GIXXER CHATTER

[Bam55]

 >:(Anyonewho has or has had a Gsxr late model, has had to deal with this. Does anyone possibly know how to maybe stop or, hell, minimize this anoying and speed killing symptom? My suspension is done, the forks are up 7mm and the rear shock is set at 338mm in ride height terms. Mostly occurs during hard braking. Give me some pointers everyone, otherwise the only way I thik I can fix it for good is get some more Yamahas ???

[r6_philly]

rotors may be bent

[grim_racer]

I don't know about the late model, but I had that problem on my '92.  Mine was the rotors.

[Frank_Angel]

What band tires?

[sdiver68]

I was able to mostly dial mine out with rebound adjustments on the Penske.

[Super Dave]

It's not the rotors, as you know, PJ.  The chatter is regular across the board on many newer GSXR's regardless of the tire.  Speed may be a concern, if someone isn't going fast enough, they are not going to feel it.  

Uh, my GSXR is gone...

[TZDeSioux]

/quote]

Yamahas phucking rule man!

[OmniGLH]

Chatter under hard braking?

Ok... I thought this "chatter" everyone talked about was a slight chattering under cornering coming from the front end.  My bike had a nasty tendency to run wide on exits, and if I pushed it harder, you could feel the front slide a bit, and kind of "chatter" through the bars.  I solved it by adding one click of rebound damping to the forks.  

But under braking?  I don't think I've ever noticed it... can somebody maybe describe it a little better?

I've got an '01 750... Traxxion forks (set at stock height) and a Penske rear (at +10mm)

[sdiver68]

Yeah, the GSXR's chatter so badly by design that Yates was barely able to finish races... :o

I never had the chatter issue out of my front, well almost never, when competitors who finished behind me were complaining about it constantly.  A couple of time's I thought I did, but resolved it by improving my line through the braking/turn-in zone.  Maybe had I been on a Yamaha the line wouldn't have mattered....

I had some rear chatter issues, mostly solved by rebound adjustments on the Penske as previously noted.

Therefore, I believe it's a tuning and/or geometry issue with specific bikes.

[r1owner]

If you are talking about the back brake, then yes, I have that problem as well  on my 2K1 GSXR 600.

I was getting real bad chatter going into 7 at Gateway last year under heavy braking.  A lot of people were telling me to just not use the rear brake, but I can't stop myself from using it. ;)

The GSXR seems to chatter a lot more (from the rear) than my R1 ever did, but I have certainly pushed the GSXR harder (and beyond ;)) than I ever did on the R1.

I think it has something to do with the bar that attaches the caliper to the swingarm.  The R1 (and I believe the R6) do not have that.

I never once got the back end of the R1 to chatter like on the GSXR.  ???

I should also mention that the suspension on both bikes was completely stock.

[OmniGLH]

Ohhhh is that what you're talking about?   The rear end bouncing around when you're jamming on the brakes?

Question:  do you rev-match on your downshifts, or just drop down a gear and dump the clutch?

[r1owner]

Well, I try to rev match, but I might not have been doing it too well in that particular corner.  I had problems with it all weekend.

I still think the GSXR is not as forgiving of not getting the RPM's just right as my R1 was.

[Eddie#200]

Well, I try to rev match, but I might not have been doing it too well in that particular corner.  I had problems with it all weekend.

I still think the GSXR is not as forgiving of not getting the RPM's just right as my R1 was.

If I don't get the rev match right during the downshift my 99 GSX-R600 will chatter.  I found being more deliberate with the throttle blips helpped me.

[OmniGLH]

Yes... rev matching will stabilize the bike a lot.  The gixxer's throttle response is kinda slow compared to other FI bikes (not sure what year your R1 is... but the '02 has incredible response...) You've REALLY gotta stab the throttle hard.  Plus, you want to make sure you downshift quickly.  Since I usually pit along the end of the front straight at BHF, I hear a LOT of Am's coming down on the brakes, grab the clutch, motor drops to idle, then they click down, and then they drop the clutch.  So you hear a lot of "bbbddddddddddd" as the back end is bouncing all over the place, and the engine is trying to brake.  You want to be swift at it... your rev match should really only take as long as you need to move the shifter.

[r1owner]

Since I usually pit along the end of the front straight at BHF, I hear a LOT of Am's coming down on the brakes, grab the clutch, motor drops to idle, then they click down, and then they drop the clutch.  So you hear a lot of "bbbddddddddddd" as the back end is bouncing all over the place, and the engine is trying to brake.  You want to be swift at it... your rev match should really only take as long as you need to move the shifter.

Come on now Jim, you've seen me ride... I'm not that[/i] bad am I?

[OmniGLH]

Come on now Jim, you've seen me ride... I'm not that[/i] bad am I?

