Brake System Vehicle Level Review, Components, Inner Parts and Function for Racing Vehicle and Sports Car

Brake System Review, Components, Parts and Physics for Racing Vehicle and Sports Car 

Know-how Required 
Different Types of Weight of Car, front and real calipers, Brake Pad, Brake Fluid Volume, front to rear weight bias, rear traction, lower polar moment of rotation, Skid, Tyre Thread Design, Car Center of Gravity and many more technical terms 

Brake System Review of racing car and sports vehicle is more complex considering very high value of g, jerk, skid, drift and topple problem. For engine components intake manifold, throttle, fuel injectors please read previous blog. 

Race vehicle acceleration might go up to 5g; frequent breaking a 545 Kg vehicle at high acceleration is very tiring job for driver (Guiggiani, 2014, p.107). Basic brake design challenges, cause/effect of specifications and requirements are explained in Table 1 and Table 2 below.  We can further improve braking if vehicle centre of gravity height is lowered and shifted near to rear wheel and Wheel Base is increased(Heißing & Ersoy, 2010,p.111). However it comes under chassis design and required complete design change subsequently we have assumed that chassis design parameters are based on brake design and then try to further optimize brake parameters such as pedal liver ratio, calipers piston diameter and master cylinder bore.

It is proposed to use hydraulic brake to meet formula Ford rules. Hydraulic brake is light weight, low cost, easy to layout and does not require external power (Erjavec, 2003, pp. 49-67). Front Rear Split Brake is preferred over Diagonal Split Layout because larger front weight transfers while braking in high speed racing. Maximum 2 Piston are allowed per wheel with maximum diameter 45mm consequently to minimize applied force from driver, Master cylinder diameter will not be kept too low so pedal liver ratio has been increased up to 5 (Scraba, 2007, pp.90-92) . At 1g, driver can apply breaking force approximately near to his/her weight (Assume 75Kg) this can cause brake pipe pressure up to 200 Bar accordingly seamless Cu-Ni Alloy pipe with flare end will be used for safe brake pipe design (Lipowsky & Arpaci, 2008, p.125); for further safety improvement Brake Pressure Sensor has been assembled, this will detect any leakage in brake system.


It is considered that Total weight of car 5346N (545Kg), Wheel base 2700mm, Front Axle to centre of gravity distance 1900mm and height of centre of gravity 350mm. Static vehicle weight distribution  would have be around 33/66 for front/rear respectively then common child part of calipers and brake disc/pad would have been used for both front and rear wheel brake. 

Front and rear calipers piston has been kept 45mm to use common part for cost reduction however to avoid rear wheel lock we have reduced mean effective radios of rear disc and softer material has been used for rear brake disc/pad. Mean effective radios of braking disc is 230mm and 200mm for front and rear respectively.  Most importantly disc and pad material selection depends on formula ford race track layout, number and curvature of corner and environmental condition so physical braking distance test and endurance test will be done on actual formula ford race track only.



 End of Life Vehicle regulation does not permit Asbestos as Brake Pad. Carbon sintered steel will be used for brake pad as it is long lasting so it will be good for formula ford race track. Front Rear Split Brake is proposed due to front weight transfer while braking however weight distribution in static condition plays major role is deciding front and rear brake calipers piston diameter and disc size.


The pads and rotors wear at analogous rates consequently they must not become too thin. Rotor disc is sized to provide a thermal mass that is capable of absorbing and dissipating breaking heat without oxidizing or melting. Calipers clamping force can be regulated for front and rear brake with help of brake bias adjuster. 

Tyre thread wear rating governs wet and dry traction so selection of good tyre is very significant though it is fixed by formula ford rules. Large diameter rotor generates greater force to stop wheel. A thick and vented rotor which can adjusts amount of cooling air will be suitable for formula ford. Brake rotor material affects its thermal characteristics, friction and wear properties. Pad coefficient of friction varies with its temperature therefore for variable friction, larger rotor diameter and tyre traction ability calibration must be done for different braking condition.  Multiple piston calipers offer force is distributed across the pads better, yielding a better contact area. Also Total brake fluid volume is lesser, so more clamping force is achieved. Unmarked calipers disk rotation will leads to uneven pad wear, noise, and piston damage.

