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2004 Ducati ST3
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Discussion Starter #1
I purchased some used early ST4S forks with the plan being installing them on my ST3. Once I pulled the old ones out it became clear than they are around a inch LONGER than the early ST4S forks due to the different triple tree top clamp. My question is, can an earlier ST4 top clamp bolt onto my ST3 forks so I can use these beauties?
 

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My friend put early ST4S forks on his 2004 ST3, but before he put them on, LE Lindemann when they were in Campbell, CA stretched them. I rode the bike many times, with the ST4S forks with the stock Showa rear shock and it was a very nice ride. LE Lindemann is now in Palm Springs, I had them do some work on my Showas & they are spot on! The other way to make the change over is buy old ST3 forks and have a cartridge kit put in or put the kit in your current front forks. I have a 2004 ST3 & went ahead and put GP Suspension SuperBike kit in some donor forks, I really like that set up.
 

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The top clamp will bolt on, but you will need to also use the older bars. You may need longer or shorter brake and clutch lines too. Honestly, there is nothing special about the ST4s forks except the gold sliders. Even if your ST3 forks are the pre load adjust only variety, the fully adjustable Showas are flawed in that the compression circuit has very little (if any) effect unless the rebound adjuster is fully closed. You be better off selling off the ST4s forks and putting the money into your current forks, that fit, to get them right. Springs, valving, oil selection that works for you will be much much better than a set of OEM ST4s forks that will also need tweaking to work well for you.
 
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2004 Ducati ST3
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Discussion Starter #4
The top clamp will bolt on, but you will need to also use the older bars. You may need longer or shorter brake and clutch lines too. Honestly, there is nothing special about the ST4s forks except the gold sliders. Even if your ST3 forks are the pre load adjust only variety, the fully adjustable Showas are flawed in that the compression circuit has very little (if any) effect unless the rebound adjuster is fully closed. You be better off selling off the ST4s forks and putting the money into your current forks, that fit, to get them right. Springs, valving, oil selection that works for you will be much much better than a set of OEM ST4s forks that will also need tweaking to work well for you.
Yes, I've been feeling the same way. I am discouraged, but determined the make my forks work better. I'll give them the same treatment and maybe add Racetech Gold Valves. Thank you for your input. The Ducati Forum is the best!
 

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the non adj forks are fine as a basis for reworking. the adj bit is just a waste ime, most people won't touch the adj even after direction to play with it.
 

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Examining the Possibility:
Would the internals only, from a 748-916-996 front forks, be a direct bolt on, into the ST4s forks? Has it been done by anyone? Any opinions? Any directions?
Ride safe
Stelios
 

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Ping Yorik. I believe he did that to his ST3. As I remember it there is a length issue. Maybe it makes the forks a bit shorter.

That would eliminate the wonky compression circuit issue of the STs and would be a lot less expensive than aftermarket cartridges. You'd still want to address springs, maybe valves and oil weight if you're going to that extreme.

Belter makes a very good point. Once they are set up, how often do you plan to adjust them? I did RT Gold Valves and springs that match my weight along with 5WT oil. Spent some time setting them up and aside from service, new seals and fresh oil at least once since the work, haven't messed with them. Just installing the correct springs (if needed) and fresh oil can really liven up what you already have. The Gold Valves are an excellent improvement to high speed compression, especially on our crap roads, but not a must do.
 

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Thank you SS904,
I will try to contact Yorik, if I can find the way to do it.
A couple of questions.
A. What brand of 5WT oil. In my last change I followed the instructions of the service manual which states 7.5 WT. The recommended brand was Shel advance or Donax TA. I do not remember what brand they used. I have read in this forum the paper from a gentleman with a comparison list of most oils in the market. Every 5wt oil was different in the comparison chart. So go figure.
B. The quantity of oil recommended is qcm 504, or 109 mm of oil level.
C. I feel the spring is too hard for me. How do you make sure that the spring is for your weight?
Any suggestions?
I do not like the behaviour of the forks in medium speeds, when you apply the brakes and you release them before a tight turn. It almost bounces back on my hands.

Thanks again
PS. To the OP. Sorry for adding my comments in your post. I hope it can add some assistance.
Regards
Stelios
 

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First thing to do for both your shocks and forks is to adjust sag. Both static and dynamic. By performing this exercise, you will be able to determine if the spring rates are correct for you. Once that is determined, then you can tinker with adjustments to compression/rebound if equipped.

There are numerous post on this form that detail the procedure for setting sag. There’s a ton of YouTube videos too. Well worth doing this first before you change anything.


Sent from my iPhone using Tapatalk
 

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What Mike said about sag. There s really no point in doing anything to mod your OEM suspension until you can hit those numbers. It is ground zero.

Oil. I use Bel Ray 5wt. I like it, I know what to expect when I replace it.

Air gap. OEM service manual specifies an air gap. Normally this is read as a level measured with springs out. This assumes you are using OEM springs. If you are using OEM springs, then the air gap when you put the spring in will be whatever Ducati actually wanted it to be as the spring will displace the oil and raise that level you just measured with them out. I like Race Tech's method much better and it makes sense as they are a supplier of aftermarket springs... It is what I always use and it works for me every time. When I say it works for me, I mean I have tested the suspension travel used by temporarily placing a wire tie around one fork tube and riding the bike. If the forks do not bottom and I am using most of the available travel, I'm happy. If the forks bottomed, I'd need to add a bit of oil, if I was using too little travel, I'd take some out. Race Tech specs 110mm WITH THE SPRINGS INSTALLED. If you install other than OEM springs there is a very good chance, pretty much 100%, that you are going to displace more or less oil than you would have with OEM springs. This invalidates the no-springs level given in the manual.
 

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if it has std springs they're too soft, and don't have enough preload. the std oil level is quite high, so you get a lot of air spring effect in the last 1/3 of the travel, which is why they don't bottom with the soft springs.

i did bit of playing with oil heights and wrote some reports on it. didn't actually do an st fork i don't think. hopefully they'll load, sometimes is odd for me. these are two of several reports, there's a list on the top rh side for links to the others.


you can see how linear and not high the 748 fork load is even with the 1.0kg springs they have.

the oil height with spring in method is more consistant if you're using thin wall preload tube and shorter aftermarket style springs where the spring is covered by the oil. i'd think 110 springs in would be 160 or lower springs out, which is low. but it will make the fork action quite linear through the whole travel.

std spring is around 0.82. a 0.9 or 0.95 is better, and i start with 20mm minimum preload when i set the spacer length. i'd use maxima 5 weight oil, which is about 16 cst. i've tried bel ray 2.5, which is 10 or so cst i think, but even that didn't reduce the high speed compression harshness like a good revalve will. playing with them, or having them played with, will give the best result.
 

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There is an other alternative for Race Tech, K-Tech piston kit: 20SSK-SHO-13 which i installed to my ST4. It takes little machining and tinkering but it moves the rebound adjusting needle from top of the fork down to piston, separating rebound and compression adjuster circuits. Can recommend.
 

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Thank you All very much for the recommendations and info.
I will try ( rather retry) to get the recommended sag.
If that fails, I will go for the suggested spring and oil, and maybe the valves (It will depend on the cost and what difference it will make).
I will keep you informed when I start the process.
Thanks again
Stelios
 
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