I’m not guilty: the end of the brake pad benchmark test
The great-grandfather of one character in a famous film once said: “I have the desire to buy a house, but I don’t have the opportunity … I have the opportunity to buy a goat, but I don’t have the desire”. And drank to ensure that the possibilities coincided with the desire. We had a desire to make a comparative test of brake pads, but it was not possible to put different pads on the same car with the same driver: it would have taken too long. Therefore, we took one car and put different pads on it from different sides. And you could, like that great-grandfather, just drink.
Two steps back
Let’s first go back a little and remember what path we have traveled from the start of our not very scientific experiment to its finish.
So, we bought two sets of front brake pads for the second-generation Ford Focus. The first pads are well-known in Russia Valeo, the second – slightly less known, but also good LPR. Before committing this blasphemy, we machined the brake discs – the competitors, approximately equal in value, must have equal conditions.
Immediately after installing the pads, without even leaving time for lapping, we drove the car onto the brake stand. On the right are Valeo, on the left – LPR.
First, at the stand, we made sure that the disks are equally flat – the ovalization is 1%. Shock absorbers, whose operation also affects the braking force (leaking shock absorber can allow small “jumps” of the wheel, which significantly reduce traction), also turned out to be normal and the difference in the efficiency of their work was only 3%. So we can safely say that the working conditions at the right and left shoes are almost identical.
Well, and most importantly – the difference in braking force was only 8%. The left block gave 1 880 N, the right one – 1 970 N. The difference, let’s face it, is insignificant. In part, it can be explained by the fact that Ford Focus, for all his modesty today, is equipped with ABS and ESP, so that he tries to align the braking forces himself. On the “nine” it would be more interesting to experiment, but the choice of pads for Ford is more interesting.
Then we drove five and a half thousand kilometers on this car, drove back to the stand, then removed the pads and checked their wear. Briefly recall the numbers.
Let’s start with the stand. We specifically went to the same stand: it would be at least a little more objective. And we got this result.
To begin with, a small ovalization of the disks appeared during this run. The difference of 1% is attributed to the measurement error, so it can be said that over 5.5 thousand runs, no block has spoiled the disc. Almost because we saw something when we removed the pads. But more on that below.
But the difference in braking force has become much more noticeable. If in the first measurement the difference was 90 N, then in the second measurement it was 130 N. And this is already much more than the error. The undoubted leader was the production of Valeo.
By the way, you should pay attention to how effectively the pads began to work after burnishing. The braking force of LPR increased from 1,880 N to 1,930 N, while Valeo grew from 1,970 to 2,160 N. Most likely, for this, it would be enough to drive not more than five thousand, but two hundred kilometers – for this run, the pads would have time to get used. But it is not important. Most importantly, they began to work better, and Valeo – much better.
Now back to the disks. We found out that the stand did not reveal a violation of their geometry. But the fingers found what the stand can not see – noticeable scratches on the left disk. It is noteworthy that there are LPR pads, which showed markedly more significant wear. It would be logical to assume that soft pads should wear less disk, but the opposite was true: large blotches were painted out of the lining of the pads and spoiled the disk. Valeo’s lining structure is more uniform, and the disc with these pads looked like new.
It makes no sense to go to the booth for the third time: the efficiency of running-in shoes will not change. This time it is interesting only to measure the thickness of the pads and look at the condition of the discs. Well, describe the overall impression of the ride with different pads. Let’s remove our experimental and see how they lived there in calipers.
Let’s start with the codec LPR. Immediately struck by the state of the disk: the grooves on it more and more. Now you don’t have to run a finger over it, like on the back of a beloved woman, in order to understand that there is wear on the disc.
Now pull out the pads. Outwardly, nothing particularly bad or good is visible. Everything is relatively smooth, although the chipping of large particles is very noticeable.
The border of the working surface is all in holes. It is not surprising that such large pieces intensively scratched the disk. However, there is nothing criminal in it: the wear of any brake disc is inevitable, and with this thought somehow you have to learn to live further.
What will the caliper tell us? This is more interesting.
Let me remind you that the thickness of the new pads was LPR was 17.6 mm. During the second measurement, it became 17.1 – 17.3 mm, and the outer pad worn out more.