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Topic Review (Newest First)
09-18-2013 05:32 AM
1Gary I looked hard at Brembo slots.Seems to me they are somewhat selling snake oil.I also talked to a number of people that bought them.In the real street you have to be putting the vehicle into a road race situation or a very fast race only car for them to have the effect they are suppose to have.
Back on topic,there are a number of upgrades to say a 11" drum.Now I have seen ppl drill holes in the backing plates.For me I wouldn't do that for a number of reasons and maybe the core reason is I would have a fear of weakling the backing plate where the shoes,wheel cylinder is mounted.As for drilling the drum surface braking area,it is the sum total of the shoes surface to drum that makes it a upgrade or not.To take anything away from that is counter productive.
09-17-2013 11:05 PM
malc Here´s a slotted disc.....
09-17-2013 10:20 PM
1Gary I went to the Kelsey-Hayse brake school in the late 1960's and at that time a T-bird's dics brakes where going for $300 bucks a side.Everyone was predicting doom and gloom for the auto industry.Boy did we get that one wrong.Look how cheap you can get dics pads now and how advanced they have gotten.
09-17-2013 01:25 PM
oldbogie
Quote:
Originally Posted by xxllmm4 View Post
Thanks for all your input... Now if anyone has had REAL experience directly related to drilling drum brakes feel free to chime in
Wow I just wandered into this, what a mine field.

Back when drums were the only brake system avaialble every trick in the book and then some more were tried. You name it:

- Bigger diameter drums for larger but in the same line of cars were used such as using station wagon or light pick up brakes on sedans.

- A highly popular conversion with racers were the use of Buick's aluminum drum with a cast iron wear surface.

- Air supplied to the backing plate which was drilled. This was done as ram from the developed vehicle speed or from heater fans ducting fresh air into the backing plate. Even liquid cooling of the shoes was tried complete with pumps and mini radiators.

- Higher coefficient of friction such as metallic shoes was used, this quickly exceed the strength of the bell shaped drum and increased wear to a fantasticly fast rate.

- And yes drilling the friction surface and/or holes into the face of the drum which proved to be downright dangerous was tried with mixed result but was shortly banned at all tracks by rule.

None of this proved satisfactory, while we racers looked to Europe where disks were common, the American manufacturers claimed that disks could not work on big, heavy American cars. This claim rather flew in the face of Budd streamline railroad passenger cars having disk brakes sine the late 1930's and military aircraft using disks since the 1940's. It took Detroit a long time to arrive at the disk as this battle palyed out through the 1950's and most of the 60's.

The last input to my list, the drilling of drums and the fact it proved to be not very effective if not dowright dangerous is because of the different way drum brakes stress the rotating stopping surface compared to a disk.

1) The disk's rotor is fully supported by structure. The pads apply a compressive load to the rotor by squezzing it. The rotational load is taken in shear, that is an angle in plane with rotation.

2) The drum is partially supported by structure, it is essentially a bell where the forces have to migrate from the applied zone through a 90 degree angle into the top of the bell or hub. In the hub the forces react into the axle in shear as they do ina disk but getting there is a lot different route. The opposite end is open and unsupported, this creates whats called an overhung moment when the btrakes are applied that wants to bend the friction surface away from the expanding shoe. This puts the mounting face and friction surface of the drum under tension and bending where the frication surface becomes the hub, tension and bending being any material's directions of least strength. Then to compound the strength issue these tension/expansion forces are expected to make a 90 degree turn from the friction face into the hub. The drum would like to explode. Then as it heats, it gains dimension in diameter which is to say it is moving away from the brake shoe, This is fade (or at least one component of fade) which causes the driver to step harder so the shoes will chase the drum which makes more heat, eventually the whole is so hot the brake fluid boils. At that point there is no more braking. Add to this situation the mouth of the drum (did I say bell) being unsupported expands outwardly more then the supported hub end a condition called bell mouthing (imagine that) so the brake shoe is losing contact area which drives the temperature of the available contact area to even hotter temperatures.

