fork damper tube dimensions

[kblackburn]

Hi Guy's ,
Has anyone got their forks in bits at the minute, and could give me the dimensions of the damper tube,

length of tube, distance from the top of the tube to the top out spring collar, I have had my vfr forks in bits to fit vtr internals and mixed up the damper tubes, so need the vtr dimensions confirming.

regards

kev

[sirch345]

Kev,
Are you referring to item No3 in the diagram below



If so Roger Ditchfield's information below (in blue) should help you (by the way if you didn't already know, Roger D is a VTR guru)

The OEM Standard spring is 310mm long and the OEM steel spacer is 100mm.
If your spring was shorter than 310mm then they should have supplied a spacer tube for you to cut to length.
As there is no pre load in a standard fork on assembly if you have shorter springs then the bike will be lower at the front as if you had pulled the fork leg through the yokes. The maximum pull through I recommend for the road is 5mm to 7.5mm max. Racers or Trackday guys often go to 10mm on a TUNED fork. If your springs were less than 300mm in my opinion you are beginning to overload the front tyre and run an increased risk of the front end "washing out". I do recommend that you investigate this at the first opportunity if only to satisfy yourself.

Roger's quote taken from here:-
http://www.vtr1000.org/phpBB3/viewtopic ... h&start=15

HTH,

Chris.

[kblackburn]

Hi Chris,

no it's item no 12 with the top out spring, I had both the vfr and vtr forks stripped at the same time and I think I have assembled them with the wrong damper tubes, so if someone has the measurment;s for the vtr I can sort it out,

many thanks for your imput

regards

kevin

[popkat]

I would guess the VTR forks are shorter, so if you put the cartridge in with the VFR tubes you may only have the length of a VTR fork.

Why do you think you've assembled them wrong ?

[Cadbury64]

I've got some diassembled 1998 VFR800 dampers in my garage at home; let me know if you still need some measurements off these. I'm pretty sure that you can swap the dampers over between the VFR and VTR and have no difference in assembled fork length; I put VTR damper parts into my VFR with no length changes at all. It would be the position of the bottom end of the top-out spring that would make a difference if any. I can't comment on the length of the staunchion tubes however, these could be different and would make a difference to the fork length. The VTR fork cap is longer than the VFR so you will need a shorter spacer for the spring.

[kblackburn]

Cadbury64,

If you would be so kind to measure from the top of the damper tube to the collar for the top out spring, that would help, as I belive the position of the top out spring is different between the two models.
could I ask if you made any changed to the valving, did you use the vtr vales and shims ?

regards

kevin

[Cadbury64]

These are the measurements for VTR damper tube:

Overall length: 289mm
Bottom of tube to bottom of top-out spring: 162mm
Top of tube to top of top out collar: 98mm

I think the 162mm is the critical measurement; the inside bottom of the staunchion pulls up against the bottom of the top-out spring to determine the full length of the fork. If the bottom of the top out spring sits closer to the bottom of the damper, you'd have a shorter fork.

Regarding valving, I'm pretty sure the VTR and VFR use nearly identical stock shims and valve bodies. My view is that the stock compression valve is too restrictive, but the rebound valve is OK (but a bit light on shims). My VFR now has a RaceTech Gold Valves in the rebound position, and a Daugherty Motorsports compression valves (very similar to RaceTech). I run 2, 0.15 x 17mm main shims in compression, and 6, 0.15x17mm main shims in rebound.

Just to be clear, I re-used the VFR damper body, but installed the VTR damper rod/rebound adjuster/cap. No change in length with that set-up. I run 0.9 kg/mm springs in that.

I have also worked over my VTR's front end, I put some Showa 3-port face-bleed pistons in compression (probably out of a Suzuki but don't ask me which one) with a RaceTech C33 shim stack, and have the stock rebound piston with 3, 0.15 x 17mm main shims. I use 0.85kg/mm springs in that.

Hope all that makes sense, happy to clarify as needed.

[NZSpokes]

My K4 Bandit 1200 has the face bleed pistons.

[kblackburn]

Cadbury64,

you sir are a star,
thank you very much for your help, I will venture into the garage and sort it out.

best regards

kevin