Nelz

I was reading this article on circle track magazine, and then back to the LS1 brake thread which is now partly on the lukestaff site. (I posted the link with piston caliper area of various calipers.)

http://www.circletrack.com/chassiste...g_system_heat/

This:

http://lukeskaff.com/?page_id=333

and if you need the formula for area of circle it's here:

http://www.mathsisfun.com/area.html

Your stock Delco Moraine Caliper has more piston area and thus are better than the 1LE calipers based on theory.

Going through the book Brake Systems by Mike Mavrigian and Larry Carley, the reason for multiple pistons if a function of pad sizing. One large piston pressing on a small pad does a great job of pushing the pad against the rotor. But if you make the pad longer and use the same piston, only the middle is being pushed and the outer ends of the pad don't clamp onto the rotor and can actually cause the pad to flex and warp.

So basically, comparing piston numbers the stock Delco Morraine calipers were not that bad.

The rubber hoses flex and the size of the rotors were small. But if you didn't want to go to the trouble of upgrading to LS1 brakes you could just upgrade some minor pieces around it during your next brakes pad change.

The only improvement that GM could make would be a more rigid caliper. But if you're staying with the stock brakes, in this order:

0. Rebuild your pistons with rebuild kit from Napa/Autozone/Rock Auto or where ever. Basically you get to clean the piston and install new boots and seals. This is easier to do with the front. I would recommend the AC Delco kit as I believe they include a new piston. I have part number 18K256X on my way and will you know if it is or not. If it's the rear and your e-brake is stuck, I would just get a rebuilt one.
1. Metal or Braided brake lines instead of rubber. (You will notice a difference with this even if you do nothing else and even if your calipers do not need rebuilding. I would still check to make sure your caliper pistons are not sticking though.)
2. Slotted rotors (use your old pads if there is material left to bed in the rotor by stopping slowly by applying gentle pressure for about 10 miles and then hit the brakes hard for 2 to 3 applications. You could use temperature indicating paint to see if you bed the rotors in properly. Proper temperature should be at least 600 degrees F and possibly up to 1000 deg. F)
3. Hawk pads. I use the HPS, but it looks like they now have an HP+ for autocross and track
4. Optional. If you do this upgrade, you do it at your own risk as too much line pressure to the back will cause over steer. https://www.thirdgen.org/forums/brak...e-upgrade.html
5. Optional. Flush the brake system and install DOT 4 fluid. It is compatible with 3 and has a higher boiling point. Do NOT use DOT 5 as it does not mix with 3 or 4 and requires everything be clean from the start ie. New brake system from booster, to all the lines otherwise it gets air bubbles from some reaction to Dot 3/4. DOT 4 has a higher boiling point than DOT 3.
6. Buy the stickiest tires you can afford. Look at this article and copy the tires that they wear. I would have put this as number one, but heck, you may as well get your brakes in good working order first. It's the rubber that makes contact with the road, but the brakes still have to work. Notice the cars with the non carbon fiber rotors and which tires they use. You need a tire that can outperform those in any newer and updated tire test.

http://www.motortrend.com/features/mt_hot_list/1112_22_cars_that_stop_from_mph_in_less_than_100_feet/viewall.html

(Do NOT buy cross drilled rotors. They crack and do nothing to enhance performance.)


Short of doing the above, there is no cheaper way to make your stock system better unless you go upgrade to LS1 and bigger brakes (use the C5 caliper as it is more rigid if it fits in your wheels) as you physically cannot get the same mechanical leverage from the 10.5" disk brakes. The above mods just got everything you could do out of the 10.5", but the LS1 and other mods go to 14" rotors and there's lots of more physical mechanical advantage with the larger rotor. But wow, look at the CTS-V brakes. Those pistons have a lot of area. Big bucks to replace them too!

87350IROC

iTrader: (2)

That is quite a simplification to declare a larger a piston area to be better. The OEM calipers also have larger piston area than the Corvette ZR1 calipers and pretty much anything else made since the 80's. Does that make them better, heck no.

While it is true that a larger piston area means more brake force for the same fluid pressure, that is just one factor in how a brake system performs.

I personally can't stand large piston area calipers as they tend to have long brake pedals. I like a short pedal, even if it requires more effort. Brakes are very much a feel item, as all of them have enough torque to lock up the wheels. So the question is, do you like a long or short pedal?, do you like a soft or a hard pedal?

