Homemade buggies. According to the logic of things, the common technical requirements and design experience of many teams should have long led to the development of some kind of “ideal” buggy scheme. But it is unlikely that even today you will find two identical cars among the cars that arrived at any starts. And no wonder: each team, if it is truly creative, has something of its own, special, and everyone has different opportunities. We hope that our experience will be useful, first of all, to young sports teams.

According to the current classification, MSHI buggies belong to the 1st class and are built from the most affordable units and assemblies included in the kit supplied by DOSAAF. This power unit allows you to design an excellent motocross machine. Its rear location ensures that the drive wheels are loaded, which is very important for a car of this type.

Neither forcing the engine nor reducing the overall weight of the structure will noticeably change the dynamics of acceleration if there is no reliable adhesion of the drive wheels to the support. But overloading the rear axle is also inappropriate: handling and longitudinal stability will become worse due to the weakening of the adhesion of the front wheels to the road. In our car, the weight distribution on the front and rear axles was 40 and 60%. This ratio, according to our calculations, is close to optimal.

In addition, the rear engine installation made it possible to position the driver more comfortably than in a buggy with a classic transmission. The seat is placed exactly along the longitudinal axis and, in accordance with the selected weight distribution, is shifted forward. In this position, the driver controls the car more accurately, and when cornering with a skid, it moves along a smaller radius. The frame is a welded tubular frame.

In its manufacture, pipes from available structural steels were used: for the main frame, safety arcs and the main load-bearing elements of the suspension beams - pipes sized 42X2.5, for side protection - 35X2.2, and for other, less loaded elements (protection of the power unit, fenders , wing brackets) - size 32X2. The assembly of the frame begins with the lower frame.

In the front part, the brackets of the lower front suspension arms are welded to its short longitudinal pipes, and the brackets of the rear suspension arms and the lugs of the front support of the power unit are welded to the transverse beam on the opposite side. The operation of the undercarriage units depends on the geometric accuracy of the assembly of all elements of the lower frame; therefore, welding is carried out on a slipway of steel channels.

Then two U-shaped safety arcs are welded to the frame. Connected at the upper and middle levels by longitudinal pipes, and at the lower by transverse ones, they form a rigid frame. The front of the frame is wedge-shaped. Its dimensions allow you to place the steering gear, control pedals and fuel tank. On the low racks of this part of the frame, the brackets of the upper arms of the front suspension are welded, and between them on the spar are the support lugs of the shock absorber. The part of the frame behind the rear roll bar serves to mount and protect the power unit.

pendants homemade buggy- independent. Front on triangular wishbones, welded from steel pipe 28X2.5. The lower arms are reinforced with a longitudinal crossbar and have a bracket for mounting the shock absorber. Installation on the frame - through standard rubber-metal silent blocks. The ball bearings and the steering knuckle are “Zhiguli”, but the axis of the fist is machined to fit the dimensions of the Zaporozhets axle, since the wheel hubs were taken from this car.

The rear suspension is mounted on standard ZAZ trailing arms. Reinforcing steel plates 4 mm thick are welded to their ends. The shock absorber bracket and the eyelet for connecting the belt-limiter of the maximum lever travel are also attached to them. High demands are placed on the chassis of a cross-country vehicle.

The main task of the suspensions is to maximize the contact of the wheels with the ground in difficult driving conditions and effectively dampen the resulting vibrations. On the MPI buggy, the front and rear suspension arms are equipped with aviation-type hydropneumatic shock absorbers, which ensure operation with a maximum travel of 240 mm for the front and 300 mm for the rear wheels. But more affordable spring-hydraulic shock absorbers with springs from the ZAZ front suspension and shock absorbers from trucks behave quite satisfactorily here.

The steering mechanism is rack and pinion. It is lighter and more compact than a worm gear, has a smaller gear ratio (1:10) and is therefore more convenient for a sports car. The standard ZAZ-968 engine has a power of 40 liters. s, however, it can be increased by 30-50%. Forcing methods are standard. Pistons with connecting rods are adjusted by weight. Balance the crankshaft with the flywheel and clutch assembly. Improve the filling of cylinders with a combustible mixture. To do this, the inlet and outlet channels in the cylinder heads and nozzles are carefully cleaned and polished.

