SSBC_Lead

When it comes to spending money on our truck, there are a few things that we pay less attention to, that are more important than the braking system. We will spend thousands of dollars on go fast parts or look good parts, but only if something wears out, do we typically upgrade something that can keep us safe and our trucks in one piece.

IMG_3490We have lots of plans for our project MCLB Heavy Hauler and we want to make sure that nothing stops us short of completing our project. With all of the modifications we have planned for this project, we want to make sure the truck can handle anything we are doing. We have already fully built the transmission and bumped the power by almost 200 hp and over 400 lb-ft of torque. We figured this was a great opportunity to turn to the experts at SSBC (Stainless Steel Brake Corporation) for some stopping power before we do the long bed conversion and start hooking up some heavy trailers.

“We really see a need for upgraded brakes on trucks because of long and hard braking cycles.When towing down long grades, it is pretty common for the rotors to get hot and the brakes start to fade. The same thing happens with big tires because of the additional rotational mass. That is why we offer slotted and cross drilled rotors for most truck applications. They help the rotors stay cooler which keeps the braking constant,” said Michael Jonas, Owner of Stainless Steel Brake Corporation.

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The discoloration of this rotor is a tell tell sign of overheating or excessive heat during breaking.

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The slots and holes in the rotors increase the heat transfer to the environment.

What is really going on

From Newton’s second law of motion, we know that energy is conserved. Energy in minus energy out equals the energy of the system. If we apply this to our trucks, we can say that the energy of our vehicles at speed can only be reduced by another form of energy. This energy comes in the form of heat energy via the braking system (ignoring drag and other much smaller forces).

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Ever wonder why your brakes squeal when you need to change your pads? Manufactures install a metal tab to rub against the rotor when the brake pads need to be replaced.

As the brakes are applied, the force of friction between the brake pad and the rotor cause the rotor to heat up. This heat is then dissipated by the surrounding air. The force of friction equals the force of the pad against the rotor multiplied by the coefficient of friction of the pad.

In an ideal world, the coefficient of friction between the pad and rotor would remain constant throughout the operation of the brakes. In reality there are two major things causing the coefficient to change during operation. As the rotors start to get relatively hot (red) the coefficient of friction reduces and the amount of heat generated from the brakes decreases. This phenomenon is typically called brake fade. When driving down a long grade or hard braking for an extended period of time, the brakes become less effective until they start to smoke and almost completely stop working. Unfortunately, around this time, the rotors themselves start to fail via warpage and stress cracks.

The other way the coefficient of friction changes is by dirt and debris that gets in between the pad and rotor. Pads are designed to wear out. We all have seen the brake dust collect on our wheels. This dust is also on the pads and rotors. As the pads are applied, tiny particles of pad material are broken free from the pads, creating imperfections. This reduces the coefficient of friction between the pad and rotor interface.

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Our truck still had a decent amount of pad life left. On the left is the old pad, on the right is the new pad.

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Notice the two pistons in the caliper (lower left of the photo). These pistons are what the brake fluid acts on and what engages the brake pads.

Modifications

Heat Generation

There are two aspects of braking, heat generation and heat dissipation. Heat generation is a function of the force of the pad against the rotor and the coefficient of friction. The coefficient of friction is a characteristic of the pad itself. In order to change the coefficient, we would have to change the pads. There are aftermarket pads available that have different coefficient of friction. Simply by changing these, there will be more heat generation and the braking distance will decrease.

The slots act as a windshield wiper for your pads – Michael Jonas, SSBC

As discussed above, the coefficient of friction does change due to dirt and debris on the pad and rotor. What companies like SSBC do to address this, is slot the rotors. “The slots act as a windshield wiper for your pads. When the pads stay cleaner, they last longer. The slots also eliminate any dirt or debris from getting between the pad and rotor,” explained Jonas.

The other factor of heat generation is the force being applied. As you apply the brake pedal, there is a plunger in the master cylinder that is moving fluid from the reservoir into the brake lines. The more fluid that is pressed into the brake lines, the more pressure in the brake lines. As the brake lines start to increase in pressure, the pistons inside of the caliper starts to move. As they move, they push against the brake pad. Once the brake pad engages the rotor, the pressure in the system starts to build. The force applied to the rotor is determined by multiplying the brake pressure by the area of each piston.

Without swapping master cylinders or changing the ratio on the brake pedal, the only real way to change the force being applied by the brake pad is to change the calipers. Generally, factory calipers have one to two pistons in the front calipers. By upgrading to calipers with more piston surface area, more force can be applied with the same amount of pressure.

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Upgrading to slotted and cross drilled rotors is a very cost effective way to reduce brake fade and increase braking ability.

