Drilled brake drums - Fuel Economy, Hypermiling, EcoModding News and Forum

IsaacCarlson · 11-03-2016, 05:52 AM

I drilled my truck brake drums.

My brakes should be cleaner, quieter, and have less drag due to the lack of brake dust buildup. Don't freak out, I only drilled 64 holes in each drum.

Yes, you can buy drilled drums and yes they are safe. I am very excited to see how well it works.

Don't worry, there is a pattern to the holes, it only looks random. The vent holes are .2" and the big air inlet holes are 1/2". 64 holes, with 3 stages on each if you count drilling and chamfering. That comes out to 384 holes drilled/chamfered. 400 holes if you count chamfering both the inside and outside of the inlet holes. Yes, it took forever. Yes, I broke and had to sharpen many drill bits. Some are gone forever, in that drill bit heaven in the sky...

I will do better on the next pair.

The car drums are next.

Template in drum

Pilot holes

Reamed holes

Inside

Outside

Finished pair

jamiec · 11-03-2016, 07:16 AM

Nice work I am looking to here how they work out. Did you check the weight difference
before and after the holes?

oil pan 4 · 11-03-2016, 10:14 AM

I have aways been told by people who have used drilled disc brakes that the drilled ones eat up brake pads a lot faster.

It may not be a horrible idea since it would release water or dust stuck in the rotor.

Fingie · 11-03-2016, 11:16 AM

I should check my car's drums

cool idea.

I think they did this on sports cars before disc brakes got more popular.

IsaacCarlson · 11-03-2016, 01:05 PM

A lot of performance cars did use vented drums. A lot of bikes did too.

I did not chech before and after weight. I would guess the difference to be less than a pound.

As for wear, I have seen brakes with thousands of miles on them that still look like new. The key is to sweep the entire shoe/pad.

I am going out right now to put them on the truck. I will post the results.

IsaacCarlson · 11-03-2016, 02:41 PM

The test drive is complete and I am happy. I am absolutely amazed. The brakes are so smooth and quiet. I removed the pressure pin on the pressure regulator for the rear lines, so they get more pressure, but I left the regulator spring and piston in there to give the rear brakes better feathering ability. It provides a tiny bit of softness below ~200 psi. That is the stock knee point for the regulator. The rears will lock just before the front on blacktop, and all 4 will lock at about the same time on gravel.

My reason for wanting more rear brake pressure is payload related. This truck carries a lot of weight on the rear axle, and that weight does not transfer to the front when braking. If empty braking is balanced, then loaded braking will be way off. The truck weighs almost 3x its own weight when loaded, so a little rear bias when empty is fine with me if it means stopping when loaded. Skidding the front tires and not having rear brakes is not cool when you weigh 13k.

Joggernot · 11-04-2016, 11:09 AM

Quote:

Originally Posted by IsaacCarlson

I drilled my truck brake drums.

My brakes should be cleaner, quieter, and have less drag due to the lack of brake dust buildup. Don't freak out, I only drilled 64 holes in each drum.

Yes, you can buy drilled drums and yes they are safe. I am very excited to see how well it works.

Don't worry, there is a pattern to the holes, it only looks random. The vent holes are .2" and the big air inlet holes are 1/2". 64 holes, with 3 stages on each if you count drilling and chamfering. That comes out to 384 holes drilled/chamfered. 400 holes if you count chamfering both the inside and outside of the inlet holes. Yes, it took forever. Yes, I broke and had to sharpen many drill bits. Some are gone forever, in that drill bit heaven in the sky...

I will do better on the next pair.

The car drums are next.

Template in drum

Pilot holes

Reamed holes

Inside

Outside

Finished pair

For some reason I can't see the photos.