History and experience of us old farts show that messing around with drum brakes is simply non-sense. This was a well travelled road that finally arrived at disk brakes in America starting in the late 1960's, but what a battle to get there.

Bogie
09-17-2013 07:29 AM
cobalt327
Quote:
Originally Posted by xxllmm4 View Post
Yes I have made my mind up. I was kind of looking for input from people who have ACTUALLY had experience on the subject.
Actually, what you typed was:
Quote:
Lets hear your thoughts and if you have ever used drilled drum brakes.
What you got was our thoughts, plain and simple. Just because these thoughts mostly do not support drilling you seem to now want only input from those who've done this, hoping that will support your desire for this to be a "good idea". I can tell you right now, there's not going to be much if any empirical input, simply because it's an ill conceived idea from the get-go, IMO.

As far as only wanting ONLY first hand experience on something, one need not hit one's thumb w/a hammer to know it will hurt.

Quote:
I could care less if their $99 for one or ten. I have a drill press and drills... Cost to me is $0.00
Your cost is only your time, at least until the drums start failing. Hopefully the only cost will be for replacement drums and not for repairing more severe damage caused if and when the drum fails.

Good luck on whatever you decide.
09-16-2013 10:58 PM
cobalt327
Food for thought...

The following was first posted on another forum. The subject is drilled rotors, thought of by many as a universally accepted "good thing". So if this is about rotors, what does that have to do w/drums, you may ask? Well, many of the same "improvements" and "advantages" to drilling rotors are said to apply to drums as well.

Quote:
Darrick Dong; Director of Motorsports at Performance Friction:
"Anyone that tells you that drilling makes the disc run cooler is smoking crack."

Wilwood Brakes:
Rotors are drilled to reduce rotating weight, an issue near and dear to racers searching for ways to minimize unsprung weight. Drilling diminishes a rotor's durability and cooling capacity."

From Waren Gilliand:
(Warren Gilliland is a well-known brake engineer in the racing industry and has more than 32 years experience in custom designing brake systems ...he became the main source for improving the brake systems on a variety of different race vehicles from midgets to Nascar Winston Cup cars.) "If you cross drill one of these vented rotors, you are creating a stress riser that will encourage the rotor to crack right through the hole. Many of the rotors available in the aftermarket are nothing more than inexpensive offshore manufactured stock replacement rotors, cross drilled to appeal to the performance market. They are not performance rotors and will have a corresponding high failure rate"

Baer Brakes:
"What are the benefits to Crossdrilling, Slotting, and Zinc-Washing my rotors? In years past, crossdrilling and/or Slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads...However, with today's race pad technology, 'outgassing' is no longer much of a concern...Slotted surfaces are what Baer recommends for track only use. Slotted only rotors are offered as an option for any of Baer's offerings."

Grassroots Motorsports:
"Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the '40s and 50s, not a whole lot. Rotors were first drilled because early brake pad materials gave off gasses when heated to racing temperatures, a process known as "gassing out." ...It was an effective solution, but today's friction materials do not exhibit the some gassing out phenomenon as the early pads. Contrary to popular belief, they don't lower temperatures. (In fact, by removing weight from the rotor, they can actually cause temperatures to increase a little). These holes create stress risers that allow the rotor to crack sooner, and make a mess of brake pads--sort of like a cheese grater rubbing against them at every stop. Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it...Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean the face of the brake pads over time, helping to reduce the glazing often found during high-speed use which can lower the coefficient of friction. While there may still be a small concern over creating stress risers in the face of the rotor, if the slots are shallow and cut properly, the trade-off appears to be worth the risk. (Have you looked at a NASCAR rotor lately?)

AP Racing:
"Grooves improve 'cleaning' of the pad surfaces and result in a more consistent brake performance. Grooved discs have a longer life than cross-drilled discs."
09-16-2013 09:35 PM
xxllmm4 Thanks for all your input... Now if anyone has had REAL experience directly related to drilling drum brakes feel free to chime in
09-16-2013 09:30 PM
vinniekq2 already answered your questions,,,no arguements coming from me. I have tried aluminum drums,riveted shoes,custom shoe material,different bore wheel cylinders...
drilling holes in drums is stupid,it allows water and elements in. drums do not work well wet.If you are racing,then use racing brakes.If you road race,dont use drum brakes.
Its not the brakes that stop your car,,,brakes only turn friction into heat. The "TIRES" stop the car
09-16-2013 08:57 PM
xxllmm4 Yes I have made my mind up. I was kind of looking for input from people who have ACTUALLY had experience on the subject.

