Damping Technology

[TDC]

What I'm looking for is someone to give me a proper technical explanation of why I should drop that amount of dollars on a new shock, not just spend the money and you'll arrive at the promised land.
Perhaps if you have one you can enlighten me a little.
I read in a magazine a quote from Ohlins press office about how when Rossi first tried the shock he didn't want it taken out of his bike... that was it, nothing else, we'll overlook the fact that it's a completely different shock, but to me my first question would be WHY???
What does it do that the previous shock didn't?
What can I expect to feel during the transitional phases of a turn?
How will it impact upon my tyre conservation during a race?

My questioning so far has led me to believe that it's a very sensitive to tyre choice with a poor range of adjustment, prove me wrong, give me a good reason to lever these dollars out of my pocket before the wife spends the money on shoes.

When I first put a TTX36 on my ZX10 last year (displacing a very well sorted 46 PRXLS) I was immediately impressed, actually stunned would be a better description.

As for the technical reason, the method of operation suggests that because of the full flow design this shock will build damping faster, that is with a smaller amount of shaft travel. I have seen you quite rightly point out if the shock has bleed it can't have instantaneous damping (not to mention compressibility of the working fluid etc). While it has bleed like a (dare I say) conventional shaft displacement device when you think about the percentage of flow that goes through the bleed assembly on this style of shock to the percentage of flow on a TTX bleed, the TTX has a significantly lower percentage of bleed.

Lets face it on a conventional shock the piston moves in response to a bump and a shock wave of fluid hits the comp adjuster making it swing open (hence the mandated small flow rates of this part of the device) it chokes and all the while not much damping has happened. Next as pressure builds the big and relatively heavy compression stack opens on the main piston as it can finally overcome the oil film attraction / stick of the shims against the piston surface and inertia then pressure on the top of the shock drops fast. Next assuming that the shaft is a reasonable size the displacement of this once again builds pressure in the top of the shock and it sort of falls in to equilibrium eventually after a few pressure spikes which are obviously reflected in the observed operation of the damper.

On the TTX all of the fluid (the same as the conventional as it starts to move) displaced by the piston is applied to the single compression circuit. (that by the way flows through the rebound bypass to make it to the other side of the main piston meaning that the dead stroke between compression and rebound is greatly reduced) Hence the damping builds very fast, far faster than the conventional designs without the sudden drop off as the other circuit starts to work. This faster build of damping and its stability has a big effect on a motorcycle with its poor sprung to unsprung weight ratio.

Theory is wonderful, but how does it work in real life? I found that the TTX gave simply unbelievable results on poor road surfaces, in fact the worse the road surface the better the TTX performed! On really smooth road sections its better but seemingly not by a whole lot, but the moment you encounter bumps, even small ones the difference is huge.

Tyre life increased more than a little bit! I get about 30% improvement in trye life (Metz Race Techs) over the aforementioned 46PRXLS.

What can you expect to feel, well pretty much nothing. The characteristics of the shock are so neutral its odd at first, which very quickly turns to increased levels of confidence after just a few corners. It just sticks, at first I though it was lacking feel, it wasn't it just had more traction available everywhere it took awhile to re find the improved limits of adhesion.

Its useful range of rebound adjustment for a given bike spring etc combination is small. But at the same time this wasn't really a complaint just an observation. Then useful compression adjustment range is very wide, and importantly rather linear as well.

Is it sensitive to tyre choice?, sort of but less so than conventional shocks. They as supplied are very adaptable, however if you are prepared to loose some of the adjustment / adaptability range and optimize if for a particular trye construction (read Dunlop v's the rest pretty much) there are small but useful gains to be had.

These things out of the box sans a change of spring if required are really very good indeed. Would I have any hesitation in recommending a TTX36, none....

[JD Racing]

We really have no cost reasonable mechanism for adjusting the basic characteristics of the shim stack piston combination. We can adjust the low speed response by the bleed adjuster to a point, but we quickly end up in the undesirable place of having to compromise the damping response at one shoft speed to effect the target area, not ideal.

Hence we are forced regardless of brand of device to re-valve to suite the rider (including weight, height, what he she had for breakfast, style, and sometimes how they are feeling on the day), tyre, machine (including geometry, linkage ratios, weight distribution, etc) track, and conditions.....

A couple of very good posts TDC, this one and the riding impressions one were very stimulating for the brain, thanks for taking the time to write them.

