[Juan Carlos Valqui]

Hey, in my country it is mandatory by law that you make an annual technical inspection by a third party (not the dealer).

I did mine today and in the observations section they wrote: Unbalanced brake force. Rear brakes force is between 15 and 20%. (So front brakes takes 80 to 85%).

I made a quick search and found no post talking about brake force distribution.

Does somebody knows if this is normal?

I did notice that the test was made first with the front wheels and then with the rear wheels, so I was thinking that maybe the EBD was having bad readings when the rear wheels started spinning and the front where not moving. The technician made me take the test 4 times, and even the hand brake was stronger.

 

[chriskrossapplesauce]

When you are braking, the front brakes will do most of your stopping. It seems logical in my mind. Stopping distances would be much longer if we relied more on the rear brakes.

 

[DX FJC]

That is pretty normal. Your front bias on any vehicle is more than half. If they failed it, I'd look for another inspection station.

 

[CurbCrawler]

How is the measurement done, the data collected and then analyzed. It would seem to me you would have to cripple each system (front/rear) one at a time, bring the vehicle to some predetermined speed, then apply a known brake force and measure the stopping distance. I don't think it would be smart to to tamper with a braking system to run this type of test?

 

[javylsu]

A little late to the party, but whomever is doing your inspection has absolutely no clue what they're doing. Your BFD is exactly how it is supposed to be. I've had the opportunity to work with Brembo and Race Technologies engineers in the past, and it is a well-established engineering concept that 80% of the braking in any vehicle with 2 axles happens at the front. Why? Physics.

Ever wonder why everything in your car lunges to the front when you brake hard (or why you feel pinned to your seat when under hard acceleration? That's called Dynamic Weight Transfer. In order to most efficiently stop the vehicle, a relatively greater brake force must be applied to the axle where the weight is or will shift to. It's the very reason that front brakes are always larger than rear brakes.

This is a bit of overkill, but you can read up on the basics of braking by reading this presentation from the SAE (the Society of Automotive Engineers).