Het "grote" Vitpilen/Svartpilen topic
- Onderwerp starter NielsNH
- Startdatum
-
- Tags
- svartpilen vitpilen
tripleklus
MF veteraan
Haha, ja die boordcomputer is niet helemaal zuiver...
Bij Hoenderloo nog een Vitpilen zien rijden.
Bij Hoenderloo nog een Vitpilen zien rijden.
tripleklus
MF veteraan
Wel een stukje gereden maar niet op de snelweg.
Hoe gaat het met je achterveer?
Hoe gaat het met je achterveer?
Werk nog aan een iets uitgebreider verslag. De R6 schokdemper swap heeft een heel groot topic op het KTM390 forum, en dit is echt goed te doen voor iedereen met een 390/401 en een vijltje dus goed bereikbaar als alternatief. Veel info daar vandaan gehaald dus lijkt me eerlijk om te delen. En misschien dat er daar een vering-expert nog kan helpen met instellingen en benodigde veersterkte uitrekenen. 
First post on the forums. Last year while looking at big allroad bikes I stumbled across a Husqvarna 401 Vitpilen, a small naked based on the 390, sharing the frame and engine...well, sharing everything except the fairings basically. It's a completely useless bike. It won't take luggage, hell, it won't even take the OEM toolkit under the seat, no room! Being a naked, forget about any wind protection, making highways not terrible, but not enjoyable. A girl tried sitting behind me and right there and then decided she wouldn't ride pillion with me, so that's out. So I've got no other option than riding single on windy roads, and it's an absolute blast! The light weight and responsiveness of the small engine is great fun throwing around in the twisty bits!
However, even during the test ride I noticed something you already knew. The pogo stick that KTM/Husqvarna fitted on this bike does not deserve to be called a motorcycle rear shock. Now being a test ride, I wasn't really pushing it. Hell, even at the time of writing, I'm nowhere near the limits. And it's hard to pinpoint what I didn't like about the shock...it felt like it was to easy to go through the stroke, then bouncing back out without any dampening?
Someone on a local forum tried the R6 swap but said it wouldn't fit on newer years. I would like to make a hopefully useful contribution or share my project/experience, maybe someone more knowledgeable can run with it and perfect it further, or shoot it down and prevent me from catastrophic failure!
So, there's been a great deal of information on the swap of 2nd Gen R6 shocks onto 390's in this community and it all seems to have started with @Formula390's input. This whole thread has been nothing but informative for which I'd like to thank all of you. Since Formula390 started this swap thread with the intention of giving back to the community and I've learned basically all I know from this thread, it seems only fair to propose an alternative with the same intentions; giving back to a community.
With that in mind, please respect the following disclaimers; English is not my first language and I am in no way a suspension tuner. I've got a fairly basic grasp of suspensions but please consult a proper specialist or do your own homework before running with this, I'm open to critics or helpful suggestions.
Now that we've got that out of the way, lets get on to what could be an alternative to the R6 shock. I've heard reports of the R6 shock not fitting on newer models of the 390 and being the owner of a Husqvarna 401 '19 (Basically a KTM 390, sharing the frame and engine, only better looking!) I simply assumed that the R6 shock would not work on my bike. So, with that option ruled out, now what?
The R6 shock swap thread thought me the ideal length of the spring would be 305-310mm, slightly longer than the stock shock, giving a bit of added clearance to avoid dragging hard parts at lean angle and accomplishing a bit what one would get by sticking the forks through the clamps, geometry-wise, raising the rear a bit.
From there, I went searching for a) shocks at that length range and b) R1 2007 and R6 1999-2002 swaps. Why? Well, if the 2nd Gen R6 shock fits our bikes and I've seen the R1 2007 being mentioned as an alternative, reasonably, other bikes that fitted the R6 shocks as upgrades would have compatible rear shocks. The counter-argument could be that if the other bikes fitted the R6 shock as upgrades it would also stand to reason that their shocks would also lack in some way. But, we can't have it all with a budget, right?
Anyway somewhere along that process I stumbled along Ducati ST4 owners swapping shocks from Ducati 916's and several of the Monster series, apparently all shocks with an eye-to-eye of 305mm. Both of the shock clevises are eyes instead of a fork, and while the 916 series shock has a piggyback reservoir as part of the shock body, the ST4 appeared to use a remote reservoir. Well, with a remote reservoir, this shock could fit anything, either with stock or aftermarket exhaust!
Without doing much other research, I went onto the local Ebay alternative and found a Ducati ST4 shock for a few tenths. After having a few beers and a f*ck-it moment, I was now the proud owner of a Ducati ST4 shock, knowing pretty much nothing about it except it is supposed to be 305 mm eye to eye in length.
Upon arrival, I was well pleased. Sure, there was a lot of road grime, but having read the R6 thread, the bottom-out-bumper looked brand-new after some cleaning, the chroming on the damper rod has some very minor scratching though that appears more pronounced on the polished surface, it is neglectable for now, no pitting. Overall, really pleased.
