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Discussion Starter #1
Well, I just got back from a several day riding trip to NorCal and man, was it great! Lots of spirited riding two up with my wife on the big dirt bike keeping company with a bunch of VFR 800 and VFR 1200 riders and even an 800Xc rider thrown in. Toward the end of the trip I started noticing a "shudder" in the front end under hard braking when slowing for 2nd gear and slower corners. My bike is a 2015 with only 15,200 miles (I am blessed to have multiple bikes to ride), all maintenance up to date (14k mi) including brand new brake fluid done at the dealer this time so as to properly flush and bleed the ABS system (I don't have the gear or expertise to do that), tires are Avon TrailRiders with a new one on the back and the front has about 6k miles with even-looking wear.

What are the first things to think about? I lifted the front and tried to assess steering head bearing slop by pulling back and forth on forks and gently moving side to side. No play detected and no notchiness in the steering. So I'm thinking about replacing the front tire and of course looking at the brake pads when I do that. If I still have the problem, then I'll take it to the dealer to check the rotors and the wheel for runout. Am I missing anything?

Thanks.
 

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Discussion Starter #2
Oh and has anyone tried the Pirelli Scorpion Trail II and how would you feel about running it on the front with the Avon TrailRider on the rear until the rear is changed? Thanks.
 

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Agreed. I would carefully inspect both discs for decolorated areas or possibly some drops of oil were picked up.

However it may be the tire because issues with the rotors should manifest themselves at any speed under hard braking, not only when getting to a certain slower speed.

Also don't rule out the head bearings. I think impossible to feel that they are loose by pulling on the wheel. I bet you they can do with some tightening.
 

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My Vee was very sensitive to my front tire choice. Vees have a steep steering head angle and they are picky about front tires. Even the tires I found to work best on the Vee, would shake some as they wore.

If a Vee shakes only during braking, I would look at the brakes of course. But if it shakes just due to engine braking or while under partial throttle, I would look at my tire.

The Strom used to and I assume still does use a ball bearing in the steering stem. Switching to roller bearings is a good upgrade.
 

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Tires, especially those with large gaps in the tread like the block/knobby type, can do some weird things under hard braking.

But since it has had the brakes serviced there is chance that some fluid or even caliper grease got on the rotors. I have seen this cause the brakes pulse on my bike before. And it can be very hard to get cleaned completely off. Warped rotors are uncommon, the loose bobbin pin mounts can make up for a LOT of runout on a rotor disc.
 

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Well, ... a several day riding trip to NorCal and man, was it great! Lots of spirited riding two up with my wife on the big dirt bike keeping company ... Toward the end of the trip I started noticing a "shudder" in the front end under hard braking when slowing for 2nd gear and slower corners. ... tires are Avon TrailRiders with a new one on the back and the front has about 6k miles with even-looking wear. ...
Your trip sounds fantastic, I wish I had been there. When you add up the words I've highlighted it sounds like normal, expected behavior. Normal for the end of a ride wherein you (and your wife) are all dialed in and pushing. I think there is a good chance that your front tire, at 6K miles, may be just fine for casual solo riding but you are achieving that point of the tire protesting (feedback). That fine point of performance just before the ABS kicks in. Congratulations !!

I noticed in another post you made today that you are, more and more, embracing the art of trail braking. Again, congrats.

I also use the Avon TrailRiders on my V2. I'm on my second set and will buy a third. On my SV650 I am using up the last of my Avon Distanzia tires (now extinct). I know that block treads can not match track tires for that last 3-7-X% of cornering performance. But I'm thankful for the feedback they give me when I get into that boy-racer zone. Over the years since I was a boy and a racer _ I've learned to take a hint from my tires before the front end "tucks". I mean who hasn't seen Rossi tuck the front while managing a big lead?

So I see, from your description, that every thing is normal. Go ahead and scrub your rotors and maybe take an intuitive crank on that stem bearing, etc. But just replace the front tire before your next hot ride with the boyz.
 

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What are the first things to think about? I lifted the front and tried to assess steering head bearing slop by pulling back and forth on forks and gently moving side to side. No play detected and no notchiness in the steering. So I'm thinking about replacing the front tire and of course looking at the brake pads when I do that. If I still have the problem, then I'll take it to the dealer to check the rotors and the wheel for runout. Am I missing anything?

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Did you check all the associated bolts on the front? Axle and it's pinch bolts, brake caliper mounts, fork triple tree pinch bolts?

Did you have extra weight on the back? If so and you didn't up the shock preload or exceeded it the balance of the motorcycle is biased even more towards the rear. Usually that will induce front end shimmy or in extreme, tank slappers! Could show up as brake shudder I guess.
 

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Discussion Starter #9
Did you check all the associated bolts on the front? Axle and it's pinch bolts, brake caliper mounts, fork triple tree pinch bolts?



