High speed, slack driveline vibration. <UPDATE>

[Jabba]

I have had a high speed, slack driveline vibration.  What does THAT mean?  Well, if I am running indicated 70 MPH it does not manifest.  When I am running indicated 85 it does.  Basically, when the driveline is slack... no accell or decell.  

I pulled the rear end apart.  The pinion cup and U-Joint are perfect, and sloppy wet.  I can discern nothing wrong with the U-Joint.  Perhaps... it's a little "sticky".  But every U-Joint I have ever messed with was like that.  It's all tight, and the caps all rotate with the yoke.

Anyone have any thoughts?

It was like this for the WHOLE trip to Inzane and back.  About 1800 miles.

Jabba

[Ricky-D]

With those miles on the u-joint, there should be no "sticky" feel at all.

It should easily move thru it's arc of movement.

I feel it is the u-joint.

***

[Patrick]

Any u-joint should move freely.. How are the drive dampers ??

[Momz]

Replace your dampners with I/S or later model wheel dampers.

[Chrisj CMA]

Have the wheels re balanced.......under acceleration they might smooth out

[Momz]

ChrisCMA

Might be right on,...however I'd use Dyna Beads and replace the schrader valve witha 90 degree "Patchboy".
But if the wheel is off checking the dampners is only a small job.

[Jabba]

I've got a CT and dyna beads.  There is NO vibration under accelleration OR Decelleration.  Only a slack driveline. 

The Dampers SEEM OK.  What do  you do to "check" them? 

Jabba

[Chrisj CMA]

OK...if its not wheel balance, what about steering head.....that might act up when there are less torque force on it (ie coasting)

[Jabba]

I don't think so...

It's VERY drive line related.  If I let the play in the driveline tighten up at ALL the vibe goes away.  If I allow it to be in the "lash" then that's where the vibration is.

I am ordering a U-Joint for sure.  I had a bad driveshaft and pinion cup last year.

Jabba

[Michvalk]

If it's still apart, check to see if the new pinion cup is still tight. Just a thought

[Jabba]

If it's still apart, check to see if the new pinion cup is still tight. Just a thought

OK... Yeah it's still apart.  I have not even ordered a u joint yet.  Luckily I have a standard to ride.

Jabba

[Jabba]

Nope.  The Pinion cup is tight.

It's GOT to be the U-Joint.  It's "Sticky" on 1 axis, but not the other.

I am replacing it and putting it back together.

Jabba

[WamegoRob]

I have had a high speed, slack driveline vibration... Anyone have any thoughts?

This guy had a similar problem almost exactly one year ago... maybe ask him what his problem was?   

http://www.valkyrieforum.com/bbs/index.php/topic,31314.0.html


JABBA!

[Jabba]

I have had a high speed, slack driveline vibration... Anyone have any thoughts?

This guy had a similar problem almost exactly one year ago... maybe ask him what his problem was?   

http://www.valkyrieforum.com/bbs/index.php/topic,31314.0.html


JABBA!

ROB!!!

Yeah... except that I have already pulled it apart and last year's trouble has not repeated itself. 

But I like the way you think.



JAbba

[Cattman]

I've got a CT and dyna beads.  There is NO vibration under accelleration OR Decelleration.  Only a slack driveline. 

The Dampers SEEM OK.  What do  you do to "check" them? 

Jabba

With the flange placed in the wheel, see how much play it has.  Look at the dampners it goes into and see if they are getting oblong or show deteroiation like the shock bushings do. If so, time to replace

[Ricky-D]

Here we are,,,,, a year later.......

From:  http://www.valkyrieforum.com/bbs/index.php/topic,31314.0.html

"It is the slop between the output shaft and the drive shaft splines allowing the u-joint to get a little out of the concentric circle it runs in.

With no force on the splines the u-joint loosens up a bit on the splines and causes the out of balance condition.

A new u-joint will correct the problem for a while, but eventually it will return.

It doesn't happen at the lower speeds where the range you cruise at but get up around 80 or more and it will happen.

It seems to be pretty common I think but some may have never experienced it, and others will fail to understand or recognize what you are even talking about."

***

[Jabba]

Here we are,,,,, a year later.......

From:  http://www.valkyrieforum.com/bbs/index.php/topic,31314.0.html

"It is the slop between the output shaft and the drive shaft splines allowing the u-joint to get a little out of the concentric circle it runs in.

With no force on the splines the u-joint loosens up a bit on the splines and causes the out of balance condition.

A new u-joint will correct the problem for a while, but eventually it will return.

It doesn't happen at the lower speeds where the range you cruise at but get up around 80 or more and it will happen.

It seems to be pretty common I think but some may have never experienced it, and others will fail to understand or recognize what you are even talking about."

***

OK... so assuming this to be correct... what needs replaced?  The output shaft of the transmission?

I already replaced the driveshaft last year.

Jabba

[Ricky-D]

If you take care of all the other places where slop occurs, what you are describing will fade from importance since it is you doing the driving and you can easily avoid allowing the "loafing" where that annoyance happens.

To answer your question, yes, changing the output shaft should help cure the problem but it's no guarantee that it will not reoccur.

I think, like I said earlier, that this is occurring on all the Valkyries, just not recognized by most riders.

It seems to mainly stay above 75mph, so I just deal with it.

***

[Jabba]

If you take care of all the other places where slop occurs, what you are describing will fade from importance since it is you doing the driving and you can easily avoid allowing the "loafing" where that annoyance happens.

To answer your question, yes, changing the output shaft should help cure the problem but it's no guarantee that it will not reoccur.

I think, like I said earlier, that this is occurring on all the Valkyries, just not recognized by most riders.

It seems to mainly stay above 75mph, so I just deal with it.

***

I would THINK that the U-Joint is softer than the output shaft.  Or it SHOULD be.  Hopefully that will cure it.

I ordered a new U-Joint from HDL today.  They said they had 7 in stock.  Everything else is new as of last year and still looks to be in GREAT shape.

Jabba

[Patrick]

I haven't tried to file an output shaft.. But I have the drive shaft and u-joint.. The u-joint is soft,, but,, the drive shaft splines ruined 2 files.. Its made from some tough stuff.. So I imagine the output shaft would be pretty hard..
I have a feeling your problem is the 'sticky' u-joint.. It should move around smoothly.. It may be stiff,, but,, has to be smooth..

[Jabba]

I bought a new U-Joint today... at a dealer.  $130 plus tax.     I have another on order from HDL.

I was playing with the tolerances.  There is wear on the output shaft mating splines that WOULD allow some lateral vibration.

I am on board with RickyD's theory.

Hopefully I'll have the gumption to put her back together tomorrow.

Jabba

[Jabba]

I installed the new U-Joint.

Everything seems better.  I believe Ricky-D was on target.  There WAS more slop in the output shaft side of the Ujoint on the old joint than the NEW one.

Jabba

[old2soon]

When i start having the same driveline issues you sir have laid some ground work for us as the others did. Glad you got yer fat lady SMOOTH again.  RIDE SAFE.

[Jabba]

I personally believe that my dry splines last year, caused the wear in the U-joint, which manifested THIS year.  Hopefully EVERYTHING is right now.As a bonus... my splines are all lubed again!

Jabba

[Tundra]

Wow, they've gone up. I bought one this year, don't remember what month?
I only paid $78.00 from HDL.
  Glad you got her straight

[Jabba]

They originally quoted me $181.xx.

Daymn!

I keep thinking sending one off for machining to take a replaceable toyota joint might be appropriate.  But... in MY case... I still think it needed replaced, as it was the yoke that was worn.


Jabba