This paper presents new analysis methods for brake judder data. First, a distinction is made between Thickness Variation, TV, judder (shudder or roughness) caused by the geometry variation of the brake rotor, and thermal judder caused by thermal caused changes to the friction couple. Spectrograms of vibration signals are used to distinguish between the two types of judder. Instrumentation of vehicles in order to get significant data is also provided. A linear model is used to describe the mechanism of judder generation. Different case studies are provided. Special tools of analysis like spectrograms, power time and spectral densities, and zero crossing frequency estimates are applied to real data.