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Thread: Front vibration at speed

Created on: 11/03/22 03:37 AM

Replies: 31

Nastynotch


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Location: Lumberton, TX

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Front vibration at speed
11/03/22 3:37 AM

So I’ve been dealing with a front vibration for some time now that begins at exactly 95 mph and progressively gets worse with increasing speed. So far I’ve dialed in rear wheel alignment to within.001”,reset all suspension settings,repacked and dialed in steering head bearings, went over every single bolt in the front with a torque wrench, changed wheel bearings, and seals, checked tire for imperfections, pulled all the wheel weights(vibrations got much worse),added balance beads back in(back to square one),and installed new rotors and pads.

I’ve now discovered that there is a tiny bit of play in the front forks both forwards and backwards but there are no seal leaks whatsoever. After a quick search for parts to rebuild them, I discovered that the Kawasaki service manual doesn’t show the fork bushings in their schematic and therefore doesn’t offer them for sale, I was able to find that Ktech does offer them, so now we wait for them to get here.

If this doesn’t fix the problem I’m afraid the last remaining ounce of sanity I possess will be gone forever. Bike has 21,000 miles


* Last updated by: Nastynotch on 11/3/2022 @ 3:44 AM *



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Maddevill


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RE: Front vibration at speed
11/03/22 10:08 AM

Front and back play in the forks indicate that your steering head is loose. Try tightening up the top bolt.

Mad



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Nastynotch


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RE: Front vibration at speed
11/03/22 10:16 AM

No this is play between the outer and inner of each individual fork. I had them in a vice off the bike.



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cruderudy


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RE: Front vibration at speed
11/03/22 10:26 AM

I dont know the spec for play side to side in the fork tubes but I think there must some allowed or it could contribute to the fork up/down travel issues.

The tire/wheel dynamic balance sounds like it changed and created new cyclic force you are feeling.

Old tire?? Pothole rim ding? idk But, you are a sharp guy and know this so probably need the Hubster suspension guru to advise


* Last updated by: cruderudy on 11/3/2022 @ 10:38 AM *



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Nastynotch


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RE: Front vibration at speed
11/03/22 10:35 AM

What lead me to check the tubes for play is that while I’m getting vibration, I can look down the fork tubes and see flutter that appears to be going backwards and forwards. Not up and down with the natural stroke of fork movement.



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cruderudy


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RE: Front vibration at speed
11/03/22 10:45 AM

Since u have it all apart it would be simple to have the wheel/tire dynamic balance checked at a tire shop (while u r there to watch so they dont BS and just tell u u need a new tire) to eliminate it as root cause.



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Nastynotch


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RE: Front vibration at speed
11/03/22 10:54 AM

I’ve already had the beads removed and the tire rebalanced while I wait. Reason being I’ve got zero experience using the beads but tons of experience using weights. The tire is a Michelin Road 5 with approximately 2,500 miles on it. Plenty of tread and I can’t find a single thing wrong with it. Perfectly round and wearing evenly.

I found it interesting that the wheel had 1.75oz of weight before I removed them, but once the beads were removed and the wheel was rebalanced it took .5oz


* Last updated by: Nastynotch on 11/3/2022 @ 10:57 AM *



2013 ZX-14R SE
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Hub


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RE: Front vibration at speed
11/03/22 11:33 AM

Nasty, ever see my generic front end setup on the forks? I'm about to pull front end off for the steering bearings. The trick to the knocking is to take the up and down out so it's zero, but not past the bind by hand. In other words, I hand tighten first ring, take the up and down out, back off a touch, second ring locks that down with the tab ring bend over a slot.

Top crown goes on, one fork is moved into the mm call out of the top crown, the pinch is tightened on the top crown so the mm out is saved from moving. The tree's pinch bolts are loose. Top nut goes on the triple's stem, and it's torqued from there.

What loose threads that are drawn up on the triple's shaft is more or less an ever so slight non-bind, more like knocking on the door. It's so dialed in, sometimes I can hear the knock come in about that time to re-lube the bearing again.

I can only assume the forks were torqued before the triple's bolt was torqued, and this did not bring up any kind of play locking all pinches first?

