Suspension not correct for the job

[Robert Taylor]

How many people have bought second hand shock absorbers either off the net ( ie Trade me, E-Bay etc ), off private resellers or off part time parrallell importers and been told ''yeah that will fit your bike''. ???????

You pay your money, receive it and there often may be 3 or more possible scenarios;

1) It actually doesnt fit properly, it is not what it was said to be.

2) It doesnt work properly because the valving and springing isnt right

3) It has been to the moon and back several times, is clearly clapped out and needs recon

And you cannot get your money back.......

[Skunk]

Oh, me! And I'm sending them to you on Monday...

[Colapop]

*comment*......
Ummm... you seem to have been a little grumpy lately... everything ok?

I know that I should buy a completely new rear shock (RF900) but I have a spare one. I was wondering, can these shocks be rebuilt?

[ajturbo]

Ummm... you seem to have been a little grumpy lately... everything ok?

I know that I should buy a completely new rear shock (RF900) but I have a spare one. I was wondering, can these shocks be rebuilt?


you coming to night?

[tri boy]

Been stung twice before.
1. Shitty workmanship, plus no back up.:angry:

2. Shitty Hagon shock.

The money i spent was totally wasted, never to be recouped, and would have paid 3/4 the cost of the Ohlins:love: that is now fitted.
Ya live and learn.

[merv]

Not me, I've only bought bikes new and left them stock except my WR250F and I bought a short arse Ohlins shock off you for that.

[Robert Taylor]

Ummm... you seem to have been a little grumpy lately... everything ok?

I know that I should buy a completely new rear shock (RF900) but I have a spare one. I was wondering, can these shocks be rebuilt?

No, just overbusy. Too busy that I shouldnt really be posting on this forum.

But there is a LOT of shonky stuff being done and Ive had these issues rattling around in my head for years. So thought, right lets air them. There will be some who dont like what I am saying, but hey someone has to stand up sooner or later and say ''this is just not good enough''

Yes, the RF900 shock is indeed rebuildable. I havent got the capacity to do it but can reccommend a number of people who can.

[limbimtimwim]

I just discovered today that the shock in my RVF (That I paid $300 for..) has not being replaced with another RVF shock.

So WTF is it!? And is it my old spring? I suspect it is out of the earlier (much earlier) VFR K model.

That might explain why the bike was touching down so early. I don't remember it doing it so bad at Manfeild, I was attributing it to me being faster, fatter and trying harder than I did two years ago. No, I'm probably as slow as I ever was.

Gah! I will be there on Monday asking them questions. Not naming names, yet.

[Robert Taylor]

I just discovered today that the shock in my RVF (That I paid $300 for..) has not being replaced with another RVF shock.

So WTF is it!? And is it my old spring? I suspect it is out of the earlier (much earlier) VFR K model.

That might explain why the bike was touching down so early. I don't remember it doing it so bad at Manfeild, I was attributing it to me being faster, fatter and trying harder than I did two years ago. No, I'm probably as slow as I ever was.

Gah! I will be there on Monday asking them questions. Not naming names, yet.

Thankyou for that post, your situation is by no means unique and highlights a very real problem too frequent in the industry;

INDIFFERENCE

IGNORANCE

THE DESIRE TO MAKE MONEY WITH LITTLE OR NO CONSIDERATION WHETHER IN FACT THE GOODS ARE SUITABLE FOR THE PURPOSE FOR WHICH THEY ARE SOLD

But balanced out against that how much of a rod may you have created for your own back by sourcing a used replacement as cheaply as possible?

There is a hell of a lot more to selecting a shock than will it fit?

Most modern single shock rear bikes have a linkage system to transfer wheel motion via the swingarm, via the link to the shock absorber.

There is a linkage ratio and that varies quite widely from bike to bike, model to model. Simplistically how it is measured is to measure any given unit distance of rear wheel vertical movement, and for that distance seeing how far the shock absorber shaft moves. At the latter stages of available travel you will find that the shock shaft moves further for the same unit distance of wheel movement. That means it moves at a higher velocity. This to assist final bottoming resistance.

Now consider the humble door closing damper. If you push on the door slowly there is a certain amount of resistance, but if you try and push on it abruptly you will notice a lot more damping resistance. DAMPING RESISTANCE INCREASES WITH VELOCITY.

