Race Tech pistons in stock cartridges

[JD Racing]

The rebound port size is to my mind really dialed on this piston as it doesnt place an over reliance on shimming to produce enough high speed rebound force, which often delivers an unwanted compromise in having too much low speed force. That as you know is a major flaw with the Traxxion 20mm rebound pistons, the port size is actually too big.

Would you therefore say that the rebound port on the Ohlins 20mm kit sold for the 1098 is too big then as it's an identical size?
http://www.hksuspension.nl/beheer/pd...web_ohlins.pdf

[Robert Taylor]

Would you therefore say that the rebound port on the Ohlins 20mm kit sold for the 1098 is too big then as it's an identical size?
http://www.hksuspension.nl/beheer/pd...web_ohlins.pdf

Its actually a 25mm upgrade piston kit to fit in the standard 25mm cartridges in the Ohlins kitted version of that bike. As you well realise the mass flow in a 25mm cartridge is different to that in a 20mm, for any given distance of movement. I feel Ohlins have got the rebound port size about right in that piston, as they have on the midvalve port size. Its the same piston fitted into the FGK cartridges and we have done a lot of work with the shimming on both faces of that piston with very stellar results.
We have now fitted a few of these pistons into 1098s and the improvement is huge. What the Italians insisted on as a production setting for that bike just doesnt cut the mustard, it blows through its stroke in the front and the rear link is little better than something they made to fit with a real abrupt ratio curve. The piston kit ditches / bins the original rebound pistons with checkplate midvalve and goes to ''bending shim stack type'' You actually dont need to purchase the whole kit as it sells you extra springs you dont require and the base pistons supplied are in function and flow terms almost identical to the original, albeit they are alloy with shorter length ports. Imagination and following the upgrade spec card sorts that out, but best left to an experienced road focused suspension engineer. Without exception every customer we have done this mod for has been over the moon.
With a little humility an assembly mistake I made yesterday whilst dynoing alternative settings made me abundantly aware how port size affects slope angle on a damping graph. I was working with the new Race Tech 25mm cartridges that employ bending shim stack midvalve rebound pistons. I inadvertently reversed one of the pistons whilst trying to multitask talking over the phone. The dyno graph showed a marked increase in compression slope angle and a markedly weaker rebound curve. I should perhaps have picked it up whilst I was bleeding that cartridge as it no longer felt pressure balanced, that indeed proves that there is not a huge safety window before you run into pressure balance issues.

[JD Racing]

Ahh I see, my mistake I had thought they were for the Showa forks, it's a shame they've not done more with their 20mm kits there would be a massive market for them were they to develop them more, although sorting out their delivery problems would be more usefull right now.

I've found that tiny ports have a huge impact on damping but it's surprising how small ports can be before it becomes all shim controlled in the speed ranges we deal with. Giving the shims an easy life seems to be more critical, 3 and 4 port designs allow the shims to fold easily but there are some 5 and 6 port designs out there that give some very harsh damping.

[Robert Taylor]

Ahh I see, my mistake I had thought they were for the Showa forks, it's a shame they've not done more with their 20mm kits there would be a massive market for them were they to develop them more, although sorting out their delivery problems would be more usefull right now.

I've found that tiny ports have a huge impact on damping but it's surprising how small ports can be before it becomes all shim controlled in the speed ranges we deal with. Giving the shims an easy life seems to be more critical, 3 and 4 port designs allow the shims to fold easily but there are some 5 and 6 port designs out there that give some very harsh damping.

