I just got a Watsonian Grand Prix attached to a BMW R18 Classic and if I take my hands off the handlebars the bars will start oscillating or low speed wobble. Is this normal? I have a 2002 Harley Davidson Heritage Springer mounted to a Liberty Sidecar that does not do this, however the spring has had the rake altered and the R18 has not.
Not a normal action when a rig is properly set up. Anyone can bolt a sidecar to a motorcycle, but the superpower comes from systematically tweaking adjustments until the rig is “balanced”. Im not an expert on this subject and someone more experienced will be along shortly.
Meanwhile, what air pressure are you using in the front tire? Yes, it can make a big difference. Try going to 40, then 45. If the head shake persists, then it’s not just tire pressure.
Illegitemi non carborundum est!
William @wahlbornwi-rr-com, what Thane @thane-lewis stated above is all correct, and I will add:
You said that you JUST got this Watsonian w/BMW R18 rig.....that begs the questions:
How long ago did you acquire this rig?
Are you 100% certain that the sidecar is a real, and official Watsonian sidecar ? (there are imitations and copies out there)
WHO did the installation of the sidecar to the motorcycle ?
YES, the lack of "trail reduction" at the front end will indeed affect wobble and oscillation especially at lower speeds, until the inertia of the mass has sufficient thrust behind that mass to overcome any inherent wobble or oscillation.
The tire pressure in that BMW R18 front tire will indeed make a difference, and unfortunately the majority of 2 wheeled motorcycle riders ride with underinflated front tires.
I strongly suggest checking, and adjusting the tire pressures at all 3 wheels.
For a beginning set-up, set the tires as such
Front tire at 40 psi...cold.
Rear tire at 42 psi...cold.
Sidecar tire at 35 psi...cold.
Having said that, I need exacting details about the current tires/tyres on this rig, at all 3 wheels, meaning, brand, model, age, mileage on them, etc.
Setting the tires to correct tire pressures is the easy thing, the almost NO cost thing.
The more expensive this is correcting that front end of the motorcycle, to reduce trail...."IF" it is needed to be done.
Contact Dave Hannigan at Hannigan Motorcycles, Murray, Kentucky, and ask Dave, or Stephanie, or RuthAnne....do THEY usually reduce the trail on the front end of THIS motorcycle, specifically the newer BMW R18's, or do they not do that ?????
Also, ask Jon @sidecarusa if he has had experience in these R18 bikes, if he has had to reduce the trail on these bikes.
Not 100% of all motorcycles need to have the trail reduced on the front end for use as a sidecar rig tug.
But....I believe that at least 90% of the motorcycles I have come across do need to have that trail reduced at the front end, specifically for sidecar duty use.
Jon @sidecarusa, what say ye ?
The "fix" may possibly be simply installing a steering dampener on the front end, attached at one end to the sidecar frame, and at the other end to the right side down tube of the front forks, to DAMPEN any wobble or oscillation, but a professional needs to look this entire rig over, and make professional suggestions for how to eliminate that wobble and/or oscillation.
Therefore, it begs the last question (for now)...WHERE do you live ???????
Two Million Mile Rider
Exploring the World in Comfort
It is not a real watsonian sidecar its infact a texas sidecar. I have built a couple r18 bikes before I was at tsc and never had this issue... I also didnt modify the front ends in any way. It could be a set up issue or a manufacturing issue hard to say unless I went through it.
For the record I didnt build this rig so cant speak too much on the quality or specifics
Meanwhile, what air pressure are you using in the front tire? Yes, it can make a big difference. Try going to 40, then 45. If the head shake persists, then it’s not just tire pressure.
Risky, unless you are trained to deal witht that kind of trouble, it may also work up to 60 and suddenly start again but as you know, more speed, more energy....
First is first, have a professional checking the hardware and THEN look for a fine setup....my 2 cts.
William @wahlbornwi-rr-com, what Thane @thane-lewis stated above is all correct, and I will add:
You said that you JUST got this Watsonian w/BMW R18 rig.....that begs the questions:
How long ago did you acquire this rig?
Are you 100% certain that the sidecar is a real, and official Watsonian sidecar ? (there are imitations and copies out there)
WHO did the installation of the sidecar to the motorcycle ?
YES, the lack of "trail reduction" at the front end will indeed affect wobble and oscillation especially at lower speeds, until the inertia of the mass has sufficient thrust behind that mass to overcome any inherent wobble or oscillation.
The tire pressure in that BMW R18 front tire will indeed make a difference, and unfortunately the majority of 2 wheeled motorcycle riders ride with underinflated front tires.
I strongly suggest checking, and adjusting the tire pressures at all 3 wheels.
For a beginning set-up, set the tires as such
Front tire at 40 psi...cold.
Rear tire at 42 psi...cold.
Sidecar tire at 35 psi...cold.
Having said that, I need exacting details about the current tires/tyres on this rig, at all 3 wheels, meaning, brand, model, age, mileage on them, etc.
Setting the tires to correct tire pressures is the easy thing, the almost NO cost thing.
The more expensive this is correcting that front end of the motorcycle, to reduce trail...."IF" it is needed to be done.
Contact Dave Hannigan at Hannigan Motorcycles, Murray, Kentucky, and ask Dave, or Stephanie, or RuthAnne....do THEY usually reduce the trail on the front end of THIS motorcycle, specifically the newer BMW R18's, or do they not do that ?????
Also, ask Jon @sidecarusa if he has had experience in these R18 bikes, if he has had to reduce the trail on these bikes.
Not 100% of all motorcycles need to have the trail reduced on the front end for use as a sidecar rig tug.
But....I believe that at least 90% of the motorcycles I have come across do need to have that trail reduced at the front end, specifically for sidecar duty use.
Jon @sidecarusa, what say ye ?
The "fix" may possibly be simply installing a steering dampener on the front end, attached at one end to the sidecar frame, and at the other end to the right side down tube of the front forks, to DAMPEN any wobble or oscillation, but a professional needs to look this entire rig over, and make professional suggestions for how to eliminate that wobble and/or oscillation.
Therefore, it begs the last question (for now)...WHERE do you live ???????
What Jon and FM said are the first steps to diagnose. Should not wobble.
In my opinionated opinion, likely a setup/install issue.
If tire pressure changes don't completely fix it:
1. What is the sag set to, front, rear, and sidecar suspension? Too much sag on rearshock will certainly cause low speed head shake on most rigs. If sag is more than 30%, under load, you may need more preload, or if not possible, stiffer springs at one or more locations.
2. If sag is correct, is there any flex between sidecar and bike? Walk up to the nose of the sidecar and push down, release, repeat. Watch the front wheel of the bike. Front suspension of the bike should compress immediately, no delay. If it looks like the sidecar nose dives before the bike, there is likely some flex in the mounting system that should be corrected.
3. Steering dampers are great for offroad silliness, but are a bandaid that should not be needed for a well setup road rig.
4. We will assume that your toe in of the sidecar wheel is set correctly, maybe 19mm or so, since you do not mention pulling to the right. However, if the the toe ini is little, to negative, that could cause some wobbles. Worth checking and knowing what it is, for future adjustment, if you ever need to separate the tub from the bike, then reattach.
Good luck, let us know what you try and if anything works.
@ben-franklin Agreed to all, no question about that, BUT, what if something simply and stupidly broke...or get loose....
Re-tight everything, may be will tell?