Intending to tear it apart anyway and see what's what, let's get to the fitting part first. Below, some measurments of my own with a vernier caliper that's presumably slightly off (I've had a noticeable amount of readings ending in x.8, so I've went ahead and round it off to the nearest number) and some measurements of the all-knowing internet.
Husqvarna 401 2019;
Room between the singarm flanges (not including the raised boss of the mounting points!); 35mm
Width of the upper mounting flanges; 35mm
Width of the upper shock eye; 32 mm
Width of the lower shock eye; 32 mm.
Upper eye/bolt ID; 10 mm
Lower eye/bolt ID 10 mm
Ducati ST4 shock, exact year unknown;
Width of the upper shock eye; 23 mm
Width of lower shock eye; 23 mm
Width of the rebound adjuster casing; 36 mm
Nitrogen pressure (Racetech.com); 165 psi
Rear sag (Racetech.com); 35 mm
Stock Shock Spring Rate (Racetech.com); 9.8 kg/mm
Some random internet values;
ST2 & ST4;
305mm length
748 & 996;
305 mm length, 71mm stroke.
749;
305 mm length, 71mm stroke.
Monster 1000 '03-'05 & S4RS;
305mm length.
Ohlins STX 46 DU321 fitting;
M800 '03-'05
M996 S4R '03-'05
M1000 '03-'05
M620 '01-'05
M659 '06-'08
M750 '01-'02
M800 '05-'09
M900 '01-'02
S2R1000 '05-'09
S2R800 '05-'08
S4 916 '00-'05
Length 305mm, 66mm stroke.
Honda NC700/CBR600F
305 mm length.
Honda RS125 '99-'00
310mm length.
Honda CBR900RR '98-'99
305mm length.
Kawasaki 900R Ninja;
310mm length.
R6 '99-'02;
Length 305mm.
Width of both upper and lower eyes; 30mm
Lower bearing race; 17 OD x 12 ID X 30 W
Nitrogen pressure (Racetech.com); 165 psi
Rear sag (Racetech.com); 35 mm
Stock Shock Spring Rate (Racetech.com); 9.3 kg/mm
Great, so that was my notebook with the numbers out of the way. Let's get going and see if this was just a fucked idea or actually has some merit.
Knowing the R6 and the ST4 have a 0.5kg/mm difference in stock spring strength and keeping in mind the stock R6 spring might often work for lighter riders during the swap to the 390, I'm not too worried. The original 390 progressive spring has a wider range to contend with!
Other than this minor flaw, it seems to fit. Obviously the rebound adjuster is hitting on the swingarm flanges. The only way fitting it was placing some M8 rod through the swingarm flanges allowing for a slight 2 mm off-set fitment. Still, well pleased, the upper eye seemed fine and no part of the shock that is interfering is holding any oil or gas pressure so this may still be do-able for anyone with simple handtools! The banjo fitting of the ST4 shock body to the remote reservoir seemed fine to me, I fail to see how that could be an issue for interference for anyone otherwise considering the R6 swap.
So, still making broad assumptions, let's tear this shock apart, see what's what, file down the rebound adjuster and get on with it! The Racetech instructions may be helpful with this process. IP Sk Rebuild STD
So, without these instructions I went ahead and built a spring compressor from 6x30mm flat bar steel and M10 threaded rod. BE ADVISED: PLEASE CONSULT YOUR LOCAL SHOP OR SUSPENSION TUNER!
Notice the 6x30mm flat bar steel is buckling in some places, I've drilled the holes 10,5 to allow for some angling of the steel to the shock spring. However, the use of the threaded rods to compress the spring damaged the threads sometimes. After the third time of use, I failed to notice the nut AND thread started turning instead of just the nut. When relieving the pressure because the spring had buckled in a strange angle, I've failed to notice the bars sticking to the threaded rod. In effect, the nut I was holding back turned out of the rod, jumping across the room, releasing all tension on the "spring compressor". The pieces of flat bar steel I didn't care enough for to smooth the edges jumped open and turned up- and outwards. At the time of writing, I've only found the washer which bounced of the cat tunnel. Yes, I've got a cat and I'm very happy she wasn't walking around during this moment of stupidity, I'm guessing a M10 nut pressurized by a 9.8kg/mm spring wouldn't have been benificial to my pets health. It would probably have an adverse affect on my knees too, which were close as well. Enjoy tinkering with your motorcycle, please don't be a Darwin award, get the proper tools or use a local shop.
Well, I managed to get the spring off, complicated by the fact the original shock collar added approx. 10-15mm preload and I didn't manage to turn the preload collar during the original fitment, it was just stuck.
Anyway, during this process I severly lacked in shooting pictures but most of the process speaks for itself. Otherwise the Racetech instructions should help or google rebuilding Showa Ducati ST4. (The remote reservoir shock unit is apparently a 46 mm Showa shock unit.)
RELEASE THE NITROGEN PRESSURE!
