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Discussion Starter · #1 ·
On my 01 996 at 50MPH and above I get a slight shimmy in the bars. The shimmy never grows exponentially with speed, always the same 1/4” left right movement on the bar ends (as in an extremely small headshake movement). I only notice it if I apply very light pressure on the bars or take my hands off the bars completely. I can physically see the bars moving. If I’m riding with normal pressure I don’t feel it at all even at much higher speeds.

Wheel bearings are tight, head bearings are tight, fork stubs aren’t bound up on the axle. I also took the pads out, put 200 grit sandpaper on a surface plate and rubbed the pads on it and scuffed the rotors with a red scotch brite pad then re-bed the brakes in. Shimmy is still there after all this.

So getting onto my question, could my rotors be warped? They are snowflake rotors and I’ve heard they warp easily. I was also thinking tire balance? Those are really the only two variables left unless I’m missing something.

What do you guys think?

Thanks in advance!
 

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check your tyre pressures, --rotors if you are rolling say 50 mph and very lightly apply your ft brakes do you feel the shimmy get worse? if not then your rotors are probably not warped--but this is an objective test--50 mph or 80 mph should not change the outcome at speed just barely apply the ft brakes to scrub off speed --I mean at 50 mph it may take you still 300 ft to stop--very light on the brakes--if you feel pulsing then you may have warped rotors--if not look harder--are your tyres balanced?--also look to the rear-swingarm piviots -are they torqued correctly--rear tyre pressure? rear wheel bearings? rear shock?---and the dreaded cracked swingarm or frame?? look carefully at everything that is a known issue--then keep looking
 

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also sorry for some of my suggestions regarding cracked frame & swingarm--I for some reason thought I was in the supersport forum l0l--but look at the other things problems at the rear of the bike can many times make you think you have problems in the front end
 

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Discussion Starter · #5 ·
You probably checked tire pressure in there somewhere.
Yes. Set at 33 psi. Manual states 32.7 I think.

check your tyre pressures, --rotors if you are rolling say 50 mph and very lightly apply your ft brakes do you feel the shimmy get worse? if not then your rotors are probably not warped--but this is an objective test--50 mph or 80 mph should not change the outcome at speed just barely apply the ft brakes to scrub off speed --I mean at 50 mph it may take you still 300 ft to stop--very light on the brakes--if you feel pulsing then you may have warped rotors--if not look harder--are your tyres balanced?--also look to the rear-swingarm piviots -are they torqued correctly--rear tyre pressure? rear wheel bearings? rear shock?---and the dreaded cracked swingarm or frame?? look carefully at everything that is a known issue--then keep looking
Thanks for all the ideas.

I do notice a slight pulsation when I apply front brakes at said speed. When coming to a stop though I can feel one spot that drags more so it’s actually more noticeable at slow speeds than higher speeds as far as brakes go. One spot drags much more like I’m squeezing the lever more but I’m not. This is why I deglazed the rotors and pads. I figured there was a build up of material in one spot but that didn’t fix the issue.

As far as torquesgo, when I bought the bike a little over a month ago I torque checked everything (it also just had a fairly extensive service with a receipt showing what was done). Also installed new rear shock bearings as the old ones had play in them. No play in rear wheel bearings or swing arm bearings. Rear tire pressure at 37 psi, manual is 36.x I think.

I do know the previous owner had new Dunlop Q3s installed not much time before I purchased the bike. There is wheel weights on the rims but obviously don’t know if it’s correct unless I had them balanced again. Or they may have been balanced without rotors installed. Don’t know exactly as I didn’t have them done.

I installed a ducabike ride height rod as well. Ride height is 10mm higher than the standard setting using a gauge. Forks are set at 4th line. (Used section 8 settings but didn’t go as aggressive on rear height as I thought it’s just too high for street riding). But I had the shimmy before installing and adjusting rear ride height so I don’t think that’s the issue.

also sorry for some of my suggestions regarding cracked frame & swingarm--I for some reason thought I was in the supersport forum l0l--but look at the other things problems at the rear of the bike can many times make you think you have problems in the front end
Thanks.
 

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.........-but look at the other things problems at the rear of the bike can many times make you think you have problems in the front end
Tire pressure OK then.

This is what I was thinking about. I had a rear puncture (on a 2003 Tuono) cause the front to wobble slightly.
I rode on wondering wtf. did not know of any puncture. Shortly the front started to wobble more, then headshake, turning into tank slap.

I managed to get stopped safely and the back tire was shredded. Which I saw after I checked the front and saw it was fine. TLDR, yes an issue with the rear can feel like a problem with the front. If I feel any such issue in future, I will be stopping right now! to check it out.
 

