Brake Pedal Throbs with Windshield Wipers
 

I noticed today that there is a slight throb in the brake pedal every time the windshield wiper cycles... kinda like a heartbeat. It seems "normal," but I was wondering about it... is it just the drain on the electrical system affecting the ABS?

Now that was a descriptive thread title.

Sorry, I don't have anything to add other than that. :)

I think it's normal. I drive a Honda CR-V and it does the same thing. Kind of annoying if you ask me. Though I didn't realize that in the 8 before. You'd think they would mount the wiper motors so that it isolates any type of vibration or "throbbing" from reaching down to any of the pedals.

Don't think I didn't read it three times before hitting the button. I was tempted to go with the ever popular, "Is this normal?" :)

Give me a few days to try that out on one of the cars at work before I answer.

Technically, what you describe is impossible - the electrical drain the wipers cause should have NO effect on your hydraulic/vacuum operated brakes! But sometimes weird things happen, which is why I want to try this on a car first. I'll get back to you with the answer.

Just speculating here... Haven't people mentioned that the reason the Mazda Speed J-spec strut tower brace is a 4 point, is because it acts as a "brake stop" bracing the brakes on the firewall? I remember something about the firewall flexing under braking because the firewall is not strong, and we all know our brakes are... So if the firewall was flexing I'd think that any activity (i.e. windshield wiper movement) would be amplified through the brake pedal maybe due to small misalignment after flexing? Just speculating...

Sorry Megareds, I didn't have time to look at an 8 this week, lots of other things on. DJ freon's theory is probably on the nose though, more likely than not mechanical torque transfer through the firewall. Nothing to worry about methinks.
Sorry for makin promises and not keeping them...

I didn't notice this yet (had the car 3 weeks). If I do start to notice it now i'm gonna kick your ass! lol jk'ing!

It's certainly not a problem... just an observation. At the time, I thought it was an electrical throb, but it could easily be mechanical.

I just checked this on a new 8, nothing.
Maybe your wiper motor is loose? Or maybe it is the ABS going through its test at start up? Take it to a dealer - something may be loose.