I've drilled the dust cap pressed in place on the ST4 shock. Be careful with the pressure, the dustcap is ca. 1 mm thick, a mm below that is the schrader valve and it's cap. For me, I've drilled the cap and then some of the schrader valve cap. Afterwards I stuck a screwdriver or any other tool in and pried the cap out. Beneath that there is the actual seal head with the nitrogen bladder. Great news, unlike WP shocks, it's a seal head with an actual schrader valve even with a nice cap. I've drilled through the dust cap into the actual cap on the valve but I wasn't intending on re-using this part anyway. You may also elect on drilling off-centre.
Removed the spring by compressing the spring enough to remove the lower collar beneath the spring. It has a slot in it allowing it to slip out when the spring is compressed enough. It has to go around the chromed part of the rod, it will struggle around the jam nut holding the lower clevis. (AGAIN; PLEASE HEED THE CAUTION, THIS IS NOT THE PROPER OR SAFE WAY TO GET THE SPRING OFF! GO TO A SHOP EQUIPPED TO DEAL WITH SPRINGS.)
Great, so now the nitrogen pressure is off and the spring is removed. Being a remote reservoir, I've removed the line between the reservoir and the shock body. Now, both the bladder side and compression adjuster side of the reservoir should be able to be easily pressed down and their respective circlips removed allowing to slide out either side.
Note, trying to move the lower clevis into the shock body may give you an indication on the binding of the seals and damping rod. Not being a suspension expert, I came to the conclusion that everything moved as I expected thus it would be alright. Without any pressure trapped inside, it al moved smoothly without any binding so I went ahead...
So, this leaves us to get the damper rod and valving body out of the shock body. Tap the end cap with a chisel/screwdriver/punch-trouch of your choice. this wil get the cap lifted, although crooked. So work at the edges available to you and try to get it out as straight as possible. Below it, you'll find the actual seal head, held back by a circlip ring.
After working out the circlip ring and a lot of pulling and wrestling, I gave up on just pulling out the actual seal head. I've greased the seal head and shock body with vaseline (petrolatum?) and started tapping on the lower end clevis, working my way around it.
So, so far, the bottom-out-bumper seemed to be in great shape and the chroming seemed to be very much alright, there was a fair scratch on the seal head though is was below the actual O-ring. Pretty certain it was already there but I may have caused it with the removal. Anyway, sanded it down with grit 400 and scotch brite and guessed it would be okay, not sealing anything really. So far, so good assuming this is a approximately 20 year old shock. Being in aviation maintenance I used mostly isopropylalcohol to clean components, pretty sure the average brake cleaner would accomplish the same thing with regards to road grime.
Anyway, I went for the clevis. Placing the damper rod (Gripping the nut on top of the damper rod that holds the valve stack, this nut is peened) in a vice and putting a 1/4" drive extension through the clevis the clevis threaded right off, leaving the jam nut in place at approx. two threads from the end of the threaded part of the rod. Looking at it, I decided the rod was threaded much more into the clevis then 1½ diameter of the shank and leaving it two threads more out would get me. approx 307mm height, smack in the middle of the quoted 305-310mm ideal shock length.
NOTE: After fitting the shock and a few more beers thinking about it, I realised, extending the clevis from the rod end also meant that the needle riding on the rebound adjuster was sitting lower by the same distance. In effect, yes, there is some ride height to be gained however, you're losing a big chunk if not all of the rebound adjustment. I've since reverted to the stock height value at the next fitting of the shock.
With the shock apart and not seeing any signs of trouble or wear I focused on the most important issue...The only thing holding me back on fitting is this shock is the width of the rebound adjuster between the swingwarm. So, I clamped the lower clevis down in a vice and started filing. Whenever the groove in the rebound adjuster screw started looking low I simply turned the adjuster out and used a small hacksaw (metal saw?) to deepen the groove. Satisfied with the depth of the groove I turned the rebound adjuster all the way in and resumed filing until satisfied.
After filing down the rebound adjuster on both sides I was hoping to remove the rebound adjuster completely for you know...research, pictures, whatever. The rebound adjuster is peened on the opposing side of the adjusting screw. However, I failed to remove the adjuster even with the peening filed down so I've skipped that.
Checking with a vernier caliper I determined that enough material was removed to be able to fit the lower eye clevis in the swingarm. It did turn out to be a with a little clearance, fitting snug and rubbing a bit of powdercoat away from the swingarm. I am able to rotate the shock or lower eye a bit, I'm guessing there's not even 0.5mm clearance. Fine by me, at least it's not binding and it wil chafe away at the swingarm powdercoat anyway if it was binding!
Fitting is not definitive, need to create a suitable clamp and added a bit of vinyl tape to prevent chafing at the frame tube with regards to the reservoir.
The width between the swingarm mounting bosses and the actual lower shock eye and the upper frame mounting and upper shock eye are filled with black nylon washers. To get to the desired width I've sanded the nylon washers on a flat surface on a sanding paper until all fitted snug. Not entirely sure on the specs of the washers anymore, think these were 8.0 mm thick with a ID of 10 mm.
