So, anyway, back on topic. I've been thinking about running some ducting to my brakes. I don't have the fog lights but I'm thinking I might order a set of the fog light surrounds in the lower front bumper from a Fiat dealer. If I'm not mistaken these are about 3" diameter. Behind these I'm thinking of setting a 3" collar on the back. I haven't worked out how yet, if it's possible then probably some high strength glue of some description and a couple of few inch long lengths of PVC plastic pipe. Just a collar for the high temp flexi hose to be jubilee clamped to. Then run a high temp flex hose, cable tied along the chassis rail or whatever gets me closest the suspension then across a suspension arm with the end of the flexi blowing on the brakes. I think I'll need a mesh cover as well for the fronts to stop it sucking stuff into my brakes. I figure some black fine mesh shaped and trimmed over the top of a capped 3" piece of pipe and pushed into the holes from the front.
Some highly amateurish maths seems to indicate that I can expect about 100cfm of air velocity at about 70mph for a 3" opening. To put that into perspective a decent hoover will manage about 60-70 cubic feet per minute. So imagine your hoover on steroids blowing cool air on to your brakes all the time.
I've heard anecdotal evidence to suggest this dramatically improves the life of brake discs. In club level racing people have reported up a 6x increase in disc life.
So, I reckon the fog lamp surrounds and black metal mesh to make it look nice and professional. The mysteries here for me are a couple:
- Do I try to duct the air to the centre of the disc as much as possible? Conversations with a formula ford chassis designer seem to suggest this is the best course of action. But that's largely formula ford experience I'd imagine. I've seen evidence that big heavy saloon cars vent the whole 3" directly on to a section of the disc and rely on the natural rotation of the wheel to rotate the disc and disperse this cold air feed across the disc. Anyone have any first hand experience of this they can comment on?
- What fastener methods? At the disc end this could possibly be achieved by an alloy bracket that's bolted through via some other components bolt. Fasteners to keep the pipe in place would be stainless steel. It's not easily corroded and they're cheap.
- What to do at the back of the fog light surrounds to attach hose. At the front of the car the whole collar and assembly there will depend on what the back of the fog light blanks look like. I need to see some first to get an idea of the best approach. I may be able to fabricate an alloy collar or they may have a lip already as part of the fog light surround and I can just hollow out the back. That'd be nice.
- Hose choice and routing. The choice is easy, plenty of high temp flex hose out there. The routing not so much. I haven't really pulled off enough covers to get a better picture. Chassis rails are a possibility. I'm guessing at some point I'm going to need to punch a whole in the arch liners to route the hose out to the hub/brake assembly. Hmm. I need to jack it up and have a fiddle I think.
So anyway, can anyone offer my a valid reason why this is a good/bad/insane idea?
Edit: For those having trouble visualizing this ranting, this is sort of what I'm thinking:
