The collision of the rebound tap into the BV was a problem for my open style forks also.
I adapted a KYB MV body onto the WP base bolt.
Adding just few mm at the BV would allow direct contact on mechanical bottom out.
What ever fork you modify, these are always valid concerns.
PK
KTM Cone Valve
Started by
russ17
, Mar 27 2009 07:48 PM
76 replies to this topic
Posted 21 December 2009 - 05:22 AM
I use 0.5 - 0.8mm clearence between the 2 at full bottoming
on the fork legs I think there is usually about 300mm between top and bottom bushings at full extension, +/- 10% should be fine.
on the fork legs I think there is usually about 300mm between top and bottom bushings at full extension, +/- 10% should be fine.
Posted 21 December 2009 - 08:27 AM
Bushmechanic said:
I use 0.5 - 0.8mm clearence between the 2 at full bottoming
on the fork legs I think there is usually about 300mm between top and bottom bushings at full extension, +/- 10% should be fine.
on the fork legs I think there is usually about 300mm between top and bottom bushings at full extension, +/- 10% should be fine.
what is the largest spacer you've successfully put between the cart and seal head? i've not measured exactly yet but it looks like there's alot of fork leg left,i guess that will be the next step; to see exactly what will jive before ordering parts.
michael,you being right there in austria maybe you might have some back door connections? also,if one used the same rebound stack as before is the tap bleed or needle the difference in the reb issue? because it looks like the same mv piston and the new cv piston adapter doesn't seem to hinder any flow on reb,might increase it though with the little scallops?
Posted 21 December 2009 - 09:02 AM
ncmountainman said:
michael,you being right there in austria maybe you might have some back door connections? also,if one used the same rebound stack as before is the tap bleed or needle the difference in the reb issue? because it looks like the same mv piston and the new cv piston adapter doesn't seem to hinder any flow on reb,might increase it though with the little scallops?
Unfortunately not. All the WP parts have been moved from the Netherlands to Austria this fall so getting special parts was a chaos. Funnily I do get my WP parts from Germany
Just like the DDT the CV needs some extra bleed vs a conventional MV setup. Unfortunately an AFFBO (additional fixed free bleed orifice aka bleed hole in the piston) didn't do the trick. WP uses a bleed shim on the rebound and if you remove it performance noticeably deteriorates. On the mid to high speed part though the CV feels like it is adapting to extreme conditions easily - really good stuff. Time for some around-the-corner thinking ...
Michael
Posted 21 December 2009 - 03:05 PM
I have a 30mm cartridge extension and 323mm travel. the other 8mm increase I got by shortening the BV and MV stems and spring guides to let the forks compress further.
there is plenty of overlap between the top and bottom bushings at full extension IMHO
I would go to a 50mm extension but the limiting factor is how far the springs can travel before being overstressed or coil binding. Ive also lowered the bike 25mm by reworking the frame so it sits lower than before.
if its only 5mm you need you can reduce the thickness of the BV and the MV or just shorten the BV and MV stems a tad, I would do that before shortening the rod.
the best way is probably to add the washer in the cartridge since this will give a gain in performance at the same time, you need to make sure the piston band still has contact with the cartridge wall at full extension.
there is plenty of overlap between the top and bottom bushings at full extension IMHO
I would go to a 50mm extension but the limiting factor is how far the springs can travel before being overstressed or coil binding. Ive also lowered the bike 25mm by reworking the frame so it sits lower than before.
if its only 5mm you need you can reduce the thickness of the BV and the MV or just shorten the BV and MV stems a tad, I would do that before shortening the rod.
the best way is probably to add the washer in the cartridge since this will give a gain in performance at the same time, you need to make sure the piston band still has contact with the cartridge wall at full extension.
Edited by Bushmechanic, 21 December 2009 - 03:37 PM.
Posted 22 December 2009 - 12:08 PM
Bushmechanic said:
I have a 30mm cartridge extension and 323mm travel. the other 8mm increase I got by shortening the BV and MV stems and spring guides to let the forks compress further.
there is plenty of overlap between the top and bottom bushings at full extension IMHO
I would go to a 50mm extension but the limiting factor is how far the springs can travel before being overstressed or coil binding. Ive also lowered the bike 25mm by reworking the frame so it sits lower than before.
if its only 5mm you need you can reduce the thickness of the BV and the MV or just shorten the BV and MV stems a tad, I would do that before shortening the rod.
the best way is probably to add the washer in the cartridge since this will give a gain in performance at the same time, you need to make sure the piston band still has contact with the cartridge wall at full extension.
there is plenty of overlap between the top and bottom bushings at full extension IMHO
I would go to a 50mm extension but the limiting factor is how far the springs can travel before being overstressed or coil binding. Ive also lowered the bike 25mm by reworking the frame so it sits lower than before.
if its only 5mm you need you can reduce the thickness of the BV and the MV or just shorten the BV and MV stems a tad, I would do that before shortening the rod.
the best way is probably to add the washer in the cartridge since this will give a gain in performance at the same time, you need to make sure the piston band still has contact with the cartridge wall at full extension.
the piston band shouldn't be an issue as the stock piston gets moved up by the adapter,i just need to figure out how much taller the new stem is compared to stock.
you say 'add a washer in the cartridge' i was under the impression you were putting a spacer on the outside between the cart bottom and the lip of the seal head (where it tightens against the bottom of cart) one could actually cut some threaded spacers off old carts in a lathe to the exact length and thread them on the seal head?
if i'm wrong here do you have pics or better details of where the washer goes?
thanx ncmm
michael do you have a height measurement(from where it meets the rod) of the cv stem assmbly, and a stock (4860) comparison if you have one handy:worthy: oh ya and the threads are the same as stock right?
Posted 22 December 2009 - 02:08 PM
Quote
the piston band shouldn't be an issue as the stock piston gets moved up by the adapter,
unless you're going for more travel, to just keep everthing as is then yes it won't matter since like you said its just to restore the clearence that is lost from the longer stem and the longer stem moves the piston.
you're right about where the washer goes and the old carts sound good. I will have done this in TCs soon, but ATM im just talking outta my butt
Posted 23 December 2009 - 05:15 AM
ncmountainman said:
michael do you have a height measurement(from where it meets the rod) of the cv stem assmbly, and a stock (4860) comparison if you have one handy:worthy: oh ya and the threads are the same as stock right?
I didn't measure the length, but the piston is a "stock" KTM MV piston (12mm rod) and so you should be albe to estimate the length from the pics. As for the threads on the CV tab I didn't have it apart. Logic and experience with WP would dictate that the threads are the same as on the std MV tabs.
Just another note on the cartridge extension - take the top out spring into account when calculating max length!
Michael
Posted 23 December 2009 - 05:48 AM
Drehwurm said:
I didn't measure the length, but the piston is a "stock" KTM MV piston (12mm rod) and so you should be albe to estimate the length from the pics. As for the threads on the CV tab I didn't have it apart. Logic and experience with WP would dictate that the threads are the same as on the std MV tabs.
Just another note on the cartridge extension - take the top out spring into account when calculating max length!
Michael
Just another note on the cartridge extension - take the top out spring into account when calculating max length!
Michael
the top out spring hits against the cart seal head inside the cart on full extension,does it not? if so than spacing the seal head in the manner i described above would make up the difference without shortening the top out spring?
the only thing i see changing is the amount of main spring preload that must be added as compared to the new spacer to maintain original preload.
addendum: i think i now understand what you meant about the top out; to take into consideration the extra travel when the springs compress on full extension...i see said the blind man,thanx!
Edited by ncmountainman, 23 December 2009 - 10:10 AM.
Posted 23 December 2009 - 10:28 AM
ncmountainman said:
addendum: i think i now understand what you meant about the top out; to take into consideration the extra travel when the springs compress on full extension...i see said the blind man,thanx!
Yup, was just too lazy to type it out as I knew you are a smart guy
Depending on the main spring, preload and situation this may fully compress the top out ...
Michael
Posted 30 December 2009 - 02:36 PM
jeddclampette said:
MIchael , that's some NICE parts! 
So what do you guys think about this modded midvalve? It looks to be along the same principles, w/ PMK's belleville idea.
This was modded to my WP4860 many yrs ago.
So what do you guys think about this modded midvalve? It looks to be along the same principles, w/ PMK's belleville idea.
This was modded to my WP4860 many yrs ago.
That is a NOST midvalve setup!
Posted 09 February 2011 - 11:32 PM
Hello from Finland! I've been all over the net, and I've noticed that you seem to have the best knowledge about WP Cone Valve forks.
I've been through the Cone Valve thread, and I would like to have more info.
Is it closed cartridge?
Does it have bladder or piston, or is it open cartridge?
How do the fork seals come apart, by screwing??
Just about anything about those forks!
It would be nice if you would have time to take some pictures also!
And a repair manual would be awesome!
I'm about to buy a pair of those, if I can come up with the moneyour experiences about Wp Trax would be nice too!
That I already have for my 2008 250 SXS-F
Regards
Risto
Servus,
It would have been better to ask your question in the CV thread here just to keep any info in one place.
I have been asked several times about my opinion on the CV forks and despite being very happy with them now I would NOT recommend them. AFAIK the current version (mine is a 2009 model) is not different to mine, but possibly the quality is better now since being manufactured in Austria. But the forks as I got them were an average fork with a great concept for a superior price with a questionable rebound setup and poor workmanship. I spent many hours blueprinting and modifying parts, then completely changing the rebound setup. So don't get me wrong, IMO the CV is a great concept, but they package as it is (or has been) delivered for such a price tag is a impudence.
Regarding your questions, yes it is a closed cartridge fork incorporating an ICS (instead of the bladder). The seals and lower bushing sit in a separate holder which is screwed onto the fork tube - ingenious concept which works very well. Pictures are in the CV thread here and I don't have any manuals in electronic form.
As for the TRAX I just have not enough time on it to make a judgement, but I like what I have seen so far.
Michael
Hi!
Thank you for your answer!
Youre right about the thread thing.
If you take the forks apart, and have the energy, please take more photos from the internals.
Risto
I've been through the Cone Valve thread, and I would like to have more info.
Is it closed cartridge?
Does it have bladder or piston, or is it open cartridge?
How do the fork seals come apart, by screwing??
Just about anything about those forks!
It would be nice if you would have time to take some pictures also!
And a repair manual would be awesome!
I'm about to buy a pair of those, if I can come up with the moneyour experiences about Wp Trax would be nice too!
That I already have for my 2008 250 SXS-F
Regards
Risto
Servus,
It would have been better to ask your question in the CV thread here just to keep any info in one place.
I have been asked several times about my opinion on the CV forks and despite being very happy with them now I would NOT recommend them. AFAIK the current version (mine is a 2009 model) is not different to mine, but possibly the quality is better now since being manufactured in Austria. But the forks as I got them were an average fork with a great concept for a superior price with a questionable rebound setup and poor workmanship. I spent many hours blueprinting and modifying parts, then completely changing the rebound setup. So don't get me wrong, IMO the CV is a great concept, but they package as it is (or has been) delivered for such a price tag is a impudence.
Regarding your questions, yes it is a closed cartridge fork incorporating an ICS (instead of the bladder). The seals and lower bushing sit in a separate holder which is screwed onto the fork tube - ingenious concept which works very well. Pictures are in the CV thread here and I don't have any manuals in electronic form.
As for the TRAX I just have not enough time on it to make a judgement, but I like what I have seen so far.
Michael
Hi!
Thank you for your answer!
Youre right about the thread thing.
If you take the forks apart, and have the energy, please take more photos from the internals.
Risto
Posted 09 February 2011 - 11:47 PM
Hiya again!
We took forks apart for some basic seal service.
But the question is:
How do you take the spring preload aduster combo apart?
Aluminium tube that comes down from the top cap to the sping, is attached to spring preload adjuster combo with a lock ring.
How do you take this apart?
Someone has messed it up earlier, there are marks of 'violence' in aluminium tubes and the other fork doesn't have the lock ring anymore.
Do you just heat the aluminium tube and then it comes over the lock ring, its a quite 'close fit'??
Thanks from advance!!
Risto
PS. I took also some pictures and try to post them.
Have you played wit the Trax shock lately??
We took forks apart for some basic seal service.
But the question is:
How do you take the spring preload aduster combo apart?
Aluminium tube that comes down from the top cap to the sping, is attached to spring preload adjuster combo with a lock ring.
How do you take this apart?
Someone has messed it up earlier, there are marks of 'violence' in aluminium tubes and the other fork doesn't have the lock ring anymore.
Do you just heat the aluminium tube and then it comes over the lock ring, its a quite 'close fit'??
Thanks from advance!!
Risto
PS. I took also some pictures and try to post them.
Have you played wit the Trax shock lately??
Posted 10 February 2011 - 05:40 AM
ristovu said:
How do you take the spring preload aduster combo apart?
Aluminium tube that comes down from the top cap to the sping, is attached to spring preload adjuster combo with a lock ring.
How do you take this apart?
Aluminium tube that comes down from the top cap to the sping, is attached to spring preload adjuster combo with a lock ring.
How do you take this apart?
On my fork there is no such "lock ring". The spacer tube just slides over the preload adjuster with a tight fit, but no heat is needed for disassembly/assembly. Somebody really seems to have messed up that fork. If you post a pic I can tell if your fork is different.
Quote
Have you played wit the Trax shock lately
I almost feel ashamed to write that, but I didn't touch the TRAXX so far
This shock works so well on the 350SXF that I can hardly believe it - no complaints, neither on the track nor offroad.
(I have to look inside sooner or later if I can find a KYB label as this can't really be a WP 
).Michael
Posted 04 March 2011 - 12:17 PM
ristovu said:
How do you take the spring preload aduster combo apart?
I got a used CV fork/Traxx shock from a "factory supported" rider for a good price but in extremely poor condition. Had to dissassemble it completely so I finally got a picture. You need a special tool (6) and lots of heat to remove the ring-nut (4) which holds parts (3) and (5) together. First you need to remove the lock-ring (2) and unscrew (1).