I could care less if their $99 for one or ten. I have a drill press and drills... Cost to me is $0.00
09-16-2013 08:50 PM
cobalt327
Quote:
Originally Posted by xxllmm4 View Post
Funny, because I can't seem to find a single person who has actually done it that has anything bad to say about it.
Seems you have made your mind up regardless of any input here, so what are you waiting for? Says you'll get up to 10% more "stopping performance" (whatever THAT is), so figuring the rears do 30% of the stopping on a normal vehicle under hard braking (70/30 front/rear), you're gonna gain a whopping 3%. Now, is $99.00 for one drum or two... LOL
09-16-2013 08:38 PM
xxllmm4
Quote:
Originally Posted by eloc431962 View Post
I have to agree with this after further research and it didn't take much more to figure it out , that the bottom line as said this is really a waste of time . better off the way it is then to go and do this. JMO

Cole
Funny, because I can't seem to find a single person who has actually done it that has anything bad to say about it.

Looks like Brothers actually sells them now. 71-87 Drum Brake - Rear - 1/2 Ton - Cross-drilled - Brothers Chevy & GMC Classic Truck Parts
09-16-2013 04:59 PM
cobalt327
Quote:
Originally Posted by eloc431962 View Post
I have to agree with this after further research and it didn't take much more to figure it out , that the bottom line as said this is really a waste of time . better off the way it is then to go and do this. JMO

Cole
The weight transfer under hard braking loads the fronts WAY more than the rears. So personally speaking, I believe rear drums are often perfectly adequate unless the vehicle is being road raced. At that stage, disc brakes are the obvious solution. But for rear drum brakes I like the your idea of taking advantage of the OEM venting, especially if ducting is providing airflow to them. This is providing the rear brakes are being worked hard, being as how brake fade is what hurts drum brakes a lot more than disc brakes.

Providing the drum brakes are adjusted correctly and the hydraulic system free of air and the fluid is dry, using good brake shoe compounds like was mentioned already, along w/cooling ducts (if needed for the way the vehicle's being driven), and possibly going to a larger shoe/drum combo like was done years ago (using police/station wagon drums often gave added width and/or diameter), or possibly swapping the cast iron drums out for aluminum drums like were found on some G-body cars (and possibly others) will be about as good as rear drum brakes are going to get. I say possibly because even though they saved a little weight and cooled better, the aluminum drums were still rather small. Fine for a street/strip vehicle but not so much for road racing.
09-16-2013 03:46 PM
eloc431962
Quote:
Originally Posted by cobalt327 View Post
I would be concerned about causing stress risers at the drill holes. The holes would need to be chamfered on both sides to hopefully prevent this. Even then there's the concern (for me) of warpage caused by the holes. The holes would need to be drilled so as to have them equidistant from each other, then the drum should be rebalanced for best results. I would be concerned about dirt/sand entering the brakes through the holes in the event the vehicle was driven through puddles, etc.

All in all, I think your time and energy would be better spent elsewhere.
I have to agree with this after further research and it didn't take much more to figure it out , that the bottom line as said this is really a waste of time . better off the way it is then to go and do this. JMO

Cole
09-15-2013 05:05 PM
AutoGear One of my friends races in NASA (no not Space NASA) any the drilled rotors get replaced a lot faster than OEM solid rotors due to cracks propagating from the holes in the surface. There is a company that makes very high end shoes called muscle car brakes Muscle Car Brakes
They make some very trick stuff if the prospect of discs doesn't fit your needs
09-15-2013 04:03 PM
techinspector1
Quote:
Originally Posted by cobalt327 View Post
All in all, I think your time and energy would be better spent elsewhere.
There's the bottom line.
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