Front tire vibration after fork oil change

[06fiz600]

Tires are Michelin Pilot Road 3 with 6,000 miles on them. They look like they are cupping. I always keep track of my pressures, every week or two and never let them get below 30 psi.
But the front end is much firmer now with the 10w fork oil in it. I followed the instructions and put the correct amount in.
Maybe this is why I now notice the tire possibly being out of balance?
I know the forks were way too soft stock, slow rebound could cause this wear?

The tires look to have at least another 6000 to go..
what do ya think?

 

[FinalImpact]

It seems unlikely but I'd guess its possible. At what speeds and what do you feel? Is there a chance you're payin more attention now and it was there all along?

Any chance you slid the wheel in backwards? I'm not sure its possible but you might double check. The tires are marked and the spokes openings are to be on the trailing edge, not the leading edge facing forward.

Any chance the wheel was knocked over and dinged the rotor? You could block the nose and hold a pen against the fork tube and check the rotors for run out as well as any binding with calipers.

That's all that comes to mind as improved dampening can mask vibrations to some degree while less dampening usually allows vibs to be more apparent.

 

[TownsendsFJR1300]

You can also check the balance of the wheels/tire itself.

Lift the front end, remove the calipers and loosen the axle. Once the wheel spins freely, if its out of balance gravity will bring the heavy side down to the bottom. It'll be quite obvious.. Re-balance as necessary with stick on weights...

Slow rebound shouldn't cause the cupping, low air pressure isn't helping...

As noted by Finalimpact, the softer forks was probably masking the already out of balance tire..

 

[Wolfman]

Cupping normally only happens when you are running real low trye pressures on a road based tyre, that isnt meant to run at such low PSI.

Having said that, i have found Michelin's do tend to cup, regardless of tyre pressure...it may just be the tyre???

:thumbup:

 

[QwickFliCk]

maybe your forks are not parallel.. you can try this=being sure your axle is torqued to spec before hand... loosen your pinch bolt...while it is loosened stand up the bike straight and push down on the handlebars/ triples a couple times...this will straighten out the forks...then tighten the pinch bolt to spec. 23nm... hopefully this helps:thumbup:

 

[QwickFliCk]

check this out i learned this from someone else not this guy...but its the exact same concept:

[ame=http://www.youtube.com/watch?v=c0dkpQJREno]Performance Upgrades- Proper Front Wheel Installation - YouTube[/ame]

 

[TownsendsFJR1300]

check this out i learned this from someone else not this guy...but its the exact same concept:

Performance Upgrades- Proper Front Wheel Installation - YouTube

Very informative, thank you. A new SOP to use!!

 

[FinalImpact]

People - careful how you interpret that video:

The FZ and the R6 forks effectively allow one fork leg to float and depending on WHEN you tighten the pinch bolt it may or may not capture the fork in the proper location and you can end up with caliper alignment issues as well as excessive stiction in the forks.

The hub and wheel spacers amount to a fixed distance which is directly related to the triple clamp spacing of the forks. They ALSO maintain the correct spacing for the calipers to the hub and disc assembly.

The axle tightens into the fork and secures everything to one side by compressing hub and spacers against ONE fork tube. This maintains the calipers relationship to the brake disc on the hub. However the other side has nothing to pull fork into the hub! It is meant to be pushed together so there is NO GAP between the FORK and Axle Spacer where the dust seal rides.

The FZ6 Axle is bolt and it pulls the axle, into the Right side spacer, the hub, and the Left spacer into the Left fork but you must push the Right fork tube inward while tightening the RS pinch bolt.

The R6 Axle uses a bolt into the Axle to pull the axle, Left spacer, the hub, and Right spacer into the Right fork but you must push the Left fork inward while tightening the pinch bolt.

If you have stiction issues that are resolved by loosening the pinch bolt on the fork end that floats LEAVING A GAP AT THE SPACER TO FORK (near axles), its likely that one or both of your forks are bent!

I know - I said allot. Read it a couple times and draw yourself a picture based on this and what you saw in the video. I'm just saying think about what you're doing when working on the front end. Don't leave a GAP!

 

[06fiz600]

Thanks everyone for the responses,
The wheel/tire is definitely going the correct direction. And the vibes are most felt at 30-50 mph. Up at about 80 mph it's smooth. I know it's NOT from tire pressure being too low. But the rear is cupping slightly too...most likely balance check is what I need.
I bought some stick-on weights and am going to make a balancing stand to put the wheel on.

 

[PhotoAl]

My second PR2 is nearing the end of it's life and it cupping just as the first one did. Have run higher air pressure than the first but it still cupped. I think it has to do with the blocks and the hard compound in the center and soft on the outside. The softer compound wears faster and contributes to the cupping. It is not too bad and the bike handles well so I don't worry too much about it. Tire is howling more now. Will replace in the next three months or so.

 

[QwickFliCk]

People - careful how you interpret that video:

The axle tightens into the fork and secures everything to one side by compressing hub and spacers against ONE fork tube. This maintains the calipers relationship to the brake disc on the hub. However the other side has nothing to pull fork into the hub! It is meant to be pushed together so there is NO GAP between the FORK and Axle Spacer where the dust seal rides.

The FZ6 Axle is bolt and it pulls the axle, into the Right side spacer, the hub, and the Left spacer into the Left fork but you must push the Right fork tube inward while tightening the RS pinch bolt.

The R6 Axle uses a bolt into the Axle to pull the axle, Left spacer, the hub, and Right spacer into the Right fork but you must push the Left fork inward while tightening the pinch bolt.

If you have stiction issues that are resolved by loosening the pinch bolt on the fork end that floats LEAVING A GAP AT THE SPACER TO FORK (near axles), its likely that one or both of your forks are bent!

are you positive on this info? im not saying your wrong or im right...just wondering cuz i have a gap on my right fork and the spacer...the spacer is snug against the rim..and the left fork side is snug against both fork and rim...what would happen if there is a gap?

 

[FinalImpact]

are you positive on this info? im not saying your wrong or im right...just wondering cuz i have a gap on my right fork and the spacer...the spacer is snug against the rim..and the left fork side is snug against both fork and rim...what would happen if there is a gap?

To your point - the Service Manual doesn't say anything but; "Before tightening the wheel axle nut, push down hard on the handlebar(s) several times and check if the front fork rebounds smoothly."

However - during the R6 Fork install I wondered through the stealership and looked at all the FZs and the R's using this same axle setup - NONE have a gap. So, I guess I have to say I'm not 100% but draw your own conclusion.

Also - if you loosen one side of the top & bottom triple and rotate the main fork tube and the gap changes - its a very good indication you have a bent tube.

 

[06fiz600]

Just a follow up...I had the front tire rebalanced...it was off .5 oz and the vibes are still there. The rear tire looks cupped too but after 6k I migt just hold it out. The forks are definitely stiffer. I may have reached the harder compound on the rear tire.