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Monday, September 14, 2009

Sidecar Mounting Made Reasonably Easy

Sidecar Mounting Made Reasonably Easy
Mark Zimmerman

Originally published in the May 2000 issue of Walneck’s Classic Cycle Trader

You read the title right. Mounting a sidecar is reasonably easy. It’s not simple and it’ll probably take some effort to get the outfit handling and steering the way you want it. But mounting a sidecar to a motorcycle is well within the abilities of anyone who can swing a wrench and read a page or two of instructions. If you purchase a new sidecar, especially from a dealer or manufacturer, the instructions are provided (or should be) and help is just a phone call away. But if you purchased a used chair, especially one that has been through an owner or two, instructions may be a little harder to come by. Since you’re reading Walneck’s, I’ll assume you’re in the market for something and since this is our sidecar special edition, I’ve gotta figure that some of you are looking for hacks. Since used outfits seldom come with instructions the powers that be have asked me to give you the quick and dirty on sidecar mounting.

Outside of these instructions, some common hand tools and a little patience, my only other suggestion would be to enlist the aid of a friend, particularly a large friend, like my buddy Pete. When you’re done buy him some beer and a pizza, then take him for a ride. If you don’t have any large friends call me; I’ll send you Pete’s number.
The basic ides boils down to this: the sidecar and motorcycle should be assembled to provide as rigid and flex-free a unit as possible. This is one reason why modern “unit” outfits like the Armac work so well. They incorporate a subframe that stiffens and complements the motorcycle frame.

Outside of the rigidity issue which is largely a function of the design and structural integrity of the sidecar and it’s mounting hardware, there are three adjustments that will have to be made.

The first is the sidecar Lead. Lead is the distance the sidecar wheel leads the rear wheel of the motorcycle. In other words, the sidecar wheel must be placed some length in front of the motorcycles rear wheel. Usually lead is somewhere around 9 inches. Bear in mind that lead is the distance between the tire’s centers (the contact patch), not between the leading and trailing edges of the tires.

The sidecar must also Toe-in slightly. Toe-in or more commonly just Toe is the angle of the sidecar wheel in relation to the bike. Toe helps the outfit maintain a straight line and affects steering stability and effort. Toe-in is usually between 1/2 and 1 inch.

The third consideration is the motorcycle Lean. For a long time everyone though the motorcycle should lean away from the sidecar. The theory was that the weight of the bike, sidecar, and any passengers or luggage, would tend to compress the suspension and effectively “fold” the bike and chair together like a carpenter’s ruler. Currently the thinking is that the bike should either lean slightly toward the sidecar (1-5 degrees) or stay perfectly upright. I’ve ridden sidecars set up both ways. The last hack I rode was set up with 0 lean, a modern Armec and arguably the best one I’ve ever ridden. On the other hand, my Watsonian-Triumph outfit had about 1/2 inch of lean out and was just as much fun. Of course it had nowhere near the power, brakes or cornering prowess of the Armec. If you feel like experimenting, try it both ways, if not see what the manufacturer recommends.
If your sidecar was purchased new you’ll probably need to do some initial set-up of the car itself. Depending on how it was shipped that may mean simply unpacking it. Or it may mean bolting on the wheel, fender, windshield, and so forth. My feeling is that you’re probably better off just bolting on the parts you need to mount the chair to your bike. You’re probably going to be doing a fair amount of prodding and pushing before you’ve got the whole plot assembled, not to mention some huffing and puffing. The fewer parts that get in your way the less likely you are to damage them. Besides once the sidecar is in place it’ll be a whole lot easier to work on.