I mean, the only way fore and aft would happen is if the races floated in the frame's neck, and that's saying no up and down play at all. Make sense?

Another trick is about the pinch bolt sequence. 3 tier would be a torque at a time times 2 or 3 rounds of stager at the set of 3 pinch bolts. Just saying it's a lot of back and forth going on as it loads.

Racing days and the tire boys are out there, they use the same knife point pizza cutting wheels to statically balance the GP bikes too.



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Nastynotch


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RE: Front vibration at speed
11/03/22 12:46 PM

Hub I will keep this in mind when going back together. However I’m not having any steering issues, or noises before or after doing the bearings.

What’s your thoughts on the forks having play foreword and backwards? I put a dial indicator on them and had .010” in both directions for a total of .020”. Seems like an awful lot.



2013 ZX-14R SE
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Hub


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RE: Front vibration at speed
11/04/22 9:44 AM

I would think that much play would open the lip of the seal and leak. We have the same amount of mileage and I can't see a seal leak on mine.

I think the measurement is the other way around. Say it's 10 one way and 10 the other, I would think it would be 5 and 5 equals 10.

It's like the 14 being stroked from 1352 to 1441, would be a 2mm crank length, but it's lmm at BTC and 1mm at TDC. That's how I'm looking at the fork having that .005" split.



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VicThing


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RE: Front vibration at speed
11/05/22 9:06 AM

21k miles probably encroaching fork/shock servicing, especially depending on how you ride.

I had my forks and shock (they can rebuild/upgrade the stock shock) serviced by Traxxion last year and am very happy with the results. They found my fork shafts were slightly out of round and corrected it, which is something most of us wouldn't be able to do just servicing ourselves. I would say if you have some play in your fork tubes that's definitely something I would be getting checked out. I asked Traxxion how often they recommended I get mine serviced, and they recommended 25k miles, don't know if that's standard or can vary rider to rider.

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Nastynotch


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RE: Front vibration at speed
11/06/22 1:13 PM

Thanks guys, parts will be here next week so I’ll report back on the conclusion, or continued efforts elsewhere. Only thing left is to replace a seemingly good tire.

Hub if I pull all the slack to one side and set the dial indicator to zero I’d get .020” pushing it to the opposite side towards the dial indicator.


* Last updated by: Nastynotch on 11/6/2022 @ 1:18 PM *



2013 ZX-14R SE
2 Wheel dyno works flash
custom machined bar risers by yours truly
Muzzys black stainless slips
V1 custom mounted
Zero Gravity DB screen
Yoshimura fender eliminator
Black powder coated wheels

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Hub


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RE: Front vibration at speed
11/06/22 6:09 PM

https://www.ronayers.com/oemparts/a/kaw/56e72def87a8660e60bbe0dd/front-fork
This is 44065 and 44065A. That would be bushing sleeve inner and outer numbers respectively. Though it's a dirt bike, I'm pointing out the 2 outer and inner bushings that would wear and move the fork fore and aft and give that kind of number.

https://www.ronayers.com/oemparts/a/kaw/56e720c587a8660e60bbd58c/front-fork
But this front fork shows no bushing, no slider insert at the fork leg. If say you can't replace the bushings to get the slop out, it's new unit complete, or new part assembly that comes in the 'sub-line out' showing the boxed in unit complete to get the sleeve, would be buying the 44008/A to shore up the slop.

Notice in the owner's/shop manuals 'service intervals' page. Shows everything to change but the fork oil. So basically it's saying it's just like the rear shock oil and can't change that out, so it more means, 'when fork seal leaks on that inspection interval,' it's saying, wink-wink, no leak, no need to change oil until the seal leaks.

Then the manual has a section as if buying a replacement part and these are the tools needed, how to measure the oil, etc. So the what might think is excessive play, the seal would surely load that one direction on the brakes, lip seal would take less than .020" movement to move the seal away from the tube, the fork would leak somehow with that much play, the scoring of the tube would pop up on the extension of the fork, but I'll assume there is no leak, no line scoring, no change of less slop of the fork leg if you moved the leg 90° from where it sits, meaning, with the axle thru both tubes, but that one leg spun to 90° then measure the fore and aft, and if the numbers read the same?

