Size of the bush plain bearing of Peugeot, Citroen rear beam

Size of the bush, plain bearing, of Peugeot, Citroen, Samand rear beam

Original needle bearing is pressed into the arm on the outer diameter A, with the help of the needle rollers it swings in the inner diameter B, on the axle's surface. The friction force, appearing between the bearing racer surface and the arm mounting surface, than the one between the axle's (pin's) surface and the bearing rollers.

That is why the bearing swings the way it should swing, shifting on the inner diameter B. For the bush placed instead of the bearing to function properly – swing on the inner diameter, and don't swing on the outer one – it is necessary, to specify the right preload on the outer diameter A and the gap on the inner diameter B, for the friction force on diameter A to be more than the one on the inner diameter B.

While estimating the rear beam bush sizes one may use the size of the rear beam needle bearings. But it isn't quite right to associate the needle bearing size with the size of the bush size. The bearing and the bush are made of different materials, so softer polyamide or bronze bushes are likely to create lesser preload on the outer diameter A after some run. Estimating the diameter B according to the needle bearing is quite complicated, because there is no inner race and the diameter is created with rollers edge. The plays between the rollers make the exact estimation of the diameter impossible. That's why the inner diameter of the bush B is estimated proceeding from the axle diameter, bush material and necessary gap.

The procedure of estimating the inner diameter B is very responsible. If the diameter is larger, the gap between the rear beam bush and axle (pin) will be too large. It will be followed with thrash and play, which will enlarge the gap. If the size is too little, it may lead to growing friction and lack of sliding. If the friction on the diameter B is too high, the bush may turn over without fastening on the diameter A, gradually destroying the rear beam arm mounting place. That's why finding the "happy medium" for the inner diameter is even more complicated than estimating the bush outer diameter.

The length of the bush (the C size) may be larger than the analogous size of the rear beam bearing of Peugeot, Citroen, Samand, it may be limited with the size of the arm matching site. The larger the C size is, the less the unit load on the plain bearing is, this will result in increasing its useful life. At the same time increases the importance of the right estimation of the A and B diameters, because of growing risk of the bush sliding on the outer diameter, in the arm matching site. Apart from it, the more size C is, the harder the rear car suspension will be.