The joints of the connections of the head with the collectors are checked for the absence of "steps". Of the carburetors used on the ZAZ-968, we recommend choosing the DAAZ-2101-20 - it is easier to adjust. Set it to a slightly over-enriched composition: so that the engine runs without “failures” and spins up quickly. Attention should also be paid to the air purification system, monitoring the condition of the VAZ air filter element. When competing in dry weather, it quickly becomes clogged with dust and impairs the performance of the power system. Another reserve for boosting the engine is the setting of the exhaust system.

It is known that resonance phenomena in the exhaust pipe can be used to improve the cleaning of cylinders from exhaust gases. This is done by selecting the dimensions of the exhaust pipes. On our machine, one of the four-in-one methods has been successfully applied. It is calculated by an empirical formula and refined empirically. You can read more about this in the books: Nazarov M. M. Special cross-country cars - buggies. M., DOSAAF, 1980; Morozov K. A., Chernyak B. P., Sinelnikov I. I. Features of working processes of high-speed carburetor engines. 1., 1971.

Standard gearbox, gear for homemade bagia unsuitable. Fourth gear in the race is practically not necessary to use, and the range of gear ratios between second and third is too large. Therefore, we installed the third gear instead of the fourth, and instead of the third - a homemade spur gear pair. The improved box has the following gear ratios: I-3.8, II-2.118, III-1.75 and IV - 1.409.

The wide track increased the stability of the car, but forced to lengthen the axle shafts. So that they do not disengage from the main gear at the lowest position of the levers, the travel of the suspension levers was limited by strong canvas belts. The same limiters are installed in the front suspension. Discs, hubs and brake shields "Zaporozhets" used unchanged. Tires - either from "Volyn" (LuAZ), or special - NK-9.

The latter provide reliable traction when driving through mud and at the same time self-clean well, but on dry surfaces they require more skill from the driver: due to the reduction in the contact patch, the car “holds the road” somewhat worse. Sheathing the frame with duralumin sheets performs not only a decorative and protective role. It also serves as a strength element of the structure. Sheathing sheets of the driver's compartment, sidewalls, front and rear bulkheads, as well as the bottom are attached to the frame tubes with aluminum rivets. This increases the rigidity of the frame.

The thickness of the sheathing sheets at the bottom is 1.5 mm, along the sides - 1.0 mm, the remaining elements from the sheet are 0.8 mm. For greater rigidity, the sheets are zigzag. It is longer and more difficult to connect the skin with rivets than with bolts, but such a fastening is more reliable and does not come loose from shaking. Only the wing skin is bolted to its tubular frames: ease of repair or replacement in case of accidental damage is more important here. But for the same reason, tubular fenders are made removable, fixed along the sides of the machine.

Rice. 1. Frame homemade buggy assembly (right suspension arms are conditionally not shown): 1, 2 - safety arcs, 3, 4 - engine mounting brackets, 5 - protective frame of the power unit, 6 - rear arm limiter lug, 7 - arm reinforcement, 8 - rear suspension arm , 9 - removable bump stop, 10 - knuckle, 11 - lower front suspension arm, 12 - front suspension upper arm, 13 - shock absorber.

Rice. 2. Body frame (side view).

Rice. 3. Carcass frame with suspension arms: 1 - lower arm, 2 - side member, pipe 42X2.5, 3 - cross beam, pipe 42X2.5, 4 - rear suspension arm, 5 - shock absorber bracket, 6 - stopper eye, 7 - engine bracket.

Rice. 4. Placement of the power unit: 1 - engine, 2 - engine bracket, 3 - gearbox control lever, 4 - protective frame, 5 - exhaust system, 6 - extended axle shaft.

Rice. 5. Front suspension: 1 - wheel hub, 2 - steering knuckle, 3 - ball joint, 4 - upper arm, 5 - brake hose.

Rice. 6. Rear Suspension:
1 - limiter, 2 - shock absorber bracket, 3 - suspension arm, 4 - axle shaft.