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Discussion Starter #1
Hey guys. I’m be noticed a few times when traveling at greater speeds than say 50 mph, if I’m compelled to stop suddenly for any reason - the front end seems to vibrate.

I do NOT have ABS.

It doesn’t seem to alter control over my steering. And stopping power doesn’t seem to fade under these conditions.

Could it just be that I’ve maxed the compression of the fork springs and am feeling bumps from the road? I’m no fat *******. I’m 6’-0” and about 180 lbs.

My only other guess is there could be air in the brake lines from the factory. But the reservoirs don’t seem to be milky or anything. I’m stumped?
 

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Discussion Starter #3
Yeah. That makes sense. Cheap enough and easy enough to do myself. It’s a place to start. Thank you
 

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Is the vibration subtle or pronounced?

How are your tires? In particular, is there any cupping on the front tire? If your tires are good, then consider looking over your front brakes carefully for anything amiss. Perhaps the rotor is warped or the brake pads are abnormal as Tracy indicated.
 

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Discussion Starter #7
First things first - only 1600 miles on the bike. No hard racing or heavy canyon riding. Just for background about the bike.


The tires are fine. No cupping, uneven wear, or any other anomalies to be seen.

I’ve run my fingers along the rotor - unfortunately I don’t have a front stand yet to spin the wheel and check it that way - but I can’t detect any difference in the surface of the rotor. For reference, I had a warped rotor and on truck and was able to tell immediately upon running my fingers over the surface. I do acknowledge that it could be warped and I may not be able to tell.

The vibration only occurs under heavy braking. Again, with the warped rotor on my truck, the vibration was evident no matter how hard I applied the brakes, and in fact was worse under gentle application

I think I’ll start with swapping out for new pads and proceed from there. Thank you all. This community is nothing short of awesome to a newb.
 

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First things first - only 1600 miles on the bike. No hard racing or heavy canyon riding. Just for background about the bike.


The tires are fine. No cupping, uneven wear, or any other anomalies to be seen.

I’ve run my fingers along the rotor - unfortunately I don’t have a front stand yet to spin the wheel and check it that way - but I can’t detect any difference in the surface of the rotor. For reference, I had a warped rotor and on truck and was able to tell immediately upon running my fingers over the surface. I do acknowledge that it could be warped and I may not be able to tell.

The vibration only occurs under heavy braking. Again, with the warped rotor on my truck, the vibration was evident no matter how hard I applied the brakes, and in fact was worse under gentle application

I think I’ll start with swapping out for new pads and proceed from there. Thank you all. This community is nothing short of awesome to a newb.
Yeah you pretty much need a front stand so the wheel can spin freely and check it that way. It's pretty much impossible to feel, because the warping is usually minor, could be like 0.020 inches off or something small like that which you wouldn't be able to notice by running your fingers over it, but you can see it when you spin the wheel. If you only have 1600 miles and the bike was only used for typical street riding, I can't imagine the rotor warping at this point though. Look at the pads and see how worn out they are and if they're worn out evenly or not. Do you have the stock rubber line or a SS brake line?
 

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Hey guys. I’m be noticed a few times when traveling at greater speeds than say 50 mph, if I’m compelled to stop suddenly for any reason - the front end seems to vibrate.

I do NOT have ABS.

It doesn’t seem to alter control over my steering. And stopping power doesn’t seem to fade under these conditions.

Could it just be that I’ve maxed the compression of the fork springs and am feeling bumps from the road? I’m no fat ***. I’m 6’-0” and about 180 lbs.

My only other guess is there could be air in the brake lines from the factory. But the reservoirs don’t seem to be milky or anything. I’m stumped?
I have the Non-ABS version as well for last 2.5 months. I have never had any vibrations from the front end. I have had the back tire lock up/slide at very slow speeds (less than 15 mph). This happened two times, one I just went through water and second in light traffic (oil maybe?)
 

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Discussion Starter #10
Yeah you pretty much need a front stand so the wheel can spin freely and check it that way. It's pretty much impossible to feel, because the warping is usually minor, could be like 0.020 inches off or something small like that which you wouldn't be able to notice by running your fingers over it, but you can see it when you spin the wheel. If you only have 1600 miles and the bike was only used for typical street riding, I can't imagine the rotor warping at this point though. Look at the pads and see how worn out they are and if they're worn out evenly or not. Do you have the stock rubber line or a SS brake line?
Typical street riding. I’m a total newb - but have some mechanical know-how to use your guys’ suggestions and see what I can do for myself. The vibration hasn’t gotten any worse since I first noticed it... So that’s a silver lining.

I’ll see about getting a front stand to get the wheel moving and eyeball it. I’ll check the pads tomorrow - but the last time I looked a couple of weeks ago - all seemed to be wearing evenly - and the vibration issue was present.

I am indeed running the stock lines. New brake lines are on my to do list. Could crappy stock lines cause a pulsating/vibrating feedback through the front end on heavy braking?
 