I don't know if you have had much to do with Penske or Maxton/Koni shocks but their high speed adjuster does change the shim stack characteristics. The Penske is a far nicer and far easier to use, the adjuster working on a shim stack in the reservoir, the Maxton adjusts the preload on the main piston. The Penske adjuster works in the lower of the highspeed range so that at certain settings there is some overlap, this overlap area is particularly usefull allowing you to tune the two together to find a setting that may have required a revalve with another style of adjuster.

[JD Racing]

no that would be your selective comprehension...


I think maybe...your either taking the piss...or your trying to discredit people?

Robert believes in the product he imports and see's it as being the future with regard shock technology. I'm a born skeptic but can appreciate the technology involved in the TTX, there is information I need in order to believe that the old style of shock is flawed to the extent it needs a complete redesign and if it is then this is the way forward. Luckily for us all Robert has taken the time to share information with us, nobody representing any other manufacturer has made the effort. I've learn't a considerable amount from our exchanges, and I'm quite sure that asking questions or making points that stimulate debate does not discredit anyone.

[Robert Taylor]

A couple of very good posts TDC, this one and the riding impressions one were very stimulating for the brain, thanks for taking the time to write them.

I don't know if you have had much to do with Penske or Maxton/Koni shocks but their high speed adjuster does change the shim stack characteristics. The Penske is a far nicer and far easier to use, the adjuster working on a shim stack in the reservoir, the Maxton adjusts the preload on the main piston. The Penske adjuster works in the lower of the highspeed range so that at certain settings there is some overlap, this overlap area is particularly usefull allowing you to tune the two together to find a setting that may have required a revalve with another style of adjuster.

I too thank TDC for the effort he has put into his posts. It is as well to remind that on the TTX design the external compression adjuster is not regulating flow into the reservoir, as it would on a conventional shaft displacement damper. Shaft size is 14mm so it displaces a lot less fluid than say a WP 18mm or Penske 5/8 inch. And there are no pressure balance problems inherent in ''flow regulation into the reservoir '' designs.
I am well aware of the overlap between low speed and high speed settings on the Penske, and therefore how you can shape the damping curve below about 250mm/second. But the reality is that unless you have a very knowledgable suspension technician to hand with lots and lots of setup experience and ( preferably ) a dyno to have tested and thoroughly understood how you can manipulate same then it is just not a holy grail. To that end I can well remember Shaun being troubled in understanding how this worked at a race meeting and coming and asking me several times. I also dont favour the rebound action with this design and I believe that Ohlins have the best rebound damping response in terms of finding off corner traction. While its an oversimplification to say so, off corner traction is all about rebound.
The race car specific TTX40 has 4 external adjusters i.e low and high speed compression plus low and high speed rebound, plus a valving reference program. The external response range is fantastic, but even then there are alternative internal setting parts, this gives over a million possible setting combinations. To get the very very best out of it you need top level datalogging and technicians that can understand it. There is only one set up like that here in this pacific basket case, Carl Hansens TVR Tuscan race car.
You mentioned in a previous post the Ohlins TT44, another lovely piece of kit. It had 3 compression adjusters, a ''true'' low speed adjuster, mid speed and high speed. The low speed adjuster worked exactly like if you had a range of main shaft bleed jets, except you could quickly twist it a few clicks externally instead of laboriously lifting the lid on the shock, changing the jet and rebleeding it. Or in the case of a Penske, disassembling it and drilling another bleed hole in the piston! Meaning you need at not inconsiderable expense spare pistons. Lets also not forget that with EVERY brand of shock you need to revalve and respring acording to customer height weight and speed, to suggest otherwise would be mischievous and misleading. A 5 foot 60kg rider is going to require something quite different to 6 foot 110 kg.
Here in NZ we also race through the winter in conditions of very low grip placing an emphasis on ideally being able to optimise very low shaft speed bleed. And I will re-emphasise, with a conventional shaft displacement shock that means pulling it apart and (relatively quickly) changing a shaft bleed jet, drilling the piston or changing the piston. As the ''nose'' of a damping curve is primarily effected by internal bleed size the external low speed adjuster has very little effect and is in reality a mid speed adjuster.
EXCEPT TT44, TTX40 and in a similiar way TTX36. If you were only allowed 2 external adjusters on that TT44 it would be a no brainer, rebound and that wonderful very low speed compression adjuster, analogous to being able to externally adjust internal shaft jet size. Wonderful for quickly adjusting damper response for low grip/ wet track conditions etc.
Interestingly I offered one of these dampers to Shaun several seasons back and he for whatever reasons didnt commit. Craig Shirriffs subsequently embraced the concept and comprehensively won a 600 title with it.
The TTX36 also has similiar low speed damping response and as stated previously is just going to get better and better whilst the development budgets in other camps appears to be a little stagnant.
In a weeks time I will be contracted by Ohlins to help with World Superbike pre season testing. We will see how different the stuff is that is used by these teams.
For the road race Nationals we will have 3 technicians to hand to look after our customers, that is an important part of the equation.