Normally the sidecar is connected to the bike via three, or more likely four, long adjustable arms. The arms are connected to the bike using heavy clamp-on type brackets.
Ideally the brackets should be placed as far apart as possible. Usually there are two brackets located on the bottom and two on the top. The first job is going to be locating suitable positions for the brackets.
The main idea is to space them far enough apart to provide the necessary rigidity and still maintain adequate clearance for the rider and passenger as well as clear the exhaust system, brake pedal, fuel tank and whatever else is positioned smack dab in the way. Mount the brackets only, the arms will be installed later, and just snug them up. Chances are that you’ll be adjusting them again. If possible use self-locking nuts on all of the bolts.
Place the bike on it’s center stand for the moment and position the sidecar along side it, as close as possible. With the help of some wooden blocks and a floor jack or two, brace the sidecar so that it sets as close as level as practical. Measure the distance between the tire contact patches trailing and adjust accordingly. If the sidecar provides dimensions, most will, you’re way ahead of the game. When it’s close, install the lower mounting bars. Remember for maximum strength and rigidity you want to place the sidecar as close to the motorcycle as possible.
The toe should be adjusted next. Place a straight plank, a 2 X 4 works nicely, alongside and contacting the sidecar wheel. Place another one alongside the motorcycle wheels touching the sidewalls of the tires (compensating for any difference in the tire width). Measure the difference between the front of the sidecar tire and the back compared to the straight edge laid against the motorcycle wheels. Adjust the arms until the front edge of the sidecar wheel is between a 1/2 and 1 inch closer than the rear. My suggestion would be to split the difference and start with 3/4 inch of toe-in and see how the outfit handles.
Once the lead and toe-in are set, the lower brackets and arms should be tightened securely. Remove the supports and re-check all of your dimensions. Install the upper arms next. The upper arms control lean. Decide whether you want the bike to lean in, lean out, or remain in neutral (straight up and down position) and position the bars accordingly.
Bear in mind that all of the specifications and settings are just rough guides to get you started. Once your outfit is up and running you may find that further adjustment is needed.

Once the bike and sidecar are bolted together you may want to make a few detail modifications. For starters, consider lowering the overall gearing. Start by dropping one tooth from the countershaft sprocket and see how the bike pulls. The front forks will probably want heavier oil and stiffer springs or at least some more pre-load to cope with the extra weight. Likewise the rear shocks, at the very least, pre-load should be increased to max. If that won’t do it then stiffer springs and shocks are in order. Tire pressure should be increased by 5 PSI. You may also want to look into heavy duty sidecar tires and fit them when the solo tires have worn out, and rest assured they will, in short order. Wider handlebars will help you cope with the increased steering effort and you may also find that a steering dampener is helpful.

Riding a sidecar is completely different from piloting a solo. The sidecar requires a lot more input from the rider. The rider must steer the sidecar through turns by turning the front wheel. The sidecar also tracks a lot differently. Under acceleration the rig tends to drift toward the sidecar, during braking it tends to pull away. The pilot must counteract both of these traits.
When the sidecar is mounted on the right, as it should be here in the U. S., it will tend to lift on right hand turns. During hard left hand turns the rear wheel of the bike will tend to lift. Left-hand turns should be taken on the throttle avoiding wheel spin. Right hands turns should be takes by gently accelerating through them, remembering that the sidecar, especially if it’s empty will tend to lift. Some old hand sidecar drivers recommend carrying some ballast, usually in the for of a 50 LB bag of cement or sand to counteract the chair’s tendency to lift.

If the unit pulls toward the sidecar, increase the lean-out slightly. If it pulls away from the sidecar, decrease the lean slightly.
If the steering is heavy in one direction, but light in the other, the lead must be adjusted. Decreasing lead will it easier to setter toward the sidecar. Increasing the lead makes it easier to steer away from the car.
If steering is heavy all the weigh around the trail should be reduced if possible. Wider handlebars will also help.
Expect a front-end shimmy, particularly during deceleration. A steering dampener, the bigger the better, should help.

A properly set up sidecar is a lot of fun. When it comes to attracting attention, and as a practical solution to “where do I stow my gear, kids and wife” dilemma they’re hard to beat. Take the time to set your unit up correctly and you’ll be rewarded with miles of trouble free use.

(1) With a Cozy sidecar, the only function of the struts and brackets is to rigidly attach the sidecar to the scooter or motorcycle and establish lead. Toe-in and lean are adjusted by changes in the sidecar suspension greatly simplifying installation and alignment.
(2) Sidecars-by-George has steering dampeners available for Vespa style scooters click here to see one, see any good motorcycle dealer for other machines

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