Forks

[youngy]

"Revalved" stock fork. As a damper rod fork can only be "revalved" by enlarging or brazing up and redrilling the fixed holes and/or changing oil weight treat suppliers of this service with caution.

"Revalve" is a generic term. People offering this service can either be trusted or not, usually following a recommendation from someone having experience of their services. There are suspension gurus that can make a damper rod fork work very well.

Upgraded internals with stock forks. Splits into three categories.
a) Upgrades to the damper rod. Racetec from the USA and I belive K-tec from the UK offer competing versions of the same concept. The stock damper rod has the compression holes drilled to offer no resistance and a replacement valve is placed between the spring base and the top of the rod. This valve operates in the same way a valve in a cartridge damper lowering resistance (damping) as shaft velocities rise.
b) Replace damper rod with a catridge kit. A company in the USA ( http://www.Traxxion.com ) offers complete cartidge kits for the SV650-41mm damper rod fork like the TRX. Expensive at over $us1000. Ohlins and WP do not offer kits for the TRX.
c)Thundercat/YZF600 front end. Easy swap. Adds proper cartridge dampers with adjustments for way less than any other alternative but still will neet to be resprung and revalved to suit TRX. Maintains geometry,speedo, clamps, wheel, mudguard. Looks stock for those with insurance and or enforcement issues. Supply of straight front ends not good in Oz.. better in UK.

Any more ideas out there?

DFH

a) I wouldn't trust K-tech. They messed me about and cost me a fortune on a set of forks. They also made a shit job of it. Others, however, have had better experiences.
With a Race Tech valve emulator you lose the ability to adjust rebound damping.

c)Cat front end needs spacers machining up for the TRX front wheel. TRX mudguard isn't a direct fit on the Cat forks. You could use FireStorm forks too.

Think I'll go iron my underwear now.

[slow codger]

Thought Firestorm were 43mm?

Dave E

[youngy]

Mais non. they are 41mm. but they have no compression adjustment.

Some CBR600s and VFR750s had 41mm RWU cartridge forks. Also early ZX-6Rs.

[slow codger]

Yep agreed, how easy is it to retain the TRX front wheel?

Dave E

[cheesie]

diz ohlins springs + ohlins oil = ohlins internals

[dfh]

"Revalve" is a generic term.

.. used by by the less honest to attract the less informed. There are no valves in a damper rod fork. As you pointed out the skilled can recalibrate a damper rod to good effect, by altering the resistance values at a given shaft velocity. But the resistance curve, a simple expodential curve, remains the same shape with its tendancy to hydraulic lock at higher shaft velocities.

The function of variable resistance valves in hydraulic dampers is to modify the shape of the resistance/shaft velocity curve, somthing that cannot be achieved simply by juggling hole sizes and oil viscocity. Adding regressive valves to a hydraulic fork changes the shape of the resulting curve with the aim of reducing resistance as shaft velocity increases allowing, in the case of front forks a high resistance at low shaft velocities -to control dive- and low resistance at high shaft velocities -like a square edged bump.

With a Race Tech valve emulator you lose the ability to adjust rebound damping.

This is true, but is not the big issue that it may at first seem.

Shaft velocity in compression is a function of the vertical acceleration of the wheel caused by the road surface. So as you can imagine this covers a huge range of values... enough to regularly reach hydraulic lock in a simple damper rod fork set to provide some control at low shaft velocities. The race tech emulator, like all valves, acts to delay this point until its outside the everyday operating range of the fork.

Shaft velocity in rebound however is primarily a function of spring rate. It does not matter how fast you put energy into a spring - a big hit or a long squeeze- it will always rebound at the same rate. What this means is once fitted to the bike there is a much smaller range of possible rebound shaft speed values. Match the oil weight to the spring, and even a simple damper rod orifice without adjustment can make a reasonable job of rebound damping. This is why top-end suspension often has high & low speed compression adjusters, but only one for rebound.

Thanks for the heads up on K-tech.

DFH

[kebab19]

Kooki,
I had thundercat forks fitted to mine - they are not quite a straight swap, but near enough.

Mudguard mounting points are in different places. You can use T'cat mudguards, or make up little metal plates for retaining the standard TRX mudguard.

Spacers. Once fitted, forks are not as wide at spindle end. You need spacers either side of wheel, just over 5mm thick.

Thats all, apart from the fun of sourcing them. Last set on the 'bay went for £221!

[Quan-Time]

yup. Im fairly sure its just a straight bolt in 100%.

i THINK the rear wheel is a straight bolt in aswell if you want matching wheels.

[youngy]

a simple expodential curve

wassat then?

[dfh]

a simple expodential curve

wassat then?

Sorry for the spelling snafu... try this. http://en.wikipedia.org/wiki/Exponential_growth

DFH

[youngy]

oh yes I'm aware of an exponential term, just wondered if this was something new and clear

[dfh]

oh yes I'm aware of an exponential term, just wondered if this was something new and clear

No,.. just my subconscious desire to save wear and tear on the 'N' key... DFH