Junak Motorcycles

Today in Motorcycle History

Junak Sidecars

Polish WB1 type sidecars, Hungarian Oceania type sidecars and others were used by Junak.

Types of sidecars adapted to Junak

Junak was designed with the possibility of attaching a sidecar to it. The junak M07 used Hungarian Oceania and Polish WB1 type carriages with a very interesting design, as well as other ones produced by various companies (not only SFM). Junak's frame adapted for four-point attachment of the trolley, through two spherical handles and two struts. Ball holders are screwed into the lower part of the frame. At the front, by the engine mounting pin, and at the rear, near the passenger footrest. And above, the struts were screwed to the clamps put on the frame tubes, under the head tube (under the tank), and under the seat, at the height of the fender.

Sidecar type WB1(?) of the first production, next to Junak M07. Most likely still a prototype

At first glance, both strollers are the same, but after a closer look you can see the differences, and I don't mean only the wheel, the fairings and the invisible embossing patterns in the sidecar attached to the M07 are different.

WB1 type sidecar at Junak M10 already in production version. Gondola sprung on rubber belts, near the sidecar on a long, one-sided rocker. The springing element is a junak damping element (rear shock absorber). The frame had a step to facilitate entering the sidecar.

The next version of the trolley for junak. WB3A, the soft suspension of the gondola was abandoned, it was rigidly attached to the frame of the trolley, and the wheel was suspended on a short push-arm. Several rubber rims are the element that cushions the movement of the wheel. Passenger comfort has significantly deteriorated compared to the WB1. Production costs have decreased

Three different models of junak gondolas on the same type of frame. The wheel is suspended on a long trailing arm that encloses the bogie wheel on both sides. The spring element is a horizontal spring. It was possible to adjust the initial tension. The frame had a step to facilitate the passenger's entry into the gondola. Gondolas were available in cargo and passenger versions.

Disclaimer. I do not agree with much of what is written below, but it *may* be of use to those new to sidecar riding which, to my mind, is a wonderful way to enjoy the sport and completly different to the solo experience. My personal favourites have been an R69S with Steib (@ 5 years) and a V-Max Watsonian (also @5 years). Apologies for the poor translation. "..." denotes indecipherable text which has been omitted from this version. (Ed.)

N.B. This article assumes the sidecar is mounted on the right, for countries which drive on the right. Many countries have the sidecar on the left - Britain, Australia and New Zealand, for instance. Why is this so, you may well ask. 'Able was I ere I saw Elba.'

Sidear setup

the principle is simple the wheels are to be converged and deflected outwards like in a car. there is one small difference, the motorcycle with sidecar only has three wheels. for clarity: the horizontal axis of the trolley wheel should be convergent to the axis of the motorcycle wheels by about 1-2 cm (the smaller the slack in the sidecar suspension, the smaller the convergence). we measure the convergence by placing strips, pipes along the wheels at a height of approx. 15 cm (e.g. on bricks), so that they touch each tire in two places. by measuring the distance between the slats in front of the motorcycle and subtracting from the measurement from behind the motorcycle, we get the difference, which is the convergence. the motorcycle is to be tilted from the vertical by a few degrees (2-5), away from the sidecar. the wheel of the sidecar should also be tilted from the vertical, in the other direction. in addition, the entire team must be positioned so as to be able to be led, while maintaining a uniform speed, without a tendency to turn to either side.

With too much inclination of the motorcycle from the sidecar and with too much convergence, the motorcycle will tend to turn to the left (away from the sidecar), and with the motorcycle leaning to the right, or the divergence of the wheels, the motorcycle will turn right (to the sidecar). driving such a team will be strenuous and maintaining the direction of travel will require a lot of strength, sometimes even fighting with the steering.

Riding a motorcycle with a sidecar cannot be compared to riding any other vehicle. Driving a team has nothing to do with riding a solo motorcycle, except maybe the riding position and the steering aids. These are quite two separate issues. A motorcycle with a sidecar will not succeed in... and such structures are built, but here we are talking about a classic harness. The lack of the possibility of leaning in turns is not the only difference related to the way the sledge is led. The main difference is the asymmetry of the vehicle, and therefore it will behave differently in the right and left turns.

In addition, when driving a solo motorcycle, we subconsciously break off the reflexes learned in our youth, whose existence we are not even aware of. Namely, wanting to turn (let's assume) left, we subconsciously make a minimal movement of the steering wheel to the right (so turning to any of the sides earlier for a fraction of a second we turn to the opposite side). Physics does the rest. The motorcycle leans to the left and the wheel, most often by itself due to the gyroscopic force, turns to the left. Sometimes needing our help (understeer motorcycles) or slowing down this phenomenon (oversteering).

It is this reflex learned over the years that is a problem for motorcyclists switching from a solo machine to a motorcycle sidecar combination. It is worth watching children learning to ride bicycles. Giving a child a bicycle without side wheels, they cannot ride it, but after attaching side wheels can do so - as soon as they learn that pedals are used for propulsion.

After developing the appropriate reflexes, the child begins to ride without using supports. To make it more interesting, I noticed one relationship. At the first contact with a motorcycle with a sidecar, those who have not previously ridden a motorcycle fare better. A motorcyclist who has switched from a solo motorcycle to sidecar combination in a turn will feel like leaning the motorcycle towards the inside of the turn, and will make this minimal movement (subconsciously) in the opposite direction and immediately after that will start to turn the handlebars in the direction of the turn, but not feeling the lean of the bike, or even feeling the opposite lean, will not turn. Subconsciously, the rider will react appropriately for the solo: no tilt - don't turn!.

Such a rider strains their hands wanting to turn and subconsciously straightens the steering wheel at the same time. This goes on until the reflexes are broken. The next difference is the behavior of the machine during acceleration and braking. When accelerating, the motorcycle wants to go turn towards the sidecar, which, due to its weight, stays behind.

The case is different when braking. The sidecar, which has accelerated so far, wants to overtake the motorcycle (we are talking about sidecars without a brake and a drive on the wheel of the trolley) the whole thing turns towards the motorcycle. These effects pose certain dangers. When entering the right corner too fast, the centrifugal force wants to push the bike out of the corner. With good traction, the motorcycle will not slip, but the sidecar will be lifted. It can be a lot of fun, but it's a bit dangerous, but it's not violent and it's manageable. Before the motorcycle lifts the chair, it will squat down a bit, letting us know about the danger. It is worse when we exaggerate the speed in the turn and moreso when we have a passenger aboard. When turning too fast to the right, the front wheel and the wheel of the wheelchair are loaded, while the rear wheel is relieved. If the rear wheel stops touching the ground, the motorcycle is supported on only two wheels, and each of them "feels" to go in a different direction. And very soon the "nose" (front) of the sidecar's gondola touches the ground, and then the driver's seat becomes a catapult. Of course, this can be prevented.

Drive slower in left corners and react quickly to even slight lifting of the rear wheel (you can't always feel it). It can also be used for normal driving. Wanting to enter the left turn, we approach it from the outside, brake in the turn, while tightening the turn. The lower the speed we have, the more we can tighten the arc. We end the maneuver near the right edge. When taking right turns, you should approach it from the inside, while overcoming the curve, you should accelerate slightly, while straightening your track a little, so as to finish the maneuver close to the road axis.

Source: Junak.net Archive