So, now, for the results....I've driven about 800 km (500 miles for the imperial users) so far with this shock. And I'm really happy with it. It's firm, and the stock Ducati spring seems to be too stiff for my weight (80kg with gear) but it feels like a huge improvement. Hard to tell through text what I like and it may not be for you or your weight may be better suited. With the stock shock I felt it would smash through it's range on bumps and then extend pretty much undampened. Now, I like a firm rear, my previous road bike was a racetrack-setup CBR600F by the previous (heavier) owner. Maybe it's a matter of preference. But with this Ducati shock the rear feels planted over bumps. It will compress somewhat then extend controlled. For reference, with my licenseplate-holder/tail-tidy I could hit the rear tire with the stock shock. With the ST4 shock, I'm not even close bumping on the seat with all my weight. This shock feels really steady. Being a bit on the stiff side it will probably give me less traction on rough surfaces or small disturbances on the road surfaces but it feels less like a trampoline, less movement and disturbance on notable humps. This shock transfers more of the big movements right up your back instead of collapsing while keeping the rear wheel planted. Hitting the throttle right before a speedbump will have you jumping a bit but if you're not actively looking for it, it's just firmly planted.
Disclaimer, your happiness may vary. Between the race-setup CBR600F and this bike, I've driven supermotard with a KTM 525 EXC that's setup real soft on the rear, acting like a trampoline. I guess I'm not that picky and just disliking the stock rear, got a bit of a placebo effect or just like very different things for differing conditions and riding styles.
With the ST4 shock, I've only gotten a static sag of 15mm and a rider sag of 15 mm, so obviously, this spring is too stiff for me. I would like suggestions for a replacement spring, happy as I am. Also, I haven't been able to service the nitrogen bladder up to the right pressure. Long story short, some workplace-good-idea-fairy reduced the low pressure adapter from 300 to 100 psi. The high-pressure adapter up to 3000 psi didn't have a quick-disconnect so when servicing up to 200 psi assuming some pressure loss, I unfortunately dropped to 80+ psi while disconnecting. So, there's still room for better setup, I just felt like sharing even now. Been working on this for a while on a local forum, decided that it's time to finish this alternative, recieve feedback and see if I'm a whackjob or this may be helpful.
To be fair, if anything, the added length of the shock makes me feel more incapable in the sense that I'm not foreseeing dragging any hard parts or even my own knee in the near future. After a few year of supermotard on the track I'm still getting used to cornering with the knowledge there might be a guardrail, lamppost or an other fixed obstacle on the outside and the riding postion on the Husq is not yet "me". But I'm assuming, hoping and guessing that will come back with time, for now this feels unnatural compared to dragging the inside feet for a bit, sticking a leg out, leaning the motorcycle underneath me instead of leaning into the corner and keeping the bike as upright as possible. Also not helped by KTM's decision to fit a 150 rear tyre where only a 140 maximum should be fitted onto the rim...
However, even during the test ride I noticed something you already knew. The pogo stick that KTM/Husqvarna fitted on this bike does not deserve to be called a motorcycle rear shock. Now being a test ride, I wasn't really pushing it. Hell, even at the time of writing, I'm nowhere near the limits. And it's hard to pinpoint what I didn't like about the shock...it felt like it was to easy to go through the stroke, then bouncing back out without any dampening?
Someone on a local forum tried the R6 swap but said it wouldn't fit on newer years. I would like to make a hopefully useful contribution or share my project/experience, maybe someone more knowledgeable can run with it and perfect it further, or shoot it down and prevent me from catastrophic failure!
So, there's been a great deal of information on the swap of 2nd Gen R6 shocks onto 390's in this community and it all seems to have started with @Formula390's input. This whole thread has been nothing but informative for which I'd like to thank all of you. Since Formula390 started this swap thread with the intention of giving back to the community and I've learned basically all I know from this thread, it seems only fair to propose an alternative with the same intentions; giving back to a community.
With that in mind, please respect the following disclaimers; English is not my first language and I am in no way a suspension tuner. I've got a fairly basic grasp of suspensions but please consult a proper specialist or do your own homework before running with this, I'm open to critics or helpful suggestions.
Now that we've got that out of the way, lets get on to what could be an alternative to the R6 shock. I've heard reports of the R6 shock not fitting on newer models of the 390 and being the owner of a Husqvarna 401 '19 (Basically a KTM 390, sharing the frame and engine, only better looking!) I simply assumed that the R6 shock would not work on my bike. So, with that option ruled out, now what?
The R6 shock swap thread thought me the ideal length of the spring would be 305-310mm, slightly longer than the stock shock, giving a bit of added clearance to avoid dragging hard parts at lean angle and accomplishing a bit what one would get by sticking the forks through the clamps, geometry-wise, raising the rear a bit.
