Internal Brake Lines

[pettsy]

After stripping the rear axle off my 325 to fit poly bushes,i found the steel brakelines are pretty rough. As its going to be a trackcar i've thought about running the replacement copper brake lines internally instead of underneath the car.

Has anyone allready done this on theirs? If so do you have any advice/guidance?

Cheers, Pettsy

[nickso]

i did it on mine, probably the worst part of it is finding somewhere suitable to enter/exit the cabin. im going to change the front entry on mine over the winter as im not happy with it.

[pettsy]

Where have you currently got the entry/exit, and how come you are going to change it?

[nickso]

it currently comes through the large wiring grommet under the brake servo. it was only really a stopgap to get the car on the road for the last part of the summer. im installing a brake bias lever over the winter so im going to reroute the line so its shorter and also remove the bmw restrictor from the line. all this will be made easier when there is no engine in the car.

[BigT]

The wiring grommit is the best place to enter and running the lines across the gearbox tunnel where the majority of both fuel and brake lines are run in motorsports cars...remember if you decide to run the fuel lines through the car its a tad whiffy! lol

[pettsy]

lines are nearly finished,just waiting for the bias valve to turn up

[mt1104]

how hot do these brake lines get, I assume they need to be covered somehow?

[BigT]

Dont get hot at all so no need to cover up!

[MarkT]

It's only the fluid in the calipers that should get hot. Good modification, especially if you drive like I do! Not done a set of brake lines, but I have done a set of fuel lines on an old 306. Shite when your in the middle of nowhere and it'd be even worse if it was the brakes. You only use those when you really need them lol

[moggy]

Does anyone have a feel for the lenght of time/degree of difficulty in doing this job?

[mt1104]

also where do you exit to rejoin the rear brake T?

[nickso]

i moved the T inside using the original bracket backwards. then drilled and grommetted two holes for the lines to come out above the brackets for the flexi lines. if you look carefully you can see the spot welds for the flexi brackets from inside the car.

[pettsy]

we've used the now redundant holes for the abs wires,then piped back underneath to the standard flexi mounting points.

[crossie]

The wiring grommit is the best place to enter and running the lines across the gearbox tunnel where the majority of both fuel and brake lines are run in motorsports cars...remember if you decide to run the fuel lines through the car its a tad whiffy! lol

If you use the correct fuel lines then the car will not smell.
they are a slightly different to the normal braided pipes.

[ShakeyC]

In most MSA/FIA run events internal brake lines is not allowed for safety purposes. In event of failure or accident you could end up with 400+degree highly flammable brake fluid vapourising you, they are outside for that reason.

Internal fuel lines not such a major issue its cool liquid and not under as much pressure or critical to driver safety you just slow down and pull off the track and jump out. Some old cars ran internal fuel lines from factory too.

[martinpallot]

In most MSA/FIA run events internal brake lines is not allowed for safety purposes. In event of failure or accident you could end up with 400+degree highly flammable brake fluid vapourising you, they are outside for that reason.

Internal fuel lines not such a major issue its cool liquid and not under as much pressure or critical to driver safety you just slow down and pull off the track and jump out. Some old cars ran internal fuel lines from factory too.

Interesting, in the world of rallying it is commonly recomended that all lines run inside the car. This is also the case in most racing applications, 400 degree brake fluid is unlike seeing as this is double the boiling point of most brake fuids!

[ShakeyC]

I think your taking 'inside' literally they are run inside a rail/tube not actually inside the cabin exposed. And yes if your pushing hard 400+ degree is fairly common temp to reach in competition.

A typical trackday driver barely get beyond 150 degrees but thats not to say its not dangerous or hot.

[ShakeyC]

Straight from the 2009 FIA book

Appendix J ”“ Article 283 for cross country cars, basically all forms of rally and autox racing under FIA and MSA

3.2.1) Fuel lines must have a minimum burst pressure of 70 bar (1000 psi) at the minimum operating temperature of 135C
- Lubricating oil lines : these must have a minimum burst pressure of 70 bar (1000 psi) at the minimum operating temperature of 232C

When flexible, these lines must have threaded connectors and an outer braid resistant to abrasion and flame (will not sustain combustion).
In the case of fuel lines, the metal parts which are isolated from the shell of the car by non-conducting parts must be connected to it electrically.

3.2.2) Lines containing hydraulic fluid under pressure must have a minimum burst pressure of 280 bar (4000 psi) at the minimum operating temperature of 232C
If the operating pressure of the hydraulic system is greater than 140 bar, the burst pressure must be at least double the operating pressure.
When flexible, these lines must have threaded connectors and an outer braid resistant to abrasion and flame (will not sustain combustion).

3.2.3) Lines containing cooling water and lubricating oil must be outside the cockpit. Only the tank for the hydraulic fluid and the master cylinder for the handbrake circuit will be accepted in the cockpit.

3.2.6) The electrical cables must be protected by coverings which do not sustain combustion.

3.2.7) Self-sealing fast connectors of the same make as the flexible lines on which they are fitted may be installed on all the lines excepting the brake lines.

3.3 All groups
The lines must be protected externally against any risk of deterioration (stones, corrosion, mechanical breakage, etc.).

Summary is basically you cant just run normal brake lines inside the cabin exposed, the above min criteria must be met.