Heat dissipation

Having the ability to generate more heat is great. It gives the braking system the ability to start removing energy from the vehicle much quicker. Unfortunately, the increase of heat to the system, causes the rotors to heat up much quicker and the coefficient of friction starts to decrease much faster because more heat is being generated than can be dissipated.

The factory designs their braking system to work together. They spec the system to be able to dissipate so much heat over so much time. If more heat is generated in a short period of time, then the rotors will heat up, reducing the coefficient of friction on long or hard braking cycles. To address the heat side of the equation, the surface area of the rotor can be increased (larger diameter rotors) or vents can be added to promote heat transfer with the surrounding air.

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By increasing the diameter of the rotor, there is more surface area for heat transfer.

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Notice how small these pistons are inside the caliper. Even with six pistons (three times as many as the factory caliper), there is only about 25 percent more force being applied to the pads. This is because the pistons are smaller with less surface area for the brake fluid to act on.

Our option

For us, we determined the best option was to address the coefficient of friction issues under long/hard breaking cycles. When we are driving through the mountains with a heavy trailer, we don’t want to be concerned with brake fade. The first thing we decided was that we were going to add SSBC’s slotted and cross drilled rotors on all four corners. This will help maintain a firm break pedal feel and keep the coefficient of friction high so we don’t need to push harder on the brakes to stop. While the rear brakes don’t brake as much as the front, they do provide a decent amount of braking and after having been a tech and seeing rear rotors cracked and warped, there was no way we weren’t going to upgrade the rear rotors as well.

Once we upgraded the rotors, we opted to upgrade the front calipers to SSBC’s six piston calipers. Now before we explain why, lets look at what happens with the factory system.

What is going on

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Notice the thickness difference between the two pads. Also, notice the lower pad isn’t warn evenly.

The factory calipers are pretty large and apply a good amount of force. There is no denying that the calipers on our ’06 Ram 2500 are good. They are two piston calipers. Both pistons are on the same side of the caliper. As the brakes are applied, the pistons push against the inside brake pad. In turn, the brake pad puts a force against the rotor. The rotor is fixed in place thanks to the lug nuts holding the wheel on. To keep the caliper from pushing away from the rotor, the caliper is designed as a “C”. The back side of the caliper is located on the other side of the rotor and has another pad. As the caliper starts to push away from the rotor, the outside pad (wheel side) engages the rotor and now both sides of the rotor are being used in the braking system.

What happens is that more force is being applied to the inside brake pad than the outside. This will not only cause the inside of the rotor to heat up quicker, but it will also, wear the pads unevenly.

SSBC’s solution

If you tell someone you have six piston calipers people usually assume six times the braking. In fact that isn’t the case at all. There is only so much room within a caliper. After a second piston is added, each additional piston means that the pistons are all smaller in diameter. The smaller diameter results in less surface area per pistons. If there were six pistons on one side of the caliper like the factory, the factory two piston caliper would probably have more force.

The six piston caliper from SSBC has three pistons on each side of the caliper. This results in a uniform pressure being applied to both sides of the rotor (about 25% more). With uniform pressure, the rotor will experience even heat distribution throughout and the brake pads will wear evenly as well. Three pistons on each side result in a more evenly distributed pressure across the entire pad. This ensures the frictional force being applied is uniform throughout the rotor / pad interface.

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Even with more pistons, the physical size of the caliper is basically the same as the factory caliper.

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The brake fluid enters the center of the caliper and there are bleeder valves at the top and bottom. of the piston. While these should be tight from the factory, always make sure both are tight before driving.

Testing

Weight Distribution

IMG_3541We weighed the truck with and without the trailer. The trailer had a tongue weight of 620 pounds. Once the truck was hitched, the rear of the truck squatted down. The shift in stance moved an additional 220 pounds to the rear. All said and done, the truck had about the same weight on each axle (3850 pounds).

With more weight on the rear axle, it takes more force from the caliper to lock up the rear wheels. This means that more braking can be done by the rear brakes loaded than unloaded.

Having been a journalist for more than a decade, this proved to be one of the trickiest parts of this install. To truly isolate the brake system and test it, there are lots of parameters that need to be held constant and we have to have the ability to consistently apply the brakes a set amount. After spending almost two months, we determined that the only way we can do a true back to back comparison was a full hard braking event from 60 to 0. We opted to conduct the test with the truck as it sits (7,060 lbs). Then to illustrate how much of an effect weight has, we conducted a second test with a trailer having a small load on it (12,300 lbs truck and trailer). The brakes on the trailer were disabled so only the truck’s braking system was being tested.