[JD Racing]

I'm personally very interested in the electronically mapped shock that WP are working on, they have a gps system which tells a control unit exactly where the bike is on the track and then via an electronic control valve adjusts the shock accordingly.

[cowpoos]

GPS is give or take 3 foot acurate...and not in anyone direction...I would hate a major damping change happening at the wrong time...in fact that sounds dangerous!!

[HDTboy]

I'm fairly sure there are differing levels of accuracy amongst GPS systems, Poo.

That sounds like an interesting concept. Why haven't motorcycle suspension manufacturers gone down the road of varying viscosity fluids? Such as in the Ferrari 599 and C6 Corvette?

[JD Racing]

I'm sure they don't intend using that one sensor in isolation, just as you wouldn't solely use a throttle position sensor to control your fuelling. Were you to also use parameters from the throttle position sensor, brake pressure sensors, gyro, fork and shock pots I'm sure you could make it pretty accurate after all Moto Gp bikes use a similar system to control fuelling for each corner.

[Shaun]

GPS is give or take 3 foot acurate...and not in anyone direction...I would hate a major damping change happening at the wrong time...in fact that sounds dangerous!!

So, do you not like it when your stearing damper does it job then? ie, a major change in damping

Stearing dampers work well when they do not fall off ( Because fitted wrong) or brake

[cowpoos]

I'm fairly sure there are differing levels of accuracy amongst GPS systems, Poo.

ummm...yep I'm sure there is...but the USA military arn't very well known for sharing their toys...



but as it stands 3 foot is pretty good acuracy for a GPS system

[Shaun]

I'm sure they don't intend using that one sensor in isolation, just as you wouldn't solely use a throttle position sensor to control your fuelling. Were you to also use parameters from the throttle position sensor, brake pressure sensors, gyro, fork and shock pots I'm sure you could make it pretty accurate after all Moto Gp bikes use a similar system to control fuelling for each corner.

Hey, can you go and teach the rest of the GP paddock about this wonderfull electronic age we now live in, we might just see them going a bit quicker, safely.

[cowpoos]

I'm sure they don't intend using that one sensor in isolation, just as you wouldn't solely use a throttle position sensor to control your fuelling. Were you to also use parameters from the throttle position sensor, brake pressure sensors, gyro, fork and shock pots I'm sure you could make it pretty accurate after all Moto Gp bikes use a similar system to control fuelling for each corner.

yes...A similar system to how the fueling/ignition on MOTOgp bikes work would be good...but would reliy on interacting with the bikes ECU? so would have to be brand specific I suppose?? Havn't other companys gone down the path of electronicly varible suspension on motorcycles before??

[JD Racing]

a 10s search on google brings up:

http://www.racelogic.co.uk/?show=VBO...ts-Basestation

[Robert Taylor]

So, do you not like it when your stearing damper does it job then? ie, a major change in damping

Stearing dampers work well when they do not fall off ( Because fitted wrong) or brake

And you know VERY VERY VERY well that the steering damper fitted was the WRONG WRONG WRONG one for the bike and therefore had clearance issues lock to lock and the fitting geometry and therefore effective damping force was incorrect. Your supplier / purchaser and fitter at the other end of the world should have been aware of same and I personally pointed out as much to you.
If you are going to play games like this it wont be too long before you need to seek legal counsel to defend yourself in a libel suit. As there will be residual anaesthetic in your system from your horrific ordeal I will overlook this very mischievous outburst.

[Robert Taylor]

yes...A similar system to how the fueling/ignition on MOTOgp bikes work would be good...but would reliy on interacting with the bikes ECU? so would have to be brand specific I suppose?? Havn't other companys gone down the path of electronicly varible suspension on motorcycles before??

Yes, you will see new generation electronic aids on Ohlins suspension units for motorcycles in the not too distant future.
As so often happens electronic aids can often owe more to marketing than true function, and to that end some of the electronically assisted steering dampers on modern sportbikes owe more to marketing.