Problem with high speed wobble

COst1100rider

Joined
Apr 9, 2012
Messages
14
Location
Florissant, CO
Bike
2004 ST1300
I posted this in the general info section but thought I'd get more feedback in here.

I just bought a 2000 ST1100 last week after looking for over a month. The bike has 47,000 miles and is in pristine condition. The only obvious thing it needed was tires, which I promptly took care of. Here's my question.

Now that it has new tires (Michelin Pilot 3's) it rides great until I get up to about 75 mph. Then things get a bit funky. The bike starts to sort of wobble. Not really a shake or a wobble but more like the feeling you get when you're riding across a bridge deck with metal grating. I didn't speed up to see if it would go away or get worse. It goes away as soon as the speed decreases.

Any ideas as to what is causing this? Surely this isn't how the bike should handle at speed. Could it be the tires? I suspect the steering head bearings but have never felt this due to worn bearings.

Any ideas or advice is welcome. Thanks.
 

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That is not the high speed wobble that the ST1300's can exhibit at much higher speeds. New tires can give a twitch feel untill they've scrubbed in for hundreds of miles.

But you may have something invoved on the bike....so some questions:
  • Are tires at 42 psi front & rear? Are they installed directionally correct? (arrows matching rotation direction?) Are they the correct size for the 1100? (My ST1100 got twitchy with a 170/60-17 rear...not stock size).
  • Topbox installed? How much weight is in it?
  • Were you behind a large vehicle? Or were there cross winds or wind gusts?
  • Have you checked for loose axles or other components? (While on centerstand, find out if there is any lateral play of any components, like the wheel, on either axle. Check the torque of both axles and all bolts. Look for missing bolts or spacers, on axles and on brakes.)
 
I would say the tires....I just put a set of the Pilot Road 3's on my bike about 3000 miles ago and love them. They transformed the way my bike handles.
If I were you I would put the bike on the center stand. Start the bike and make the rear tire is off the ground. Put the bike in first gear and let the rear tire spin.
You can now step behind the bike and see if the tire is tracking "true" (watch the center and see if it "wanders". Then look at the top of the tire while standing off to the side
of the bike to check for "bounce" how much does it roun out radially (movement up and down). These factors are due to a poorly manufactured tire and it should be warrentied and replaced.
It is a bit more difficult to do the front tire check as you will need to place an object (block of wood, bottle jack etc...) under the engineto raise the front wheel off the ground while the bike is on the center stand.
Do the same checks by spinning the wheel by hand. I will often use a 1.0 travel dial indicator (as I am a machinist) to check for the tire runout. It is more difficult to see as you cannot just simply watch the tire spin like the rear test.
Maybe an extra set of hands would help you with this check.\
My guess is that it is faulty tires. I am sad to say. I am a huge fan of the Michelin PR tires but not everyone gets it right ALL the time.
It could possibly be too that whoever installed the tires did not "set" the bead correctly. The tire will wobble because of this too.
 
Tires would be my first suspect. 'Specially if ya rode the worn tires with no problem before the change.

ST11's don't usually exhibit a wobble, unless you have worn bearings. A bad rear wheel bearing, usually the left side, will 'cause this and 47K is about the right mileage for such.

I'm running a Federal Formoza car tar which causes a wobble starting at about 90, stable below that. With regular bike tars she has never shown a problem, especially as low as 75.

Keep us poSTed.
 
I'm going to guess weight behind the back axle. Top box is way back, and the bags on the 1100 sit plenty far back, too.

Try it with the top box off. After all the tire suggestions above:)
 
Thanks everyone, for the advice. I'll check on everything you've mentioned this afternoon. Couple of clarifying questions/comments:

BakerBoy - you mentioned 42 psi front & rear. Dealer mentioned they set at 36 front and 42 rear per manufacturing requirements. Are you saying the tires need to be at 42 psi? I do have a topbox but as of right now it's empty. Also, the "wobble" was most pronounced when I was driving directly into a fairly stiff wind. When I rode with a crosswind I didn't notice the wobble.

George - I only rode the bike with bad tires for a short bit as they were totally shot. I did ride it for about 10 miles at highway speeds, on the way to the dealer to get new tires, and don't recall the wobble. However, it didn't corner worth a crap because the tires were flat and had no tread. Having just written that I now suspect the new tires are the culprit. I'm hoping it's because they're new and not defective.

Thanks again for the tips. Keep 'em coming.
 
If all else doensn't pin-point the problem, I'm gonna suggest pulling the wheels and checking those bearings. Any ruffness sez time for new ones. No guarantee the dealer checked them.
 
BakerBoy said:
That is not the high speed wobble that the ST1300's can exhibit at much higher speeds. New tires can give a twitch feel untill they've scrubbed in for hundreds of miles.

But you may have something invoved on the bike....so some questions:
  • Are tires at 42 psi front & rear? Are they installed directionally correct? (arrows matching rotation direction?) Are they the correct size for the 1100? (My ST1100 got twitchy with a 170/60-17 rear...not stock size).
  • Topbox installed? How much weight is in it?
  • Were you behind a large vehicle? Or were there cross winds or wind gusts?
  • Have you checked for loose axles or other components? (While on centerstand, find out if there is any lateral play of any components, like the wheel, on either axle. Check the torque of both axles and all bolts. Look for missing bolts or spacers, on axles and on brakes.)
Click to expand...

^ perfect place to start! I'd be unloading that top box first...
Next; is the windshield stock?
 