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Discussion Starter · #7 ·
.........-but look at the other things problems at the rear of the bike can many times make you think you have problems in the front end
Tire pressure OK then.

This is what I was thinking about. I had a rear puncture (on a 2003 Tuono) cause the front to wobble slightly.
I rode on wondering wtf. did not know of any puncture. Shortly the front started to wobble more, then headshake, turning into tank slap.

I managed to get stopped safely and the back tire was shredded. Which I saw after I checked the front and saw it was fine. TLDR, yes an issue with the rear can feel like a problem with the front. If I feel any such issue in future, I will be stopping right now! to check it out.
At least you got stopped safely!!

I’m pretty OCD with maintenance stuff, and I check pressures before every ride just to be safe. Only takes a minute to know tire pressures are good.

I did think about removing the front pads and going down the road and back just to see if the wobble goes away. Then I’d know it’s a rotor issue, but it’s not exactly the safest way to diagnose an issue especially with the rear brake on the 996 being borderline useless.
 

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On my 01 996 at 50MPH and above I get a slight shimmy in the bars. The shimmy never grows exponentially with speed, always the same 1/4” left right movement on the bar ends (as in an extremely small headshake movement). I only notice it if I apply very light pressure on the bars or take my hands off the bars completely. I can physically see the bars moving. If I’m riding with normal pressure I don’t feel it at all even at much higher speeds.

Wheel bearings are tight, head bearings are tight, fork stubs aren’t bound up on the axle. I also took the pads out, put 200 grit sandpaper on a surface plate and rubbed the pads on it and scuffed the rotors with a red scotch brite pad then re-bed the brakes in. Shimmy is still there after all this.

So getting onto my question, could my rotors be warped? They are snowflake rotors and I’ve heard they warp easily. I was also thinking tire balance? Those are really the only two variables left unless I’m missing something.

What do you guys think?

Thanks in advance!
You’ve got an issue & I’m gonna say that it’s not a warped disc !
Had a brand new , outta the box CBR1000 that had a similar wobble. While riding no hands on de acceleration it would always develop a wobble at 100kph , this could be stopped by simply putt 1 finger on the bar ,, take the finger off & it was fine until you slowed to 80kph & the same would again ,, then again at 60kph.
It was a balance problem.
 

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Front tyre pressure seems low... my 748 runs 34F/39R
Any lower in the front and it wont steer well.
 

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Discussion Starter · #10 ·
You’ve got an issue & I’m gonna say that it’s not a warped disc !
Had a brand new , outta the box CBR1000 that had a similar wobble. While riding no hands on de acceleration it would always develop a wobble at 100kph , this could be stopped by simply putt 1 finger on the bar ,, take the finger off & it was fine until you slowed to 80kph & the same would again ,, then again at 60kph.
It was a balance problem.
That sounds very similar. Yea all I really need is the pressure of 1 finger and the bars completely stop shimmying. I feel nothing in the chassis when the bars shimmy without pressure on them and still nothing resonating through the chassis when I do put pressure on the bars.

So you’re leaning towards a wheel balance issue. Since I know the bike has new tires on it too maybe the shop didn’t balance them correctly!!

Currently waiting on a pit bull front stand for the bike since I can’t use the one I have for my GSXR. Once that comes in the first thing I’ll do is have my balance checked.
 

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Discussion Starter · #11 ·
Front tyre pressure seems low... my 748 runs 34F/39R
Any lower in the front and it wont steer well.
Both the manual and tag from the bike state cold pressure at 32.7 front 36.9 rear. Bike turns in fine for me!
 

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Try some different settings on the steering damper (just little changes to begin with);
had the same experience on my bike (996SPS) years ago, and it's completely gone ever since.....

Peter
 

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Both the manual and tag from the bike state cold pressure at 32.7 front 36.9 rear. Bike turns in fine for me!

Your the one with the issue not me so what have you to lose by trying my suggestion?
Air is pretty cheap.
 

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Try some different settings on the steering damper (just little changes to begin with);
had the same experience on my bike (996SPS) years ago, and it's completely gone ever since.....

Peter



Shouldn't have a shimmy with or completely without a steering damper.
Something is up.
 

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So you say the head bearings are tight. That's usually the blame for this. You loosened the top triple clamp and tightened the special nut to torque specs? Did you lift the front end, pull back and forth on the wheel and listen for a clunk? With the front end lifted, turning the wheel do you hear any bearing noise?

I think I would concentrate more efforts in that area.

The one other thing I can think of is make sure the tire bead is seated all the way around by following the little ridge in the rubber and making sure it is the same space from the rim.
 

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Discussion Starter · #16 ·
Try some different settings on the steering damper (just little changes to begin with);
had the same experience on my bike (996SPS) years ago, and it's completely gone ever since.....

