Date: Tue, 17 Jul 2007 06:11:32 -0700
Reply-To: Don Hanson <dhanson@GORGE.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson@GORGE.NET>
Subject: Re: More brakes.
Content-Type: text/plain; charset="iso-8859-1"
A good explanation.
While the braking system can be altered to work more effectively, the vehicle dynamics, the loads at the wheels themselves can't be altered so easily without altering the configuration of the whole vehicle. The two factors work together, through the available traction, to stop your van.
You could put F-1 carbon rotor 6 piston full ABS/traction control brakes on the rear end of a Vanagon, but you probably wouldn't get much improvement in the stopping ability..The vehicle dynamics just don't allow that, because as you brake, the weight distribution shifts most of the traction onto the front wheels. Once you have the rear wheels locked, bigger back brakes are not going to change a thing..A fancy ABS might help a small amount..but the available traction to slow the vehicle simply is not there, on the back wheels, due to vehicle dynamics..
With many vehicles, you can even overcome the available traction using the dorky little parking brake! Like the Rally drivers or the stunt drivers do during those wild drifting corners..
But better, more effective front brakes are something I'll be looking into fairly soon.
Not relevant to Vanagons, but interesting is: My (sold now) racecar, which started life as a street Porsche 928, had a very effective brake system as it came from the factory. And a powerful V-8 motor and plenty of excess weight..As this vehicle progressed to race winning configuration, the most effective modifications were not to the motor, but to the brakes. We mounted some Brembo Big Red 6 piston front brakes on 13.5" hollow core holed brake rotors and my lap speeds increased dramatically, as did my ability to maneuver (safely?) for a better position amongst the other racecars..Most passing on a road race course is done by 'out-braking' the cars you're contending with...
Don Hanson
----- Original Message -----
From: Loren Busch
To: Don Hanson
Cc: vanagon@gerry.vanagon.com
Sent: Monday, July 16, 2007 11:55 PM
Subject: Re: [VANAGON] More brakes.
RE: Braking effort/distribution
There are two factors here that can be confused. First is the distribution of braking force from the brake system of the vehicle. The distribution of braking force, front vs rear wheels, is controlled by the design of the brake system in the vehicle. No matter what you do, that remains the same regardless of speed or how hard you push on the brake pedal (unless designed to not have a linear response to pedal pressure). The second factor is the load distribution at the wheels during braking. That does change depending the dynamics of the situation and can result in all kinds of loads at the wheel. The part of this discussion that started this thread was talking about the braking system itself, not the dynamic load distribution during braking. | 
