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Brake System Info - Need Help

Muskrat

Well-known member
Joined
Jun 13, 2004
Messages
2,107
Location
Lexington, KY
For one of my classes we need to model the braking system on our cars. I decided to use the Galant for this project, but it's not at school with me, and I need some help from you guys getting some spec's.

I've found what I can from the Factory Manual, here's what I'm still missing.

1) Height of the Center of Gravity
2) Compressed Tire Radius (Stock Wheels and Tires. Height from Center to ground)
3) Rotor weights (Front and Rear)
4) Distance from Pedal to Pivot on brake pedal (see top pic - measurement A)
5) Distance from Pushrod to Pivot on brake pedal (see top pic - measurement B)
6) Caliper Piston Diameter's for front and rear
7) Brake Bias Ratio

If anyone knows these values, or could go out to their car and measure them, I'd be very grateful.

 

Struc

Well-known member
Joined
Nov 24, 2008
Messages
764
Location
Oconomowoc, WI
Quote:
2) Compressed Tire Radius (Stock Wheels and Tires. Height from Center to ground)



If you put the stock tire size in the Tire Size Calculator, you get 12.1" radius.
 

Muskrat

Well-known member
Joined
Jun 13, 2004
Messages
2,107
Location
Lexington, KY
Thanks, but that's the uncompressed tire radius.

Compressed radius (also known as the rolling radius) is the distance from the center of the tire to the ground, which will be smaller due to deformation from the load the car exerts on the tire.
 

Dialcaliper

Well-known member
Joined
Jun 22, 2007
Messages
1,284
Location
Mountain View, CA
2)The rolling radius is usually only a few percent off of the tire diameter. Tirerack has some "revs per mile" numbers for some tires that you can back calculate to actual rolling radius.

6) Front caliper is twin 42mm piston, rear is a single 35mm piston

7) The Bias Ratio is essentially 1:1. The prop valve is 1:1 up to 740 psi, and then the rear tapers off at 60% of the additional pressure on the front. There's some info Here

Also, per the FSM, the brake booster is 6:1 boost over the pedal pressure. (measured at 62 lbs pedal force which would make 372 lbs of pressure on the master cylinder pushrod). Not sure if it matters for your model or not.
 
Last edited:
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