Did you have extra weight on the back? If so and you didn't up the shock preload or exceeded it the balance of the motorcycle is biased even more towards the rear. Usually that will induce front end shimmy or in extreme, tank slappers! Could show up as brake shudder I guess.
Good points...all fasteners torqued to spec. I've been riding the Strom with my wife since I bought it new, so I have the preload clicks memorized for how much gear we are carrying to get the best ride vs. solo, etc. The best indicator of not enough preload seems to be the occasional dragging of the side stand or center stand foot in a deep corner...

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Tires, especially those with large gaps in the tread like the block/knobby type, can do some weird things under hard braking.

But since it has had the brakes serviced there is chance that some fluid or even caliper grease got on the rotors. I have seen this cause the brakes pulse on my bike before. And it can be very hard to get cleaned completely off. Warped rotors are uncommon, the loose bobbin pin mounts can make up for a LOT of runout on a rotor disc.
You're right. A lot of the time, uneven braking force as the rotor turns is due to uneven friction between the pads and rotor. Either due to contamination, or due to the development of "hard spots" on the rotor.
 

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i'd look at steering head bearings. common on V1 and Wee stroms. don't know why, but they were problematic for years with barely loosening and even re-torquing didn't always fix. Considering that the frame and headstock of a V2 isn't much different than a V1, it wouldn't surprise me if this was the issue. I've redone a pair of Wee's and a V1 with roller bearings and it solved the problem every time. the parts are cheap (under $40), but it's labor intensive, so beware.
 

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Discussion Starter #12
i'd look at steering head bearings. common on V1 and Wee stroms. don't know why, but they were problematic for years with barely loosening and even re-torquing didn't always fix. Considering that the frame and headstock of a V2 isn't much different than a V1, it wouldn't surprise me if this was the issue. I've redone a pair of Wee's and a V1 with roller bearings and it solved the problem every time. the parts are cheap (under $40), but it's labor intensive, so beware.
Yeah, I replaced the steering head bearings with All Balls roller bearings in a 2004 VFR (a friend of mine did all the work and supplied the tools necessary). It was an involved job...

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While you are in there... if the fork oil hasn't been changed by 14K it is due. Old oil thins out when warm. Excessive brake dive can overload the front tire. Insufficient rebound damping on rear shock allows the back to pogo up under braking. Are you using all your fork travel?
 

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While you are in there... if the fork oil hasn't been changed by 14K it is due. Old oil thins out when warm. Excessive brake dive can overload the front tire. Insufficient rebound damping on rear shock allows the back to pogo up under braking. Are you using all your fork travel?
Not using all or near all the fork travel, but I would like to experiment with a heavier fork oil to reduce brake dive.
 

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It's probably a brake pad or disc issue. Poor quality brake pads tend to perform worse under repeated hard braking. Warped rotors aren't unusual with the mileage you have, especially if they have a spirited owner! As they heat up, they cause a shudder or vibration under braking as well.

I haven't found that worn out fork oil will cause a shutter, but it will certainly cause unwanted vibrations to be more noticeable and make the front end just fill sloppy in general.

Wheel and a triple tree bearings can definitely cause issues if they're worn.

Maybe start off with the easy stuff, some GOOD brake pads and take another look at your rotors and front wheel bearings. If that doesn't do the trick, then move on to the more work intensive stuff like upper bearings and fork renovation.
 

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Discussion Starter #16
All good info and suggestions guys, thanks. I ordered a new tire and some EBC HH pads. I'll detail the brake rotors with scotchbrite pad and brake cleaner, put it up on my wheel balancer and look for any gross rotor or wheel bearing issues, change the pads and tire and then test ride it. Will report back.

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I am thinking disc also. I had the same issue on my former KTM 950SM and the first think I checked was the discs for warping. they were'nt warped so I tried rubbing them down with fine emery and that helped but the judder soon returned. In the end I replaced both discs and that solved the problem. Further research revealed that occasionally the quality of the metal in a disc can vary on its circumference with one small patch being grippier on the pads than the rest of the disc. Tha then causes the judder.
 

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I got a bit of juddering as my old stock brake pads wore down - usually under hard braking too. Replaced with HH rated pads, and the brakes never felt so wonderful - you'll really like the improved braking feel with just the pad swap.
 

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Riding Two-up in the mountains, lots of hard braking (OP mentioned trying to keep up with some fast movers), so there could be some brake rotor warpage occurring too - hard braking can also heat up the pads so much that you may get a bit of pad glazing which would account for the inconsistent juddering while braking hard - the pad is grip/slip/grip/slip at a very high rate.....I'd swap the pads first before getting new rotors - that may be the fix.
 

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Discussion Starter #20
Front wheel off this weekend, cleaned up rotors with scotchbrite pad and lots of brakleen. Wheel bearings feel smooth with no play. In the process of cleaning up calipers and pistons. Since it has only 15,000 miles and I don't ride it on salted winter roads at all and not much in the wet I don't want to do a complete caliper overhaul. So anyway I think I found the problem...on piston is not moving much at all even after repeated washings with brake fluid/toothbrush, trying to push it in and out. I'm waiting on a Motion Pro piston removal tool so I can grab it and turn it to free it up.

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