Ohlins 30mm Cartridge Kit

[slowpoke]

I see K-Tech in the UK have put out a kit for the GSX-R1000 K9 onwards...
Converts the BPF to one side comp, one side rebound.
Looks like this is the new trend

It's funny how this is splitting of the functions between left and right legs is seen as a radical advancement when all it comes down to is KISS: Keep It Simple Stupid. Why have the complexity and associated cost of manufacturing cartridges that incorporate both functions when a simple effective solution is to split the functions and manufacture 2 different simplified components. Sounds like good engineering and business practice.

[Robert Taylor]

It's funny how this is splitting of the functions between left and right legs is seen as a radical advancement when all it comes down to is KISS: Keep It Simple Stupid. Why have the complexity and associated cost of manufacturing cartridges that incorporate both functions when a simple effective solution is to split the functions and manufacture 2 different simplified components. Sounds like good engineering and business practice.

Seperate duties for each leg has been around for a while in a number of forks, its nothing new. But it is now embraced more and more in the racing world. For poor buggers like me its great, total time to revalve ( for example ) a compression fork 15 minutes, and it doesnt have to come out of the bike.
We spend our time doing this work, less time talking.

[Yankee Doodle Dandy]

A 30mm piston for any given movement displaces about 44% more fluid than in a 25mm system.

Where these fork cartidges are not a threw rod design, how is it displacing 44% more fluid with the same size damping rod?

[Robert Taylor]

Where these fork cartidges are not a threw rod design, how is it displacing 44% more fluid with the same size damping rod?

Ill rephrase that sorry, what the bigger piston size is pushing......

[Yankee Doodle Dandy]

Since JD mentioned them -

K-Tech has a new major US distributor and some US teams have partnered with them. It will be interesting to see how things go as the distributor has traditionally has been a drag racing type of business but is branching out to all disciplines of racing.

While I could be wrong, I do not expect any type of real trackside support for K-Tech in the US at this time.

I did find their cartridge offerings to be interesting though:

Sealed cartridge
31mm control pistons
20mm displacement pistons
8mm damping rod

8mm damping rod is smaller than anything else out there to my knowledge.

With the specs listed I am wondering if the cartridge is similiar to a twin chamber cartridge with the smaller cartridge mated to a larger section where the "control valve" is located.

While not as edu-ma-cated as others, I am wondering if they used a 20mm cartridge for quicker response with the larger valve.

Kind of funky looking -



I see the top of the cartridge has an o-ring on it which makes me think that the cartridge seals itself against the inside of the fork wall and the they must use a seal at the damping rod like an Ohlins gas charged fork/dirt bike forks.

From the Daytona pics I saw this morning the two small red parts replace the compression adjusters as plugs as they fit flush.



The spring preload adjusters are two different colors so I am thinking one fork handles compression with the other configured for rebound.

[BMWST?]

Seperate duties for each leg has been around for a while in a number of forks, its nothing new. But it is now embraced more and more in the racing world. For poor buggers like me its great, total time to revalve ( for example ) a compression fork 15 minutes, and it doesnt have to come out of the bike.
We spend our time doing this work, less time talking.

the forks on my ol 1989 r100gs (marzocchis) have rebound in one leg and comp in the other

[Pixie]

This jar theory.................by fitting bigger cartridges, that doesn't mean the air volume is suddenly bigger does it, less oil maybe but the missing oil is taken up by more hard parts.................so instead of half emptying the jar, we are putting a solid in to lessen the fluid volume, now shake it and there won't be much difference.

Surely a one way valve with larger return ports would cause alot less cavitation than a two way system, and also cause less frictional heat build up as a by product, thus remaining more stable temp wise.

Do seperate damping cartidges compensate for not being pressurized because of the much lessened oil disturbance from smaller 2 way valving forces.....................?

True cavitation in suspension dampers is not mixing the gas above the damping fluid with the damping fluid.Cavitation voids are mechanically created vacuum cavities and/or cavities containing vapour of the fluid under the mechanical stress.This happens because the fluid was mechanically depressurised below it's vapour pressure.And this is why gas pressurisation reduces cavitation

[Robert Taylor]

True cavitation in suspension dampers is not mixing the gas above the damping fluid with the damping fluid.Cavitation voids are mechanically created vacuum cavities and/or cavities containing vapour of the fluid under the mechanical stress.This happens because the fluid was mechanically depressurised below it's vapour pressure.And this is why gas pressurisation reduces cavitation

Well said, many fork designs are right on the ragged edge of cavitation and Ive seen a few setting changes carried out that have tipped them over that edge. Very aggressive settings can end up being softer as cavitation is huge.
Gas pressurisation does indeed minimise cavitation, but the amount of pressurisation required is also indicative of how well pressure balanced the unit is. When we are talking shocks its not uncommon to see a pressure of 20 bar in a single tube emulsion shock that lacks an internal base valve and has a very stiff rebound stack to control firm spring rate selection. At the other end of the scale Ohlins TTX36 run at only 6 bar. Ohlins TTX gas motocross fork cartridges run at 5 bar.
The higher the gas pressure you have to run the greater the seal friction can be, something that is often not accorded too much importance.