Nononono... I was just showing an extreme example.  Usually the guys I see doing it THAT bad are the first-timers (guys who took the Breuer school the day before.)  They usually catch on pretty quick... but I bet most of them still don't do it quickly enough, and see this rear-end chatter everybody talks about.

[Super Dave]

Yeah, the GSXR's chatter so badly by design that Yates was barely able to finish races... :o.

Yates' fork internals have no relationship to the one's that are available to us.  Potentially, were talking about his having forks that have internals worth more than what we pay to get ours off the show room...

[sdiver68]

Just teasing about Yates....  ;)....I knew you couldn't let that one go.  Hey, if I take one of your classes next year I don't know if you'll be able to separate the smart alek from the serious  ;D

[Bam55]

Okay guys, guess I should have said, I am a top ten expert in Mid-West racing and I've won alot of races. I also am a four year Vision Sports Instructor. Does that make me special, HELL NO!!! My point for my original question was to see if any of you knew some simple way to deal with it, bent rotors, not rev matching, change my race lines, whatever.  I broke a 1:14 the last time at B-Hawk, still not enough to win but the chattering under hard braking in 1, 4, and 7 is so unsettling :o that it ruins the turn in then inturn ruining the exit speed. The tires I use are Pirreli/Metzler.
   None of those things have any bearing on what Dave and I worked on the two years of owning the GSXR's Dave admitingly pointed out what we worked on with this chattering, this question was not to see if you could help me fix it, it was to hear some input and see how many people new about suspenson. A couple of the early guys were on to this when they just said stuff about adding some compresion or rebound. Bent bent rotors?? :-/ I Give some of u credit though;)Keep on Racing!!!! say it with me Super Dave............I LOVE RACING...... I WILL NEVER QUIT..........I LOVE RACING......I WILL NEVER QUIT.......

[OmniGLH]

Huh... well... then I have no idea what you're talking about  :) I run consistent 18s at BHF, so maybe that's not fast enough yet to notice it? *shrug* All I know is, I've never really noticed it.  My last guess would be that it's the track...  tho I imagine you would've ruled that out by now... not to mention, if it were the track, then Gixxers wouldn't be the only ones who experience it.  I'll be the first to admit that I don't know a DAMN thing about suspension setup  8)

Ask me again mid-way through next season, hopefully I'll have cut a 15 or two, and learned a little bit more about suspension setup.. maybe then I'll have noticed it  :D

[bfkidd]

Ok, yes mine did chatter like crazy when it was new. Then I destroyed that one and got another one. So I have had 2 '01 750's. And yes, they both chattered like crazy under braking going into corners. Both time the forks were done to spec and the shock was shimmed. What fixed it? I took the bike to Eric Gray and he fixed it. Was it the Penske? Was it the GMD setup? Dunno. But I had to really work hard before to keep it under control, and now I am lazy with my downshifts and my blipping and it never does it! Well, under very rare circumstances it feels like it might want to start, but it never does. I am very thankful that I don't have to deal with it anymore.

I believe it has to do with the shock more than anything but that is just my guess.

Yes these bikes do it like crazy until it is fixed. It isn't bent rotors and it isn't riding technique. It is just something that has to be tuned out. Believe it!

[Super Dave]

Just teasing about Yates....  ;)....I knew you couldn't let that one go.  Hey, if I take one of your classes next year I don't know if you'll be able to separate the smart alek from the serious  ;D

Serious?  Me?  Dave like to play...

[Bam55]

Dave (Rosno) ;D and I figure, mind you this is a guess after making a quite time consuming change, if the chain has less length to the adjusters it (Chattering) seems alot more drastic. We tried the same gearing with less and more chain availability, with the adjuster toward the back, taking the wheel base wider, it seemed non-existant. Find out if your friend (ERIC GRAY) did this or maybe what he did do to remedy this wonderful rear wheel chatter. Oh yeah, my suspension has been done since the first time I ever rode the GSXR ;)

[r1owner]

Dave (Rosno) ;D and I figure, mind you this is a guess after making a quite time consuming change, if the chain has less length to the adjusters it (Chattering) seems alot more drastic. We tried the same gearing with less and more chain availability, with the adjuster toward the back, taking the wheel base wider, it seemed non-existant. Find out if your friend (ERIC GRAY) did this or maybe what he did do to remedy this wonderful rear wheel chatter. Oh yeah, my suspension has been done since the first time I ever rode the GSXR ;)

Hmm...that's interesting.  It kind of validates the R1 theory of a longer swingarm then.  Cause the R1 never seemed to ever want to do that.  I remember that one of the R1's revolutionary traits (for streetbikes) was the longer swingarm.

[Super Dave]

The longer swingarm on the current Yamaha's stems from the stacked gearbox.  But by doing that, they are able to keep the bike's Center of Gravity (CG) forward.  We can talk leverage ratios, etc.

