OzVMX Forum
Clubroom => Tech Talk => Topic started by: ghostdancing on December 28, 2016, 04:14:02 am
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i'm tempted by these vintage aftermarket products.. do they work? are they affordable\durable? pros. and negs? looks like it's a technical way abandoned\aborted today (at least for offroad motorbikes).. at the end why?
availability and prices today?
i remember there was (in the 90s) an italian small factory named double system, that made some nice air shocks (mainly monoshocks for road racer bikes)..it disappeared some years ago.
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I had the KYB air shocks on my KX250A5, they worked good while it was a 250 but seemed underdamped after I fitted the 400 engine.
They have 3-way adjustable rebound damping; with a low air pressure setting, you compress the shock about 1" and then rotate through the three detents.
They have a low strength spring inside them; they work like a set of late 70's air-assist front forks; changing the oil height changes the rate of compression resistance, changing the air pressure changes both ride-height & spring strength (compression resistance).
I thought they looked cool, not sure if they were as refined as Fox air shocks, as I've never sampled them. I think I would like to have them in my rear suspension options, if I want serious race stuff I'd go for Ohlins.
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depends on what you are after - I had a set of Fox Shox - good when set up and "period correct" however are not as good as a set of modern Ohlins or Works Performance. So are you after looks or are they for a racer???
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Fox airs are bloody good. Their period popularity was no accident. They are fully rebuildable with all seals and the bladders easy to get; as is the comprehensive owners manual. Damping is controlled by a Holley main jet so revalving is a $5 diy if you are mechanical. The best thing about them is the ease of spring rate change. I have a set on one bike and am looking for another for my RM370 as a test alternative to Ohlins.
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In my current range of shocks , I have KYB air / Fox airs / Ohlins and Gazi they all have interesting features that make them different. Probably the best overall shock for all conditions are the Ohlins. Best for MX on my 77 KTM are the fox airs they seem to load the front tire and gives great feed back so you can carry more corner speed plus they resists big impacts better. They are shit on anything else and hopeless at trail ridding or Vinduro. The KYB look the coolest and fall somewhere in between but have no real stand out feature. The gazi are great as they are easy to buy and set up and have the best traction of any shocks I have used, the rear sticks like glue. They do bottom a bit to easy and kick on big braking bumps.They dont give the good front end feel.
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tnx guys for your opinion and experience; i do not race the bike, it's just because i'm searching a new pair of shocks for my bike, and looks like i have anyway to spend big money to get something nice: i admit that the correct look is one of the main issue for me.
i also have a muffler pipe clearance problem (right side shock upper mount).. do you know the max outer diameter of the shock body (upper finned section)?
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Sounds like you have a KLX?. It is do-able but you just need the taller top mounts like this.
Body OD is 68.40mm
(https://fhqjcw.bl3301.livefilestore.com/y3pukhSWZMKoBi_JrtmFbVETl6j-qxbbFgd0TRunu2cZgiDW1qV1nbRvhut-gXKJk5FQPoCbuHPVT-IssHr-9UlxoqOfS0eCbrnVLK_ZayCkJyDBQci09qo7YQwNHBKo8gWEZTeu_5LWI6jq-ABSdwVUny6OR4ETre_quWGjYSV6-g/klx_zps16c3b44f.jpg?psid=1)
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nice kawi in this pic.. my bike it's an XT250 with a KLX swingarm (twinshock conversion) and IT250 forks; tnx for the info.. probably the KYB are slight smaller diameter? (it looks so in the pics i have seen in the web..)
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The gazi are great as they are easy to buy and set up and have the best traction of any shocks I have used, the rear sticks like glue. They do bottom a bit to easy and kick on big braking bumps.They dont give the good front end feel.
Sounds like the spring rate is a bit soft and the rebound damping is not right. No front feel means too much weight on the rear end. Tried dropping the forks through 5mm?