Beleive me this happens.....''Ive bought an 05 CBR600 shock and Ive fitted it into my SV650. It rides like a board, Ive got no grip and threw it down the road, I think the spring is too firm''

Well yes the spring is too firm but that is only part of the reason. It came out of a bike that has a relatively ''slow'' linkage ratio that moves the shock shaft very slowly, so it has a valving spec that has a lot of low speed compression damping. Allied with that it has a 11 to 12 newton spring, also because of the leverage applied to it by the swingarm. And for the weight loading of the bike.

The longer the arm, the greater the leverage. For example on a GSXR1000K5 the difference in spring rate required between rear axle full forward and full back is half a newton in spring rate.

A firmer spring also requires more rebound damping force to control it. At fully compressed the firmer spring will have a lot more total force than a soft spring and will deflect the internal shim stack more readily and further .So more internal high speed rebound damping ( shimming ) is required.

Back to the SV650, its linkage system for any given wheel movement accelerates the shock shaft further and therefore faster, so it ''builds'' damping more readily. For the correct sag ratio correlation and dynamic ride height control it needs a spring rate within 7.5 to 9 newtons for average rider weight range.

So even if you change the spring rate the ( for example ) CBR shock is likely to have too much low speed compression damping and too much high speed rebound damping. The internal valving needs changing!

''FULLY ADJUSTABLE SUSPENSION'' This often used and somewhat misleading statement has about as much credibility as Helen Clarks election billboard shots, the ones with perfect dentures. The reality is that external clickers predominantly only adjust internal bypass bleed. They DO NOT fundamentally alter the valving ( damping )character of the shock, which is specifically set up for the original bike it was intended for, its linkage ratio, its swingarm length, its weight, torque induced acceleration squat etc etc. The reality is that the clickers will only adjust damping within a very narrow range and will NOT magically make the shock suitable for a wide range of bikes.

Example, you fit the CBR shock to your SV with an appropriate spring and then find that on the track the rebound action is lethargic. So you withdraw the rebound clicker out a huge number of clicks to improve the action. You feel an improvement and think , well thats as good as it gets''. In reality you have improved it, but only to a very finite degree. But what you have also done is to give it too much free bleed at low velocity shaft movements. that makes the bike loose, it tops out too readily under brakes and also sets a lower than possible limit to off corner traction. Also, the needle is now so far removed out of the bypass jet that there is no response range left to fine tune it.

There is always a window of range where a needle and jet is in a sweet spot of response range and correct low velocity shaft control. If you are out of that range it is telling you that you need to revalve the shock. There is a choice between mediocrity or striving for improvement. ( Bear in mind also that most oem shocks are not that ''accomodating'' for quick and easy revalving, nor is there a large setting bank of data as exists for high quality aftermarket shocks designed for quick and easy setting changes by factory trained technicians )

Taken out of an Ohlins catalogue is the following text;

''We start by choosing a type which we tailor make for your specific bike. The basic set-up, both the design of the shim stacks and the calibration of the adjusters, is tested both on road and track. They are the results of true tests with your bike and no guesswork!''

IE;

The specific shock is made to fit the specific bike, properlyand with appropriate fitting clearances through the full range of movement.

It has the correct length and stroke.

It has the correct spring to give the correct correlation of free, rider and dynamic ride height

It has correct internal valving that is complimentary with the motion ratio imparted to it by the linkage

It is backed up by the availability of a factory trained technician with all the proper equipment, service tools, direct factory access and specialist investment in equipment such as spring rate testers and shock dyno. There is a limited and tightly controlled number of service agents with the same mentality of doing the job properly.

There is a mentality that is not appropriate when dealing with shock absorbers.

When it comes to messing with suspension on high velocity motorcycles the deplorable old cliches ''she'll be right'' and ''kiwi can do'' just dont cut it

[slowpoke]

''We start by choosing a type which we Taylor make for your specific bike. The basic set-up, both the design of the shim stacks and the calibration of the adjusters, is tested both on road and track. They are the results of true tests with your bike and no guesswork!''



I've just corrected your spelling mistake Robert...

[Robert Taylor]

We also sell a number of Used Ohlins shocks, when we have them to hand. They are delivered set up specifically for the purchaser and reconditioned so they are fresh.

