome tubes are different lenghts so you need to put all the internal gubbins out of your vfr into the vtr lowers. The only change will be the lowers
     
  3. NIBBLER

    NIBBLER New Member

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    Thanks Darth. That would seem the only available option unless I swap out both the VTR stanchions and VTR Lowers. Lets see if anybody out there can answer the questions I have asked. It would have been good to get the compression damping.
     
  4. raYzerman

    raYzerman Insider

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    I am not quite understanding... you want VTR lowers and VTR cartridges with VFR tubes... why not swap out the entire fork and you have it all, no fuss no muss? Sorry I don't know the answer to the hole in the VFR tube, but you might be onto something about the compression damping... again, I'd just swap the whole fork.
     
  5. Captain 80s

    Captain 80s Member

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    I didn't realize the VTR had external compression adjustment. They obviously both HAVE cartridge compression damping. I think a lot of people going this route tend to have custom damping done since they are apart in any case.
     
  6. NorcalBoy

    NorcalBoy Member

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  7. Terry Smith

    Terry Smith Member

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    VTR's don't have external compression adjustment, just the rebound adjuster needle which reaches from the fork cap down to the rebound valve. Compression damping bypass control is by way of a 0.1mm spacer shim between the valve and the shim stack (exactly the same/as bad/ as the VFR). The external hole in the stanchion may be to facilitate air purging during filling but it can't have any effect on damping, which all takes place in the cartridge.

    I bought some bent VTR forks, threw away the stanchions and kept the lowers and the damper parts including (obviously) the fork caps. Reassembled that with my VFR uppers. All of which worked great, especially as I also had some decent springs and valving from DMr in there.

    The extended fork length is controlled by the top-out spring on the cartridge meeting the lip on the inside of the stanchions; my recollection is that the cartridge dimensions are identical between the VFR and VTR so the fork length ends up the same using the VTR lower/cartridge and the VFR stanchion. In any case it is not a big deal to slide the forks slightly up or down in the triples if some ride height adjustment is needed.
     
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  8. NIBBLER

    NIBBLER New Member

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    Hi raYzerman. Basically its easier and way cheaper to find slightly bent or badly pitted VTR forks and swap the parts. My stanchions are mint so I would really like to reuse. A decent un pitted whole VTR front end is a considerable expense by comparison. Also I want to do the job as I haven't done this before.
     
  9. NIBBLER

    NIBBLER New Member

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    Hi Terry. Thanks for the wealth of info and the explanation of the rebound adjustment needle. I cant understand how the fork caps fit thought as the I/D is different. If you say they fit then fair enough, you have done the job. Worst case scenario is I reinstall the VFR internals if I encounter a problem. Great stuff.
     
  10. Terry Smith

    Terry Smith Member

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    No worries; if you need any actual measurements I have my modified forks hanging in the garage (I sold my VFR with the 600F4i/6G parts installed). Figured I'd save these for some future project...
     
  11. NIBBLER

    NIBBLER New Member

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    I have yet another question.... most likely Terry Smith can answer this one...
    I have the option to reassemble the VFR Uppers with the VTR Lowers with.....
    1. With the standard VFR Internals.
    2. With the VFR cartridge but an upgraded spring. ( Linear or progressive ? )
    3. With the standard VTR internals.
    4. With the VTR cartridge and an upgraded spring. ( linear or progressive ? )
    I don't particularly want the extra expense of upgrading the cartridges. Also the VTR is lighter than the VFR by 25kg when full of fluids. I have removed all the delinked stuff so a weight saving there. But I presume the extra weight is going to make the VTR internals work harder from the off. Also what weight of fork oil are the converts using and with which set up? I weigh 76Kg which is allegedly spot on for the standard spring rate on the VFR, but like everybody else find them under sprung and over damped.

    Thanks
     
  12. Terry Smith

    Terry Smith Member

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    First off, you will find that the VFR and VTR use identical damper parts; by that I mean the valve bodies and shim stacks are the same on both. The over-damped feel is due to the small ports in the valve bodies which will be the limiting factor in damping force on a big hit. Take a look at Gold Valves and you will see the ports are many times bigger, so on a big hit the shims can deflect and cope with the higher oil flow with less harshness. The pic below shows the VFR/VTR piston at the bottom, and a higher flow piston (not a Gold Valve but similar) above.
    upload_2020-2-11_8-56-7.png

    Where the two dampers differ is solely in the low-speed bleed on the rebound valve; the VTR has an adjusting needle , the VFR just has a fixed orifice. More adjustment is nice to have, so I'd definitely be using the VTR part here. If you do that, you'll be using the VTR fork caps, so the spring spacer will need to be changed to suit as the cap is deeper on the VTR. PVC pressure pipe is ideal as an easily cut spacer, and you should look for about 15mm of installed preload.

