Brake Cable Routing Path
- Ahnaf Mamun
The purpose of this page is to document the research and decision-making regarding the parking brake routing path. Apologies if my usage of technical terms and overall knowledge is wrong, feel free to let me know and I can change things up!
Research
ASC Regulation On Brake Cable (10.5.D)
Design Constraints
Brake cables need mounting for the ends that are getting attached to the caliper and that mounting bracket has to be about the rotation axis of the wheel. Essentially, the cables have to first travel in the direction seen below, towards the front of the car.
Routing the cables through the outside of the Chassis will not be feasible due to the rib location.
Location of Ballast Box and seat could cause issues
Plastic coating of the brake cables can be worn down due to water and road salt
Brake cable can produce screeching noises when in contact with the drive shaft, important to route the cable away from moving parts
Brake cables can easily be caught in between spring loops (coil-overs) on the shocks which could cause failure
Brake cable bend radius
Conclusion
The cable must travel within the Chassis and first go forward to the front of the car
The cable must have proper clearance from obstacles such as the FSU, hot surfaces, and environmental factors.
Should be routed in such a way that it is easy to maintain/inspect
Example/Types of Parking Brake Routing
Mazda Navajo Cable Routing
Brake cable from each wheel meets in the center and travels on the same line until they reach the hand brake
Hinges are used to keep the cables in place (see 19-25 or 9.8-13)
Emergency Brake Cable Layout
The website uses the same Handbrake that we use, a good resource to check out
Two main types: center pull and side pull
As we previously saw on the Mazda Navajo routing, they used a center pull.
Since our handbrake will be towards the right side of the driver a side pull could simplify the routing
Sources:
Note: Much of this research came from reading car forums about parking brake cables and people's experiences.
https://www.hotrodhotline.com/emergencyparking-brakes-hot-rods
Lokar's Universal E-Brake Cables - Rod & Custom Magazine
How to Attach Emergency (Park) Brake Cables? - In The Garage with CarParts.com
https://www.wilwood.com/PDF/DataSheets/ds701.pdf
https://partsavatar.ca/brakes-and-rotors--brake-cables
https://www.ffcars.com/threads/e-brake-cable-routing-bend-too-tight.296689/
Design Options
Original Idea: The Umbrella
Pros:
Meets criteria of first traveling toward the car
Uses a center pull style and both cables are collinear making it easy to maintain and inspect (easy to locate cable routing)
Cons:
Will interfere with the floor-mounted ballast box
Not much geometry for the line to follow through the center of the car
Second Idea: The Cheese String
Pros:
Meets criteria of first traveling toward the car
Uses side pull style
Eventually, both cables become collinear, although it might be hard to locate the blue cable
Can follow the outer edge of the chassis, allows for the use of zip-ties to fasten
Cons:
Shorter pathing could cause issues depending on the length of the cable
Bend of the blue line could be hard to replicate and could interfere with the accelerator or brake pedal
Will have to loop around to reach the back of the Handle
Third Idea: Almost a Heart
Pros:
Meets criteria of first traveling toward the car
Uses side pull style
Eventually, both cables become collinear, although it might be hard to locate the orange cable
Can follow the outer edge of the chassis, allows for the use of zip-ties to fasten
Cons:
Radius bend might be impossible around the seat
Cable might not be long enough to complete this route
Bend of the orange line could be hard to replicate and could interfere with the accelerator or brake pedal
The bend around the seat could also be troublesome
Fourth Idea: Hug
Pros:
Meets criteria of first traveling toward the car
Uses a center pull style, both cables are collinear (easy to locate and maintain)
Steers clear of the ballast box
Cons:
Not much geometry for the line to follow through the center of the car
Two sharp bends might to hard to replicate with brake cables
Will have to loop around to reach the back of the Handle
Fastening Plan
For this portion, I will tentatively be following through with “The Cheese String” routing method. Although, I believe these techniques can be transferred.
Zip Ties
Zip Ties are often used to fasten brake cables, for our specific use zip ties can be can be used to attach the brake cable to the outer end of the chassis.
For an idea, zip-ties can be added about where the black lines are on the drawing below. This would manage the cables well for inspection and allow them to be somewhat fastened.
How to deal with bends
These first bends around the corner can be routed using the pre-existing chassis beams and supports, similar to the photo below
Notes: Brake cable steers clear of the shocks coil-over, the cable is zip-tied to the chassis causing a natural bend
More aggressive bends can be created by using clevis/hinge-like items to path the cable in the direction it needs to go. This can be seen in some of the photos below.
The brake cable changes direction when it meets the clevis
Links to some hinges:
63 Parking / Emergency Brake Cable Clamp - Front With Reinforcement | Muscle Cars & Classics
https://www.lokar.com/ebrake-cables.html (Bottom listing EC-80WC)
Brake Line Mockup
Here is an example of the brake cable line in the Dynamics top level.