Every Ohlins shock has on its cylinder head ( the top casting that everything scews onto ) a code number, identifying what it is. This is a two letter prefix followed by a 4 number prefix, not to be confused with date stamp codings on the other side of the shock.

For example HO6060 is a shock for an 07 Honda CBR1000RR.

Many shocks are sold secondhand over Trade Me, E-Bay or locally by more traditional methods. Sadly, many private onsellers often care a little less than they should whether the shock is correct for what it is being sold for ''Yeah it will fit'' Many people have paid their money to find otherwise.

Any prospective purchasers should ask the seller what the code on the shock is, plus the numbers written on the fitted spring. It is also wise to ask if the shock is as originally built or has it been respec'd to fit something else during its lifetime. When was it last serviced and was it done by an approved Ohlins tech etc etc? Usually you will have to allow for rebuild ( possibly revalve ) and a spring for your own personal stats.

Before committing feel free to call me so I can verify if the shock is exactly what it is represented to be. This is a complimentary no strings service we offer. It could save you from being ripped off

[cowpoos]

No, just overbusy. Too busy that I shouldnt really be posting on this forum.

But there is a LOT of shonky stuff being done and Ive had these issues rattling around in my head for years. So thought, right lets air them. There will be some who dont like what I am saying, but hey someone has to stand up sooner or later and say ''this is just not good enough''



I knew you would enjoy this Forum ;)

[limbimtimwim]

But balanced out against that how much of a rod may you have created for your own back by sourcing a used replacement as cheaply as possible?Cheaply as possible? No, I'd pay a fair amount for a straight one. And I think your quote for a damper and spring was quite reasonable considering what I'd be getting. The thing is, I'm in it for having fun, not winning. I have to balance out fun and dollars.

Yeah, I did take a chance, but I also trust the supplier and I think they will make good.

[Mekk]

Thankyou for that post, your situation is by no means unique and highlights a very real problem too frequent in the industry;

INDIFFERENCE

IGNORANCE

THE DESIRE TO MAKE MONEY WITH LITTLE OR NO CONSIDERATION WHETHER IN FACT THE GOODS ARE SUITABLE FOR THE PURPOSE FOR WHICH THEY ARE SOLD

To be honest I think a lot of us don't really consider the points you have raised. I for one are glad you have, as it means I'll definitely be looking more seriously into suspension issues on my next purchase.

It makes you wonder how many other aspects of the industry and other industries are doing similar things. It makes me bloody angry.

One of the only weapons we have against such things is the spreading of information on reputation with the right facts. Safety regulations are one thing, but there'll always be someone looking to make a quick and easy buck at the expense of the consumer. Always someone who is too lazy, too incompetent or too ignorant.

I appreciate the facts and information you're giving us as it'll help with weeding these spineless creatures out. The idea of crashing because of someone else's incompetence is something I am very interested in avoiding.

Cheers.

[ajturbo]

ok mr taylor... ( related to the taylor in Queen?)

i have a rg 50... CB 125 twin ( with a honda front end. inclosed disc)

how much to make em ....................... work?

( yes i know that chucking the rider away will be a great start!)

[Robert Taylor]

ok mr taylor... ( related to the taylor in Queen?)

i have a rg 50... CB 125 twin ( with a honda front end. inclosed disc)

how much to make em ....................... work?

( yes i know that chucking the rider away will be a great start!)

There is not a great deal you can do with such forks other than shorten the springs a little to increase the rate ( if reqd ) and mess with oil viscosity. It is probable that emulators are not available in a small enough size, subject to knowing what the i.d of the fork tubes is.

[Robert Taylor]

Cheaply as possible? No, I'd pay a fair amount for a straight one. And I think your quote for a damper and spring was quite reasonable considering what I'd be getting. The thing is, I'm in it for having fun, not winning. I have to balance out fun and dollars.

Yeah, I did take a chance, but I also trust the supplier and I think they will make good.

Okay, that part of my diatribe was pre-judgemental, sincere apologies for that! Perhaps I should have said ''as cost effectively as possible''

Note that most of my suspension sales are to road riders, but also to many road racers who may never stand on a podium. But the benefits are still the same i.e more mechanical grip, much more responsive to adjustment, more ride compliance, better tyre life, safety etc etc.