From there, I went searching for a) shocks at that length range and b) R1 2007 and R6 1999-2002 swaps. Why? Well, if the 2nd Gen R6 shock fits our bikes and I've seen the R1 2007 being mentioned as an alternative, reasonably, other bikes that fitted the R6 shocks as upgrades would have compatible rear shocks. The counter-argument could be that if the other bikes fitted the R6 shock as upgrades it would also stand to reason that their shocks would also lack in some way. But, we can't have it all with a budget, right?
Anyway somewhere along that process I stumbled along Ducati ST4 owners swapping shocks from Ducati 916's and several of the Monster series, apparently all shocks with an eye-to-eye of 305mm. Both of the shock clevises are eyes instead of a fork, and while the 916 series shock has a piggyback reservoir as part of the shock body, the ST4 appeared to use a remote reservoir. Well, with a remote reservoir, this shock could fit anything, either with stock or aftermarket exhaust!
Without doing much other research, I went onto the local Ebay alternative and found a Ducati ST4 shock for a few tenths. After having a few beers and a f*ck-it moment, I was now the proud owner of a Ducati ST4 shock, knowing pretty much nothing about it except it is supposed to be 305 mm eye to eye in length.
Upon arrival, I was well pleased. Sure, there was a lot of road grime, but having read the R6 thread, the bottom-out-bumper looked brand-new after some cleaning, the chroming on the damper rod has some very minor scratching though that appears more pronounced on the polished surface, it is neglectable for now, no pitting. Overall, really pleased.
Intending to tear it apart anyway and see what's what, let's get to the fitting part first. Below, some measurments of my own with a vernier caliper that's presumably slightly off (I've had a noticeable amount of readings ending in x.8, so I've went ahead and round it off to the nearest number) and some measurements of the all-knowing internet.
Husqvarna 401 2019;
Room between the singarm flanges (not including the raised boss of the mounting points!); 35mm
Width of the upper mounting flanges; 35mm
Width of the upper shock eye; 32 mm
Width of the lower shock eye; 32 mm.
Upper eye/bolt ID; 10 mm
Lower eye/bolt ID 10 mm
Ducati ST4 shock, exact year unknown;
Width of the upper shock eye; 23 mm
Width of lower shock eye; 23 mm
Width of the rebound adjuster casing; 36 mm
Nitrogen pressure (Racetech.com); 165 psi
Rear sag (Racetech.com); 35 mm
Stock Shock Spring Rate (Racetech.com); 9.8 kg/mm
Some random internet values;
ST2 & ST4;
305mm length
748 & 996;
305 mm length, 71mm stroke.
749;
305 mm length, 71mm stroke.
Monster 1000 '03-'05 & S4RS;
305mm length.
Ohlins STX 46 DU321 fitting;
M800 '03-'05
M996 S4R '03-'05
M1000 '03-'05
M620 '01-'05
M659 '06-'08
M750 '01-'02
M800 '05-'09
M900 '01-'02
S2R1000 '05-'09
S2R800 '05-'08
S4 916 '00-'05
Length 305mm, 66mm stroke.
Honda NC700/CBR600F
305 mm length.
Honda RS125 '99-'00
310mm length.
Honda CBR900RR '98-'99
305mm length.
Kawasaki 900R Ninja;
310mm length.
R6 '99-'02;
Length 305mm.
Width of both upper and lower eyes; 30mm
Lower bearing race; 17 OD x 12 ID X 30 W
Nitrogen pressure (Racetech.com); 165 psi
Rear sag (Racetech.com); 35 mm
Stock Shock Spring Rate (Racetech.com); 9.3 kg/mm
Great, so that was my notebook with the numbers out of the way. Let's get going and see if this was just a fucked idea or actually has some merit.
Knowing the R6 and the ST4 have a 0.5kg/mm difference in stock spring strength and keeping in mind the stock R6 spring might often work for lighter riders during the swap to the 390, I'm not too worried. The original 390 progressive spring has a wider range to contend with!
Other than this minor flaw, it seems to fit. Obviously the rebound adjuster is hitting on the swingarm flanges. The only way fitting it was placing some M8 rod through the swingarm flanges allowing for a slight 2 mm off-set fitment. Still, well pleased, the upper eye seemed fine and no part of the shock that is interfering is holding any oil or gas pressure so this may still be do-able for anyone with simple handtools! The banjo fitting of the ST4 shock body to the remote reservoir seemed fine to me, I fail to see how that could be an issue for interference for anyone otherwise considering the R6 swap.
So, still making broad assumptions, let's tear this shock apart, see what's what, file down the rebound adjuster and get on with it! The Racetech instructions may be helpful with this process. IP Sk Rebuild STD
So, without these instructions I went ahead and built a spring compressor from 6x30mm flat bar steel and M10 threaded rod. BE ADVISED: PLEASE CONSULT YOUR LOCAL SHOP OR SUSPENSION TUNER!
