New (to me) 98 Valk, with a vibration..

[olddog1946]

I just bought another Valk, with 59K on it. It has a vibration, most noticeable at 1500 and  3500 rpm upon deceleration. I originally thought the u joint or pinion cup, but pulled all that yesterday and installed a new Ujoint, a pristine drives shaft, and a good pinion cup.  I couldn't really find anything noticeable in what I took out but had those parts available and changed em out. Final drive splines are perfect. I do have rattle in the motor when it's cold, that goes away when it warms up a bit, (thinking valves need adjusted) but the motor runs great, get 33 mpg at 75-80 mpg, no misses, etc. My vibration will also occur while slowing, clutch disengaged, and worsens when I hit the rear brake...so Now, I"m back to the final drive or wheel...bearings felt good with axle in and rolling the tire with some tension on the axle, dampers are a bit sloppy (aluminum pieces are loose inside)....

THOUGHTS.....??????

[nogrey]

I just "acquired" a similar vibration in two of my Valkyries. Tore them both apart several times to no avail. Finally realized that the vibration began when I replaced the rear tire on both of them at the same time. For me, it's just the tire.
There was a thread awhile back about that rattle you're talking about. In that thread, it turned out to be the alternator. Rattles are tough.

[Chrisj CMA]

Put the bike on a lift, get the rear wheel off the ground.  Then grab the bottom of the wheel and try to move it side to side.  Any movement will feel like a tiny "tic tic" but it means you have a bad wheel bearing.

[KG]

Shock bushings easy to check and inexpensive to replace. When you decelarate you unload the rear end and can cause vibration.  Is bolt centered in bushing have someone sit on it and recheck.

next time you have the tire off you may also want to check swing arm bearings.

[Paxton]

"... Good, good, good Vibrations..."   The Beach Boys? 

[nogrey]

Shock bushings easy to check and inexpensive to replace. When you decelarate you unload the rear end and can cause vibration.  Is bolt centered in bushing have someone sit on it and recheck.

next time you have the tire off you may also want to check swing arm bearings.

How do you check the swing arm bearings?

[olddog1946]

UPDATE:  I adjusted the valves this morning,  and took it out for a ride...runs good...the vibration I feel in my butt when throttling down, is also there when I coast and use the rear brake to slow. So, I'm inclined to believe I'm looking at a wheel bearing going bad. I agree that shock bushings will affect the bikes handling, I'm not sure about them causing any vibration (actually almost a buzz riding on that rock hard Mustang seat).  I do, however have the set of shocks I removed from my 01 that I can give a try.   IF that doesn't help the pull the rear wheel again and see what I can see.

[Brian]

I too felt a strange type driveline bump while throttling back mostly when using the highway pegs. I replaced the OEM dampers in the rear wheel and the bump is gone. If you have slop in yours you can trying shimming them in place using cut strips of gasket material or milk jug plastic temporarily till the new ones come in. I have used strips of an aluminum beer can as shim material before. It works fine. I drink a beer or two while working on the bike anyway so the material is kinda free.

[olddog1946]

another UPDATE:  I got the new shock bushings and was pleasantly surprised. The vibration has lessened considerably and maybe wouldn't even be noticeable with something other than the Mustang seat (and me knowing it's there) . I'm still thinking the rear end ...I was so happy that the splines, etc looked pristine that I just threw it back together without double checking the o-rings were all there. I now have a set of bearings, and once I get the cobras cleaned up I'll get the pipes and bearings installed and hope for the best.

[O-B-1]

Guess I will have to check out your second steed, Rick... Once I get my Phat Gurl rolling again. Have to go to Michael J's again and get one of you two to buy this time!

[Attic Rat]

Old dog I had one in the shop last year doing the same thing. It turned out to be rear wheel bearings.

[The emperor has no clothes]

I too felt a strange type driveline bump while throttling back mostly when using the highway pegs. I replaced the OEM dampers in the rear wheel and the bump is gone. If you have slop in yours you can trying shimming them in place using cut strips of gasket material or milk jug plastic temporarily till the new ones come in. I have used strips of an aluminum beer can as shim material before. It works fine. I drink a beer or two while working on the bike anyway so the material is kinda free.

Kinda free dampeners

[olddog1946]

another UPDATE:  Installed new (VTX1800) shock bushings, pulled the final drive again. I was so excited by the good shape of the gears that I didn't really check the O-rings, this time I did a closer inspection and found that the 0-ring on the wheel was missing, So I replaced them all, and then I took the wheel, inserted the axle into one bearing at a time and held the wheel up and had my neighbor turn the wheel...smooth as glass. I also installed a good set of later model dampers.  So I put it all back together again,, minus the OEM pipes. I stuck my old noisy ass cobra's on so I could hang onto the unmolested pipes,,,,,,,,vibration is STILL there...

I'm running out of ideas.
Has any one with Mustang seats had some transfer of vibration through those rock hard seats?

[Challenger]

I also have developed a vibration on decel or coasting below 30 mph, It started when I installed the new Michelin Commander rear tire, Gone from 42 psi down to 32 in 2 lb increments, harmonics change a little, but still there.  Everything was checked out, drive shaft and u-joint were perfect. Re-lubed splines, I took everything back apart this week and all looks good, Replaced wheel bearings anyway, New shock bushings went in with tire change, Buttoned everything back up and road it tonight, Vibration still there. If I lean slightly, it disappears and reappears when straight up, I'm calling it the new tire and going to ride the snot out of it.

[olddog1946]

This morning I took off the Mustang seats and installed the OEM seats off my neighbors 97.  Now almost unnoticeable (and I'm looking for it). It's just time to ride it I guess.

[art]

I had bad vibration during deceleration from high speed, clutch disengaged and no braking. I did a indicator check of the runout of the drive shaft. It was out about 1/32" . I took it to work in a machine shop and straightened it to .005" and most of the vibration was gone after that. The shaft can be bent, just a little info.

[olddog1946]

I had bad vibration during deceleration from high speed, clutch disengaged and no braking. I did a indicator check of the runout of the drive shaft. It was out about 1/32" . I took it to work in a machine shop and straightened it to .005" and most of the vibration was gone after that. The shaft can be bent, just a little info.

That's interesting, However I changed the drive shaft (out of my 01) and u-joint (new), and I had no vibration while the shaft was in the 01. The vibration was there before and after the change out. I wanted to keep the drive shaft that came with my replacement final drive mated together when I replaced the final drive in the 01.