~ Making Progress On My Suspension Issues ~

[diamonddog-2]

My '01 900S is busy getting the upgraded Ohlins DU 440 shock upgrade [OVERTIME$$$!].   I've had 2 meetings with local suspension dude, Anthony Decker, about addressing the front suspension as well.  He pulled the forks apart and found that, although somebody had changed the oil at some point, they refreshed the forks with something around a 20 wt oil in place of OEM. He also found the valve/shim stacks were buried in sludge at the bottom of the forks. The compression setting [at the bottom of the forks?] was adjusted all the way in too. The fork tubes were also mounted pretty low on the triple tree.  I went to a local bike shops seminar on suspension and tires a while back with the hope of walking away with a SLIGHTLY less hazy grasp of how all the suspension mechanics work together.  Good information on both suspension as well as tires!
A couple of things Anthoney showed me were (1) the difference in the valve design. Showa, Race Tech and Ohlins. I found it interesting how the Ohlins valves were rounded on all the openings, maybe making a difference on fluid turbulence [and air bubble creation] as the oil is worked through the suspension?
The other thing I saw was just how freaking hot the fork oil can get. The OEM shims, which were a nice polished stainless steel when they left the factory, had been blued on the surface over time.  I'm told it's due to the heat that's generated from repeated compression/rebound on roads and the friction [and eventual heat] it generates that gets transferred to the oil and internal parts.
It was a heck of a visual aid.
The seat is back from upholstery shop with added height of 1 inch. 1/2 inch added fresh foam and 1/2 inch added gel insert. My butt/knees might last longer than 40 minutes now.   Once the bike is back together and the temperature is up a bit, I'll head to the shop for a final adjusting session and get 'er dialed in, hopefully.
Being more of a casual street rider, it's all more suspension, rider position, front geometry and tire information than I've ever had before.
"Knowledge GOOD."    [grunts and hits head with wrench]
That is all ... as you were. 

[MonsterHPD]

Seems you are spending money in the right places, suspension upgrades may not always be so bling, but they really do make a difference.

A couple of years ago I participated in a 2-day dyno session, comparing various versions of the Showa forks, as well as some Öhlins R&T43 forks. I have loads of data from those 2 days, and maybe this comparison can be of interest:

Skärmklipp by torbjörn bergström, on Flickr

It shows some different settings on the "short-needle" setup (i.e., the stock Showas as used on Monsters, SSie´s, ST´s etc), same with Öhlins piston / shim kit, and some "long-needle" modified forks (i.e., with the rebound needle moved down to the normal position inside the cartridge.

As you can see, compression damping on the short-needle versions don´t really change much from full open to full closed, but rebound adjustment is quite effective. Maybe this could explain that your forks had comp adjusers fully closed, and maybe also explaining the thick oil: Thick oil and fairly wide open rebound adjustes might give a useful setting on both compression and rebound? I´ve never tried that,so I´m just speculating?

The graphs also show that compression damping is quite dependant on rebound setting; open the rebound at all will kill most of the compression damping.   

Sludge will form, sometimes surprisingly soon. Like this one, maybe ...?

P1030027 by torbjörn bergström, on Flickr     

[diamonddog-2]

Thank you MonsterHPD. That's some great information that I'll try to pass along. From looking at it, I'm not sure what it all means myself but I will take your word for it!.     Suspension guy said that Ohlins was his component choice to rebuild forks with [as well as shock replacement] due to his ability to talk with specific people who could answer questions. He tried working with Race Tech [at my initial request]  but had limited success getting answers to questions. There's also some of the performance dyno charts for Ohlins parts that are available.

In my own experience working with molten metal dynamics, I've been a big proponent of soft angles when casting jewelry models. Sharp 90 degree turns just create turbulence and tiny bubbles. In my line it's called porosity. It can be either minimized or pretty much eliminated if designs use softer angles.  I guess the Ohlins valve design, with the softer edges,  kind of made more sense to me because of that.....but who knows!

I was told the sludge build up was pretty significant and was most likely impeding the ability of the valving/shim stack to work properly. 

[koko64]

Any updates?

[Moronic]

Well diamonddog-2, it sounds like you have made some good decisions and gotten some good help.

I too will be very interested to hear of the outcome.

BTW: don't be discouraged if initial impressions fall short of your expectations. Getting the good stuff on is the first part; setting it up is the next. After that is just the enjoying.

Since you have chosen the same shock as koko64, you may find his experience helpful.

[diamonddog-2]

You guys are just the best.       Thanks for keeping an interest in my project.

Ok, here's the only update so far....... 8 inches of new snow yesterday [as well as lower temps]  is gonna keep everybody off the roads for a while longer.  Man, and we were SO CLOSE too.  I had seen a few guys out riding over the last 2 weeks.   I actually started having dreams of riding the 900 and pulling wheelies without even trying!! The front end was gently and slowly coming up with just a small twist of the throttle .... it was fantastic.  Anyway, while combing through the '01 Anthony had discovered a small leak in the tank seam, a worn fuel line issue and a seal on the half time shaft that was leaking. We also decided to switch to a new gear shift as the old one was a bit twisted and had been welded at some point but was feared to be weak.  He had also told me about a fairly common leak issue with a plastic nut located at/near the underside of the tank? ...... possibly where the filter/pump assembly is mounted?  Anyway, he had some [about 50] metal replacement nuts machined to cure that problem. It seems the OEM plastic ones break down over time or just crack? That was more of a preventative upgrade.
As far as suspension progress? I kinda let him work at his own pace, figuring he'll let me know when he needs to talk about anything.  When we last spoke, he was thinking that everything will have been done near the end of April and he'll have me up to the shop to measure sag and begin to dial in the suspension.

