Shock Swap with 99-02 R6

[Lankho09]

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 just 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 0.2mm 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.

 

[Lankho09]

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...

 

[Minispeed]

Well I'm about to be number 2 trying the Ducati st4 shock. Got it from ebay and sanded down the rebound adjuster today. I just have to go pick up some washers for the mounting bolts before I mount it on my 2018 RC390. Got the part that comes close to the swingarm down to 33mm wide. I'll have an r6 shock for sale now.

 

[Lankho09]

So, what's your experience so far?

I'm still intending to fit a lighter spring for my weight but those aren't cheap, I'm happy with the base. Took her a few days into the mountains in Germany, the rear is firm but very manageable, no pogo stick!

 

[louis041]

Looking to do this as well, purchased an 06 shock to find out it wont fit due to the air box and exhaust being in the way on a 2019 RC390.

Will post results once it comes in.

Louis

 

[louis041]

Shock came in today and it is noticeably longer than the oem. I measured and it's about 330mm (see photos), maybe this was not for an ST4?

 

[Duke390LV]

I just finished reading this thread (two or three times) and am looking for some advice - there is some great information here and some great research has been done.

I found an R6 shock 10' away and picked it up yesterday. I have disassembled it and it looks to be in good condition, but I have no experience with tearing shocks apart.

How can I replace the rubber bumper on the shaft? It is cracked and should be replaced.
If I was to replace the ramp preload adjuster with the RaceTech threaded version, how do I pull it off? I cannot slide it off over the rebound adjuster. Probably the same answer as previous question.
I found these on Ebay: Faulkner's Suspension Coilover. At 7" * 2.25" ID, these look to be a direct fit.

I weigh in at just over 200lbs (usually closer to 190lbs) and imagine I would add about 20-30lbs with gear and load on bike. Am I right that 12.5kg/mm (700lbs/inch) would be about right?

Thanks!

 

[Duke390LV]

Update ('99 R6 shock):
650lb spring (11.5kg/mm), replacement bumper and reservoir cap ordered. Shock disassembly in progress. Nitrogen released and oil drained.

Seal head stuck and will not budge (2x circlip which would require creative grinding). Once parts arrive, I will look to get it refilled with new oil and recharged, leaving the existing seal head. It looks to be in good condition with no leaks.

 

[Tricky]

Hi all, first post but a long-term lurker here- very useful forum.

I've previously had a 2017 390 Duke and about 6 months ago picked up low miles 2016 RC390 to become a little trackday toy- I've swapped the rear shock for a re-sprung R6 unit thanks to here, and want to sort some stronger front springs.

My issue is that the only ones I can find here (I'm in UK) are KTech listed for the RC390 Cup bike, and the main KTech dealer here is unable to tell me whether they will suit the stock RC390 forks- I searched through this thread but couldn't find what I want - does anyone know for certain, or even better, give me a UK supplier or KTech (or any other manf) part no to go searching with?
I'm looking for 8.5n/mm , 0.9kg/mm or close to

All help gratefully received- thanks!

 

[Minispeed]

Shock came in today and it is noticeably longer than the oem. I measured and it's about 330mm (see photos), maybe this was not for an ST4?

I don't think that's the correct year shock. That looks similar to others that i remember seeing in my search.

I finally got around to installing the shock thanks to whoever posted the info with the video of the race shop that used the method of lifting the rear wheel while using the stock kick stand. Previously last year i had tried another method using some straps from bar to ceiling but wasn't happy with the stability so i was looking into a bike lift for this. Glad i didn't have to spend the extra money but more importantly garage space.

Then i got called in to watch the kids while my wife went in an online meeting. Have all the bolts in just need to put some lock tight on and torque them then a ride.... First impression when sitting on it much less sag.... I had the stock preload on about 3 clicks from the bottom and I'm 230 naked...St4 is now on about 3 clicks down from the top. I do not race or carry a pax so I'll test out 9.8kg/m before i decide if I'll buy a 12ish.

 

[Minispeed]

Wow!!!! Bye bye pogo stick. Only did about 6km in 2nd gear for all corners but why did i ever wait. From the previous photos on the husk bike you can really see how little room the newer rc390 exhaust leaves. I wrapped the hose going to the external reservoir in header wrap to protect from the heat. I would have much more room if i loosened it and rotated it 180 degrees but then i think I'd let some pressure out?

 

[Xtremsiege2]

Think i'm going to stick with the R6 rear shock over the ducati, however that ohlins or showa with the separate reservoir would be ideal its also more money. Found a shock in decent shape for around $30 and will change the fluid in it. Thanks for everyone who posted in here with pics!