View Full Version : Front end chatter

06-08-2010, 08:03 PM
so I searched and nothing too specific so apologies if the answer is here and I can't find it. Basically the problem starts to get bad in fast corners above 60 or so. It feels like the front is skipping along the surface which is giving a pulsing feel through the bars.

The tires are the stock Dunlop with about 1450 miles on them. Tires are 29F and 30R but I tried 32 in both and also 24F and 27R all with basically the same skipping sensation. Bike is road only but at a pretty fast pace. All we ride are mountains in WV and VA and we know the roads very well so I would say we ride 8/10's track pace. Not trying to brag, just trying to give perspective.

Allen Noland set it up for my weight because we weigh about the same so I'm confident the suspension is in the ballpark, I just need a starting point to start tweaking.

Thanks for any help.

06-08-2010, 08:10 PM
Fresh fluid in the forks?

Allen Noland
06-08-2010, 09:30 PM
. Basically the problem starts to get bad in fast corners above 60 or so.

You could just slow down a bit....:rolleyes:

06-08-2010, 10:18 PM
You should try it at 100mph it sucks hard!

06-09-2010, 10:02 AM
Now that the obligatory smart ass answers have been submitted could anybody give some other tips? And Allen, Remember I know where to find you.:gunner:

06-09-2010, 10:19 AM
You could just slow down a bit....:rolleyes:

Not an option.

06-09-2010, 10:19 AM
You should try it at 100mph it sucks hard!

I have and it does!

06-09-2010, 03:19 PM
I had the same problem. After stock susp was set up for my weight (175 lbs) and changed to better tires, problem is gone. The front feels very planted and feedbacks with confidence. I'm riding on Bridgestone Battlax BT-003R's. The stock Dunlops sucked really badly...

06-09-2010, 03:32 PM
With 1450 on the tires its possible that the front has some cupping due to a combination of set-up and resulting wear. If you are really pushing in the twisties 1450 is pretty high mileage.

I agree that the stock Dunlops don't cut it. I went with Michelin Power Ones front and rear along with proper suspension set-up for my weight and have all the confidence in the world in the bike now.

06-09-2010, 04:32 PM
Dunlop and Pirelli tires have totally different construction. Can you take a pic of your front tire? Looking for a good view of the sipes accross the tread, with as much detail as possible. You can tell alot from your tires.

06-09-2010, 05:33 PM
I didn't even think about the tires cupping. That does make sense cause the problem just started last weekend. I figured it was due to me getting used to the bike and pushing harder. I will check when I get home and let you know

06-09-2010, 05:45 PM
My bike only has 400 miles on it. I changed the tires at around 325, so, even new, the Dunlops just didn't cut it.

06-09-2010, 05:52 PM
Mike, while the cupping may have something to do with it, i don't think it does. I did an exhaustive search on the subject matter as I have the same exact thing going on with my bike ('09 SXV550, had a Husqvarna SM610 prior to which rode PERFECTLY). what i found:

-there are a ton of complaints related to such

-most likely culprit (for me) was the rear spring. the bike's sag was 70mm in the front, but 100mm in the rear. that is waaaaay off, and a likely candidate for the front end feeling so light. i weigh 179 area without gear.

-was told to lower the forks so to see "one ring" and go from there. they are all the way flush with the top of the triple clamp right now.

-was told to change the fork oil to different wts (have seen 5wt, 7.5wt, 10wt recommendations). sag seemed ok for me so i'm not going to mess with the springs at this juncture (nor spacers, air gaps, etc).

-was told to run tire pressures anywhere from 24 front to 30 front....really didn't make a difference to me.

-was told to drill holes in the front fender (towards the rear of it) because it can act as an airfoil at the higher speeds (the front end feels light to me at lower speeds too).

-was told to check the steering head nut for looseness/tightness.

-was told to change out the triple clamp for an aftermarket one.

my bike is in the shop having the rear spring installed (race-tech 6.0) and fork fluid changed out so i can't opine to how it rides. all of the other suggestions are good ones but i'm going to start with the easiest and most effective ones first (sag was obviously off).

best success with your search and search results!

06-09-2010, 08:43 PM
throw on a new front tire. That stock Dunlop is no mileage queen for fast paced street use- and at 1450 miles you might as well use a fresh one as a base line for future testing. Just sayin"

06-09-2010, 08:50 PM
Couldn't detect any cupping but I'm going to put some new tires on in the morning. I am hopful this will resolve it to a degree because as I said it didn't have this problem the firs 1200 or so miles.

I also want to clarify that the front doesn't feel light, it feels like the front is pulsing for lack of abetter term. That being said I will definitely be upgrading the suspension as funds allow. I want to get to know the bike better and improve my sumo riding skills so I have a better idea of what I want to accomplish with mods. I will report on the effects, if any, of the new tires tomorrow after I put a hundred or so on them.

06-10-2010, 04:46 AM
Get rid of the stock tyres, they're crap.

The recommended tyre pressures are very high. I'm 6'/95kg/210lb ready to ride and on the road use 24psi (1.65bar) front and 26psi (1.8bar) rear (cold) but run a 160 on a 5" rim (Alpina). Works much better.

06-10-2010, 09:56 AM
So, you never answered the question about your fork oil.