47K is enough mileage for the rear shock to be shot. Mine went out at 35K. Have you done any suspension maintenance or adjustments? The bike may also be due for a fork oil change and while you are at it maybe upgrade the front springs too.
 
Wjbertrand - haven't done anything other than buy it and ride it right over to the dealer for new tires. Was out of town fishing until last Friday when I finally had a chance to ride it. That's when I noticed the funky handling at around 75 mph. I'm not a great mechanic and this is the first "older" bike I've owned. Other than leaking oil how would I know if the rear shock needed rebuilding? For that matter how about the front springs?

Was going to ride it today and try it without the topbox but it's storming and crazy windy out. I'm also still in KC Missouri waiting for the weather to clear so I can ride it home. Not looking forward to riding I-70 with the funky handling. I'm storing it at my nephew's house because of the threat of hail and tornados. I'll check out all the previous suggestions when I go pick it up to ride home.

Meanwhile, keep the suggestions coming. Thanks.
 
COst1100rider said:
BakerBoy - you mentioned 42 psi front & rear. Dealer mentioned they set at 36 front and 42 rear per manufacturing requirements. Are you saying the tires need to be at 42 psi?
Click to expand...

36 front and 42 rear is correct. ST1300s are 42/42.
 
COst1100rider said:
Wjbertrand - haven't done anything other than buy it and ride it right over to the dealer for new tires. Was out of town fishing until last Friday when I finally had a chance to ride it. That's when I noticed the funky handling at around 75 mph. I'm not a great mechanic and this is the first "older" bike I've owned. Other than leaking oil how would I know if the rear shock needed rebuilding? For that matter how about the front springs?
Click to expand...

I've attached a basic set up guide I wrote a while back, some of it will be a bit of trial and error. The document refers to a rear shock but the same principles apply to the front. With a fork you have to install a longer spacer or higher rate spring to correct preload. For damping changes on the ST which has no adjustments you have to change the fork oil viscosity or perform some re-valving. Most folks seemed pretty happy with after market springs and a switch to 10wt oil for the fork on this bike. Pretty cheap to do also. The OEM rear shock is not rebuildable so replacement is the only solution once worn out. Works, Progressive, Race Tech and others make replacement rear shocks.

If you are lucky, maybe just dialing in some more preload and rebound damping at the back will settle things. Of course this all assumes there are no other mechanical problems like those mentioned above in this thread.
 
As Hound says, 36/42 are the correct recommended pressures for the ST1100, I run my slightly higher on the front at 38.... this gives better wear than 36, but I would start with the recommended settings.
 
42 front and 42 rear here.
I find the front end feels 'less good' at anything less.
 
Mine got bad as soon as I put a PR2 on the front. It corners better than ever but wanders bad around trucks on the interstate. I suspect the XL Clearview doesn't help, and it seemed worse when I put the Progressive shock on with the preload cranked up to ride double. With my wife on its better, alone its bad. I thought it was the 170/60 I had on the rear but its no different with the 160/70 Z6 on there now.
Murf
 
COst1100rider said:
Thanks everyone, for the advice. I'll check on everything you've mentioned this afternoon. Couple of clarifying questions/comments:

BakerBoy - you mentioned 42 psi front & rear. Dealer mentioned they set at 36 front and 42 rear per manufacturing requirements. Are you saying the tires need to be at 42 psi?
Click to expand...

PSI ought to follow what tire manufacturer has on tire sisewall......not the bike manufacturer's suggested. That front aired up to 42psi should help.
 
Perhaps someone here in CO can take it for a spin to feel it. Worth a try if it isn't resolved with the above suggestions. :yes:
 
OK, finally having good weather and had a chance to check things over in prep for the trip home from KCMO to Colorado. Here's what I found:

Front - tire is 120/70zr/18 and the tire is mounted correctly with the directional arrows pointed right. Also noted there were new weights and could tell where the old weights were. Put the bike in the centerstand and jacked the front wheel off the ground. No side-to-side or up-down movement or "notchyness" in the steering head, no sloppiness in the front axle and appearing to be assembled correctly, also spun the tire and no noticable out of roundness.

Rear - same thing, nothing out of the ordinary, no out of roundness or sloppiness. The size is 160/60zr/17 (as opposed to the spec calling for 160/70/17). I did adjust the pre-load to be about in the middle of the range.

Checked the air in both tires and guess what? Yep, you got it! Front was reading 30psi, rear was 32psi. I asked the dealer when I picked it up and they said it was set to 36/42. Now the weather/temp is about the same as when I picked it up last Tuesday and it's only been sitting for 5 or 6 days. Either I have a pretty healthy leak or someone if full of crap. Guess what I'm betting!

I aired it up to the 36/42 as per spec and took it for a ride. Felt WAY better but could still detect a bit of "twitchyness" at around 75mph. So I went back and aired it to 40/42 and rode again. This time it was like it was on a rail until about 95 when I could feel a bit of the old twitch. That's as fast as I rode it. But I'm pleased enough that I'll get home in one piece. Thanks for everyone's suggestions. I really appreciate everyone's time and expertise. Also, when I get home I'd love to meet up with other ST owners in Colorado and have them look my bike over to tell me what to be aware of.

BTW - I determined that my speedometer reads about 10% faster than my actual speed. Is there a way to recalibrate the speedo. Any help on that is greatly appreciated. Also, can anyone tell me if the change in rear tire size will be problem? Thanks
 
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