The nice thing about larger rotors is they buy you better torque without the disadvantage of a longer pedal. See below.

Right click, view image, for larger

Nelz

I always wondered about that too. If theory states that piston area is number one and then rotor. This thread was more written with the intent of getting everything you can out of what came stock if you didn't get the PBR's from factory. I have an 88 non performance brakes. And thanks for the chart, it really makes it easier to see the data in one post.

A true test would be to take one car on the same day to the same track and temperature and do a brake test with stock Morraine calipers and hawk pads with braided or steel lines and then compare them to any other brake setup afterwards.

I'm curious about not only the piston affecting braking but also pad contact area with the rotor itself. The size of contact area of the pad, the bite of any and all leading edges of the pad to rotor also would affect performance. This would be just the caliper without the leverage of the increase in size of rotor.

But keep in mind, all the new cars have ABS and better tires than the 80's which significantly improve on braking even with a smaller piston area. The tires alone, with way better engineering are a huge factor as they contact the road. It crosses my mind a lot about at which point is there too much clamping force provided by the piston brake to cause brake lock up and decrease braking performance (and if that line of thinking is correct.)

87350IROC

iTrader: (2)

Sure, but what is your definition of performance? A single stop 60-0? 10 stops in a row 60-0?

If all you care about is a single stop 60-0, any of the brake kits in my list will be equal. The 100% stock setup will lock up any realistic tire you can put on these cars.

The value of the other kits is the following, in no specific order:

Thermal management, many stops in a row
pad / rotor life
pedal feel (travel and effort)
looks

The pad area actually doesn't come into the equation at all since pads are very stiff. Pad volume is important for thermal management and life, nothing more.

The type of tire or abs does not affect the hydraulic advantage or the brake torque of the system. Rather the tire's grip and size will drive the brake torque required to reach the grip limits of the tire. Even so, the OEM setup is perfectly capable of locking up modern rubber.

Brakes are a balancing act. The reason why we see smaller piston areas these days is due to the use of larger rotors. With a smaller rotor, you need a bigger piston area to maintain a necessary maximum brake torque. This is at the cost of a long pedal. The beauty of large rotors is they are basically free mechanical advantage (at least with respect to braking feel). They give you more torque without changing how the pedal feels when creating a certain fluid pressure. You can see this in effect in the last two columns of my chart.

John

TTOP350

iTrader: (8)

All rotors crack, the holes help stop the cracks from going to the edge of the rotor and making it a throw away. It also helps a lil bit with increasing the surface area to help ditch the heat..
For a street car holes are fine along with mild track use, comp rotors I'd go with a slotted part.

Nelz

Well, in terms of thermal management, there are some things you can do to the stok caliper. It's not much but you can ceramic coat the inside caliper body and use brake pad spacers as a thermal barrier and you can use a heat emitter coating on the outside of the caliper body.

It's not much, but if we are talking about getting the most out of the stock stuff it would help with the multiple stops from 60.

Nelz

Swaintech does this for Outlaw brakes. Apparently the heat emitting out paint sheds heat 50% faster than a non-coated caliper. They thermal barrier the inboard side including the piston face that faces the pad. They even ceramic coat the brake pad backing plate. This is for NASCAR but I'm not sure if this is overkill as the pads themselves have to reach a certain operating heat range quickly on the street to be effective.

Nelz

Not cheap!

http://swaintech.com/race-coatings/a...s-price-sheet/

87350IROC

iTrader: (2)

Thats great and will keep heat out of the fluid, but...

What about heat in the pads? what about heat in the rotor?

The fluid is easy, use 600 degree boiling point fluid and you are done. What is more problematic is how little heat the stock rotor can shed.

And finally who is going to put $400+ in thermal coatings onto a $13 caliper?

Just in coatings you have basically bought yourself a LS1 swap.

Nelz

Thats what I thought when I looked at the price!

Nelz

I remember reading in a Hot rod article a long time ago that there was a way to bent the backing plate to allow more cool air to vent into the rotors. It was a shootout between Guldstrand engineering and Herb Adams. Unfortunately it didn't show how to do it. I suppose you could make some brake cooling ducts somehow

Nelz

https://www.thirdgen.org/hotrod-shoo...-prep-july1982

There's the photo. 1982 wow. That's how Guldstrand bent the backing plate to channel cool air towards the rotor.

Nelz

Well, the part number I referenced is actually the rebuild kit for the rear and includes the caliper pin housing, but no new piston and not boots. Guess I'll have to head to NAPA for that.