I have been working on suspension (street and dirt) as a hobby for years now, and have always noticed a dramatic improvement when going to fresh fluid, especially if you are replacing the old with a good SYNTHETIC. Motorex, Amsoil, and RaceTech (which I have been told is just re-badged Motorex) are all top-notch synthetic suspension fluids.

I noticed that my SXV had a case of very bad fork stiction when I first got it. It didnt matter how well I aligned the forks, they always seemed like they were sticking too much. This noticeably improved when I switched to synthetic fluid, as did the handling of the bike.

I have a suspicion that the problem is really tire-related, though.

06-10-2010, 03:24 PM
So I put the new tires on and the problem is still there. I really tried to pay attention to what was going on and varied my pace a lot in the corners. My best analogy is that it is like riding on a slight washboard. The feeling is there even when straight upright up to about 40 MPH after that it disappears. In the corners it is there from about 50 and up. What is weird is that if i'm in fast sweepers,90MPH and up and I ride it street style it is pretty stable but in tight stuff leg out style it goes back to washboard mode,

I had a friend ride it and he felt it also. What we can't figure at this point is if it is really from the front end. It may be in the rear or both. The thing that is strangest is that it didn't have this problem for the first 1100-1200 miles.

I put Pilot Powers on it and was running 30F and 33R. Any suggestions as to pressure would be appreciated. I also dialed a couple clicks of compression and rebound first in the front and then the rear, no noticeable difference.

I think fork oil is next on the list. But why did the problem appear out of nowhere and not a slower deterioration if it is the fork oil?

06-10-2010, 08:29 PM
When I raced an EX500, they were notorious for terrible front end chatter once you got into the 1:23's at Loudon. What I found worked best was being VERY tedious about the fork installation process...

You need both forks at exactly the same height. If you were slightly off, then the extra preload in one fork (from using the axle to essentially jam the axle bores level even if the forks weren't) would cause the forks to bind just enough when keeled over (which adds extra lateral loading to the fork bushings) that they would stop working well enough and the whole front end would skip like mad.

It was worst in turn 9, which is a decreasing radius off camber corner - for what its worth. Most of us ran without front fenders as well, since you wanted to try to do everything possible to allow the flexible front end to take the bumps - fenders and fork braces made the problem worse because they would tend to pull the forks just enough out of their natural alignment to exacerbate the binding.

Sooo.. might just want to make sure that the forks are installed as well aligned as possible. Though admittedly, the SXV has a much more robust front end than my old EX500.

06-10-2010, 09:57 PM
Silly question, but has the front wheel been balanced?

06-10-2010, 10:07 PM
Loose spokes maybe?

Oh, and back to the fork oil thing:

I just changed my fork oil recently. I bought the bike when it had 1800 miles on it, now it has 2600. The fork oil was NASTY!! I am talking grey-sludge, difficult to rinse out NASTY! I took the forks completely apart and flushed everything, including the cartridges. While in there, I found one of the nuts that holds the compression stack on the base valve was LOOSE, which can have a dramatic effect on the valving. Seeing as these forks had apparently never been apart since assembled at the factory, I would suspect I am not the only one who has had this problem.

06-11-2010, 05:24 AM
Silly question, but has the front wheel been balanced?

Good question.

06-11-2010, 08:05 AM
Here's my set-up (190lb rider). Front forks - down to 4th ring. All clickers at 3/4 max. (you should run them slowly through the range to determine the number of clicks). Mine were different than the manual listed. Sorry don't remember sag settings.

Make sure you don't have stiction in the front forks. When putting the wheel back on I push the axle in snug from the right side and then tighten the left side collar bolt finger tight. The whole point of this exercise is you don't want to create stiction by pulling in the bottom of the fork legs too tight. Then I tighten the two right side pinch bolts. Next I pump the front end up and down several times and then tighten the left side pinch bolts to torq spec and then left side collar bolt to torq spec. Then loosen the right side pinch bolts again and pump the front end up and down several times and then retighten the right side pinch bolts to torq spec. I do this on all my bikes and it works well.

06-11-2010, 08:18 AM
Another possibility although less likely is a warped rotor. Put the bike on a stand with the front wheel elevated and spin it briskly listening for the tell tale dragging sound at intervals (with not pressure on brake lever). If not detected repeat with light brake lever pressure.

06-12-2010, 07:43 AM
So update time. We took the tires off and remounted them and rebalanced. Then dialed in a little more preload. Did the rotor test and it is dragging at intervals so will check the alignment of everything else later today.

I am very happy to report that while there is still a tiny bit of chatter on hard left ganders(possibly due to rotor?) the bike is back to being better than I am. Thanks for all the input.

06-12-2010, 07:56 AM
How did you add preload and how much?

06-12-2010, 08:36 AM
How did you add preload and how much?

To clarify, added a turn on the rear. I talked to Allen and we both thought it might be more of a rear suspension issue.

06-12-2010, 05:55 PM
I had chatter and low grip in the front on my 08 550 on race track.
Tried differnent tire brands,pressures,suspension settings no change.
In the end put the forks as high as could in the clamps and fixed it made it bit twitchy but just got to hand on tight.
Tried my mates 550 with triple clamps and that was 100 times more grip again,unbeleavable the difference.Guna get a set now.
My situation maybe different to yours.

Allen Noland
06-12-2010, 06:09 PM
I am very happy to report that while there is still a tiny bit of chatter on hard left ganders(possibly due to rotor?).....

...or a wheel bearing.