There are ways and means to get a good and quality result at the most economical cost. Im away now for a couple of days and will try to post again on Monday night.Originally Posted by hayd3n
Forum whore
There are ways and means to get a good and quality result at the most economical cost. Im away now for a couple of days and will try to post again on Monday night.
Where's the ride?
Has an inertia valve that closes when the bike tries to dive but opens when the wheel tries to rise... something like that. Pretty good (impressive) improvement for a damper rod fork, but still well behind the performance of a cartridge fork. In particular it can't handle a complex series of bumps.
Edit: given the genesis of this thread, I should note that I didn't test them vis-à-vis RaceTech emulators.
Cheers,
Colin
No8 Wire Extraordinaire
Ha, yes I was thinking; there, I've learnt something, a new word at the least. Hmm, not in my 1968 Oxford Concise. Hello google. Nope, not a'mercan spelling. Seems to be derived from 'Lacks' rather than 'Lax' which seems a bit counter intuitive."laxadaisical"
Show off
(think it is lackadaisical.Hitcher, help................)
. .
But anyway, a good read.
Don't you look at my accountant.
He's the only one I've got.
No8 Wire Extraordinaire
Exsqueezeme? Weren't you born in the UK? My understanding of the British automotive industry, (to name just one) was that starved of all capital to upgrade, the push was to continue manufacture of old crude designs with known faults on antiquated machinery that was a few decades past its best by date & so be it. While this policy was obviously spurned from a rampant need to repay considerable post war dept it ultimately set the path to kill manufacturing in the UK.
Sorry not trying to take this off path, but we used to deal with Brit made stuff & have always been under-whelmed with the attitude to quality.
So an on point question, much as one tries to retain a square fitment for the spring, surely it deflects one way or other as it compresses. How measurable would this pressure of the deflection get with a cocked seat? I mean if I was stupid enough to put a old thin forkspring on my press & press it (with totally flat surfaces) without a guide, it would surely bend out to the side in short & spectacular order.
Don't you look at my accountant.
He's the only one I've got.
Tearing Choppa a new A'Hole
Video it and post the hilarity that ensues please Dave.
Vote David Bain for MNZ president
No8 Wire Extraordinaire
How would you like to play Lenny for this experiment? (Simpson's reference). You may need to remove your glasses.I'll rig a remote trigger for the press, so I'll be like the dentist who disappears around the corner when taking your x-rays.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
No, my English grandfather was a Royal Army sniper in WW1 and survived the Somme etc. My mother was concieved in England but was born in Eltham, Taranaki. My father was in the RNZAF during WW2 but was seconded to the RAF as a radar engineering officer, based in the UK when those German chappies were being a touch belligerent. I lived in the UK for five years during dear old Maggie Thatchers reign and am an unashamed anglophile and royalist.
In spite of my Rule Brittania sympathies its a bit of a giggle re your references to such ''success stories'' as the company that produced such delights as the Morris 1100 with ''hydrospastic suspension'' and Austin landcrabs etc!!!
With fork springs with end conditions / unsquare ends etc anything that automatically introduces even more sidethrust has just got to be bad. The more you work with a lot of this stuff the more you realise just how shonky and laxadaisical ( ! ) a lot of it is!
Im now taking a few deep breaths before my next assault on the subject of emulators and other variations, but being Tueday evening an English period drama on Prime at 2030 hours beckons first and foremost!
on the up
Jeez Robert. Talk about being a cocktease!
And I to my motorcycle parked like the soul of the junkyard. Restored, a bicycle fleshed with power, and tore off. Up Highway 106 continually drunk on the wind in my mouth. Wringing the handlebar for speed, wild to be wreckage forever.
- James Dickey, Cherrylog Road.
on the up
Having said that, I am also sitting in the lounge on the laptop in front of same said programme.
And I to my motorcycle parked like the soul of the junkyard. Restored, a bicycle fleshed with power, and tore off. Up Highway 106 continually drunk on the wind in my mouth. Wringing the handlebar for speed, wild to be wreckage forever.
- James Dickey, Cherrylog Road.
Forum whore
You cant beat the complexities in those programmes and the English humour. What I dont get though is how with all of those English period dramas etc how they cram all of their filming into the only 2 fine days they get per annum?
No8 Wire Extraordinaire
For sure it just seems wrong to have the mating edges on the piss & I suppose this off angle to the fork spring will not have a nice effect on the Damper rods as it pushes them off skew. To some extent this must happen anyway & the sturdiness of the damper rod will alter the sealing I guess.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
Yes, fair comment. The more you look at this stuff the more its a real can of worms and full of some very laxadaisical engineering.
Forum whore
On compression stroke ( delection over bumps, brake dive ) the flow and damping control is effected by some holes drilled near the base of the damper rods . Im not going to get into the complexities of flow between lower chambers as it would require a series of drawings and more time than I have got. Suffice to say oil is forced through those damping holes and then flows upwards through the middle of the rod. The problem is that at low fork shaft velocity ( smooth face ''bumps'' and initial brake dive velocities ) those holes are too big causing the forks to feel sloppy and uncontrolled. They also blow through their stroke under brakes. If anyone has ridden any of the later Chinese made GN250s they will understand exactly what I mean, although in fairness a lot of the issue is also spring rate, or lack thereof. As will be the case with many lower cost commuter bikes.
