Damping Technology

[White trash]

Excuse my ignorance but how do the TTX cartridges differ? And can I be placed on the "I want some" short list please Robert.

[Shaun]

Bear in mind though that the pistons in these forks are for the old check plate mid valve system. And the top caps are oem which are a pain to work with compared to the Ohlins caps. All Ohlins cartridges for sportbikes are now delivered with ''bending shim stack'' mid valve type pistons, and base valves to match. So unless the very latest stuff is tested such a test would not be totally subjective. Time and technology is relentless.

OK OK, so do you want me to lend you a set of forks as well, so you can set up the very latest Ohlin's ( Now 95% owned by Ohlin's again) product you can supply for our test rider above?

Only trying to help the customer net work here to make there own opinion after a test report, from a stranger to you and me.

What would you like to do here Robert?

PS, just as well you never did fill yourself with illegal product stuff in your life ever mate, other wise you may not have made it eh Good on ya

[Shaun]

Bear in mind though that the pistons in these forks are for the old check plate mid valve system. And the top caps are oem which are a pain to work with compared to the Ohlins caps. All Ohlins cartridges for sportbikes are now delivered with ''bending shim stack'' mid valve type pistons, and base valves to match. So unless the very latest stuff is tested such a test would not be totally subjective. Time and technology is relentless.

Sorry mate, but just to clarify here, the Ohlin's fork caps you mentioned above, are they the style You showed me in your work shop the other day that were jamming/seizing up, if the exact Ohlin's tool was not used on them?

[cowpoos]

Max is in a position where he pretty much has to use a check plate, using a 20mm cartridge and a 12.5mm damper rod the pressure drop across the rebound piston is far greater than with a 25mm cartridge and a 12mm rod, this pressure drop makes the piston more susceptible to cavitation if a mid valve shim stack is used.
The oem manufacturers can get away with a light stack as they use a 10mm rod and add bleeds to the piston so cavitation doesn't become an issue.
The 25mm cartridge has a much larger area and swept volume, the larger area means that to achieve the same damping force less pressure has to build in the cartridge so there is less pressure differential across the piston so a shim stack could be used without the risk of cavitation. The much larger swept volume means that the ports need to be much larger to achieve the desired flow rate and that the shims will have to deflect further to give the desired increase in valve open area. Shims are only effective at low lifts beyond this their bending characteristics change, so here a check plate can also be desirable.
Adding a shim stack to the midvalve increases the overall damping coefficient of the forks, to prevent the forks becoming too hard often the base valve then needs to be softened to compensate. Softening the base valve can lead to having a less powerfull compression adjuster.
You can't soften the base valve too much or add too much stiffness to the midvalve as it then becomes difficult to build pressure in the cartridge, this can lead to a pulsing in the cartridge at the top of the stroke. As the forks start to compress there is insufficient air pressure within the forks so the rebound piston instead of flowing through the oil pushes a slug of oil in front of it, the base valve faced with 4 times the volumetric flow rate it's designed for generates 16 times the resistance, the forks stop for a fraction of a second then the midvalve opens, the pressure drops and the above is repeated, if your hard on the brakes the forks will continue to dive the internal air pressure will rise and the forks will start to work efficiently. If you'd just brushed the brakes to check your speed you'd feel this pulsing through the bars, this was very common when Ohlins were using a massive stack of wave washers or a real heavy duty check plate spring.
The strong point about a 25mm cartridge tends to be they offer more support on the brakes, at these shaft velocities the overall damping coefficient of the 2 stacks really kicks in, providing of course that's what you want. How riders like the forks to compress on the brakes varies as much as braking styles, some riders like to brake progressively others like to wait till the very last second then grab a huge handfull of brake. Some riders like the forks to compress quickly and load the front tyre so they can get maximum feel and turn in real easy, others like a slower dive with the forks operating higher in the stroke through the turn. A lot of riders don't know what the hell they want they just use what the guy is winning uses, sometimes this is a backward step as often the guy who is winning usually has the talent to ride around on anything.

Phew, I somehow managed to write all that without being an importer of the top 3's products, how the hell did that happen.

Actually Id like to see Max answer that one as it is the best description I have seen yet re the 20mm versus 25mm schools of thought, especially with respect to pressure balance.

My description of how you become conversant with suspension to a high level ( that you have clearly demonstrated ) cited clear examples of one route to do so. Add to that time overseas ( for example ) with top level race teams, not as a ''parts fitter'' but clearly involved in the deep end of working with suspension internals. This takes considerable time and years of hands on experience plus a ''touch'' that is focused towards very pedantic assembly precision. Not a job for those with a sledgehammer and ''she'll be right'' mentality. Doing a course or two does not make one an instant suspension guru.

As Ohlins has very large prescence and respect in the racing world I am assuming that you have worked with it overseas?

okay boys.....how about some pictures.... you just can't find a picture or schmeatic of a midvalve,etc on the internet!!

this is a brillent tech article...keep it up guys. very interesting!!

ps: robert...why is it the the TTX system doesn't allow for high speed adjustment externally...is the engineering to hard?

Pps: its obvious in WSBK,BSB,MotoGP,AMA etc that ohlins have gas cartridge front forks,because of the external gas resivors...are Showa,whitepower,etc use gas cartridges as well?? or just high end forks with normal [but obviously high end] cartridges inside?

[Mental Trousers]

.... lots of technical stuff ....

Phew, I somehow managed to write all that without being an importer of the top 3's products, how the hell did that happen.

Geek

I'd also like to say it's a pleasure having Robert, Max, Shaun & JD Racing here. This is one of the few threads where I've read every post and been fascinated by the entire thread. It's fantastic stuff.