The brake force bias must be such that the rear brakes never lock up before the fronts. If the rear tires lock up before the front tyre, then center of mass will travel arbitrarily. Higher (66%) rear weight gives a good front to rear weight bias, rear traction, lower polar moment of rotation and easy handling.

Child Part
Requirement
Material
Manufacturing
Cost
Weight
Life
Design Review
Brake Pipe
Burst Pressure =200 Bar Min
OD= 10mm Max
ID=5mm Min
Factor of Safety 5 Min
Steel Pipe
Multi layer Seamless Piping with flared end
A
B
B
Ni- Alloy Brake pipe is safe and have good life.
 Ni- Alloy has higher Ultimate Tensile Strength so less material thickness pipe can be used.
For same burst Pressure weight of Ni Apply pipe is least.
Cu Alloy
B
B
A
Cu Ni Alloy *
C
A
A
Brake Oil
No Compressibility,
Anti Hygroscopic, High Dry/Wet Boiling Point,  Fix Viscosity
Silicone-based
Chemical Process
B
/
B
Anti Hygroscope property is better for glycol based fluid because water does not mix in it.  Glycol based fluid will be used in brake.
¤ Glycol Based
B
/
A
Disc
Mean Effective Radios = 250mm,
Thickness = 20 mm
Weight = 2 Kg Max
Grey Iron
Casting
A
C
B
Grey Iron is very heavy and chances of rust are high. Siliconized carbon is very costly.
Reinforced Carbon will be used for Disc as it has long life and safe.
Siliconized carbon
Sintering
C
A
A
^Reinforced Carbon
Sintering
B
A
A
Piston
Dia =45mm,
Burst Pressure = 200 Bar
Steel
Casting/Machining
A
C
B
Aluminum (ADC12) has lesser weight so Al Piston will be used. (HPDC: high Pressure Die Casting)
Titanium
Casting/Machining
C
A
A
ADC12#
HPDC, Machining
B
B
B
Master Cylinder
Bore =10mm, Capacity = 15cc, Burst Pressure = 200 Bar
Steel
Casting/Machining
A
C
B
Aluminum (ADC12) has lesser weight so Al Piston will be used.
ADC12#
HPDC, M/c
B
A
B
Brake Pad
Area =50Cm2
Depth =40mm
Thickness =15mm
Ceramic
Sintering
B
A
B
Carbon Steel Pads will be used as it has longer life and lesser cost.
¥Carbon Steel
Machining
B
B
A
Brake Pedal
Level Length =300mm
Pedal Area = 50X50mm2
Steel
Bending, Welding
B
B
A
Cost reduction through elimination of fixturing alignment, welding, and finishing operations required for the welded steel assembly. so Al will be used
Al B356 T6
LPDC, M/c
A
A
A
Brake Pressure Sensor
Pressure Voltage  0Bar 0V to 250Bar 5V
Accuracy = 1%
Piezoelectric
Electronic Chip Molding
/
/
/
Piezoelectric has better sensitivity and responsiveness.  Twisted Wire Sensor will be used to avoid electronic noise.
Piezoresistive
/
/
/
Hand Brake Lever
Length =300mm
Handle Dia = 20mm
Weight = 1Kg Max
No Sharp Edge
PA66 GF35
Molding
C
A
B
Steel will be used for hand brake lever. Separate PA66 GF35 made handle can be assemble on Lever for superior grip.
Aluminum
HPDC, M/c
B
B
A
Steel
Casting, M/c
A
C
A
Hand Brake Cable Wire
Braiding Angle, Ductility, Cable Dia/Wire Dia, Length, Elongation, Hardness
Cross Braided Wire
Drawing, Knitting
C
B
A
Spiral Braided Wire will be used as its cost is less. Knitted Wire has more strength and life but very costly.
€ Spiral Braided Wire
Drawing, Twisting
A
B
B