March 2012 Tech Talk

Tech Talk

Spotlight on Moser Engineering’s new line of Pro Drag Disc Brakes, by Luke Bogacki

As most of you know, I’m in the process of assembling a new Charlie Stewart Race Cars ‘63 Corvette bodied Roadster for NHRA Super Gas competition. Within the buildup process, I obviously had to make several decisions regarding the brand and style of components I would use in assembly of the new ride. I’m no different than any of you when determining the appropriate purchases: I’m on a budget, but at the same time I want to hit the race track with the most competitive, best looking, and safest vehicle that I can assemble.

I think I speak for a large percentage of sportsman racers when I say that I’ve rarely given brakes much thought in the past. To be honest, the only time my braking system was at the forefront of my mind for years was when I had brake system issues. More recently, however, I’ve been forced to do a little bit more research. It’s my personal opinion that as racers we’ve exceeded the specifications that the average competition braking system was really designed for. Think about it: the typical drag rear brake kit was designed for 1600 lb. dragsters that run 155 mph (the average sportsman dragster 20 years ago). Today, cars are heavier and speeds are greater. Yet with our 2000 lb, 190 mph machines we’re still depending on the same outdated braking technology.

For me, this point hit home in the annual Winter Series events in Florida. There, I routinely race my dragster(s) in a string of quarter mile events. A few years back, I went through three sets of brake pads and two sets of brake rotors during the three week stretch. I simply had too much speed, too much weight, and too short of a race track to keep from brutalizing the brake system. In all sincerity, I think we’re going fast enough in many cases to warrant the use of a parachute; but being double entered in a bracket race without any crew, I’m going to refrain from pulling the chute as much as possible. At any rate, I returned from Florida that season with a focus on finding a better braking system. I wanted something safer without as much attrition and need for maintenance. In the years since, I’ve bounced around to several manufacturers and combinations with varied levels of success.

Late in 2011, Moser Engineering introduced their new line of Pro Drag Disc Brakes. Since I’ve run Moser axles and rear end components for years with great success, I was intrigued by the thought of such an established company diving into the performance brake industry. Better yet, I knew that Rob Moser, his son Justin, and Moser employee Tim Irwin are hardcore sportsman racers themselves; so they would be tuned in to the rigors of our style of competition. At the IMIS show in Indianapolis I spoke at length with Tim, who essentially headed up the design and development of the new brake system. We weren’t far into the conversation before Tim had convinced me to purchase the new Moser Pro Drag Disc Brake kit for the rear of the roadster.

He said that when the company introduced the idea of manufacturing a drag racing brake kit, they focused on many of the same concerns that I, and many other racers had regarding braking systems currently on the market:

Ease of service in the field

Cost of consumables

Availability of consumables

Reduce rotor bellvilleing

More consistent caliper release

I don’t know about you, but I’ve had the displeasure of attempting to remove a brake rotor from a brake hat (on a typical 2-piece hat/rotor design) at the race track in the past. Due to the heat that these components endure, removing a bolt from the hat/rotor assembly is all but impossible. Better yet, some manufacturers use an allen head bolt for the job, which in my experience led to a quickly stripped out head and the unavoidable head scratching moment when I think "OK, now what?" Other manufacturers went to a one piece hat/rotor design, which eliminated that torture and removed the threat of sheering the hat/rotor bolts off under excessive braking (yep, I’ve done that too). The problem with that design is that the rotor area obviously gets more heat than the hat area, and after enough heating and cooling processes, these rotors tend to warp and bevel badly.

Tim explained how he came upon the idea for a better design within the Moser package.

"During our brake development program I was servicing one of our transmissions and while I was working on the high gear drum I realized that a spiral lock ring was the answer. With this type of retention it would only require a screwdriver to remove the rotor.

With most other sportsman kits on the market the rotor is either one piece or bolted solidly to the hat. With the one piece design there’s no choice but to throw the whole thing away. We wanted to keep the cost of the consumables down so we opted for the two piece hat & rotor assembly. With our snap ring retention system the possibility of ruining a hat by breaking off the bolts was not an issue."