We performed each test at least six times to ensure the results were consistent. With the truck empty, the stopping distance was 147.5 feet plus or minus 2.5 feet. Once we hooked up the trailer and prayed the car we had tied down wasn’t going to fly forward, we did the test again. This time, the truck and trailer took 231 to stop plus or minus 12 feet.

After completing the brake upgrade, we performed the break in procedures outlined in the installation manual (multiple 60 to 10 mph braking events and 250 plus miles of driving). Then with trailer in tow, we headed out to an abandoned air base we use for testing. We performed the same 60 to 0 tests empty and full. Each time, the truck went into ABS. We were a little shocked to see that the stopping distances were fairly similar (140.3 feet plus or minus 4 feet empty and 229 plus or minus 10 feet with trailer).

(Left) The truck and trailer are on the scales but the trailer is not connected to the truck. (Right) Truck and trailer are now connected and being weighted. Notice how only 600 pounds of tongue weight caused over 200 pounds to transfer from the front axle to the rear. This gave the truck basically a 50/50 weight distribution. Consider what happens with a 15,000 pound load. This is why air bags or helper springs are so important in towing applications.

Unfortunately, once the brakes are applied hard enough to lock up the rotor, additional braking, cooling or anything else that we changed no longer matters. The ABS system pulsates the brakes to bring the truck to a stop as quickly as it can. The seven feet of difference when braking indicates how much quicker the brakes were able to lock up. (Remember the 25 percent more force provided by the front calipers?)

Impressions

The real story here and unfortunately one that we cannot fully document, is how much better the truck feels when braking. The truck slows down much quicker under medium to hard braking compared to the factory brakes. There was/is really no way for us as a magazine to test the brakes repeatedly at 50 percent or 75 percent. So, there is no way to document how much better these brakes stop, outside of us telling you that they feel much better and we have a lot more confidence when we do tow.

If you think about the typical braking done while driving, it is usually anything from light braking to heavy braking. When it stop and go, inching along the expressway, the brakes aren’t doing much. If you are hitting every light there is or dealing with other drivers who aren’t paying attention while driving, then medium to heavy breaking is what the truck is going through. For us, we can feel a huge difference in the medium to heavy braking cycles. Just putting around in rush hour, there isn’t much difference. The few times we have hooked a trailer up to the truck, we noticed quite a big of difference under heavy braking.

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All four of our rotors needed a little persuasion to come off.

Install

The rear brakes were the easiest to upgrade. Basically, once the wheels are removed, the only thing holding the rotor on the hub is the caliper. Two bolts and the caliper comes right off. Don’t be afraid to use a little persuasion to get the rotor off if it is stuck. It had been a long time (if ever) that our rotors had been off and they were on pretty tight. After a little persuasion,  they came right off. From there, just spray the rotors with a brake cleaner (not WD40) and clean them before install.

The front rotors are a little more involved with the replacement of the caliper. If we had not upgraded the front caliper, the front would have been the same as the rears. Instead, the front was a little more involved but not more complicated.

There are lots of ways to get the pistons back into the calipers to re-install the calipers. Here are two easy ways using a c-clamp.

Following the same steps as above, the front rotors were pulled off and set to the side. The new calipers were prepped (taken out of the packaging, banjo bolts and washers set to the side and the plug removed) and set next to the truck.

To upgrade the calipers, SSBC provides the mounting bracket, pads and caliper as one assembly. We simply had to remove the two bolts holding the caliper bracket on and unscrew the banjo bolt from the caliper (note, this will cause the brake system to start leaking. Make sure you have a drain pan ready. Also, brake fluid eats paint, so do not get any on any painted surfaces.)

IMG_3518The new rotor was slid into place, the new caliper went over the rotor and was bolted into place. Then the brake line was bolted to the adapter and then the adapter was bolted to the caliper. (Note, the caliper uses a different thread pitch than the factory caliper. The banjo bolts are not interchangeable.)

Once both sides were installed, all that was really left was to bleed the brakes to remove any air in the lines. The first time we did this, we had someone to pump the brakes and it only took a couple of minutes. Unfortunately, it took a few attempts to get the brake lines clocked so they wouldn’t bind. We ended up adjusting them multiple times and each time, the system needed to be bleed. All of the remaining times, we had to use a hand held bleeder which took quite a while.

Conclusions

This is one of the easiest upgrades to do. Outside of having problems getting the brake line clocked right, we would have been in and out before beer thirty had we not been taking photos along the way. If you are still reading this, then you are easily capable to doing this upgrade. Not only will you be able to tow with more confidence, but potentially be able to avoid an accident should someone do something stupid (which never happens right?)

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