Michael
Posted 22 April 2011 - 11:05 AM
The CV fork has some issues with stock WP/aftermarket springs and after getting some PMs asking about details I'd like to post an update here. This is serious as it will sooner or later destroy the forks internals if not caught in time.
For some reason the CV lower fork legs (steel) have a little smaller inside diameter than the usual WP 48mm forks. Together with the different spring support as a result of the preload adjustment mechanism this will allow the top of the spring to rub violently on the inside of the fork leg when being compressed. Now the sharp edges of "normal" fork springs will work like a chisel and cut tiny steel flakes out of the fork leg - easily visible when you look inside the fork tube. Naturally most of those steel flakes end up on the lowest part of the fork which is the bottoming cone and from there find their way into most of the bushings inside the fork. Usually the coating of the piston rods is damaged first and a good sign that something is wrong.
The following pic shows standard springs (sharp edge) on the left, the springs that come with the CV fork (barely removed edge) in the middle and what I'm using (edge removed, smoothed perimeter, polished) on the right. Additionally I hone and polish the inside of the lower fork tubes and polish the springs - IMO the friction between springs and steel tube is just another problem WP forks often seem to have. While the break in of the forks will remedy this to some extend it cannot make up for the poor machining of the inside of the lower fork tubes and you get a lot of abrasion in the first hours of use - so change the fork oil early!
Michael
For some reason the CV lower fork legs (steel) have a little smaller inside diameter than the usual WP 48mm forks. Together with the different spring support as a result of the preload adjustment mechanism this will allow the top of the spring to rub violently on the inside of the fork leg when being compressed. Now the sharp edges of "normal" fork springs will work like a chisel and cut tiny steel flakes out of the fork leg - easily visible when you look inside the fork tube. Naturally most of those steel flakes end up on the lowest part of the fork which is the bottoming cone and from there find their way into most of the bushings inside the fork. Usually the coating of the piston rods is damaged first and a good sign that something is wrong.
The following pic shows standard springs (sharp edge) on the left, the springs that come with the CV fork (barely removed edge) in the middle and what I'm using (edge removed, smoothed perimeter, polished) on the right. Additionally I hone and polish the inside of the lower fork tubes and polish the springs - IMO the friction between springs and steel tube is just another problem WP forks often seem to have. While the break in of the forks will remedy this to some extend it cannot make up for the poor machining of the inside of the lower fork tubes and you get a lot of abrasion in the first hours of use - so change the fork oil early!
Michael
Posted 12 April 2012 - 06:28 PM
Does anyone know if the old 2mm trax are much diferent to the newer style that come with the bellow, I think 1mm? I have a 2mm and I am considering getting the clevis fork and lock ring machined smooth and making a groove in either the clevis or the lock ring for some kind of bush? Rather than spend hundreds on new parts and machining to convert to the 1mm
Posted 13 April 2012 - 03:31 AM
Careful with that conversion. I know the reduction of the Trax stroke has been touted as a "must do" by some, but I don't want to know how many actually have crippled their Trax in the process. Reason is, like with all the pre-Austria-made WP stuff, that tolerances are all over the place. Since the Trax mechanism consists of more parts that just the sliding clevis a Trax stroke of 2mm just means that the Trax valve closes/opens somewhere within those 2mm! So before modifing your parts you NEED to exactely know at which point the Trax valve actually closes. This is not trivial to find out! An indicator you can use is the wear mark on the tip of the Trax valve.
Regarding the parts I know that the new (2011-) linkage generation Trax with 1mm Trax stroke uses a slightly smaler (in diameter) Trax clevis than the older PDS version. My infos about the pre 2012 PDS Trax are not clear regarding Trax stroke and parts as I have seen quite some different configurations. I have a 2012 PDS Trax coming and should know more once I have it in my hands.
Michael
Regarding the parts I know that the new (2011-) linkage generation Trax with 1mm Trax stroke uses a slightly smaler (in diameter) Trax clevis than the older PDS version. My infos about the pre 2012 PDS Trax are not clear regarding Trax stroke and parts as I have seen quite some different configurations. I have a 2012 PDS Trax coming and should know more once I have it in my hands.
Michael
Posted 16 April 2012 - 07:05 AM
Who of you had the late 2011 or 2012 WP Cone Valve forks? Did anybody use them for Enduro? Any ride quality feedback from any of you?
Michael: does your partslist
Michael: does your partslist
4860.0915 Rebound tap cone
4860.0916 Piston Adaptor cone
4860.0923 Cone 15°
4860.0924 Cone Spring 25N
4860.0914 rebound needle MXMA4800
4860.0918 rebound bolt
fit 2012 WP fit OC and CC forks?
