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Front End Wobble on Deceleration?


RichNDC

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I have read a lot about this and I am still confused. New Tracer 900GT, about 900 miles. I have tried various suspension settings and tried with and without the side bags and with and without the top case (I bought the Yammy 50L top case).  If I am going 45, let the throttle go, at around 40mph the handlebars wobble (a good bit), but only if my hands are not on them. If I keep my hands on the bars or grip them, they don't. It's also hard to detect with hands on the bars. I have checked the tire for out-of-round or deformity, check the brake discs for warp, check the wheel bearings. Is this something to get checked out? I have not been above 80mph yet as I am waiting to get past 1K miles. I suspect the front end might shake at high speeds. I had the XSR900 for 20K miles and had it over 130mph, smooth as silk. I am puzzled. Any ideas? (I will pre-emptively thank those who make smart ass remarks--THANKS!). The only thing I can think of is the wheel might be slightly out of balance. btw--I am 5'10" 210 lbs. Doing a track day in 2 weeks, want to be sure I can let her rip. 

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Since the bike is almost new and you are planning a track day soon, have you done anything to the suspension?  Correct spring rate? set sag? adjust the clickers? raise the forks in the clamps?

You definitely want to have your suspension stiffened up a bit before doing a track day to avoid this feeling...   😎

 

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***2015 Candy Red FJ-09***

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I have set the pre load and damping at various settings to test.  Still get the wobble. Yes, on track day it will be set to stiffest, which I am happy is very easy to do on this bike. I have not raised the fork or attempted to. 

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Had this same problem with 2 different bikes. 95 Vmax and 2001 Gold wing. The simple fix for both of those was to tighten the steering head bearings to just before the point where the tightness of bearings starts to effect the steering, as in making it sluggish or make you not be able to ride with hands off bars and steer with body weight. What is being done when I did this is to have the steering bearing act as a subtle damper. Takes a little experimenting to get it right.

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When I've see wobble on the front end of a bike on decel with hands off the bars, a new front tire always solved the issue.  If you don't keep enough tire pressure in that front tire, it will wear funny and scallop.  I always keep 40 to 42 psi in the front tire and I never have that issue any longer.  I've learned this trick from multiple experienced bike guys over the years.  Some people think that high of pressure will reduce the contact patch size on road.  You can follow me and see the results for yourself.  Couldn't be further from the truth.  Keep that tire pressure up a few pounds.  You'll soon see the excellent results on better tire wear and longer tire life. 

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What are your current tire pressures? Go measure and report back please. Should be minimum 36 F and (recommended, but debatable) 42 rear. 

No where in your original post did you mention verifying those... unless I’m tired and missed it (possible).

-Skip

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My bet is still low tire pressure.  36 psi front is still too low from my experience and testing.  If the tire has been low on pressure, the scalloping of the front tire tread has already started.  Put a few more pounds of pressure in the front tire and ride with your hands on the grips.  Once you wear the front tire out and replace it, the decel wobble will be gone temporarily until the tire wears some.  It's just what happens, especially with low tire pressure.

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I've kept mine at 36, checked every day. The tire is definitely scalloped. I'll try higher pressure but that tire is probably too far gone to notice any difference. 

I still need/want to check the steering head bearings. The dealer allegedly did them at the 600 mile service but I have zero confidence in them doing what they said they did and/or doing it correctly.

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The previous posts saying to up tire pressure and/or change front tire are correct in that any small variable can change the nature of the situation in which you are getting the shakes. These are oscillations that build up and can be damped out in a variety of ways. Steering head bearings being one but not only thing.

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10 hours ago, nicksta43 said:

I've kept mine at 36, checked every day. The tire is definitely scalloped. I'll try higher pressure but that tire is probably too far gone to notice any difference. 

I still need/want to check the steering head bearings. The dealer allegedly did them at the 600 mile service but I have zero confidence in them doing what they said they did and/or doing it correctly.

Yeah, 36 psi is not enough.  The tire will still be scalloped, but you'll still notice a little improvement.  Once you get a new tire after wearing this one out, you'll see it's good as new.  It's normal to think there's something else wrong, but there probably isn't.  You can put the bike on the centerstand and prop up the front of the bike with something under the pipes (carefully). With the front wheel off the ground you can pull on the wheel from the front to see if there's any play in the head bearings.  I'll bet there is no play and everything is fine.  Once you get the thought that the steering bearings are loose, you'll keep convincing yourself of it.  Relax and enjoy that bike!

Also make sure you have a quality tire gauge.  Over and out.

Edited by fjrpittsburgh
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UPDATE--I didn't mention tire pressure, it seemed too obvious. I keep it at 36psi and typically check it prior to every ride. I have also checked the play in sterring with front wheel off the ground, no friction, very smooth. However, after talking with great local shop (not the dealer, Coleman Powersports in Falls Church has been useless, frustrating) I double checked rear end alignment. I usually use a tape measure to set evenness on both sides when setting the chain. However, just got  precise calipers with digital gauge. It was off, though with a naked eye or tape measure it seemed nearly identical. It was about 3mm difference. I have not been able to ride since this adjustment, but will tomorrow. I am betting that this does it. Again, the wobble was only happening under the following conditions: decel, 45mph, and hands off the bars. No other time. I do have a good quality and precise tire gauge. Thanks all, here and looking around the net, I learned a good bit over this. Word to the wise in N VA, stay away from Coleman Powersports. It's a clown show over there, sad to say. For those suggesting a new tire, this bike is brand new, only about 900 miles. I have spun the tire with the wheel off the ground and no visible deformity or out of round. 

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