Data logger? I missed that bit?… what data logger have you ordered please?
It was a VB300.
This guy is a bit of an expert on that topic and his blogs / website covers various professional hardware like
this and also different
software options.
I have a friend who is heavily into measurements with lasers, sonar, optical tracking etc.. suggested something like the Fluke 805 with external magnetic sensor. The combination is about $4,000. He said I might even consider renting the equipment. He is extremely well equipped, but is near Dallas, TX.
The VB300 on that linked page didn't have any supporting information about why it was ranked low other than suggesting they have older technology and didn't offer a good value. I realize that it can only measure 0-60Hz frequencies because of its 200Hz sample frequency and that is definitely a limitation, but it should give me some reasonable metrics.
The reason I picked the VB300 is that is comes with a strong magnetic mount I can just put on my seat plate. The sensor can be removed from the magnetic mount without disturbing where it is mounted for consistent measurements. The lower ~$200 cost and windows software it came with to read the results by USB helped push me in this direction.
Perfect? Not even close, but still an empirical measurement that can be compared.
Given some of this will be based on my being able to maintain a constant brake pedal pressure for a series of measurements, I think it will be accurate enough. Unless I could rig up a reverse clamp to press against the pedal... Hmmm.. Still I think having my weight in the seat will have an impact as well. Granted I could use sand bags or something as well.