Notice the 6x30mm flat bar steel is buckling in some places, I've drilled the holes 10,5 to allow for some angling of the steel to the shock spring. However, the use of the threaded rods to compress the spring damaged the threads sometimes. After the third time of use, I failed to notice the nut AND thread started turning instead of just the nut. When relieving the pressure because the spring had buckled in a strange angle, I've failed to notice the bars sticking to the threaded rod. In effect, the nut I was holding back turned out of the rod, jumping across the room, releasing all tension on the "spring compressor". The pieces of flat bar steel I didn't care enough for to smooth the edges jumped open and turned up- and outwards. At the time of writing, I've only found the washer which bounced of the cat tunnel. Yes, I've got a cat and I'm very happy she wasn't walking around during this moment of stupidity, I'm guessing a M10 nut pressurized by a 9.8kg/mm spring wouldn't have been benificial to my pets health. It would probably have an adverse affect on my knees too, which were close as well. Enjoy tinkering with your motorcycle, please don't be a Darwin award, get the proper tools or use a local shop.
Well, I managed to get the spring off, complicated by the fact the original shock collar added approx. 10-15mm preload and I didn't manage to turn the preload collar during the original fitment, it was just stuck.
Anyway, during this process I severly lacked in shooting pictures but most of the process speaks for itself. Otherwise the Racetech instructions should help or google rebuilding Showa Ducati ST4. (The remote reservoir shock unit is apparently a 46 mm Showa shock unit.)
RELEASE THE NITROGEN PRESSURE!
I've drilled the dust cap pressed in place on the ST4 shock. Be careful with the pressure, the dustcap is ca. 1 mm thick, a mm below that is the schrader valve and it's cap. For me, I've drilled the cap and then some of the schrader valve cap. Afterwards I stuck a screwdriver or any other tool in and pried the cap out. Beneath that there is the actual seal head with the nitrogen bladder. Great news, unlike WP shocks, it's a seal head with an actual schrader valve even with a nice cap. I've drilled through the dust cap into the actual cap on the valve but I wasn't intending on re-using this part anyway. You may also elect on drilling off-centre.
Removed the spring by compressing the spring enough to remove the lower collar beneath the spring. It has a slot in it allowing it to slip out when the spring is compressed enough. It has to go around the chromed part of the rod, it will struggle around the jam nut holding the lower clevis. (AGAIN; PLEASE HEED THE CAUTION, THIS IS NOT THE PROPER OR SAFE WAY TO GET THE SPRING OFF! GO TO A SHOP EQUIPPED TO DEAL WITH SPRINGS.)
Great, so now the nitrogen pressure is off and the spring is removed. Being a remote reservoir, I've removed the line between the reservoir and the shock body. Now, both the bladder side and compression adjuster side of the reservoir should be able to be easily pressed down and their respective circlips removed allowing to slide out either side.
Note, trying to move the lower clevis into the shock body may give you an indication on the binding of the seals and damping rod. Not being a suspension expert, I came to the conclusion that everything moved as I expected thus it would be alright. Without any pressure trapped inside, it al moved smoothly without any binding so I went ahead...
So, this leaves us to get the damper rod and valving body out of the shock body. Tap the end cap with a chisel/screwdriver/punch-trouch of your choice. this wil get the cap lifted, although crooked. So work at the edges available to you and try to get it out as straight as possible. Below it, you'll find the actual seal head, held back by a circlip ring.
After working out the circlip ring and a lot of pulling and wrestling, I gave up on just pulling out the actual seal head. I've greased the seal head and shock body with vaseline (petrolatum?) and started tapping on the lower end clevis, working my way around it.
So, so far, the bottom-out-bumper seemed to be in great shape and the chroming seemed to be very much alright, there was a fair scratch on the seal head though is was below the actual O-ring. Pretty certain it was already there but I may have caused it with the removal. Anyway, sanded it down with grit 400 and scotch brite and guessed it would be okay, not sealing anything really. So far, so good assuming this is a approximately 20 year old shock. Being in aviation maintenance I used mostly isopropylalcohol to clean components, pretty sure the average brake cleaner would accomplish the same thing with regards to road grime.
Anyway, I went for the clevis. Placing the damper rod (Gripping the nut on top of the damper rod that holds the valve stack, this nut is peened) in a vice and putting a 1/4" drive extension through the clevis the clevis threaded right off, leaving the jam nut in place at approx. two threads from the end of the threaded part of the rod. Looking at it, I decided the rod was threaded much more into the clevis then 1½ diameter of the shank and leaving it two threads more out would get me. approx 307mm height, smack in the middle of the quoted 305-310mm ideal shock length.
NOTE: After fitting the shock and a few more beers thinking about it, I realised, extending the clevis from the rod end also meant that the needle riding on the rebound adjuster was sitting lower by the same distance. In effect, yes, there is some ride height to be gained however, you're losing a big chunk if not all of the rebound adjustment. I've since reverted to the stock height value at the next fitting of the shock.
