Seeking advice on routing... brake lines!

[PeterAllen]

I'm concerned that the extractors (headers) will be too close to the brake lines and wondered if it was okay to route them through the inner guards close to the firewall, although that would leave them more exposed to debris thrown up by the wheels.

I've also noticed headshield sheaths available to cover the lines, are they any good?

[Tommy]

Peter,
I, too, was concerned about heat from the exhaust causing problems with my brake and clutch fluid. So I installed insulated sleeves like these over the brake lines: click here.

I've since driven my car hard at track events on hot summer days (35 C) with no signs of fluid boiling. I also use high temp brake fluid.

[Jaydee]

I asked my brake guy about sheething, and he said you might have condensation build up, corrosion, and you wont be able to see it. And if you think about how hot brake discs and calipers get, it shouldn't be a problem unless they are touching the exhaust.
JD

[CHANMADD]

Right..... Keep the steel hoses on the rear side of metal frame pieces and definately out of the inner fender where debrs can squash the pipes............

[Modena]

I wouldn't think this would be a problem - underbonnet temps reach maybe 70 degrees I think, even if it's higher and closer to 80-90, this air temp is very low compared to the temps experienced by the fluid in the caliper! My theory is as long as there is an air-gap of at least several itches between exhaust and brake hard-lines it will be fine. I guess you would want a larger gap for flexible lines or they may perish early.

[Tommy]

Peter,
The topic of heat transfer is not a simple one even for us engineers. So it is hard to say whether or not you will need heat protection for your brake lines. But let me expand a little on why I went with a heat sleeve.

This Wikipedia article on heat transfer is a little technical and not particularly easy to read: click here. But it points out that heat can be transferred from one object to another through three means. Conduction occurs when the two objects touch each other. I assume your brake lines will not touch your exhaust pipes. Convection occurs when heat from the first object is transferred to an intermediate material (e.g., air) and then to the second object. It is likely that air heated by your exhaust will carry heat to your brake line, but it is unlikely that it will carry enough to cause the brake fluid to boil, IMHO. The third method of heat transfer is radiation. That is the heat you can feel with your skin when you get close to an incandescent light bulb or a burning fire. This is the heat transfer I was most concerned about. While running hard at the track, exhaust pipes can get very hot and produce a lot of radiated heat.

The advantage of the heat sleeve is that it limits both convection and radiation heat transfer. Hot air cannot travel though the foil sleeve to reach the brake line, and much of the radiated heat reflects back off the foil. These effects are best if the sleeve is large enough to fit loosely and leave an air pocket between it and the brake line.

I've not heard of a problem with condensation causing corrosion of the brake line, but I suppose it could happen under some circumstances. One solution to that problem is to use stainless steel brake line.

[Zedn]

Nulon dot 4 boiling point is over 280 deg Celsius according to their website. From a bit of research this appears to be way more than the radiant heat of headers. Let alone what it would be once getting through the hard line. Some numbers here on pacemaker website. It's advertising numbers, but it gives an idea.
Pacemaker Headers Australia - Quality Performance Exhaust Headers :: Ceramic Coating

Your headers are coated so I think it will be fine.

[Rob. Smith]

My clutch line boiled once....put some DEI heat wrap around it and then enclosed it with some thin alumimium sheet metal...looks OK and no further problems.