The Science of Stopping - Why Brake Hoses Matter

Introduction

When upgrading a braking system, most people focus on components like calipers, pads, and rotors. However, the brake system’s overall performance relies on more than these parts alone. High-quality calipers are ineffective if brake fluid cannot flow properly to the piston bores. This article explores the critical yet often overlooked role of brake hoses in achieving optimal braking performance.

What's a Flex Line?

Brake hoses, also known as flex lines, connect the strut to the caliper, allowing the wheel to move dynamically up, down, left, and right. Unlike the steel lines used elsewhere in the brake system, flex lines are generally made of rubber to accommodate this movement.

Maintenance

While brake hoses may seem like simple rubber components, their properties require special attention compared to steel lines. Over time, rubber hoses can crack and break, leading to a sudden loss of brake pressure—a serious safety hazard. To prevent this, brake hoses should be replaced at least every ten years. Aging rubber can also swell internally, restricting fluid flow and causing a softer brake pedal, which degrades braking performance over time. If the service history of your brake hoses is unknown, replacing them is a cost-effective investment in safety. It speaks to our moto; “If you don’t know when the last time your soft lines were replaced… replace them now”.

A new Brake hose (Left) and a severely swollen brake hose (Right)

Additionally, standard rubber hoses can swell under the heat and pressure of hard driving, further restricting fluid flow when performance is critical. To address this, PMB offers DirectFit™ brake hoses with proprietary LowFlex™ technology, boasting an ultra-low expansion rate of 0.14 cc/ft.

For even better performance, stainless steel braided hoses eliminate swelling entirely. These hoses feature a non-swelling Teflon® inner lining and a durable stainless steel exterior, ensuring consistent pedal feel across a wide temperature range and requiring minimal maintenance. Stainless steel hoses are ideal for drivers seeking longevity or high-performance driving where pedal feel and modulation are a must.
  

PMB's DirectFit™ Brake Hoses

Additionally, standard rubber hoses can swell under the heat and pressure of hard driving, further restricting fluid flow when performance is critical. To address this, PMB offers DirectFit™ brake hoses with proprietary LowFlex™ technology, boasting an ultra-low expansion rate of 0.14 cc/ft.
For even better performance, stainless steel braided hoses eliminate swelling entirely. These hoses feature a non-swelling Teflon® inner lining and a durable stainless steel exterior, ensuring consistent pedal feel across a wide temperature range and requiring minimal maintenance. Stainless steel hoses are ideal for drivers seeking longevity or high-performance driving where pedal feel and modulation are a must.


Rubber Hoses

PMB’s rubber hoses feature a five-layer construction designed for durability and performance, with high abrasion resistance the lowest swell rate we could get out of a rubber hose, and ultra high UV and Ozone resistance to prevent cracking and are rigorously tested to exceed all DOT requirements for brake hose quality and safety. Finally, our rubber hoses are covered by a 10 year warranty, meaning anything that could happen to them between new and a decade later is covered no questions asked.

 

Unique 5-Layer Composition 

  • EPDM Inner Layer (excellent resistance to non-petroleum-based fluids)
  • Polyester (OET) Inner Braid
  • EPDM Middle Interleaf (prevents abrasion)
  • PVA Outer Braid (provides strong bonding between layers)
  • EPDM Outer Layer for Excellent Ozone and UV Resistance

Features 

  • High-performance low expansion rate of 0.14cc/ft. at 1,500 psi (LowFlex™)
  • LowFlex™offers extremely precise pedal modulation and feel over other rubber lines 
  • DirectFit™OE designed fittings and vehicle specific lengths accommodate ease of installation 
  • Tough UV and Ozone protective EPDM outer coating
  • Tested to exceed DOT standards 
  • Unique 5-Layer Composition
  • 10-Year Warranty
  • Extreme temperature resistance -50℃/-122°F to +121℃/250°F
  • Compatibility: for all non-petroleum brake fluids DOT3, DOT4, DOT4 LV, DOT5.1
 

 Braided Stainless Steel Hoses

If you're really looking to go all out our braided stainless steel hoses are the last flex lines you'll ever need, period. They have a true lifetime warranty, meaning if they ever fail for any reason  at any time we will send you a new set of hoses completely free of charge. They're assembled with a durable 3 layer Teflon/Steel/PVC construction that provides ultra high environmental and abrasion resistance, as well as reduces heat based swell to such a minute amount (0.000295cc/ft.) that it's almost difficult to even test for. These lines are rated to withstand  pressures over 4000PSI, with a burst pressure of over 12,000 PSI and feature a three-layer construction.

Composition

  • PTFE (Teflon®) inner lining
  • Braided 304 Stainless Steel Covering
  • Clear UV Protective PVC Outer Cover
  • Steel fittings: Triple Zinc and Nickel finishes

Features

  • High-performance ultra-low expansion rate of 0.000295cc/ft. at 4,000 psi (ZeroFlex™)
  • ZeroFlex™ offers extremely precise pedal modulation and feel
  • DirectFit™ OE designed fittings and vehicle specific lengths accommodate ease of installation
  • Tough UV protective PVC outer coating to protect the braid and resist impact and abrasions
  • Protective fitting caps reduce fatigue
  • Tested to exceed DOT standards
  • All lines pressure tested to 4250 psi
  • Ultra-high burst pressure rated to 12,550-13,500 psi
  • Extreme temperature resistance -70℃/-94°F to +260℃/500°F
  • Compatibility: for all non-petroleum brake fluids DOT3, DOT4, DOT4 LV, DOT5.1

 

 

Click below if you're interested in giving your car some much needed maintenance, and use code NEWSLETTER at checkout for 20% off your new hoses.