With the shock apart and not seeing any signs of trouble or wear I focused on the most important issue...The only thing holding me back on fitting is this shock is the width of the rebound adjuster between the swingwarm. So, I clamped the lower clevis down in a vice and started filing. Whenever the groove in the rebound adjuster screw started looking low I simply turned the adjuster out and used a small hacksaw (metal saw?) to deepen the groove. Satisfied with the depth of the groove I turned the rebound adjuster all the way in and resumed filing until satisfied.
After filing down the rebound adjuster on both sides I was hoping to remove the rebound adjuster completely for you know...research, pictures, whatever. The rebound adjuster is peened on the opposing side of the adjusting screw. However, I failed to remove the adjuster even with the peening filed down so I've skipped that.
Checking with a vernier caliper I determined that enough material was removed to be able to fit the lower eye clevis in the swingarm. It did turn out to be a with a little clearance, fitting snug and rubbing a bit of powdercoat away from the swingarm. I am able to rotate the shock or lower eye a bit, I'm guessing there's not even 0.5mm clearance. Fine by me, at least it's not binding and it wil chafe away at the swingarm powdercoat anyway if it was binding!
Fitting is not definitive, need to create a suitable clamp and added a bit of vinyl tape to prevent chafing at the frame tube with regards to the reservoir.
The width between the swingarm mounting bosses and the actual lower shock eye and the upper frame mounting and upper shock eye are filled with black nylon washers. To get to the desired width I've sanded the nylon washers on a flat surface on a sanding paper until all fitted snug. Not entirely sure on the specs of the washers anymore, think these were 8.0 mm thick with a ID of 10 mm.
So, now, for the results....I've driven about 800 km (500 miles for the imperial users) so far with this shock. And I'm really happy with it. It's firm, and the stock Ducati spring seems to be too stiff for my weight (80kg with gear) but it feels like a huge improvement. Hard to tell through text what I like and it may not be for you or your weight may be better suited. With the stock shock I felt it would smash through it's range on bumps and then extend pretty much undampened. Now, I like a firm rear, my previous road bike was a racetrack-setup CBR600F by the previous (heavier) owner. Maybe it's a matter of preference. But with this Ducati shock the rear feels planted over bumps. It will compress somewhat then extend controlled. For reference, with my licenseplate-holder/tail-tidy I could hit the rear tire with the stock shock. With the ST4 shock, I'm not even close bumping on the seat with all my weight. This shock feels really steady. Being a bit on the stiff side it will probably give me less traction on rough surfaces or small disturbances on the road surfaces but it feels less like a trampoline, less movement and disturbance on notable humps. This shock transfers more of the big movements right up your back instead of collapsing while keeping the rear wheel planted. Hitting the throttle right before a speedbump will have you jumping a bit but if you're not actively looking for it, it's just firmly planted.
Disclaimer, your happiness may vary. Between the race-setup CBR600F and this bike, I've driven supermotard with a KTM 525 EXC that's setup real soft on the rear, acting like a trampoline. I guess I'm not that picky and just disliking the stock rear, got a bit of a placebo effect or just like very different things for differing conditions and riding styles.
With the ST4 shock, I've only gotten a static sag of 15mm and a rider sag of 15 mm, so obviously, this spring is too stiff for me. I would like suggestions for a replacement spring, happy as I am. Also, I haven't been able to service the nitrogen bladder up to the right pressure. Long story short, some workplace-good-idea-fairy reduced the low pressure adapter from 300 to 100 psi. The high-pressure adapter up to 3000 psi didn't have a quick-disconnect so when servicing up to 200 psi assuming some pressure loss, I unfortunately dropped to 80+ psi while disconnecting. So, there's still room for better setup, I just felt like sharing even now. Been working on this for a while on a local forum, decided that it's time to finish this alternative, recieve feedback and see if I'm a whackjob or this may be helpful.
To be fair, if anything, the added length of the shock makes me feel more incapable in the sense that I'm not foreseeing dragging any hard parts or even my own knee in the near future. After a few year of supermotard on the track I'm still getting used to cornering with the knowledge there might be a guardrail, lamppost or an other fixed obstacle on the outside and the riding postion on the Husq is not yet "me". But I'm assuming, hoping and guessing that will come back with time, for now this feels unnatural compared to dragging the inside feet for a bit, sticking a leg out, leaning the motorcycle underneath me instead of leaning into the corner and keeping the bike as upright as possible. Also not helped by KTM's decision to fit a 150 rear tyre where only a 140 maximum should be fitted onto the rim...
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In ander nieuws, de overbuurman heeft de motor omver gereden afgelopen weekend. Stond op de stoep voor m'n opritje te wachten op m'n date. Wou het zelf oplossen, gezien zijn achteruitrijden snap ik dat, die verzekeringspremie moet heftig zijn. 
Weinig schade gelukkig, spiegeltje en een bandje om de uitlaat. Alle gelakte delen lijken prima.
Weinig schade gelukkig, spiegeltje en een bandje om de uitlaat. Alle gelakte delen lijken prima.
