I have a set of Showa forks for service, that turned into trying to get one set of good forks out of two forks; can just hope the other fork will be in better condition.

These forks had worn thru the chrome on the stanchions, presumably where the lower bushes load them the most:

2019-06-29 12.19.38 by torbjörn bergström, on Flickr

My more experienced suspension friends tell me this is a common occurrence, even though I have not come across it before.

I had not really looked at the outer legs for internal wear, but they show the same type of wear patches from the bushings. I suppose if I have to re-use legs like these, I´d have to turn them 90° .... I´ll see what my contacts might have to say about this problem.

 

Quote from: Speeddog on August 10, 2019, 03:55:05 PM
Very general manual:
http://www.smartperformanceinc.com/ohlinsttxshockservice

And here´s one for the monotubes:

https://www.scribd.com/document/98723156/Ohlins-General-Workshop-Manual

Don´t know how it works with membership etc; I think I have a pdf if you send me a pm. 

Single disc bike?

Huge mileage?

Prolonged running with twisted forks?

All of the above?

I've not seen that, even on some high mileage bikes.
I'm suspecting some sort of extenuating circumstances there.

Thanks for the manuals, now the only info missing is the separator level that should be in the settings card.....maybe i can measure it when i open it. Edit: not possible, the shaft should be removed before the head , i will search..

About the fork in the pic i can only imagine the outer tube worn
My last one become a pile of crap in 10kkm with inner tube almost perfect.

I've also found that on <2002 fork tube can't be set parallel.
They can be set in the same plane (with glass plate etc) but when you tight the upper plate clamp it act on very thin part of the tube, deforming it about 0,2mm per side.
The result is a A shaped fork tube with about 0,5mm out of parallel for every 20cm of lenght.
Maybe ducati has solved this issue in rev b or c of fork plates.(they also increased the axle thickness in b or c)
Or maybe that working on aerospace market i simply became to picky

 

Quote from: Speeddog on August 11, 2019, 10:08:07 AM
Single disc bike?

Huge mileage?

Prolonged running with twisted forks?

All of the above?

I've not seen that, even on some high mileage bikes.
I'm suspecting some sort of extenuating circumstances there.

Not sure, really .... the forks came off a bike (900 SSie, double disc) which I know was written off by the insurance company after an excursion beside the road. Not obviously bent, no idea about mileage.
Edit: One more strange fact: The worn spots are about where the lower bushings will be with the forks fully extended. I would have expected them somewhat lower ....

In fact, the fork was one of the first modified as per "Showa Blues", with parts designed and manufadtured by me and my pal in 2007 or so. Not sure if they have been apart since (until now).  

Anyway, I will keep an eye on this condition in forks I do from now on.

Quote from: Dadouzzu on August 12, 2019, 06:07:41 AM
Thanks for the manuals, now the only info missing is the separator level that should be in the settings card.....maybe i can measure it when i open it. Edit: not possible, the shaft should be removed before the head , i will search..

About the fork in the pic i can only imagine the outer tube worn
My last one become a pile of crap in 10kkm with inner tube almost perfect.

I've also found that on <2002 fork tube can't be set parallel.
They can be set in the same plane (with glass plate etc) but when you tight the upper plate clamp it act on very thin part of the tube, deforming it about 0,2mm per side.
The result is a A shaped fork tube with about 0,5mm out of parallel for every 20cm of lenght.
Maybe ducati has solved this issue in rev b or c of fork plates.(they also increased the axle thickness in b or c)
Or maybe that working on aerospace market i simply became to picky

Check the manual, they inform how to set the separator piston.

I´m not sure I fully understand the out-of-parallell situation ... but it´s late here now. Maybe tomorrow ...

Don't worry, is also late here in italy i will retry tomorrow to find the poor man internal reservoir shocks separator level
.