Peter
Can’t change settings on my damper unfortunately. Maybe the damper is bad? No signs of leaking but it’s a possibility.

Your the one with the issue not me so what have you to lose by trying my suggestion?
Air is pretty cheap.
You’re right, air is cheap. I’ll try that.

Shouldn't have a shimmy with or completely without a steering damper.
Something is up.
Maybe my damper is bad?

So you say the head bearings are tight. That's usually the blame for this. You loosened the top triple clamp and tightened the special nut to torque specs? Did you lift the front end, pull back and forth on the wheel and listen for a clunk? With the front end lifted, turning the wheel do you hear any bearing noise?

I think I would concentrate more efforts in that area.

The one other thing I can think of is make sure the tire bead is seated all the way around by following the little ridge in the rubber and making sure it is the same space from the rim.
I spoke with the tech that did the last service on the bike before I bought it. The service was done recently and it’s a small independent shop so he remembered the bike. He said he did a full chassis bearing check, look for play etc etc so I’m basically saying the head bearings are good because of that. Once I get my front stand in and I can lift the from up I’ll inspect further. But I do specifically remember asking him about head bearings and he said they had no play and there was also fresh torque stripe markings he put on the special nut and top triple clamp bolts as well. Since I am having an issue though I’ll redo that torque check once I get my front stand in the mail.

Tire looks like it’s seated fine.

Thanks for all the ideas so far! I appreciate it!
 

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as stated before your tyre pressures seem good as per the book--that said I run higher tyre pressures I run 40 ft & 42 rear I have reasons for this -1) I am not running on the track just normal street riding, 2) I live in central Florida the roads here are crowned and you always wear out the left side of the front tyre badly & the higher pressures help with this a little, 3) I also get better mileage on the tyres running the higher pressures. you could bump up your tyre pressures for no reason other then a test then drop them back down if it does nothing. Just a suggestion it's free and easy
 

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tyre wear , front or rear. flat spotting is usually the culprit. rear hub or front wheel bearings. swing arm bearings or loose pivot. loose or broken engine mounts. head bearings can feel tight but be dry or notched. steering damper can have air inside or a tight spot. bent axle, forks, clamps, frame. buckled wheels. these all contribute to odd handling, shimmy etc. have fun.
 

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Discussion Starter · #19 ·
as stated before your tyre pressures seem good as per the book--that said I run higher tyre pressures I run 40 ft & 42 rear I have reasons for this -1) I am not running on the track just normal street riding, 2) I live in central Florida the roads here are crowned and you always wear out the left side of the front tyre badly & the higher pressures help with this a little, 3) I also get better mileage on the tyres running the higher pressures. you could bump up your tyre pressures for no reason other then a test then drop them back down if it does nothing. Just a suggestion it's free and easy
Yea I suppose I’ll try it. My GSXR runs 36 front 42 rear. Same size tires. Actually same brand and model tires too. Dunlop Q3. So I’ll do sir first.

tyre wear , front or rear. flat spotting is usually the culprit. rear hub or front wheel bearings. swing arm bearings or loose pivot. loose or broken engine mounts. head bearings can feel tight but be dry or notched. steering damper can have air inside or a tight spot. bent axle, forks, clamps, frame. buckled wheels. these all contribute to odd handling, shimmy etc. have fun.
Thanks for all that. I can rule out flat spots or worn tires since they only have 500 miles or so on them.

Swing arm pivots I checked. Bearings seemed fine. With the shock removed I moved the swing arm up and down and it was nice and smooth. No binding or notches.

Engine mounts are torqued and not broken.

Air in the damper is a possibility.

I sure hope it’s not bent axles, frame, forks etc. bike has zero signs of ever going down. All original fairings, no scuffs on frame or cases etc. Bike doesn’t handle weird as far as turn in goes or mid corner feel etc. If I never took my hands off the bars and looked down I would’ve never noticed the slight shimmy in the bars.

I’m still hoping it’s a simple wheel balance issue or a warped rotor causing this! 9 times out of 10 issues are something simple you just have to find it.
 

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Well then dont take your hands off the bars lol--I work on BMW's I had a customer one time with a K1200LT, said it would go into a tank slapper all the time --I rode the bike 20 miles or so and never felt anything odd at all-no tank slapper & no shimmy felt perfect, I told him this and he told me --get this--Take your hands off the bars & with your hand bump the end of the handle bar firmly then it goes into a tank slapper---I ask him this--Why the hell would you ever do something that stupid?? you are destabilizing the front end on purpose. --I'm sorry but I just cant fix stupid lol--I'm not calling you stupid but the BMW K1200LT customer was no doubt.
 
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