Nelz

The cheap way to fix this is with 3" heater hose/duct pointed at the inside of the rotor and another 3" heating duct/duct pointed at the caliper. If you're talking about track use, you need brake duct cooling.

Here are some instructions from a BMW board.

http://www.m3post.com/forums/showthread.php?t=316897

A less effective but cheaper method is to bend the backing plate back like Guldstrand did in that magazine article. Here's a pic from another BMW board of how someone did it.

http://www.1addicts.com/forums/showthread.php?t=663510

87350IROC

iTrader: (2)

Nope. There are tons of use running on the track without brake cooling. No issues. I highly doubt cooling will make the stock system do well. There just isn't enough leverage and thermal mass.

ZZ3 Z28

Does this statement refer specifically to (a) this discussion, stock brakes, (b) is it a generalization, or (c) do you have any information that folks like Brembo and SSBC don't subscribe to?

I only ask because this flys in the face of everything I've ever read about improving braking performance.

87350IROC

iTrader: (2)

(a) no
(b) yes, but basically true
(c) no, these companies purpose is to make money. Their customers want drilled rotors, so they provide them.

Drilled rotors came about in the early disc days. The old pads produced a large about of gas as they worked. The gas floats the pad on the rotor, kind of like the oil on a bearing. This reduces friction. For this reason, holes were drilled in the rotors to give the gas a place to escape. The side benefit is they add a slight bit of bite to pads. Purely a feel benefit. The downside is the holes are stress rises kt=3 and therefore are places where cracks can grow easily. Not a huge deal for a race car, but a pain on a vehicle where rotors are supposed to last forever.

Fast forward to today. Pads no longer out gas to the extent of of the old pads. People like "race car" parts on their car so they naturally want drilled rotors. Its is an appearance upgrade only. With the small side benefit of better pad bit.

If you look at today's race cars, you will find the vast majority use either blanks or slotted rotors.

Slotted rotors have the same side benefit of added bite, possibly even more than drilled holes, but have a much lower tendency for cracking.

The thought that the holes help cool the rotor is bs. The cooling air flows down the vanes of the rotor. A negligible amount of air would ever turn 90 and go through the holes. And by removing metal in the drilling process, you now have less thermal mass than before, actually increasing the temperature of the remaining metal.

InfernalVortex

iTrader: (4)

There are very few reputable brake companies that will even sell drilled rotors anymore, and if they do they emphasize that they are only okay for street use.

This is from a post I made a couple of days ago, so I will copy and paste.

Formula 1 cars often dont run grooves either, but they use carbon discs, so a little different:



Nascar truck series brakes:






http://d3pczhwof661ii.cloudfront.net...ock/Lizard.jpg

Blow that one up and you can see they even use plain discs... VERY rarely do you see drilled discs these days except on street cars.

Nelz

Not only did 87350IROC and Infernal Vortex give you the right answer, both explained it very well.


Also on Pg. 3 of this Circletrack magazine article:
http://www.circletrack.com/chassiste...ke_rotors.html

"Some racers will drill their rotors, in an attempt to make them lighter. This will only work if you race a light car over a short distance, and your track does not require hard braking. For most Saturday-night racers, drilling the rotor is not advantageous, because the surface temperature of the rotor is hotter than the inte-rior temperature. Every hole has a high thermal gradient. This causes uneven expansion and contraction, which causes cracks. When a rotor cracks, it becomes a boat anchor.

The racer who seeks a lightweight rotor would be better off with a smaller-diameter, thinner-wall rotor. Rotors are designed in different thicknesses to handle a variety of temperature ranges." -Wilwood's Doug Burke.

paul_huryk

Iron brake calipers are inferior to aluminum due to being a heat sink that is very slow to release built up heat - this causes fade and sometimes brake fluid boil. Sure you can coat them and duct air, but the materials an issue, as is the size of the rotor (10.5"), pad size, and the single piston design.

ZZ3 Z28

I see the point. Technology advances. Different materials make things we used to do obsolete.

And yes, I did read the linked article prior to responding but I took that line from the article as some knucklehead drilling his own rotors, not purchasing rotors from a reputable performance brake manufacturing company.

I'm looking to upgrade the braking on my car so now maybe I'll look at other options as well. Thanks




.