Because there are no sleeve ID or OD measurements in the book, or any for wear of parts, so as to change out a spec number breaking out of the set ID/OD windows of wear. So can two forks windup with the same clearance numbers, neither leaks, neither is line scored at the tubes. It might be normal?

My front end is not down or I'd fore and aft my legs just to see if they match yours. So as for me, I'll change seals as a set [when one only leaks] and that's when I'll change the fork oil. So for ease of mind:
1. Are the forks both measured out the same as far as fore and aft?
2. Is this one fork tube scored at the tube when fully extended?
3. Does the fork leak at all?

So the answers should be:
1. Both measure the same, yes. Then the odds of one fork only having this slop would say normal to me if both read the same.
2. No. Then where is the rub two hands together, which hand remained cold, or not worn equally at both rub marks?
3. No. Then the slop is not that loose as to make it leak under braking.

Make sense this way with the variables added of leak and scored parts?



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Nastynotch


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RE: Front vibration at speed
11/07/22 2:17 AM

I can’t say if they both measure out the same. Both had slop, but the right one was obviously worse than the left so that’s the one I measured. It also has a “bump” that I can feel while working it. Also, funny you mention spinning the tube and measuring again. I didn’t do that, but over the weekend I reinstalled them with both tubes clocked 90 from the original position. I still got vibrations but at a much higher starting speed, and not as violent. I also noticed another change. If I start applying front brake while it’s vibrating, I get a sudden sharp increase in vibration followed by a sharp decrease while never letting off the brake or decreasing speed.

This led me to do a test that was highly dangerous but I had to know. I unbolted and secured both front calipers and went out for a test. Conclusion, no change in vibration. This is by far the weirdest diagnosis I’ve ever dealt with. Parts will be here in a few days so we shall see. I agree it makes no sense why there isn’t a leak of any kind, and no scoring that I can see with them still assembled.



2013 ZX-14R SE
2 Wheel dyno works flash
custom machined bar risers by yours truly
Muzzys black stainless slips
V1 custom mounted
Zero Gravity DB screen
Yoshimura fender eliminator
Black powder coated wheels

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Hub


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RE: Front vibration at speed
11/07/22 7:02 AM



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Nastynotch


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RE: Front vibration at speed
11/07/22 9:06 AM

Same here.



2013 ZX-14R SE
2 Wheel dyno works flash
custom machined bar risers by yours truly
Muzzys black stainless slips
V1 custom mounted
Zero Gravity DB screen
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cruderudy


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RE: Front vibration at speed
11/11/22 4:17 PM

A few "why's" could be addressed and perhaps their path might provide some new info ?? idk example, there may be many whys .....

Why is there no fluid leaking out of the seals I suspect?
Tube is low on fluid
Why is the tube low on fluid

Called 5 why's in finding root cause. Once you get into the 4-5 level answer to the why question, u may have the root cause answere

The fact u rotated the tubes and the dynamics changed tells you some interface between the tubes and perhaps down into the wheel may have changed the structural dynamics and I would be looking for what that is. Probably be clearer when you disassemble for the new seals



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Nastynotch


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RE&#x3a&#x3b; Front vibration at speed
11/12/22 6:23 AM

If the tubes are low on fluid it came that way from the factory as I’ve owned the bike since new. This vibration started out of nowhere, as I’d changed nothing in some time leading to it. It started as barely noticeable; so little that I’d written it off as maybe it’s in my head. But over the course of say 1000 miles it got worse and worse.

If this fork rebuild doesn’t fix it then I’m really going to be scratching my head. I’ve even inspected the frame for cracks. One thing is for certain, we’re all about to learn something.


* Last updated by: Nastynotch on 11/12/2022 @ 6:29 AM *



2013 ZX-14R SE
2 Wheel dyno works flash
custom machined bar risers by yours truly
Muzzys black stainless slips
V1 custom mounted
Zero Gravity DB screen
Yoshimura fender eliminator
Black powder coated wheels

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Hub


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RE: Front vibration at speed
11/12/22 6:55 AM

On my end, I've been thru 4 of them. Each one had the steering bearings lubed at their 7,500 mile interval, forks never returned back to the same position, if not a deliberate 90° turn of the tubes. So it couldn't be that subtle of change even at that low mileage.

