Hi my friends, welcome to our new video Today we'll do something what usually nobody is doing at home It will be a rather special video Replacing the tires, I found that the inner profil has been worn stronger than the outer profil It seems that we have a problem with the camber angle A quick introduction to the geometry of car wheels In a first view the wheel seems to be vertical and in line with the car The wheel is a little off the vertical, this is the camber angle This is a positive camber angle A negative camber angle would look like this In addition we have a toe-in angle, meaning that the wheels aren't aligned Because the tire was worn more at the inner side, we have a problem with the camber and not with the toe-in angle Everybody will tell you to bring the car in a dedicated shop for a alignment measurement check But I'm going to show you how to do the job at home For measuring the camber angle I built this simple device This is a steel square which I mounted to wooden plate The plate can be adjusted by four bolts The adjustment can be preserved by the lock nuts This bar is vertical The adjustment of the plate or a bended plate are less important, only the vertical counts Also this direction is less important This bar must be adjusted as best as possible A better adjustment isn't possible For measuring the camber I use a 50mm gauge block I adjust the bar at the nearest point just to the 50 mm and up I find a greater distance Here an additional strip of 3 mm fits This means that on the upper point we have 3 mm more than at the lower point Now comes the theoretical part – we have to think about, what the 3 mm mean This is the wheel and here are the 3 more mm This means that we have a negativ camber angle We are going to calculate now the camber angle The camber angle alpha is here The distance between the measuring points is 361 mm The right angle is here This side is opposed to alpha This is the hypotenuse Opposite side divided by the hypotenuse is equal to sinus of alpha Thus sine alpha is equal to 3 divided by 361 3 : 361 and the arcsine of it The arcsine of it is 0.476 Usually the angle is not given in decimal degrees, thus I multiple by 60 Thus we have a negativ camber angle of -28.6 arc minutes The nominal camber angle for our Golf is 20 plus minus 30 arc minutes The measured value is 48 arc minutes off the center of the intervall We are off the allowed intervall which ranges from -10 to 50 arc minutes Thus we have to adjust the camber angle In order to get an idea of the error, I repeated the measurement several times The camber angle has been around -30 arc minutes in all measurements We simplify the procedure now Instead of calculating the angles for every distance, I calculate how much the distance at the lower point must be larger The 20 arc minutes are a third of a degree Again we need the sine, sine of alpha is equal to x divided by 361 x is equal to 361 times sine of a third degree 2.1 mm Thus the lower distance must be 2.1 mm greater than the upper distance I'll go now in the pit to adjust the wheel The camber angle is adjusted at this bolts The lower bolts is fixing the position The upper bolt is excentric and the camber angle is adjusted by turning it First we have to loosen the nuts on both bolts After 30 years, this might be a little difficult That has been the first nut and now the second one A small click Like this bolts behave after 30 years The washer under the nut should become loose now The bolt is free now That's enough I have not to loosen it more When the washer is free, we can start The camber angle is adjusted by turning the excenter bolt I turn the bolts by some degrees Now the situation has changed completely Upside the 50 mm just fit The upper distance is 50 mm At the lower point the gauge block is freely moveable With a distance gauges I find 0.1 mm This means that we have already a positive camber angle But it is not enough We would be already in the allowed range But I will adjust it a little more, our target distance is 2 mm In the first step I turned the key from here to here I´m turning now a little more The needed distance is 2 mm You see, this blade has just 2 mm.
I'll use it as a gauge At the upper distance the 50 mm gauge block fits In the lower distance the 50 mm gauge block and the 2 mm blade are fitting Perfect, fasten all and good Fasten the upper bolt to conserve the adjustment Fastening the upper nut, I have to hold the bolt exactly in positon, otherwise the camber angle will change Fasten also the lower nut Here it is no problem when the bolt is turning And for our Russian friends we take now the "динамометрический ключ" The torque for the nuts is 80 Nm The access to the lower bolt seems to be possible But soon you'll find out, it is better to remove the wheel first and we have the 80 Nm and also 80 Nm for the lower nut All is fixed now, I'll mount the wheel and we'll make a final check The final check shows that we have just 2 mm Bull's eye I'll show you now what is the error of the measurement We'll go in the mechanical shop and I'll show you how good is the used vertical Some of you will say, that it is not possible to adjust the camber angle using such a primitive device I'll demonstrate you now the error in the measurment The square has a length of 40 cm Let's assume an error of 1 mm in the vertical direction The sine of alpha would be 1 divided by 400 1 divided by 400, second sine and we find 0.14 degree times 60 and we have an error of 9 arc minutes The camber angle should be 20 plus minus 30 arc minutes Thus with an error of 9 arc minutes this range is easy to achieve I show you now with classical technics, the pyramides have been built with the same device, that the vertical can be defined within 1 mm You see, now it is absolutely parallel The bubble of the spirit level is right in the mid In order to demonstrate the maximum error, I misaligne the square so far that the bubble is at the line You see the gap is increasing upwards The lower distance is 3 mm The upper distance is 4 mm Thus the difference is 1 mm and this means 8 arc minutes This means no problem, the vertical can be achieved with the spirit level, a difference of 1 mm and the bubble is at the line Today I demonstrated how to adjust the camber angle without professional equipment There will be some critics on my method, but I demonstrated that the error is well in the tolerance Bye, bye, see you in our next video