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I’ll see about getting a front stand to get the wheel moving and eyeball it. I’ll check the pads tomorrow - but the last time I looked a couple of weeks ago - all seemed to be wearing evenly - and the vibration issue was present.

I am indeed running the stock lines. New brake lines are on my to do list. Could crappy stock lines cause a pulsating/vibrating feedback through the front end on heavy braking?
Poor mans way of spinning/checking the front wheel: Get a sturdy friend to pull the bike over to the left so the weight of the bike goes on to the side stand and the front wheel leaves the ground. On a light bike like ours it's not too hard to do as long as you have a reasonable amount of stature and strength.

No the stock lines wont create pulsing.
 

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Many, many, many years ago I dun bought my first new bike; a '86 FJ1200. Had the same problem OP describes vibration under hard braking. Mechanic pulled the wheel. and re-balanced the tyre, butt no help. Mechanic checked run out of rotors one was slightly outta spec, so they replaced it, butt no help. Mechanic, then pulled the forks, rebuilt, 'n shimmed 'em to tightest specs possible, butt no help.
Ends up the POS Dunlop tyre was slightly outta round. You couldn't see it with the nakid eye, butt after wearing it out 'n replacing it, the problem went away.
 

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Discussion Starter #13 (Edited)
@Kiwi Rider thank you for the confirmation regarding the stock lines. My understanding is that if anything - the issue with stock lines is that the brakes can feel “squishy” or “soft” under repeated heavy braking that can cause the brake system to produce excess heat and expand the rubber lines.

I’ll start with checking and replacing the pads and go from there. Front stand will be on the way soon - and I’ll check out the rotor. Might use your suggestion of getting it up on the side stand in the meantime.

Thank you everyone for the thoughtful responses. I value this community’s knowledge and experience.
 

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I have had some front brake judder with the stock pads. It tends to happen to me if I use the brakes too lightly. A couple of firm stops cures it. Rotors are not warped in my case.
 

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@Tracy - great to know! With so much compression braking on tap I usually do not end up braking very hard. I do lots of shifting; a carry over from my 2 stroke days. Performance pads will go in when I need brakes.
 

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:cool: Is bike still under warranty? I would try cleaning the pads and rotor and rebed them in to see if that helps, after cleaning all then do quick stops from 50mph to 10mph at least 3 times and see if that helps,1600 miles is not a lot, rotors and pads might be glazed and need a good cleaning, sometimes bikes that are shipped overseas have a coating on most of the metal and dealer should have cleaned the bike but could have missed some, just check anyhow...
 

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I'll add my thoughts here. I've felt something like the OP describes. What I "feel" could be an out of round front tire I suppose, will have to check that, But in my unlearned seat of the pants opinion it feels like fork flex or judder due to varying traction of the road surface the tire encounters during braking creating rapid changes in loading forces on the front end.
 

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OP may have it right with the forks having reached its full compression due to soft springs and bottoming out. The same thing happened to me once, last summer, never really cared to address it. And I'm going to suggest other factors contributing to these front vibrations.

The brakes on my bike (non-ABS) was fully upgraded to brembo the works, Traxxion Dynamics AK25 damper rod kit sprung to my weight. I did not check to verify if the forks had indeed bottomed out. However, with the proper fork spring rate, I will assume it can't be the cause. OEM Dunlop GPR's with @ 8000 km on the tires, stock tire pressures, warm tire temp. I don't think any of the parts (tires) were out of spec. And the road was flat and in great shape. This leads me to believe, it doesn't really matter the type of braking components are on the bike apart from tires and springs.

Has anybody with aftermarket stickier tyres actually lock and skid the front? Sorry I have no experience with a stickier tyre on this bike. What I believe in my case is the front tire had reached past its traction coefficient (?) and was skidding. Holee shyte! But it was not sticky enough to lock-up and throw me. Perhaps oil and other debris was on the road, I couldn't tell and didn't want to stop to look because of traffic. That would entail the rapid oscillations in the suspension stroke as the bike is losing and gaining traction. Factors to this may include tire compound/ temp/pressure, road debris (oil), irregular road surface. Would be interesting to see what affect a stickier tyre would have. It would probly just dump me off with an accidental stoppie, haha. If I moved my weight forward it would have been interesting.

Best I could describe it is like a prelude to a stoppie, the front was like a soft jack-hammer, the rear kinda light and airy, and I could feel the front subtly sway.

OR

Fork flex? Theoretically a fork brace will ensure the fork suspension stroke is not impeded by heavy braking. But these are beefy 41mm forks for a 300 and some odd pound bike. Anyhow, I do have a Ninja400R fork brace that I haven't installed. Wasn't really sure if it would help, and it's not light.

I will test this next season, specifically looking for the spring compression limit (bottoming out), affect of sticky tyres and the fork brace. I will wrap a zip-tie around one of the fork stanchions to measure its compression length, to see if it's bottomed out with heavy/emergency braking.
1. Using the brace and OEM Dunlops
2. No brace, and stickier rubber
3. Brace with stickier rubber

Maybe strap a camera facing the forks.

IMG_20191109_153744.jpg



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