    If you are going to the effort, I would strongly urge you to install Gold Valves (at least in the compression position which makes the most difference to bump absorption), and buy some straight rate springs; 0.85kg/mm would sound about right for your weight based on my own experience.
     
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  13. NIBBLER

    NIBBLER New Member

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    Hi Terry

    Thanks for the info. We are starting to get into the nuts and bolts of the suspension now and its really not something I am a specialist in. To summarise what you are saying.

    Go with the full internals of the VTR set up and bottoms in the VFR Stanchions, the VTR stanchions are too pitted to use anyway.
    If I use the whole internals then presumably I don't need to use the PVC for the spacer, the VTR is standard fit. Change the spring to linear rate at 0.85kg/mm and possibly change the damper, K-Tech in the UK can provide the spring and the Valve. I believe the stanchions are identical in the length. I will check this next time I am in the Garage. The weather in the UK is terrible due to Storm Ciara now storm Dennis. Too dark in my garage to work without the door open.

    Thanks for the patience, info and the support.
     
  14. Terry Smith

    Terry Smith Member

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    If the VFR stanchions and the VTR stanchions are the identical length then I agree the installing the VTR dampers/caps/springs/spacers should end up the same as in the standard VTR. Whether that choice of springs/preload is ideal for you is anothe matter which is why I would encourage use of decent springs.
     
  15. Darth Vader

    Darth Vader New Member

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    Im pretty sure the firestorm stanchions are shorter than the vfrs. Different part numbers.
    Thats why everybodys not just bunging firestorm forks on vfrs.
    Stand to be corrected. Ive a pair of firestorm stanchions in the garage i could measure if youve got your forks apart
     
  16. OZ VFR

    OZ VFR Member

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    Nearly impossible to find after market springs that are the same length as the stock.
    So you will definitely need new spacer for whatever set up you use.
    Spring suppliers also will sell spaces that you will need to cut to length.
     
  17. NIBBLER

    NIBBLER New Member

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    VFR FORUM INFO



    Ok I have managed to graft the VTR internals and fork bottoms onto/into the VFR stanchions.

    Just to clarify a few things.

    1. Both the VFR and VTR stanchions have a hole in them at the lower end, but this isn't shown in the Honda schematics shown earlier on in this thread. These holes help lubricate the bushes as they slide up and down inside the fork bottoms.
    2. The VFR and VTR stanchions are exactly the same length.
    3. The VFR and VTR fork bottoms are exactly the same length. The VTR looks shorter because of the extra castings around it. However the bottom fork leg casting in the VTR for the stanchion is 10mm higher compared to the VFR, when measured from the base of the fork bottom. When measured from the centre of the axles this casting is 5mm higher up in Firestorm. ( Measurement A in sketch)
    4. With the axle inserted the top of the VFR fork lower is 5mm longer, (Measurement C in sketch), which means the length of stanchion protruding from the fork lower is 5mm longer, (Measurement D in sketch). This offsets the 5mm difference in the measurement in the fork lower casting
    5. The bottom of the VTR fork bottom when measured from the centre of the axle is 5mm longer. (Measurement B in sketch) . Overall length of the VFR and VTR forks is therefore the same.
    6. The VTR Cartridge assembly appears to be 8mm shorter when the damper rod is fully extended compared to the VFR, this includes the fork caps with preload set the same. I'm using all the VTR internals so gain rebound damping adjustments.
    7. I have upgraded the VTR fork spring for a K-tech item, 8.5w. Its 5mm longer than standard at 115mm. I have chatted with a VTR owner/racer who has upgrade the spring and he says that taking 5mm of the preload spacer is not necessary. I can check this when the bike is back together and I measure the sag. Oil height is 140mm from top with the stanchion fully compressed and without the spring. Oil is Motul 10w fork oil.
    8. Overall then the VTR fork and VFR stanchion combination is 5mm shorter than the VFR fork bottom and VFR stanchions when measured from the centre of the axle. How this will affect the handling remains to be seen but when its back on the road I’ll let you know.
    In the meantime its time to rub down and spray the fork bottoms to make them look like new.
    FORK SKETCH.jpg
    FORK CAP COMPARISON.jpeg DAMPER ASSEMBLY.jpeg
    FORK BOTTTOMS WITH AXLE.jpeg STANCHION COMPARISON.jpeg
    FORK LOWERS STANCHION CASTING COMPARISON.jpeg FORK TOPS WITH AXLE.jpeg
     

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