Dat is zuur! Maar zolang het netjes wordt opgelost valt het mee.In ander nieuws, de overbuurman heeft de motor omver gereden afgelopen weekend. Stond op de stoep voor m'n opritje te wachten op m'n date. Wou het zelf oplossen, gezien zijn achteruitrijden snap ik dat, die verzekeringspremie moet heftig zijn.
Weinig schade gelukkig, spiegeltje en een bandje om de uitlaat. Alle gelakte delen lijken prima.
Ik heb vandaag de olie in de rebound vorkpoot gewisseld van de originele 4w, naar 7,5w.
Heb zo goed als geen rebound demping in de voorvork, ook niet met de adjuster helemaal dicht.
Had gehoopt dat de dikkere olie significant verschil zou maken. Maar helaas, scheelt bijna niks.
Ik ben aan het kijken naar een nieuwe A2 motor voor zo'n max €5500 (ben woonachtig in Duitsland). Nu heb ik een 0km 2019 model 401 Svartpilen gezien voor €4500, helaas door corona niet mogelijk om nu proefritten te maken maar word er wel heel hebberig door! Is er een reden dat ze zo "slecht" verkocht worden? Ze zijn zelfs goedkoper dan Duke 390s terwijl dit het "duurdere" broertje zou moeten zijn, of is het puur de onbekendheid?
tripleklus
MF veteraan
Werk nog aan een iets uitgebreider verslag. De R6 schokdemper swap heeft een heel groot topic op het KTM390 forum, en dit is echt goed te doen voor iedereen met een 390/401 en een vijltje dus goed bereikbaar als alternatief. Veel info daar vandaan gehaald dus lijkt me eerlijk om te delen. En misschien dat er daar een vering-expert nog kan helpen met instellingen en benodigde veersterkte uitrekenen.
Oei dat is een heel verhaal geworden. Ik zal er een keer rustig de tijd voor nemen want mijn Engels is niet heel geweldig...
Een veringbedrijf zal je ongetwijfeld goed op weg kunnen helpen!
tripleklus
MF veteraan
In ander nieuws, de overbuurman heeft de motor omver gereden afgelopen weekend. Stond op de stoep voor m'n opritje te wachten op m'n date. Wou het zelf oplossen, gezien zijn achteruitrijden snap ik dat, die verzekeringspremie moet heftig zijn.
Weinig schade gelukkig, spiegeltje en een bandje om de uitlaat. Alle gelakte delen lijken prima.
Dat is lullig, kijk de boel nog een keer goed na want je ziet snel iets over het hoofd.
tripleklus
MF veteraan
Ik heb wel eens gelezen dat de dikte van het ene merk voorvorkolie niet overeen hoeft te komen met dezelfde dikte van een ander merk
Klopt daar kan veel verschil in zitten.
Onze manual geeft helaas niet meer info dan dat er sae 4 in de voorvork zit. En de hoeveelheid per poot.
Zoektocht levert dan op dat de meeste ktm webshops die vork olie aanbieden motorex 4w aanbieden. Het is een aanname, maar ik ga er even van uit dat dit er in zit (ook met de link tussen ktm en motorex in het achterhoofd). Die zou een viscositeit van 16mm²/s bij 40° hebben.
De putoline 7,5W die ik er nu in heb zitten zou bij dezelfde temperatuur een viscositeit van 32mm²/s moeten hebben.
Ik zou nog dikker kunnen proberen, maar feit blijft dat het verschil tussen rebound volledig open of volledig dicht, bij mij gewoon niet is wat het volgens mij zou moeten zijn.
En aangezien de voorveren ook veel te licht zijn, ga ik gewoon op zoek naar een specialist.
Dat is waar. Het is ook belangrijk om te bepalen waar je het aan meet. Honderd verschillende oliën kunnen bij 20‘ Celcius precies dezelfde eigenschappen hebben..maar bij 100‘ Celcius heel andere eigenschappen hebben.
tripleklus
MF veteraan
Bij mij komt de voorvork mooi rustig terug omhoog, de compressie heb ik een stukje terug gedraaid want inveren ging wat zwaar. nou weeg ik maar 67kg en voor mij is die lekker straf afgeveerd. verder heb ik weinig kennis van vering en zal eens bij HK in Tiel langs gaan als de corona het weer toelaat.
mikebike nr.1
MF veteraan
Per ongeluk 2 K&N filters besteld en betaald voor de 701
Iemand hier 1 overnemen als ik niet kan annuleren?
€67 incl verzenden
Iemand hier 1 overnemen als ik niet kan annuleren?
€67 incl verzenden
Zonde, ik heb de mijne vorige week binnen gekregen
Mocht er hier niemand interesse hebben kan je het ook nog proberen in het 1290 en 1090 topic, die gebruiken hetzelfde filter (Superduke en al die adventure modellen)
boomhauer
MF veteraan
- 5 dec 2006
- 4.973
- 1.133
Dat staat er redelijk nadrukkelijk al. 