Yeah, the images didnt really indicate size. As you may well realise the 20mm piston kits were basically one of the variations of the pistons that Ohlins used in their Superbike forks which employed 20mm cartridge size up until 98, prior to going to 25mm. These are essentially road race specific for relatively smooth European tracks but also work well on our tracks albeit with a little less sharp edge bump compliance than bigger port designs, They also give excellent rider feel. The rebound piston I believe is really dialed for both track and road as you dont have to have a really aggressive shim stack to deliver the required damping force when the forks are in the full closed position and about to rebound. If Ohlins were going to develop this piston it would be on my wish list that it is turned into a bending shim stack midvalve type. But in fact that is exactly what Race Tech have done and the rebound porting side of it is oh so close to the Ohlins piston.
Big port rebound pistons are in my always accumulating experience a nonsense. Rebound is primarily an event about controlling re-extension of the fork, as it re-extends the spring force it is regulating the return of such force that progressively lessens and lessens. If youve got big ports on such a piston you need an aggressive stack to get the neccessary high speed rebound force. As you will well realise it will then deliver too much low speed rebound damping force due to the compromises inherent in shimming. That will mess up top of stroke response and off corner mechanical grip. This is also another reason why I have suggested that we can improve Traxxion cartridges, by in part getting rid of that big port rebound piston which delivers too much low speed rebound force. A smaller port piston will require a much less aggressive and more responsive stack that will give the right amount of low speed rebound damping force. Less equals more! And the smaller port size will deliver the progressivity in force required for a rebound curve, to balance against the progressive increase in spring force as the forks are further and further compressed. Thats my handle on it anyway, if you have another way of ''skinning the cat'' on that one Id be interested.
I dont reccomend the Ohlins 20mm pistons for road use in NZ because we have a high percentage of bumpy roads. Again as you may well realise there was a preloading type Ohlins 20mm piston but it too had tiny ports. It is long since out of production. My wish list would be that this is made but with bigger ports with perhaps 2/3rds of the flow area of Race Tech. Interestingly I saw some Yoshimura pistons a few years back that were a close copy of the Ohlins pistons. As are the Traxxion compression pistons but with ports that I now think from ongoing experience are a little too large in size.

As for delivery problems I hear you loud and clear and I think in all fairness that very issue is currently frustrating a lot of manufacturers of especially goods that are an assembly of many detailed close tolerance components employing various alloys. There are doubtless myriad reasons why but I know that one of the main issues is that the lead times for ordering raw materials such as ferrous and no ferrous alloys has extended dramatically over the last 2 to 3 years. The culprit cited is that China is taking more and more of the production capacity of the steel and alloy manufacturers. I will probably get maligned for saying this but my take on it is that China is the number one producer of most of the worlds very low quality and outright junk products, for that reason Id be happier if they still only produced rice and firecrackers!!

I honestly dont expect that Ohlins will do any development on those 20mm pistons because it is only a very very tiny percentage of what they do and like any factory they prioritise what they do according to their finite resources in manpower etc. Believe me I have asked this very question!

Is the 6 port piston you refer to K-Tech?

And finally JD id like to say something complimentary in spite of my consistent protestations about your preferred anonymity. Its so pleasant to have a reasoned and serious discussion without deliberately mischievous interjections of pointless drivel. Lets keep it that way or ignore same with the contempt it truly deserves.

[JD Racing]

Interesting, rebound is something I've never had problems with, from feedback I've had it's the numb part of the system, I've experimented with the same stack on very different pistons with no comment on the performance, i've done the same with compressions and had a massive response. Some stock needles are bad and need replacing but that's about it rebound wise, I've not really had any issues driving off a turn that couldn't be addressed with geometry.

The old Ohlins style 20mm piston with bigger ports is out there and works really well.

The 6 ports bend the shims in 6 planes, I thought it would bend in 3 planes, the ports acting as pairs but the bend marks show 6 distinct planes, try folding anything 6 ways at once and it's hard work.

I often wonder whether China is really gobbling up the whole worlds raw material resources or if it's just a scam to scalp us?

[Robert Taylor]

Interesting, rebound is something I've never had problems with, from feedback I've had it's the numb part of the system, I've experimented with the same stack on very different pistons with no comment on the performance, i've done the same with compressions and had a massive response. Some stock needles are bad and need replacing but that's about it rebound wise, I've not really had any issues driving off a turn that couldn't be addressed with geometry.

The old Ohlins style 20mm piston with bigger ports is out there and works really well.

The 6 ports bend the shims in 6 planes, I thought it would bend in 3 planes, the ports acting as pairs but the bend marks show 6 distinct planes, try folding anything 6 ways at once and it's hard work.

I often wonder whether China is really gobbling up the whole worlds raw material resources or if it's just a scam to scalp us?