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This topic keeps coming up on a nearly monthly basis by the same quality posters that either like posting LOL, or have agendas and have lots of time frequenting multiple forums. I composed this information to help the genuine readers, rather than seeking a confrontation with the experts above. I have set a bit of time aside to help form an opinion. . I have been involved in my capacity as R+D technician for nearly 30 years working and /or designing products for Techno Flex, WP, YSS and Promax. I have designed and improved a quiet few new products over those years. http://store.suspensionshop.org/information/ let me say this, it’s easy to knock products anomalously, but it takes knowledge to create a better product in function and price. I formed this philosophy over the many years in my job:
It’s unwise to pay too much
But it is worse to pay to little
When you pay too much, you
Loose a little money
When you pay too little, you
Sometimes lose everything
Because the thing you have bought
Was incapable of doing the things
It was bought to do
The common law of business balance,
Prohibits paying a little and
Getting a lot, it cannot be done
If you deal with the lowest bidder,
It is well to add something
For the risk you run
And if you do that, you will have
Enough money to pay
For the something better.
This is how we create a product:
First we need to know the demand and trend in that market. Then we can look at numbers that could be sold on an ongoing basis . (There is no point creating a YZ B/C shock in multiple numbers for stock ) .
What is needed to improve that model bike? What is the customer prepared to pay and what does the opposition offer .
Then we can choose from different materials and dimensions.
As a sample we use Evo twin shocks. The materials that we have today to choose from are Aluminium verses steel body, Chrome Silicon verses Piano wire, bladder verses dividing piston, ceramic verses sinter and titanium verses steel or aluminium .
For 80% of long twin shocks 12.5 mm hardened shafts work the best. If you go bigger, you get too much friction on the seals and if you go less they can bend the shafts. In order to make a shock externally adjustable, the shaft needs to be drilled all the way through and that adds considerable cost. Not also are adjustable shocks dearer to produce, you also loose valuable stroke and more things can go wrong So it’s a bit of a trade-off and at the moment adjusters are the inn thing. The most important adjuster is the rebound. That can be done in various ways. The most proven one is a needle and seat with different needle options. You should have at least 30-60 clicks of adjustment to warrant a big enough window. Unless it’s a self-adjusting high-low speed set up, compression adjusters can add a lot of confusion in setting up a bike. For simplicity reasons they are not always great and necessary. But the market wants them sometimes. Correct rebound damping and the spring to suit the rider’s weight are more important to the average user. The best solution for spring preload adjustment is a lock ring on a thread that gives you seamless choices. A fair bit dearer to produce than clips or cams, but much more user-friendly. Now to the old debate of Alum verses steel bore. Aluminium bodies are far cheaper to produce than steel bores with Alum ends. Aluminium bodies weigh a bit less than steel and can be colored with many options for bling reasons. The downside is they have much more friction and wear out in a shorter period. So for long life and better performance a polished steel bore is the answer. Of course the people that can only offer alum shocks, will deny that. We offer both type, but for the right application and price range. But when you do the Dyno test, you can’t argue with the curve. The Dyno curve on a steel body shock is so much better, they fade much later (because with less friction you get less heat and unnecessary wear) Also the oil on a steel body does not get contaminated (no contamination > no wear> longer life)
“What shocks to buy? “
As customer I would look for
Good quality steel body
Hyme joints both ends (bearings)
Pricing verses features and finishing quality
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Wasp, what was the point of that post? It is the same pro forma spiel you periofdically regurgitate. What is your professional opinion of Fox airs?
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Wasp, what was the point of that post? It is the same pro forma spiel you periofdically regurgitate. What is your professional opinion of Fox airs?
Been corresponding with the Author of the post , all clear and sorted . Thank you for input Mamas.