But when the bike is ridden over abrupt edge bumps such as a ''proud'' railway line or a pothole etc the same holes are then effectively too small, they ''choke off'' in flow rate and the fork semi hydraulic locks. This overstresses the tyre and the rider is none too happy about it as well.
As mentioned when I started this thread the time honoured ''fix'' is to fit progressive springs but in reality its a very very poor bandaid. Weak springing in most damper rod forks accounts for at least 40% of the lack of control issue and it is a first step in many forks to address that problem by fitting good quality linear wind springs of a rate appropriate for the bike, rider and application. Given that there is a secondary air spring in the forks ( the trapped air volume above the set oil level ) the last third of stroke ''progressivity'' can be very precisely tuned by the oil level. Lets call that ''SECONDARY TRAPPED AIR SPRING COMPRESSION RATIO''. If you fit progressive springs you are stuck with the progression of them , it in most cases will likely be too aggressive. But simply by varying oil level you can make incrementally small or bigger than small changes to progessivity. If progressive springs are what they are falsely painted to be why dont they use them in such demanding environments as MotoGp and WSBK where controlling brake dive is a major preoccupation of suspension tuners? Answer....its because they use tuning of airgap and because at least 50 % of the challenge is to have very effective hydraulics ( damping )
So whats involved in fitting a RACE TECH emulator? First and ideally engineer out as much of the uncontrolled bleed and laxadaisical alignment / centralisation issues as as much as possible. Contrary to the marketing mentality of ''self instal'' it requires a lathe and measuring equipment but above all lots of experience and therefore a keen eye for correcting such issues invisible to a ''first timer''. The devil really is in the detail.Then oversize the existing lower damping rod holes so that their combined flow area just exceeds the flow area of the through bore of the damper rod, which then becomes the primary flow restriction. NOTE, contrary to Race Tech self instal instructions we resist as much as possible adding extra holes. If you carry on up the rod with extra holes it actually results in a significant amount of initial fork re-extension from full closed position where there is very little high speed rebound damping. Thats a critical issue in relatively short travel road / road race forks. Those who have access to flow path diagrams will understand what I mean. 2 years or so ago Paul Thede stayed with me and I discussed this issue with him and he concurred that our explanation was correct.
A Race Tech Emulator is then sat on top of the damper rod and is ''held'' in place by the fork spring and base preload imparted upon that spring. So it is effectively sandwiched, now assuming that the main fork spring and its preload were already ''correct'' the RACE TECH EMULATOR adds another 12-13mm of preload which then needs to be reduced accordingly.
The Emulator is selected primarily by an internet search that gives you the part number and primarily it pays credence to ease of self instal and all the horrible compromises. We at CKT have in many instances and where possible fitted a listing one size larger, the criteria being to fit as big a RACE TECH EMULATOR as possible that just has clearance inside the inner bore of the fork tube. This often involves some machining of the top hat of the damper rod but it always yields a better end result.
The RACE TECH EMULATOR houses a check valve for rebound return flow and contrary to some popular misconception it does not have any influence on rebound damping. As detailed previously trebound damping is ''sorted'' only by first eliminating as much uncontrolled bleed as possible and then by oil viscosity selection. The thinner the oil that you can get away with the better as it will be less sensitive to ambient temperature shift. That also goes for oil quality, cheap yields a cheap result.
At the top of the RACE TECH EMULATOR is a spring preloaded poppett valve. Drilled in that poppett valve is a bypass hole and that small hole provides ''low fork shaft velocity'' damping control. At initial low speed movements and under initial brake dive scenarios that small bypass hole effects a NIGHT AND DAY improvement in ride height and chassis pitch control, the hydraulics are actually earning their keep! Exacerbating that improvement even further it keeps the front end riding higher in its stroke by stopping it uncontrollably blowing through its stroke. That in turn means the main fork springs are not so precompressed all the time and that helps to deliver a ride that is both more controlled but more comfortable, all at the same time.
ABRUPT BUMPS.....in that same poppett piston that the bypass hole is drilled into is a large port hole that it seals off around its periphery. This poppett piston is preloaded by a spring. When the front wheel rides over an abrupt edged obstacle that tries to deflect the forks at high velocity the max flow rate off that bypass hole chokes off and then the poppett starts to lift exposing / modulating more and more flow area. Total flow area almost always exceeds the original hole sizes processed in the oem damper rod. So this combined with less initial precompression of the fork springs delivers a hugely improved level of compliance across such bumps.
Installation of RACE TECH EMULATORS and appropriate rate and preloaded linear wind springs turns the forks into ''speed sensitive damping''. Or much better chassis pitch control and ride quality.
This is still a band aid but then Intimiantors are also, arguably moreso. More in the next post....................
Honda Lover
interesting hagon springs delivered to my door $232 made for my weight and ride style and it even comes with the required amount of oil :P
and thell stil be pretty shit but thell be a improvment for me :P
plastic fabricator/welder here if you need a hand ! will work for beer/bourbon/booze
come ride the southern roads www.southernrider.co.nz
Forum whore
Yes, improvement is a term of relativity! And to quote Paul Thede ''the best youve ridden is the best you know''. For many I guess ''near enough is good enough'' but for many more its a whole world out there of what massive improvements can in fact be made. Concedingly yes it does cost money
I look at many ''cheap and cheerful'' scooters travelling along the road with their ridiculous 10 inch or so wheels and just shake my head at their terrible ride quality and capability of throwing their ride on his / her head over the patchwork quilt of seal reapairs and manhole installations by many councils
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