Moser's innovative snap ring design makes disassembling the hat and rotor assembly quick and simple, while the dynamic floating mount allows the rotor to expand and contract freely to reduce the risk of beveling.

On the issue of rotor beveling, Tim offered the following explanation:

"One of the major complaints from rotors was beveling. Our belief was that when a rotor goes through its heat cycle (heating & cooling), it needs to be able to do that freely. With a one piece rotor or a bolt together hat & rotor assembly the inside diameter of the rotor can not expand or contract at the same rate as the outside of the rotor. We also noticed that after several heat cycles the rotor always shrunk more that than it expanded. Again with the solid attachment on the ID of the rotor it could not do that evenly. Our dynamic mounted rotor reduces the possibility of beveling by changing to a floating mount on the ID of the rotor."

As I had mentioned earlier from my own experience, brake pad life and replacement availability is a big deal. The faster we go (and the heavier our cars get), the more quickly we wear out brake pads. Depending on those factors, and length of your local race track, it’s not uncommon to get less than 100 runs from a typical set of pads. Plus, I think most of us would agree that we most often realize that we’re in need of new pads when we’re truly in need of new pads (nearly metal to metal). At that point, we literally have to have new pads to race that day (or in some cases to finish the race we’ve started). Moser addressed those concerns as well.

"Our kits use a thicker pad than our competitors, which means longer pad life," Irwin explained. "Our pads are 20% thicker than most of our competition. That allows our systems to enjoy increased pad life, despite having about 25% more pad contact area than the leading competitor. This means that our brake kits offer both increased stopping power and longer pad life."

Better yet, the Moser Pro Drag Disc Brake kits can utilize an OEM replacement pad that can be found at the average auto supply store.

"We have worked with Hawk Performance extensively to develop compounds to work in most applications and that’s what we recommend when replacing pads. However, if you get into a jam, the Moser Pro Drag Performance Brake Kits can utilize a D-43 pad from a 1 or 2 series Volvo years ‘71 to ‘93 to fit our calipers. The current design our competitors use will not allow you to run to the parts store to pick up a set when you’re in a jam. Our new caliper will."

Rob Moser heads up Moser Engineering's in-house sportsman race team.  The on track action allows Moser constant R&D while ensuring that the company keeps its finger on the pulse of sportsman drag racing.

The professionals at Moser employed the same common sense approach to all facets of their new line of brake kits, as they truly started with a blank page and set out to address all of the complaints and faults associated with typical performance brakes and components.

"During our caliper design, we made a lot of changes that we feel improved upon any product currently available," Irwin declared. "For example, we noticed that in many cases the outboard pistons were not releasing at the same rate as the inboard pistons. To solve this problem in our calipers we added a second fluid passage to the inside to aid in the application & release of the outboard pistons. In some applications this could conceivably affect reaction time by allowing the outboard pads to drag on the rotors. A simple analogy would be an airplane full of people. The ones at the back get off last. By adding another door, the passengers get off the plane twice as fast."

The features outlined above, in addition to competitive introductory pricing offered by Moser Engineering, made my decision an easy one. I elected to use the new Moser Pro Drag Brake Kit, rounding out a complete Moser Engineering rear end. The car utilizes a complete Moser aluminum 9" center section, Moser 40-spline gun drilled axles, and a Moser Engineering Driveshaft in addition to the new brake kit.

The Moser Engineering Pro Drag Disc Brakes on our new Charlie Stewart Race Cars '63 Corvette Roadster. 

At the time of this writing, I have yet to hit the track with the new machine; we’re looking at an initial test date in early April. I can say, however, that the new Moser Pro Drag Brake Kit was easy to install and looks great. I can’t wait to use it in the shutdown area!

For more information on Moser Engineering’s line of Pro Drag Brake Kits and accessories, visit or call 260-726-6689.

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