[Robert Taylor]

Sorry mate, but just to clarify here, the Ohlin's fork caps you mentioned above, are they the style You showed me in your work shop the other day that were jamming/seizing up, if the exact Ohlin's tool was not used on them?

Yes, but what is your point? I will let readers draw their own conclusions.
BTW, an adjustable pin spanner does the job and in any event undoing a fork cap irrespective of brand should be done at the fork cap, NOT the preload adjuster. Much of the oem stuff can also jam in such a way with a ham fisted approach.

[Robert Taylor]

Geek

I'd also like to say it's a pleasure having Robert, Max, Shaun & JD Racing here. This is one of the few threads where I've read every post and been fascinated by the entire thread. It's fantastic stuff.

I wouldnt neccessarily count on Max posting prolifically as he is a busy man and is probably well over some of the nonsense and brazen mind games that can go on. ''JD'' has certainly offered some stimulation.

But hey thanks. My workload is about to go ballistic so posts will be sporadic.
One point of interest is that I have been contracted by Ohlins to help with World Superbike and Supersport pre season suspension tests at Phillip Island early next month. Any points of interest that I pick up on that are not subject to embargo I will post.

[Shaun]

Yes, but what is your point? I will let readers draw their own conclusions.
BTW, an adjustable pin spanner does the job and in any event undoing a fork cap irrespective of brand should be done at the fork cap, NOT the preload adjuster. Much of the oem stuff can also jam in such a way with a ham fisted approach.

Simply curious to the fact, that is all Rob, Relax mate, you are far to young to be so stressed dude

[Robert Taylor]

OK OK, so do you want me to lend you a set of forks as well, so you can set up the very latest Ohlin's ( Now 95% owned by Ohlin's again) product you can supply for our test rider above?

Only trying to help the customer net work here to make there own opinion after a test report, from a stranger to you and me.

What would you like to do here Robert?

PS, just as well you never did fill yourself with illegal product stuff in your life ever mate, other wise you may not have made it eh Good on ya

1) I fit the upgrade parts and charge you the going rate which I think would be around $800 to $90 all up. I.e you pay. I throw the old parts in the bin.

2) You then lend the forks to the guy foc.

i.e this is very similiar to the deal you had with me for many years, I paid for the bits and labour, you used foc.

I have sold LOTS of these cartridges and therefore have no reason to expend more time and money to prove further.

Yes a clear head is indeed an asset.

[Mental Trousers]

I wouldnt neccessarily count on Max posting prolifically as he is a busy man and is probably well over some of the nonsense and brazen mind games that can go on. ''JD'' has certainly offered some stimulation.

But hey thanks. My workload is about to go ballistic so posts will be sporadic.
One point of interest is that I have been contracted by Ohlins to help with World Superbike and Supersport pre season suspension tests at Phillip Island early next month. Any points of interest that I pick up on that are not subject to embargo I will post.

I've had an email from Max saying as much. Still, he's extremely knowledable and articulate so his input, sporadic as it may be, is definitely welcome.

Look forward to hearing what the big boys are doing with their suspension at Phillip Island. It's an interesting track; high speed but bumpy with some steep changes in height and a couple of very slow, technical corners.

[Robert Taylor]

Simply curious to the fact, that is all Rob, Relax mate, you are far to young to be so stressed dude

Maybe you are far better at comedy than me, it is the ham fisted approach of many that is the stress raiser.

[DEATH_INC.]

okay boys.....how about some pictures.... you just can't find a picture or schmeatic of a midvalve,etc on the internet!!

this is a brillent tech article...keep it up guys. very interesting!!

I'm with Poo's, I need a pic/diagram to get my head around what it is excatly you are describing.....

[Coyote]

You first have to become a distributor of a leading suspension brand ( there are only 3 ) after years of learning the basics and proving yourself. You work at it for a decade or two. You spend literally tens of thousands of dollars in overseas travel to attend seminars. Such seminars are in depth distributor level, not something you can just buy into.You develop a very good relationship with the engineers. You must not be afraid to do very long hours and to test many things that wont work so well, but learn from it. You totally stay away from illegal substances that slowly destroy your brain.You invest 100k or so in test equipment and tooling to provide a full and proper service.

This doesnt happen overnight. Like Max said this is not black magic, but it is a lot of hard work.

A uni course in fluid dynamics would be a good start, but the real rewards are overseas.

Well I haven't been doing drugs at least, that's a start. Don't quite have the cash to go to the South Island let alone anywhere else across water

I might read some stuff on wikipedia to get a vague idea...

[Shaun]

1) I fit the upgrade parts and charge you the going rate which I think would be around $800 to $90 all up. I.e you pay. I throw the old parts in the bin.

2) You then lend the forks to the guy foc.

i.e this is very similiar to the deal you had with me for many years, I paid for the bits and labour, you used foc.

I have sold LOTS of these cartridges and therefore have no reason to expend more time and money to prove further.

Yes a clear head is indeed an asset.

100% Agree to all points!

apart from the old parts in the BIN!

They are bloody good parts, and I just cannot do it, some one will be extremely happy with them, when I move them on for the same cost as standard ( Original) set up I will representing in the very near future

How about I just supply you with the same forks, that you know I have with the above Kit I have spoken of, (which is great)

And you Just Fit! the latest spec Ohlins COMPLETE Kit, that you can, which you own! and get back after rider has hooned for a week? and then YOU FIT the next KIT? ( FOC)

Which will be my own cheap add hock bush fit parts, but worth a laugh mate

[soundbeltfarm]

who are the big three you.s talk about?

and who is jd racing ?