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I found Walter's words of wisdom very informative and good sound advice without the B.S., ive learnt abit more about shocks I didn't know before
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..here the autor of the post.. actually i'm looking for a good set of shock for my bike as during the building process i bought a set of that cheap chinese piggyback shocks, just to have some correct lenght shocks and carry out\testing the bike; now i need some "real" shocks.
i dont race the bike, just trail riding, no agressive\hard driving; the bike is also license plated and got front\rear light (they are period correct units..) as she is my daily drive on pavement too (sorry, there are also passenger footpegs: one of the duties of the bike it's pickup the daughter at school).. but they are small and well hidden..
i searched in the shock market for the best compromise: nice "period" look (forgot to mention that she is a beauty..)and comfort on small bumps are my needs.
asked to gazi (both gazis, australian and thai), falcon, YSS, work performance.. must say that yss looks the most helpful until now.. Walter of course sells YSS shocks, but his technical point of view is very useful for me.
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walter will see you right....
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Fox airs are unreal to look at but are hard (tedious) to get tuned correctly & I've seen one too many collapse at a race meeting, ending the riders day. At least with a spring you can still "circulate" with a blown shock. There are lots of options for new shocks & all have their pro's & cons. Personally I prefer to source used Ohlins (remote res/piggybacks) & rebuild them. Parts are easy to source & over the years of experimenting/testing, we have found some really nice valving specs for both old style & ITC style. I don't find clickers necessary if the spring rate is right.
Not sure what I would buy new these days, although I have just had a set of top shelf Ohlins built for client to suit 1983 Husky TC510. They cost LOTS of money, although not a great deal more than a couple of the other manufacturers mentioned in this thread offer.
It's a hard call if you don't know what you want, my suggestion is to really analyse what it is you're wanting the shock to do & buy the best according to your budget. There's no point paying for 50 clicks of rebound & compression settings if you are the not the type of guy to make the very time consuming effort to tune them.
K
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The gazi are great as they are easy to buy and set up and have the best traction of any shocks I have used, the rear sticks like glue. They do bottom a bit to easy and kick on big braking bumps.They dont give the good front end feel.
Sounds like the spring rate is a bit soft and the rebound damping is not right. No front feel means too much weight on the rear end. Tried dropping the forks through 5mm?
I have tried the old dropped fork trick and raising the rear height ( Gazi have a threaded shaft for adjustment ) cant get the same feel as the fox airs for front tire bite.
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The gazi are great as they are easy to buy and set up and have the best traction of any shocks I have used, the rear sticks like glue. They do bottom a bit to easy and kick on big braking bumps.They dont give the good front end feel.
Sounds like the spring rate is a bit soft and the rebound damping is not right. No front feel means too much weight on the rear end. Tried dropping the forks through 5mm?
I have tried the old dropped fork trick and raising the rear height ( Gazi have a threaded shaft for adjustment ) cant get the same feel as the fox airs for front tire bite.
just out of interest, both sets of shockers are the same length?
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Yes both same length. Thou you can adjust the Gazi length in mm. Fox Airs you can swap the tops but thats a big adjustment.
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very interesting, makes ya think, whats your thought on why shockers on the rear (al be it being the same length and adjustable) would give a different feel on the front end
cheers
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depends on how they allow the spring to unload and push the front down. lots of weird stuff happens in a shock body
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My wows are getting the correct spring the first time round, and a supplier that stocks the correct rate for MY application not an in between which is the norm these days.
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The Fox Airs have the little spring mod that most do to give some sag. The rear sits higher for longer but even at low speeds the front feels different. I have tested back to back same bike same track say day etc, 3 different shocks and on pure MX the fox airs give the best lap times.
My guess is some how they transfer more weight to the front.
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very interesting, I luv the nitty gritty's like this, good for the grey matter
cheers
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any good useable information is good for the grey matter and does alot for keeping you out of club demmenture which after seeing my old grandmother in the nursing home with alot of others I don't want to be another victim
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I had to modify one of those shocks fitted with rod ends the other day . It was meant to be for a CR 250 79 . The stroke for that model should be 148 mm . The shocks (as mentioned above ) had rod ends fitted to achieve the 445 mm , but the stroke on them was 113 mm .(Basically a 390 mm shock extended to 445 mm ) No wonder he bottomed them out constantly . Rodends are great for road racing or short circuit where you don't need all the travel that the motorcycle was designed for . But for long travel MX you want max travel (like the original shock or longer)and any head angle adjustments are done with fork heights . Just saying , thats how I would do it , but then I am not always right .