Well, I always thought for years that most of the pre-occupation was with compression events. But we continue to learn a lot about rebound, especially the shape of the curve and that is where you can find a lot of grip. I think my beloved Viking friends are well up on this and it is also conversant with their work with top out springs. That is another lengthy subject but too ''tiring'' to engage in for now! Maybe I should keep what I have learned about this to myself.

I hear what you say about those extra ports and the bending action.

And yeah there could be an element of blaming China as a convenient excuse. But the fact remains their huge consumption of raw materials is placing huge pressure on lead times. l think we should just stop buying their products, ideally.

[JimBob]

"ha haaa, I see this very same attitude......etc"
and nobody crashes when they have aftermarket suspension?
Little factoid for you..more people crash on racetracks when using aftermarket suspension cf stock suspension
(Just because 90% of them use aftermarket suspension doesnt make it less true)

"If stock suspension was as good and race bred as the manufacturers state then why do all the respective NZ champions race with top end aftermarket suspension e.g Robbie Bugden Ohlins front and rear, Dennis Charlett, Ohlins front and rear, Glen Williams Ohlins front and rear, Karl Morgan, WP. ?????"
Its all well and good associating after market suspension with winners but what you have failed to mention (understandably) is that 90% of the losers also ran aftermarket suspension. They could have lost just as well on stock suspension and saved some money in the process.

What this tells me is that it is the riders who make champions rather than their suspension.

I still stand by my assertion that if you cant push your stock equipment anywhere near the limit, then spending $1000's on upgrades is a waste of money and you would be better spending the money on learning to ride.
BTW I dont have a downer on aftermarket suspension per se, I have raced on ohlins, wp, showa, but in my opinion too many people get carried away with technology before they get the basics right. bling bling, keeping up with the Jones', hoping for an advantage, sucked in by the advertising,
But hey I have grey hair, what do I know.

I apologise for introducing such mundane matters to a serious discussion about port sizes, bending shim stacks and the lack of suspension investment by the manufacturers etc, so please treat this pointless drivel with the contempt it deserves.
Two's company, three's a crowd, so I will leave you and JD to your mutual stroking and depart!
adjö sir

[Robert Taylor]

"ha haaa, I see this very same attitude......etc"
and nobody crashes when they have aftermarket suspension?
Little factoid for you..more people crash on racetracks when using aftermarket suspension cf stock suspension
(Just because 90% of them use aftermarket suspension doesnt make it less true)

"If stock suspension was as good and race bred as the manufacturers state then why do all the respective NZ champions race with top end aftermarket suspension e.g Robbie Bugden Ohlins front and rear, Dennis Charlett, Ohlins front and rear, Glen Williams Ohlins front and rear, Karl Morgan, WP. ?????"
Its all well and good associating after market suspension with winners but what you have failed to mention (understandably) is that 90% of the losers also ran aftermarket suspension. They could have lost just as well on stock suspension and saved some money in the process.

What this tells me is that it is the riders who make champions rather than their suspension.

I still stand by my assertion that if you cant push your stock equipment anywhere near the limit, then spending $1000's on upgrades is a waste of money and you would be better spending the money on learning to ride.
BTW I dont have a downer on aftermarket suspension per se, I have raced on ohlins, wp, showa, but in my opinion too many people get carried away with technology before they get the basics right. bling bling, keeping up with the Jones', hoping for an advantage, sucked in by the advertising,
But hey I have grey hair, what do I know.

I apologise for introducing such mundane matters to a serious discussion about port sizes, bending shim stacks and the lack of suspension investment by the manufacturers etc, so please treat this pointless drivel with the contempt it deserves.
Two's company, three's a crowd, so I will leave you and JD to your mutual stroking and depart!
adjö sir

I sir also have grey hair and no hair but I also do detect in your writings an element of ''dumbing down'' and ''tall poppy syndrome'' now so endemic in this society. Please note that ( in all fairness ) my scathing reference to pointless drivel was targeted at some blatantly mischievous posts, I detected nothing mischievous in your posts.

Point of fact those that both get the basics right and embrace the advantages of technology have more show of rising to the top. Personally, I embrace those who strive to succeed and will help anyone at any level that both asks for help and strives to do better. ETC...