Another guess would be pad drag, low pressure, out of balance, or a worn tire with steps, or the rain groove has one side sticking up higher than the other side of the groove?

These frames will not take a bend. They snap clean off. And it wont take much of a hit and cracks like an egg.



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Nastynotch


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RE: Front vibration at speed
11/12/22 8:48 AM

Admittedly I didn’t service the stem bearings until now, but I will say that they along with the races looked in great shape. I pulled the calipers off, road tested, and still had the vibration. Tire is wearing beautifully without anything uneven or out of round, and I’ve had the balance checked at two different shops with the same resulting weight in the same spot.

As far as the frame goes, I just wanted to scratch that off the list as being checked. The bike hasn’t been wrecked or dropped.


* Last updated by: Nastynotch on 11/12/2022 @ 8:49 AM *



2013 ZX-14R SE
2 Wheel dyno works flash
custom machined bar risers by yours truly
Muzzys black stainless slips
V1 custom mounted
Zero Gravity DB screen
Yoshimura fender eliminator
Black powder coated wheels

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piken


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RE: Front vibration at speed
11/12/22 10:47 AM

I personally would install a "new" front tire.

On the cheap, you could try to un-mount the front tire,
rotate tire 180 degrees, mount and balance and see if there's any change.

Although rims are usually more out of balance then tires (new tires)

If there's any 14 guys around you could try to swap front tire/rim to test.

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Nastynotch


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RE: Front vibration at speed
11/21/22 2:09 AM

Update: So after a complete fork rebuild absolutely nothing changed, but at least I can say that the oil is fresh and the seals are all new. This lead me to slap a new Michelin Road 6 on the front. This actually cleared up 90% of the vibrations I was experiencing. Yes there is still something there between 105-130 almost like an oscillating vibration , but seems to somehow clear up past that. I brought the bike up to 170 and it seemed to be quite smooth and happy at that speed (me not so much because it’s been a minute since I’ve traveled that speed).

Get the bike home and throw it on the stand to do chain maintenance as I always do every 6-800 miles and once done I decided to crank the bike and watch the chain spin. I noted that there is what appears to be a slight bend in the rear sprocket. Didn’t throw my dial indicator on it to test how much but it’s bad enough that it’s obvious, so I’m replacing the whole set now. So who makes the best stuff for street use? I don’t mind spending what is necessary to get quality parts for this bike.



2013 ZX-14R SE
2 Wheel dyno works flash
custom machined bar risers by yours truly
Muzzys black stainless slips
V1 custom mounted
Zero Gravity DB screen
Yoshimura fender eliminator
Black powder coated wheels

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Nastynotch


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RE: Front vibration at speed
11/21/22 4:31 PM

Just measured rear sprocket runout at .024”



2013 ZX-14R SE
2 Wheel dyno works flash
custom machined bar risers by yours truly
Muzzys black stainless slips
V1 custom mounted
Zero Gravity DB screen
Yoshimura fender eliminator
Black powder coated wheels

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Hub


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Posts: 13727

RE: Front vibration at speed
11/21/22 8:10 PM

Yeah, .020" is the limit. I just put on an EK oring chain on the nephews bike. Need the staking tool kit. Got it at cycle gear. Second time for the same bike. But since it's cheap, the flair end sort of lasted once. So I used a small ball bearing, goop glued the ball on the flair so it would push out or squash the pin's hollow ends.

The easiest out is OEM sprockets, the EK, the flair tool and didn't turtle always say change tires as a set? Change the rear and zip for vibration. Beer says .004" is not going to out the vibe. The NEW Tire Will.

Signed,
NOLTT



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Nastynotch


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RE: Front vibration at speed
11/22/22 4:37 AM

Hub the rear tire has less than 400 miles on it so I just can’t do it. Let me rephrase, my wife would shit a brick if I did that.



2013 ZX-14R SE
2 Wheel dyno works flash
custom machined bar risers by yours truly
Muzzys black stainless slips
V1 custom mounted
Zero Gravity DB screen
Yoshimura fender eliminator
Black powder coated wheels

Link | Top | Bottom


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