Advise needed please...

[pat8228]

I went on a 300 mile trip to the Smoky mountains. During highway riding when passing trucks at 70 or 75, the bike would get a bad wobble to it from the wind turbulence (it was very scary at times). If i tried to pass one at 80+ it felt like the wobble was uncontrollable and I was going to lose control. I at one time had to slow down to pass trucks while the group I was riding with went by with no problems. they ended up a mile in front of me and I would speed up to try to catch them when no trucks were around. They had to slow up so I could keep up. I've rode cruisers for many, many years and never had this problem.
My question is what modifications can I do to eliminate or at least reduce this wobble around trucks?
Any help would be appreciated. BTW slowing down is not a good solution, lol.
Thanks

[snarf]

Make sure your front tire is balanced, check your front bearings, tighten your steering head bearing, or install a fork brace.  All will help reduce the wobble.
I would start with tightening up your head stem bearing.

[nosaint7]

Aero induced wobble can also be caused by loose fairing.  Check fairing mounts.

[Cholla]

+1 to all above plus check tire pressure. I liked 38/41

[Roadhound]

I've found that the smaller the windscreen I run, the less buffeting I get from the big rigs. I do believe that most problems are actually rider induced, nor purposely but completely by accident. If you ride with a very relaxed grip on your bars, your elbows bent, support your body with your core muscles, not your hands and arms and keep a forward lean you can eliminate most if not all of the wobble caused by the big rigs. If you have a tight grip on the bars, locked elbows and carry your weight on the bars the wind off of the big rigs is going to move you, and you in turn are going to move the bars as the wind hits you. You will be causing the wobble. Just my observations from riding a Concours for a long time, YMMV.

[pat8228]

Thanks for all the replies. I have new tires on it. Just went out and adjusted the suspension. Rear shock only had 5 lbs in it. I put 30 lbs in it (I am 195 and have side-bags and trunk, usually loaded down. The dampening adjustment was on 2, I moved it to 4 for now. The front forks was set at 3, I tightened them to 6 now. Rode it around here and it seems to ride better, a little rougher on the bumps but more maneuverability. passed 2 trucks on side streets and it seemed to be less turbulence. tomorrow I'll head for the interstate to try it.
Thanks again...I'll let you know how it works out tomorrow.

[Nosmo]

It could be a combination of several small things.  If you still have the OEM windshield, it can contribute to some extent.  The "flip" recurve at the top make a lot of turbulence.  Just about anything else should be better.  A heavy trunk box can make instability worse.  Weight up high is always bad.  My 2003 bike with the Michelin Pilot GT's, a KB fork brace, and Rifle 'shield is rock steady in any wind and even around big-rigs, all the way up to 115 MPH, the fastest I've had it (once when passing a motor-home towing a Ford Ranger pickup).

[cmoore]

Are the front springs stock? Most find the stock ones don't do well on the highway especially behind the big rigs. Too much give in 'em. I upgraded to the Sonic 1.1's some time back. I wish I had done it sooner. The ride is stiffer but much smoother out on the highway.

[RFH87_Connie]

Also, the foot scoops and anything like a Baker wing can make the bike oscillate back and forth at high speed.  I had larger home-made air deflectors that worked good in the summer for pulling in air, but when set in winter or rain mode to push air away, it would really get a bad wobble over about 75mph.  They're gone now.  You should probably also check your steering head bearing, most people find they are a little loose.  They tend to never get checked after the bike is assembled.  They can be tightened or loosened with a hammer and long punch (drift) after loosening the correct bolts.  It just takes a couple of minutes.  As someone else mentioned, check tire pressures with an accurate gauge.  Just a few pounds can make a big difference.  40 front, 42 rear or what ever works for you.  This is pretty much the max pressure.  Some people run 36 front, 40 rear.  Also, check your torque on the swing arm pivot bearings.  I few people on the old forum mentioned this as being the problem after they had chased the front end issue for days.

[SamSam]

fork brace does wonders!

[pat8228]

After making suspension adjustments, I went out on the interstate today. When I passed trucks at 60 to 70 mph there was a 100% improvement, no wobble. At 75 to 80 mph it was probably a 90% to 95% improvement, very, very little wobble. I am very happy with this. I wanted to try it at even a higher speed but traffic was too heavy to do it safely.
If anyone else is have that problem here's what I did.
Rear-Set air pressure at 35 psi.
         Set damper at 3
Front- tightened the forks all the way down to 7.
The bike seems a lot more stable on highway and normal driving. It feels better and smother when taking the curves at a faster speed. I like this set up.
Tires are newer Avons front and back in wing sizes. air pressure in tires are 50 psi which is ma# for these tires. I have the dynabeads in them for balancing (I don't like the beads and wont use them again).

[Outback_Jon]

air pressure in tires are 50 psi which is ma# for these tires.

YIKES!  That's really high.  Try it at 40 front, 42 rear. 

[pat8228]

These tires calls for 50psi.

[connie_rider]

Look again. I suspect it says 50 psi Max....

Ride safe, Ted

[Outback_Jon]

Look again. I suspect it says 50 psi Max....

+1.  The max number on the sidewall is usually not the optimum psi for general use.  Your contact patch is probably really small with that much pressure in the tire.  (And motorcycles have a small enough contact patch as it is.)  That could be contributing to your wobble in turbulence.

[Ron Dawg]

Most max tire pressures are specified as cold if I am not mistaken not at riding temperature. Seems like awhile back another thread had a reference to someone checking cold vs hot pressures and found about 3-5# increase (?) after riding a while. With the temps we have at the moment, I can imagine that much change easily. The pavement temps MUST very high right now.

[T Cro ®]

These tires calls for 50psi.

Sorry guy but I've run the OldWing sized AVON Venoms on my Concours and 50 PSI is not the recommended pressure for those tires; in fact directly from AVON they call for 36 front and 42 rear when fitted to the Wing..... You can run a little more in the front if you want but as I don't care if the tire cups some and prefer that the tires remain complaint and able to allow the contact patch to conform to lean angles verse hard as a rock with an even smaller contact patch.