I try to reword the parallel tube issue
The problem is that on 2002 bikes with fork cap flush to the upper triple tree clamps, the clamps crush the tube even with 15-18Nm and so the fork legs became out of parallel

Edit: i know, i know, my english is crap

A general question about front and rear springs rate balance:
How do you prefer?
Ohlins base rate are 9Nm Front and 100Nm rear.
S4rs for example match 8.5 front with 105 rear

I tryed 8.3 front and 90 rear and seems little understeering

Quote from: Dadouzzu on August 31, 2019, 07:29:34 AM
A general question about front and rear springs rate balance:
How do you prefer?
Ohlins base rate are 9Nm Front and 100Nm rear.
S4rs for example match 8.5 front with 105 rear

I tryed 8.3 front and 90 rear and seems little understeering

Sorry for late response, I was a week with wife on Sicily (trying just a little of my evening-course italian on unsuspecting local people....) and some projects around the house before winter sets in....

Anyway, I have no formula for balance, I just try to set reasonble sag numbers and take it from there (and experience, If it´s a bike I´ve worked on previously). Don´t remember your weight, think it was about the same as me at 60-some kilos w/o gear; if so I´d say that 8.3 front / 90 rear would be on the soft side. If you feel understeer, that might well be rear ride height too low (by linkage adjustment and / or excessive sag).

For some reason, heavier riders seem able to "bounce" the suspension by standing on the footpegs to see if the suspension sags equally fron and rear, but when I try that, nothing seems to happen ..... which is also "equal", but not very informative. It is otherwise a good indication if the balance is good or not.

As mentioned, I have 95 rear and about 8.5 to 9.0 front on the M800, which is a slightly lighter bike thn the 900 despite beeing basically the same bike (I think mine is appr. 168 kg dry, but will measure more exactly soon). For me, that works very well on street and track.

Perfetto, quindi posso rispondere in italiano?
Last week i was in china and buyng the (right )food was very difficult with the local language 

Anyway I have to discard the 100Nm because my ass can't tolerate it anymore (with stock valving & bad road & no available compr register)
I weight 62 with gear and the bike 185 with full tank ( 91f 94r)

I have also reduced the fork compression damping and plan to reduce oil height

Did you think that can be a problem if the oil level is lower than the little hole for lower bushing lubrication?

No, usiamo l'inglese per qualche altro anno, e scusate per il ritardo :-)

This discussio has twisted and turned  bit, so I´ve lost track a little bit. I´m happy to discuss suspension, but in order to get bac to the No-monster topic, maybe it´s better to move this discussion to my other "live" thread, "waste of money", which is about the M800 anyway ... OK? That hread has also branched out quite a bit, but at least it´s the right kind of bike. 

Well,
Over here riding season is over for most of us, time for an update on the HYM1100 track bike.
I have been waiting for one of my pals here to get his dyno up and running, and it has been so for some time now. Since it measures consistently, but with notoriously low (or honest …) numbers, we needed to get some different bikes tested in order to have some reference points.

I´ve also not managed to get the graph viewer SW sorted on my computer, so I only have a screen-dump of the curves from my M800, the HYM1100, and my pals 999r. For refernce, the 999r gave 142 hp on a Dynojet at a major Duc dealer.

Dyno plot by torbjörn bergström, on Flickr

The curves for the 2V bikes are pretty typical 2V curves, I think, and I would really like to be able to ”extend” the torque curve  for maybe another 500 revs, which woud really help the power. I´m told, that´s a major undertaking, so maybe later ….

For reference, I´ll show the curves froma header length test I did on the M900 some years ago (it has been on this forum in another thread, but it´s relevanther, I think). The M900 had HC pistons, ported heads (origin and quality unknown) and the usual intake and exhaust mods:

Header length comparo_M900 by torbjörn bergström, on Flickr

Interestingly, the header lengt changed the shape of the torque curves, but not the engine speed for max power, or power level, significantly. I had planned to test bare 700 mm headers as well, but that would have melted the rear tyre. I don´t really know why the 700 mm with collector and silencer is significantly better.

If I can find time and opportunity this winter, maybe I´ll try short headers and open megaphones, just to see (and hear …) what happens 😊

Thats a really good example of moving the torque curve around the rev range. Street Vs Track. It reminds me of short Vs long inlet manifold tests.

Nice illustration of tuning to win, not for numbers.