Yeah, although not as glitzy as some things I could be doing to the bike, I agree that the suspension maintenance/upgrades are gonna be well worth the effort. I almost can't wait.

  

[ducpainter]

Ducati tanks very, very rarely leak at a seam. Much more likely to be a hinge leak.

Ask him to look again.

[greenmonster]

a plastic nut located at/near the underside of the tank?

Fuel level sensor. Seldom leak but often stops working. Expensive.
Nice touch w the nut.

[diamonddog-2]

ducpainter is correct!  I misunderstood the email from A.D. telling me about the leak. It was the hinge flange area.  Anthony has used the Red Kote tank sealer for the leak issues, not only on his own bike but on maybe 50 others. The product had a good 2 weeks to setup, which is way longer than he usually gets before people are calling asking "what's taking so long with my bike?".  I'm told if I stay away from the oxygenated gas during storage and just sitting in the tank between rides, I'll extend the life of the product. I use that type of gas almost all of the time anyway. It's close by.....so why not?  I guess there are other fixes for the leak but they typically involve some welding heat?. The bike came with a nice custom paint job by the previous owner and I'm not sure it would survive.

The forks. Well, here's the story thus far .... as it happened, Anthony was visiting some fellow mechanic friends, tossing a few back  , and got into a conversation with a guy from a racing shop. It seems they do a lot of suspension set up and had started Beta testing a "new" Japanese valve design [possibly Showa?] that uses an extrusion process to smooth all surfaces and edges. There was a fair amount of consumption going on    and some apparent proprietary information was discussed. Anyway, instead of going with the Ohlins set up, Anthony decided to use the new info and go a slightly different route. He pulled apart 2 sets of superbike forks he had laying around and got the larger cartridges he wanted, installed them in my forks, with the "new" valves, shim stack and a set of Racetec springs and a few other misc. parts. After a few discussions with 2 friends, 20 hours and 3 fork rebuilds later, he thinks he's had a little bit of a breakthrough. The adjustability and response is unlike anything he's seen outside of serious $ being spent. It is [or like?] a duel stage action?   Anyway, he said if I don't like 'em he'll trade me straight up for the forks from his monster that have all Ohlins components.  He said he's doing the same build on his forks anyway. Although we spent over an hour talking about some of this stuff, I don't have much detail about it. It gets above my pay grade pretty quick. He's done maybe 200 fork rebuilds and maybe 100 out of that involve new valves and shim stacks, etc.,... so, if he's excited? cool. He said in 1000 or 2000 miles come in and he'll measure/re-adjust as needed, once everything has a chance to break in a bit.

The DU 440 gets ordered at the end of the month as part of a bigger parts order from Ohlins. If it saves him [me] on shipping costs, fine.  I'm not riding until we're in the solid 60's anyway.
We're roughly the same weight so he'll set it up just a tad stiff for his weight and will dial it in when I swing by the shop.

There it is. I swear by none of the above.   

[koko64]

  Looking forward to uour ride report.

[ducpainter]

I've heard the Red Kote stuff is good.

Brazing the hinge, and then coating is better.

Ask him what happens if the coating fails.

[Moronic]

Sounds like you might have some nice front suspension there. If it works as advertised, you'll be riding that bike for a loooong time. 

[diamonddog-2]

ducpainter:  If it fails I guess we revisit the bronzing approach for a more permanent repair, provided I'm ready to risk paint damage?  [I kinda like the current paint scheme too]   His experience, with his own tank, was that using oxygenated gas, all the time and storing it with that gas over winter, gave him about a 5 year window before it dissolves and begins leaking again.  The fact that he now uses a heavier coat, had more time to let mine cure and that I pretty much always use non-oxy gas should extend that 5 year window by....?  Anyway, by that time I might be ready for a respray.

Moronic: I guess I'll find out soon enough. At this point, I plan on keeping this bike for as long as I can get parts and physically ride so the suspension rebuild/upgrade made sense.  Just talking with you all made spending the extra $ to go to the next level made it a little easier.  When asked 'what is it specifically do you want the suspension to do?' I remembered what someone here had stated as a simple goal: smooth out the bumps and keep the tires in contact with the road.

3 to 6 inches more snow forecast for Sunday/Monday   .......       As our guy, Prince, observed "Sometimes it snows in April"

[Speeddog]

Tank hinge can be brazed without damaging the paint that's visible.

[ducpainter]

Tank hinge can be brazed without damaging the paint that's visible.

What he said. A hinge can be brazed without damaging the paint enough to be visible with the seat installed...at least I could do it. The heat affected area can be primed with a tinted epoxy primer and be very durable and corrosion resistant. Just FYI.

My experience with coatings is that they need to be removed before brazing due to the extreme likelihood of fire. It's a miserable, if not impossible job, then reapplied. When I was repairing tanks it cost more to remove an old coating than to braze the hinge and coat a tank.

Your bike, your call.