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Walter, another question... i've just discovered that the high priced\big reputation works performance shocks (gasser series, around 650usd for a set, 2 or 3 springs for each shock..) are emulsion shocks..no separation between oil\gas .
i thought that after decarbon system was introduced (oil and gas separated by a piston or a bladder) any good shock should be a decarbon system inside.. (less cavitation and all that consequent..)
what's the truth on this?
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Separating oil & gas in a non reservoir shock either costs shaft travel or increases overall length
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yes tony your point sounds correct, but we are talking about 15 - 17 inches shocks..
so the question can be: does the decarbon system (separate gas\oil) be mandatory to have a good shocsk (probably my english here is crashing..hope it's anyway understandable..)
and for walter: RZ362 YSS (no reservoir) are decarbon or emulsion?
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(https://s24.postimg.org/yfc0zlg5h/mia2016_3.jpg) (https://postimg.org/image/lnxut36dd/)free image hosting (https://postimage.org/index.php?lang=italian)
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yes tony your point sounds correct, but we are talking about 15 - 17 inches shocks..
so the question can be: does the decarbon system (separate gas\oil) be mandatory to have a good shocsk (probably my english here is crashing..hope it's anyway understandable..)
and for walter: RZ362 YSS (no reservoir) are decarbon or emulsion?
Paulo , looking at the scenery , you must live in northern Italy . I think its best if you you contact our distributor there . You may even be able to take your bike there for a custom fit (highly recommended in this case )
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Just a question on your Yamaha. I am not trying to be a smart arse as you may have a very good and legitimate reason.
Why would you fit an alloy swing-arm, sprocket and rims (I assume to reduce unsprung weight and weight overall) then fit the shocks in a manner which means 75% of the shock weight becomes unsprung weight? The shocks really need to be up the correct way with the reservoirs attached to the frame to minimise unsprung weight and maximise shock performance as they were designed to be mounted reservoir up.
As I said I am not trying to detract from your great build just an observation and question.
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@Walter: i am in south italy, in ischia , a little island in the gulf of naples (near the famous capri)..wich company is the YSS distributor in italy?
@Heaven, you point is correct: i was forced to mount the shocks in that way cos on the other side i have a muffler pipe clearance issue.. the shocks in the pics are the cheap china JBS or RFY, (i bought them just to have a set of correct lenght shocks to finish and test the bike)
BTW i opened that shocks and found that they are not "fake": are rebuildable and can work , but as come stock there is few oil and air trapped inside, i filled fresh oil and charge again gas (air, no nitrogen, just to test) and they work; main issue is that travel it's only 7cm.. basically are road bike shocks
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Chiao Bello , I thought you are up north near Asti . ( Because of the Elderberry tree) . Try Andreani . or http://www.motoshopitalia.com/yss-ammortizzatori-m-62.html
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in the north of italy there is much more vintage offroad culture and history of italian motocross\enduro is all there (there were many factories back in the days, as villa, swm, aprilia, cagiva and many more).. all disappeared today
in the south only in sicily (the big island, famous worldwide for the mafia) there is a some motor\vintage offroad culture (our last motocross champion was from there).
walter what's your opinion about the decarbon system debate.. or.. can an emulsion shocks work well anyway?
p.s. your italian is improving nicely..
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felice anno nuovo, I raced in Italy many times . Great food , great ragazzas , great tracks . Today we have happy new year , no more ammortizoro till 2017 . Happy New year .
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..that's correct... felice anno nuovo a tutti gli amici di tutto il mondo
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That's a great looking Yamaha. We took a trip to Positano a few years ago. The road riding was unbelievable. I had more fun riding 2 up on a silly 150 scooter and half helmets than I ever did racing mx or off road. The roads were amazing. Never mind you have to ride wide open or cars will push you right off the road.