MR2 Roadster Owners Club

The Workshop => Performance Related => Topic started by: Benlake on July 22, 2024, 11:13

Title: Brake Ducting
Post by: Benlake on July 22, 2024, 11:13
Was wondering if any members have removed fog light and fashioned some brake ducts? I manage to over heat the brakes sometimes and get fade. I have braided hoses and carbotech pads on standard pagid discs.

I think some ducting might help. But would be interested if anyone has tried this? Maybe it could also give pads a longer life.

I was at Blyton which is known to be very hard on brakes, due to the lack of any proper straights.
Title: Re: Brake Ducting
Post by: MrChris on July 22, 2024, 12:06
I've seen it done on others' and have been considering doing it myself. I managed to warp discs on mine. I think it should be relatively straightforward as there's a reasonable amount of space behind the bumper.
Title: Re: Brake Ducting
Post by: JB21 on July 22, 2024, 14:01
You need to relocate the washer bottle to fit ducting to the fog light holes. Never bothered as I'm lazy.
Title: Re: Brake Ducting
Post by: Iain on July 22, 2024, 15:39
Removing the disc back plates helps
Title: Re: Brake Ducting
Post by: Petrus on July 24, 2024, 20:38
Quote from: Benlake on July 22, 2024, 11:13I manage to over heat the brakes sometimes and get fade.

Swap in the Prius 2 calipers. Apart from being shockingly lighter, they dissipate heat way better.
Title: Re: Brake Ducting
Post by: mr9 on August 10, 2024, 18:55
Quote from: Petrus on July 24, 2024, 20:38Swap in the Prius 2 calipers. Apart from being shockingly lighter, they dissipate heat way better.

For sure? Aluminium conducts heat better, but if the limit is the airflow then the conductivity of the caliper housing isn't the limit.

Also being lighter will mean you got the limit quicker.
Title: Re: Brake Ducting
Post by: Joesson on August 10, 2024, 19:54
Quote from: mr9 on August 10, 2024, 18:55For sure? Aluminium conducts heat better, but if the limit is the airflow then the conductivity of the caliper housing isn't the limit.

Also being lighter will mean you got the limit quicker.


High thermal conductivity materials , such as copper and aluminum, are good at transferring heat. Aluminium being the less costly and lighter material is typically chosen for heatsink designs.

Title: Re: Brake Ducting
Post by: mr9 on August 10, 2024, 23:09
Quote from: Joesson on August 10, 2024, 19:54High thermal conductivity materials , such as copper and aluminum, are good at transferring heat. Aluminium being the less costly and lighter material is typically chosen for heatsink designs.



I did my university divan year project on heat sink materials, and there are diminishing returns depending on the airflow to the heatsink

My point was, is the problem of brakes overheating because of the steel calipers not conducting the heat from the inside on the pads to the outside of the caliper?

I don't know for sure which is why I asked, but I'm sceptical.

If the thermal conductivity is "good enough" then the airflow to remove the heat is the problem.
Aluminium isn't going to do anything other than lower the thermal mass if airflow is the issue.
Title: Re: Brake Ducting
Post by: Petrus on August 11, 2024, 00:57
Quote from: mr9 on August 10, 2024, 18:55For sure? Aluminium conducts heat better, but if the limit is the airflow then the conductivity of the caliper housing isn't the limit.

Also being lighter will mean you got the limit quicker.

It has been tried and tested with success.


You choose. Enjoy!
Title: Re: Brake Ducting
Post by: Joesson on August 11, 2024, 09:57
Quote from: mr9 on August 10, 2024, 23:09I did my university divan year project on heat sink materials, and there are diminishing returns depending on the airflow to the heatsink

My point was, is the problem of brakes overheating because of the steel calipers not conducting the heat from the inside on the pads to the outside of the caliper?

I don't know for sure which is why I asked, but I'm sceptical.

If the thermal conductivity is "good enough" then the airflow to remove the heat is the problem.
Aluminium isn't going to do anything other than lower the thermal mass if airflow is the issue.

If you accept that aluminium has a better thermal conductivity when compared with that of iron or steel, then an aluminium caliper will conduct heat better than a steel or iron caliper.
The placement of either caliper in the same airstream will mean that the aluminium caliper will conduct / transfer heat into that airflow faster than from a steel or iron caliper.
The same principal would apply with no air movement and then the coducted  heat would tend to create an airflow.
I believe that an aluminium caliper , all other conditions being equal, would result in cooler brake pads.