[JD Racing]

Jim Bob,
I've now locked and bolted the workshop doors, taken the sign down, first thing Monday morning I shall be in the welfare queue, I could no longer live with my conscience. All those people have had the cheek to call me of their own free will with handling and suspension problems and I've had the bare faced effrontery to sell those people things that in actual fact they have absolutely no use for, to all those owners of ZX10 and ZX6's whose kidneys no longer take a pounding, I'm very sorry, that wasn't in fact your kidneys complaining about a lack of compliance it was your lack of riding ability, take some lessons and you'll be fine.

[trustme]

S'cuse me while I pick myself up off the floor

[Drew]

The 6 ports bend the shims in 6 planes, I thought it would bend in 3 planes, the ports acting as pairs but the bend marks show 6 distinct planes, try folding anything 6 ways at once and it's hard work.

Testament to the quality of the materials to move so evenly.

I'm surprised to learn that they have bend marks at all though, my vision of them working was the outsied ring of the plates would move at the same time, turning the disk cone shaped while flexing.

[Drew]

"ha haaa, I see this very same attitude......etc"
and nobody crashes when they have aftermarket suspension?
Little factoid for you..more people crash on racetracks when using aftermarket suspension cf stock suspension
(Just because 90% of them use aftermarket suspension doesnt make it less true)

"If stock suspension was as good and race bred as the manufacturers state then why do all the respective NZ champions race with top end aftermarket suspension e.g Robbie Bugden Ohlins front and rear, Dennis Charlett, Ohlins front and rear, Glen Williams Ohlins front and rear, Karl Morgan, WP. ?????"
Its all well and good associating after market suspension with winners but what you have failed to mention (understandably) is that 90% of the losers also ran aftermarket suspension. They could have lost just as well on stock suspension and saved some money in the process.

What this tells me is that it is the riders who make champions rather than their suspension.

I still stand by my assertion that if you cant push your stock equipment anywhere near the limit, then spending $1000's on upgrades is a waste of money and you would be better spending the money on learning to ride.
BTW I dont have a downer on aftermarket suspension per se, I have raced on ohlins, wp, showa, but in my opinion too many people get carried away with technology before they get the basics right. bling bling, keeping up with the Jones', hoping for an advantage, sucked in by the advertising,
But hey I have grey hair, what do I know.

I apologise for introducing such mundane matters to a serious discussion about port sizes, bending shim stacks and the lack of suspension investment by the manufacturers etc, so please treat this pointless drivel with the contempt it deserves.
Two's company, three's a crowd, so I will leave you and JD to your mutual stroking and depart!
adjö sir

Definition of insanity; doing the same thing repeatedly, expecting a different result.
Your harping the same thing over and again doesn't make anyone take more notice of it, just less notice of you on the next topic.

Jim Bob,
I've now locked and bolted the workshop doors, taken the sign down, first thing Monday morning I shall be in the welfare queue, I could no longer live with my conscience. All those people have had the cheek to call me of their own free will with handling and suspension problems and I've had the bare faced effrontery to sell those people things that in actual fact they have absolutely no use for, to all those owners of ZX10 and ZX6's whose kidneys no longer take a pounding, I'm very sorry, that wasn't in fact your kidneys complaining about a lack of compliance it was your lack of riding ability, take some lessons and you'll be fine.

If you're gonna do a closing down sale, gizza list of stock eh?

[Pussy]

My take on suspension mods... as a road rider:
My K1 GSX-R1000... rebound adjustment was fairly ineffective, basically off/on. High speed compression.. like a jack hammer, hydraulic locked on me on one occasion(oil transfer ports in the compression pistons are very small) leading to an interesting front wheel slide.
I sought a solution from Robert (and,no, I wasn't trying to keep up with the Joneses) and a revalve and rebound needle replacement later had a front end feel I liked.
K3/K4 GSX-R1000... still undesirable to me damping characteristics, so initially a revalve, then gave AK20 cartridges a go. The compression damping was softened by RT to a road bias setting, and the rebound was left "as delivered". I hated the rebound characteristics of the AK20s. Too weak, and with short top-out springs (the flavour of 2004), they felt even worse... the front end would pogo up, especially in change of direction/elevation situations. I then decided to bite the bullet and go for a set of Ohlins cartridges. These worked VERY well for me. RT valved the compression side to my preference, and it was all jake. I transferred these cartridges to my K6 GSX-R1000 with the same results.
Fast forward to my present K6 GSX-R750. I left the front end stock for about 11 months. I did notice a lack of high speed rebound control in the stock Showas. Adjusted it out as best I could, but it was only a compromise, as it left the front end with a too lethargic low speed response. I did a trade with RT on the 1000 cartridges to a set for the 750. Robert and I tried a couple of different valving specs, and RT came up with the present one which I am delighted in.
Do I feel the money I have spent to be worth it? Very much so! My personal experiences with stock suspension is that most of the time it is a compromise. I would much prefer to ride on tailored (Taylored??) for me suspension. I'm no racer or trackday whiz, just an enthusiast. I do, however, appreciate having a suspension set up that works for ME, and gives a feeling of security.
Gassit Girl has the only set of Racetech G2R 25mm cartridges in NZ in her bike at the moment for evaluation purposes. She initially tried them "as delivered", found the settings not quite to her liking, so RT revalved them to mimic the rebound characteristics of the Ohlins gear in my bike (great piece of kit, that suspension dyno!). She is VERY happy with the results. Again, Gassit Girl is no gun racer... just an enthusiast, albeit a tidy riding one.
IMHO, why accept compromise in suspension, when the means are readily available to have the individual "made for you" set up? Stock gear has to cover so many unknowns, it's not possible to cater for the variables. It's not "must have bling", it's a matter of having a safe,trustworthy, confidence giving set up

[svr]

Do I feel the money I have spent to be worth it? Very much so! My personal experiences with stock suspension is that most of the time it is a compromise. I would much prefer to ride on tailored (Taylored??) for me suspension. I'm no racer or trackday whiz, just an enthusiast. I do, however, appreciate having a suspension set up that works for ME, and gives a feeling of security.

Theres a saying in moto-x that you can have too much power but you can never have suspension that is too good.
Now please no more questions for or baiting of RT so he can finish my shock. Ta.

[codgyoleracer]

"ha haaa, I see this very same attitude......etc"
and nobody crashes when they have aftermarket suspension?
Little factoid for you..more people crash on racetracks when using aftermarket suspension cf stock suspension
(Just because 90% of them use aftermarket suspension doesnt make it less true)

"If stock suspension was as good and race bred as the manufacturers state then why do all the respective NZ champions race with top end aftermarket suspension e.g Robbie Bugden Ohlins front and rear, Dennis Charlett, Ohlins front and rear, Glen Williams Ohlins front and rear, Karl Morgan, WP. ?????"
Its all well and good associating after market suspension with winners but what you have failed to mention (understandably) is that 90% of the losers also ran aftermarket suspension. They could have lost just as well on stock suspension and saved some money in the process.

What this tells me is that it is the riders who make champions rather than their suspension.

I still stand by my assertion that if you cant push your stock equipment anywhere near the limit, then spending $1000's on upgrades is a waste of money and you would be better spending the money on learning to ride.
BTW I dont have a downer on aftermarket suspension per se, I have raced on ohlins, wp, showa, but in my opinion too many people get carried away with technology before they get the basics right. bling bling, keeping up with the Jones', hoping for an advantage, sucked in by the advertising,
But hey I have grey hair, what do I know.

I apologise for introducing such mundane matters to a serious discussion about port sizes, bending shim stacks and the lack of suspension investment by the manufacturers etc, so please treat this pointless drivel with the contempt it deserves.
Two's company, three's a crowd, so I will leave you and JD to your mutual stroking and depart!
adjö sir

Of course we all strive to get into the last 10%, (& then the last 1%). The problem is that the aftermarket stuffgives you parts of seconds only per lap - but when compiled together this adds up to lots of seconds over the duration of a race, thus havin the desired effect ! (getting into the last 1% is still possible even for a codgy old slow bastard)