strange suspension issue - SOLVED!

[Magnus]

i had my forks redone with ohlins internals recently.  decent forks to begin with, showa fully adjustable, stock foggy forks.  when i get on the throttle hard, the front end lifts up and feels like it's pulling to the right, while the rear of the bike feels like it's pulling to the left.  it's a strange sensation, but that's the best way i can describe it.  and when i release the throttle, i feel it torque back to where it was.  as unsettling as this is on a straightaway, having it happen in a turn feels dangerous.

- went through a few iterations of setting up the forks myself, following instructions of the shop who did the ohlins kit install, and also the desmo times manual.
- checked chain tension, as i'm not 100% what the cause was.  it started after i had the forks done, but who knows.
- no improvement, so pulled the forks off and reinstalled again, this time being extra careful. 
- set up sag, rebound, and compression, following the instructions (to the best of my limited abilities)

still no improvement.

does this ring a bell with anyone?  what can i look at next to troubleshoot this?

my ride:
'02 S4 Foggy with 996 SSS
Penske 2-way rear shock (this i haven't touched since it was setup and installed two years ago)

[Ddan]

That doesn't sound like front end to me, but I admittedly don't know squat.  Did you check you motor mounts bolts and  swinarm bearings?

[Armor]

I had my forks done with ohlins internals.  I have no problems like yours.  Handling is much better.

[Magnus]

haven't checked the motor mount bolts yet, good idea.  swingarm bearings seems unlikely...   

has anyone else experienced this "phenomenon"?

[scott_araujo]

Yes, check the motor mount bolts first and at every oil change.

Just a thought, is your back wheel on straight?  Put a straight edge against the rear sprocket, it should be parallel with the chain.  If the rear wheel points one way or another it can feel like the bike is pulling sideways when you get on and off the gas.  You may feel this more when accelerating out of a turn, maybe more on one side than the other.

Scott

[ducpainter]

haven't checked the motor mount bolts yet, good idea.  swingarm bearings seems unlikely...   

has anyone else experienced this "phenomenon"?

Swing arm shimming loose?

[clubhousemotorsports]

From your description it sounds like lack of rebound on the fork is causing the rapid rise . you may be pulling on the bars causing the side pull. try it being careful to not add pressure with either hand.
try adding some rebound to the forks and see if it settles down some.
 If you have no luck talk to the shop that did the work, they know what they have done and might point you in the right direction.
good luck

[MotoCreations]

Swing arm shimming loose?

Bingo. 996 swingarm pivot bolt was really loose.  Mike tightened and is in business again after test ride.  Locktite and proper torque is correct solution.

A few thousands play at the swingarm actually is magnitudes more play at the rear tire itself.

No bearings in the engine case anymore -- inserts with collars machined to shim as required.

I'm thinking with all the powdercoating within the rearsets which act in doubleshear on the swingarm pivot bolt, it might have worn or compressed a bit and thus the initial free play -- which then due to vibration backed out.  It's why I always recommend doing "wrench checks" on Ducati's on a regular basis -- things can loosen up after thousands of miles after building.

Nice I'm curious to hear the report on how the properly setup Ohlins-valved front Showa shocks work on Black Fog! (in a different thread of course)

[Magnus]

Yup!  That was the ticket...   Mark suggested I check that the other day as well, I finally got around to it today.  A tiny amount of play in the swingarm translates to virtual unrideability. 

Thanks Mark, and everyone.

ps. and I'll post up a report on the forks as soon as i get some seat time in!  But in the 5 minute ride i took at lunchtime, they felt great!   

[Dietrich]

So, are you guys adding/changing shims, or just torqueing the bolt correctly?  Anyone have the torque number handy?
 

[Magnus]

just going to locktite and tighten it up, I'll have to look up the torque setting.