[max@traxxion.com]

100 times out of 100 if the back of the bike is chattering on the way into the turn, it is the rider's fault, not the bike.  This happens to even the fastest top pros.  They are using the engine to stop the bike and not the brakes.  You have to stop more before you begin downshifting, and make more deliberate blips of the throttle.

This symptom is always followed by the statement "It always seems worse in the race".  Well, that is because you are trying to go a little deeper, and a little later on the brakes.

You need to retrain yourself to use the brakes to stop the bike not the motor is all.  

This is a particularly bad habit because if you are used to using your engine to help stop the bike, when you false neutral, you will freak out and end up in the weeds every time!

[Super Dave]

Interstingly, there are schools, not mine, that are advocating not blipping between downshifts.  I'll leave it nameless.  

Tried doing it a bit myself with no real gain or loss.  Was not able to completely incorporated it, so I can't say one thing or another.

I do, however, enjoy Ducati slipper clutches.

[Thingy]

 I do, however, enjoy Ducati slipper clutches.

I wonder where you tried one of those....

[DanO966]

100 times out of 100 if the back of the bike is chattering on the way into the turn, it is the rider's fault, not the bike.  This happens to even the fastest top pros.  They are using the engine to stop the bike and not the brakes.  You have to stop more before you begin downshifting, and make more deliberate blips of the throttle.

exactly

[max@traxxion.com]

Hey DanO, is your photo icon a result of such activity?  It looks kinda ominous when taken in the context of this thread!!! ;D

[DanO966]

ummm no chatter.  I just tucked the front end.  T4 BHF.  If I had better riding posture I may of saved it.  I thought that I did, I flat-tracked it all the way across the track...man crashing sucks...lol  But not only did Jack get the whole thing on film, I learned a whole heck of a lot from that little mishap. ;D ;D
Sometime you gotta slow down to go faster!
And yeah that's me rolling thru the sand...lol

[Bam55]

So when I set my idle higher to the point of me almost red lining just to match RPM's in one practice session with each blip of the throttle and it still seems to do it? By the way where has Max been while I been fighting the GIXXER chatter? You realize Max, you are the one that sales pitched me into getting rid of the Yamaha's and getting to the Suzuki's, up until mid-last summer I had not been able to duplicate any of the Yamaha times at any of our regional tracks. I finally went into the same times after finding out the fantastic Suzuki I bought has had a throttle position sensor limiting the bike to 80% throttle ::) completely open. (I know this isn't your fault Max but I have to say something in my defense)
   The way Max has pointed out "This even happens to the fastest top pros" makes meat head club racer P.J. feel pretty secure that he can fix this with hard work. Thanx MAX!!!

 Pat Thornton
  MW/GP  Ex #55

[max@traxxion.com]

Hey, PJ, are you sure that the 80% TPS was an electrical part?  Couldn't it have been the loose nut between the seat and the handlebars?  HAHA!!!  Just kidding!!!

That sucks bad that it took so long to find that problem.  Electrical SUCKS!!!   >:(

[max@traxxion.com]

Take note that if your are a REALLY top pro, this becomes a non-issue, because this is the exact problem slipper-clutches fix.  You just come in, hand your bike to your pit crew and then ask your lead mechanic to add in some slip and reduce the engine breaking effect applied to the back tire during decelleration.  Problemo Solvedo. 8)

[Bam55]

The loose nut between the bars a seat will ALWAYS be a problem,or least as long the wife doesn't discover lock-tite!
 The guys at Mid-Cities Motor Sports (West Bend,WI) dicovered it on a Dyno,did some changing, holy cow this thing will dust my R6's now! I hopefully can determine if my "chatter" is the loose nut for sure now.
 Max, do you agree with Dave and I in our theory of the chain adjuster by being so close to the front making negative geometry under hard brakng though? If not, what is the difference if you have the same gearing with different length in the chain adjusters and where the wheel is in geomerty? And what does this do in difference under braking, entrance speed, and exit speed? Lots of questions for you, at least I'm not asking in June though!

[max@traxxion.com]

The only effect moving the wheel would have is that the closer to the pivot you move the wheel, you would have less leverage, and thus a stiffer bike.  But anytime you change your gearing, you need to reset your free sag to 10mm.  Same thing with ride height.  

Stiff springs and slow rebound aggravate this problem, and unfortunately, when left alone, racers always crank away like idiots on both of these two things.  I NEVER move spring preload once I set free sag.  You should always use AS LITTLE REBOUND AS POSSIBLE.

The problems with Americans is that we are trained to think "more is better" and with suspension, that just isn't true.  You can't just crank everything up and go faster.

In fact, we try and "idiot-proof" our suspension here so that even when cranked up by someone who doesn't know what they are doing, at least they won't kill themselves.