Nelz

https://www.thirdgen.org/forums/hist...s-87-88-a.html

https://www.thirdgen.org/forums/hist...challenge.html

Unfortunately, the stock DM brakes were not strong enough for racing in the Player's Challenge Canadian Race series in Canada during the mid-80's. So they modified the pre-88 cars with Brembo calipers with braided brake lines before releasing the 1LE's.

I'm wondering if what they found was that the fluid was boiling or if the caliper was flexing or if the pads were not cutting it.

They mandated braided brake lines in that race series so that must have helped with the rubber brake hoses flexing. With higher temperature rated brake fluid that would help with the brake boil. The Hawk pads help.

But yes, as others have pointed out. The material used in the construction of the brakes-Iron retains more heat than aluminum which is a design flaw.

87350IROC

iTrader: (2)

The problem is clearly heat rejection. The DM calipers can supply plenty of pressure with the large piston.

And I don't believe it is a flaw at all. GM engineers are not stupid. I am sure they are well aware that iron doesn't reject heat as fast as aluminum. Instead they went for an inexpensive option. It is a cost/benefit tradeoff just like every other part on the car. Brakes were certainly not sexy in the 80's. Nobody was showing off their brakes, like they do today. Doing track days was certainly not as popular then as they are now.

ZZ3 Z28

Brakes certainly are a trade off. My 1992 Lumina went through brakes like crap through a goose. The rear pads were about the size of a finger nail file and the rotors were about as formidable as a paper plate. Sexy? No. Awful all in the name of saving weight to get better gas mileage. Now to save weight for better mpg's, Kia has deleted spare tires from certain vehicles.

However, the argument is better braking. Brakes are just one part of a number of systems when it comes to a performance enhanced vehicles. Increasing hp usually demands enhancements in other parts of the car; better braking, better suspension for handling, engine cooling systems, etc may all need to be upgraded when a vehicle's performance is improved.

Discussions like this make us think about what we've done to our cars and what may need to be done to make them as a whole, better than stock.

Nelz

Hey guys, just wanted to let you know that some blogger (from China according to Whois) has stolen the above information I wrote and blogged basically copying my words and ideas (and they set the date they wrote the article further back in Word Press to say they wrote it first.)

My site is GM Brakes.org

But it looks like the guy stole almost word for word everything I wrote about the stock Delco GM brakes and posted it on their blog.

http://www.antgg.com/60/how-i-improv...aine-gm-brakes

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Administrative Contact:
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What the heck can you do to avoid your posts from being pilfered? I'm sure that they don't have thirdgen F-bodies in China and I'm pretty sure the guy didn't even read Brake Systems by Mike Mavrigian and Larry Carley. This pisses me off so much!!! They didn't buy the parts to test. (And although I know it's not as good as a big brake swap, I'm sure they didn't even bother to change the brakes on a third gen Camaro.)

Is there any way we can protect our posts? We spend a lot of time figuring out our cars and sharing the information with the community to have some stranger steal the info and claim it as their own.

87350IROC

iTrader: (2)

While it might be a bummer to see, I'm sure if you look at this forum rules, anything you post is public domain and is no longer your intellectual property. If you really think you have something special, don't post it on the internet, simple as that.

In reality everything you have posted is basic general brake knowledge. I don't see anything that needs to be protected.

In fact if you look at your website, you jacked info directly from StopTech, did you get their permission to do this?

I would just take the copycat as a compliment and move along.

Have a nice Christmas,

John

Nelz

You're probably right. But, I attribute the sources of my info whereas that a@@hole did not. He plagiarized my article word for word that I wrote for ezine articles here a long time ago (and yes, besides the fact that piston size is not everything, it's what worked for me in Canada where parts are double to triple the costs and the border and Fedex/UPS apply more expensive brokerage, customs, duties and taxes every time I buy something from the good ol' USA.) Between my automotive textbook and the Brake Systems book, tech articles from various magazines and the internet including this forum that's where I try to get my understanding of things. It just sucks when someone copies your homework word for word and doesn't even give you credit for it. But I guess that's life.

RBob

iTrader: (1)

Use USPS for shipping from the US to Canada, no fees except those imposed by Canada.

With your web site material being copyrighted and the copycat using GoDaddy (a US based company) use the Digital Millennium Act with GoDaddy to force the issue.

RBob.

Nelz

Thank you!!! Just contacted GoDaddy. This guy actually lifted all their articles from ezinearticles.com.

87350IROC

iTrader: (2)

Excellent. Good job doing the research.