I sincerely hope that the text I forwarded will be useful to you and others

[Robert Taylor]

I knew you would enjoy this Forum ;)

To paraphrase the immortal words of Winston Spencer Churchill;

''Never in the field of forum posting has so much twaddle been accredited by so many, to so few''

Just a bit of fun, the great mans post Battle of Britain speech lends itself to paraphrasing so well. As Ryan you have notably forwarded much banter I thought you were a worthy recipient!!!

[ajturbo]

There is not a great deal you can do with such forks other than shorten the springs a little to increase the rate ( if reqd ) and mess with oil viscosity. It is probable that emulators are not available in a small enough size, subject to knowing what the i.d of the fork tubes is.


OK .. as they didn't come with names ... i take it ...i.d.. stands for internal diamiter...

just a bit bigger than my thumb!....
now what you say about shorting the springs... you mean cutting????..

ooo i get to play with disc grinder???

lol

[Skunk]

Put down the grinder...
Put it down.
Now step back.

Ok. You can measure (with my vernier that you haven't given back yet) and enquire from Robert about emulators.

[Robert Taylor]

OK .. as they didn't come with names ... i take it ...i.d.. stands for internal diamiter...

just a bit bigger than my thumb!....
now what you say about shorting the springs... you mean cutting????..

ooo i get to play with disc grinder???

lol

The smallest diameter emulator available is 23.8mm so I am guessing that is still too large for your forks.

Shortening fork springs is always a very last resort if nothing is easily available, and that is very much the case for forks made for low cost commuter bikes. No manufacturer ever intended that they would be raced.

The chance of getting the spring ends totally square again are very difficult, so side thrust against the inner walls of the fork tubes intensifies. It is also very easy to over-shorten and increase the rate too substanially

[TDC]

The smallest diameter emulator available is 23.8mm so I am guessing that is still too large for your forks.

Shortening fork springs is always a very last resort if nothing is easily available, and that is very much the case for forks made for low cost commuter bikes. No manufacturer ever intended that they would be raced.

The chance of getting the spring ends totally square again are very difficult, so side thrust against the inner walls of the fork tubes intensifies. It is also very easy to over-shorten and increase the rate too substanially

Use a cutoff saw, you know the ones just like a miter saw for wood but with an abrasive blade, keeps the ends square and its easier to get them the same length.....

[Robert Taylor]

Use a cutoff saw, you know the ones just like a miter saw for wood but with an abrasive blade, keeps the ends square and its easier to get them the same length.....

That makes perfect sense. The sad thing is there are always those who are not prepared to tool up to do it properly OR have absolutely no conception of a quality job.

Last Thursday I sorted out a set of forks that had aftermarket springs fitted. The dealer had cut new alloy preload spacers. The ends were up to 3.5mm out of square. That puts a sidethrust on the springs and makes them rub harder onto the internal fork legs, increasing friction and sending shards of metal down below where it can over time get trapped in the valving. Just wonderful, for the sake of the equipment you mention or having someone square them off properly in a lathe. All of the suspension tuners that I authorise for Ohlins work have lathes or appropriate equipment for such work.

Lacklustre or no quality control sucks.

[Pancakes]

Last Thursday I sorted out a set of forks that had aftermarket springs fitted. The dealer had cut new alloy preload spacers. The ends were up to 3.5mm out of square. That puts a sidethrust on the springs and makes them rub harder onto the internal fork legs, increasing friction and sending shards of metal down below where it can over time get trapped in the valving..

Holy crap! I can do better than that in a hurry by hand!! If you do cock up something like that surely they at least know enough to throw a poked part in the bin? Thanks for the time you take on here Mr T. one of the reasons I bought brand new is from pulling heaps of bikes apart (I'm not great at it - never said they went back together again!) and some of the complete rubbish that came out of machines that were supposed to be rentals owned by one dealer the whole time (and the VIR confirmed that) was not just crap, it was amazingly shit!! Anyhoo, thanks and have fun!

[emaN]

great stuff!
thanks mr T.
I'll be in touch with Col to find out what you told him 'bout RF shocks

[Pancakes]

This Mr T has no pity for the fool. Now stop yor jibba jabba!