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What are the Advantages of Rubber Brake Lines?

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Rubber brake line hose comes as factory standard on the vast majority of cars and road vehicles, and yet it is often derided as the inferior little brother of steel braided brake lines.

Is it true that steel brake lines are always better? Or can rubber brake hose measure up?

At BrakeQuip, they certainly think so, and we talked to one of their experts about why he was standing up for rubber brake lines.

They are the current industry standard

If you have bought a car, the odds are very, very good that the brake lines are rubber, which were installed at the factory as standard. As the industry standard for brake lines, rubber brake lines are subjected to rigorous testing and observation, and after all that, they have still been found suitable for use as the industry standard across the world. Almost every factory-model automobile includes rubber brake hoses – and if there was a considerable increase in performance and cost-efficiency with the installation of steel braided brake lines, it is likely that even one car manufacturer would use them as standard.

They are more resistant to expansion than is commonly believed

The predominant consensus on online forums and chat groups is that braided steel brake lines are immune to the expansion that plagues rubber brake lines, and that a rubber brake line will stretch under immense braking force, making brakes featuring steel brake lines more responsive and efficient. However, considering the brake forces put on ordinary cars, this is simply not true.

A series of tests by pitted the expansion of rubber brake hose with the expansion of braided metal hosing under the same pressure conditions – 3500psi, or roughly double the force that would be generated in a hard braking situation. In these conditions, the rubber brake lines expanded by 1.7% and the steel line expanded by less than 1% – so, given that the test was performed at more than double the real force that would be applied to these lines, the difference in expansion resistance between rubber brake hose and its steel counterpart is surprisingly tiny.

They are more likely to be street legal

An issue often encountered by enthusiasts attempting to replace their rubber brake hose with metal variants is that steel brake lines have only recently become street-legal, and even then, only in certain forms. There are many kinds of illegal steel brake lines, but conventional rubber brake lines are street legal and always have been.

They are therefore very cost-effective

As the industry standard, and with considerably closer expansion resistance to steel lines than is commonly believed, and a much better likelihood of being street legal, rubber brake line hose is therefore a far more cost-effective brake line option than its rivals. Considering that the cost to buy the parts and have them installed is usually lower for rubber brake hose, when paired with the fact that cars ordinarily already have rubber brake lines installed, the decision becomes much clearer.