My new-to-me R1150GS/M72D combo has more bump-steer than I'd expect, and more desire to turn right than I'd like. Supposedly, the rig was setup by DMC when the sidecar was attached, but the PO didn't actually use it much, and the guy who did his service wasn't very familiar with sidecars, so things could well have been twiddled.
The sidecar frame is attached such that it has 4 degrees of lean out (to the right); the bike itself has 1 degree, to the left. Toe is about 5/8 in (all measurements with appropriate loads on bike and boat), which seems in the ballpark. That's enough sidecar leanout that the tire wear is visibly off-center to the outside and the sidecar frame is visibly downhill to the right; the inside rail of the frame is almost 1 1/2" higher than the outside rail. I always thought that the car frame should be neutral; that is, flat and parallel to the ground when loaded, with leanout of the bike to the left. The bike leanout seems reasonable, but the sidecar does not. Before I go messing with this, I'd like some input.
Comments, thoughts?
Thanks
Level the sidecar frame. Set bike leanout to about 1 degree plus and you should be OK. 5/8" to 3/4" toe in is about right with this combo. (Bike and hack normally loaded.)
Lonnie
Thanks, I'm headed to the garage.
Fresh page. Setting up this combo is a little different than most. One of the issues here is that the bike has a lot of soft suspension travel and things change once the rider is on the bike. Stand behind the rig and have another person sit on the bike and watch. The same setup is probably not quite the same as the last owner unless you are very close to the same weight. Step one is to pre-load the bike with your weight on it and use some tie straps to hold the suspension compressed at that point. This gets a little trickier from this point without a means of holding the bike up without the sidecar. With the bike held down the next thing is to level the sidecar frame left to right and front to back. Small magnetic levels work wonders here. As this sidecar is attached with A arms you will need to loosen the clamp bolts at the sidecar frame to make leveling adjustments and this can be fun without the bike held in place. I use a couple bike jacks, one front and one rear to support the sidecar. Although I loosen the upper struts at this point do not detach them both or your bike will be laying on the ground. Leveling the sidecar frame should not need much adjustment so don't worry about the leanout of the bike yet. You may need to detach one of the struts if more adjustment is needed but again, not both. With the sidecar level snug the pinch bolts and then adjust the leanout with the front strut disconnected. Remember that with the weight of the sidecar on the bike it will try to tip towards the sidecar if you have removed the jacks. Place one of the magnetic levels on the rear brake rotor and lean the bike about half a bubble out. With the front strut still off check the toe measurement. It should be 3/4 to 7/8". 7/8 usually works best. This can be adjusted by removing the 5/8 bolt through the lower front eye bolt/clevis and turning it a turn or two in the needed direction. Do not allow more than 1/2" of thread showing. Replace the bolt and recheck toe. If you do not have enough adjustment at the front eye it can be adjusted at the rear although the direction will be the opposite. Once this is complete and both struts are tight again you need to torque the pinch clamp bolts to 80 ft. lb. Test ride. These bikes have a very small amount of steering shake at low speed (10 - 20mph) but it is easily controlled with your hands on the bars. Once you get accustomed to the rig you won't notice it any more.
If you have any problems with this email me and I'll help you work it out. I do a couple of these every week. Barry barryobates@yahoo.com
Allright! set the hack frame level, bike 1 degree of leanout (loaded, both measured with magnetic protractor thing on brake disks), toe is about 3/4. Gonna fiddle a bit more, but it tracks straight, and hardly any bump steer. Have the always-present 30 ph decel wiggle, no biggie. Sparrowhawk and Hack'n, thanks a bunch!
sam - 12/10/2011 11:16 AM
Allright! set the hack frame level, bike 1 degree of leanout (loaded, both measured with magnetic protractor thing on brake disks), toe is about 3/4. Gonna fiddle a bit more, but it tracks straight, and hardly any bump steer. Have the always-present 30 ph decel wiggle, no biggie. Sparrowhawk and Hack'n, thanks a bunch!
You might want to move the toe up to about 7/8". I find that combination may work a little better there. It could reduce the wiggle as it sounds like you have a little more than I usually end up with. Assuming everything else is correct, toe adjustment is usually the adjustment to make to reduce or eliminate head shake. Also, from this point don't worry about what the lean-out measures in degrees, just if the rig is pulling to one side or the other. If it does, just give the upper struts a couple turns out or in as needed. I remove the front strut at one end and make the adjustment with the rear one. Then just align the holes on the front and connect. The number of turns used on the struts to adjust is not always the same so this way you will not have any twisting of the bike frame. B 🙂
