If the best way to find weak links is to break stuff, you might as well have someone else do the suffering for you. That pretty much sums up the history of Moser Engineering, whose decades-long involvement in high-end drag racing has enabled the company to develop some of the best driveline components in the business. Company founder Greg Moser got the bug early, when he started racing a Norton motorcycle as a kid in the mid '60s. After high school, Moser picked up a '70 Camaro and hit the dragstrip before deciding to campaign an Altered dragster in the late '70s. All the while, the inevitable carnage he endured at the track ensured that his customers wouldn't suffer the same fate.
Consequently, his growing business quickly established a name for itself in the industry, and today Moser Engineering is one of the most respected names around. Still a family-owned business that's proud of its small-town roots, the torch was eventually passed down to Greg's son, Rob, and his wife Susan, who are more than happy to carry on the tradition of on-track testing and product development. The company's current crop of in-house race cars includes three Altered dragsters, and third-gen and S-10 street/strip machines that both run 10s.
It hasn't been long since we did our homework on the latest in driveline tech, but in speaking with Rob Moser we were downright stunned at the technological developments that have transpired in only the last few months. Whether you need to beef up the driveline in a race car or a street/strip machine, here's Moser's insightful advice on how to build the ideal rearend for your application.
"Moser Engineering was founded in 1982 purely out of necessity. My dad, Greg, was building an Altered drag car and needed to narrow the rearend. Aftermarket axles were simply too expensive, so he figured out a way to respline a set of stock axles in our garage. Other racers and street rodders in need of his services soon started bringing their business his way. At the time, Greg was working as the plant manager of the Portland Forge steel mill in Indiana, so my mom, Marianne, would spend her days taking sales calls and answering tech questions. Every night after work, my dad filled orders in our garage, and the business was incorporated in 1986. By 1989, my dad quit his day job to pursue his axle business full-time. On the weekends, he dropped me off at the salvage yards to scour for old Ford 9-inch rears and axles that we would then rework and sell.
"This continued until 1991, which is when we decided to introduce our own line of custom alloy axles to meet the growing demands of the customers and their vehicles. Greg's background in the forging industry was very beneficial when fine-tuning the art of metallurgy and heat treating. It allowed him to develop not only an axle that is great for racing, but also the perfect axle for street/strip and restoration applications.
"The company has since grown to include a wide variety of rearend housings, axles, complete center sections, and virtually all other related rearend components. In the spring of 2003, my parents passed away in a tragic airplane accident along with our plant manager, Jeff Bickel, and his wife Eileen. By then I was already in charge of the day-to-day operations of the company, and we have continued to expand and grow every year since. What was once our family garage is now a full-blown, 100,000-square-foot manufacturing facility with over 60 employees."
Moser knows that many racers need to stretch a buck, and a comprehensive warranty never hurts. If you break an axle, Moser will fix it. "We offer a 10-year warranty on all our race-legal axles that are 33-splines and larger, which is a true testament to the quality of our products and the confidence we have in them," says Moser. "Moser Engineering has such a long and proven track record that we have no problem backing up our U.S.-made alloy axles with this type of replacement policy. Our experienced technicians have seen it all, and many of them are at the track every weekend racing. Having them steer you into the right product from the very beginning is a big part of the battle."
Properly sizing your axles can be tricky. Axles too small are prone to breaking, while ones too big eat up power. Fortunately, Moser has a simple formula to help select the right axles. "First multiply your engine's torque by its First gear ratio, its ring-and-pinion ratio, and 0.90 to account for driveline loss," explains Moser. "This will give you a figure that represents the maximum amount of torque transmitted to both axles if you launched at your engine's torque peak and dead-hooked out of the hole. A 30-spline axle is rated at 6,200 lb-ft, a 31-spline at 7,000, a 33-spline at 8,200, a 35-spline at 9,600, and a 40-spline at 12,000. As long as the figure from the formula is smaller than the torque rating of the axle, you'll be in good shape. Since axles are rated individually and not as pairs, sticking with this plan will make it virtually impossible to break an axle since you'll have a safety factor of 200 percent built in."
|Torque at |
|= ||Torque x First gear |
| ratio x Rear gear |
|ratio x 0.90 |
"The process of manufacturing an axle starts with the type of alloy used, which ultimately affects every process on down the line. Since we are dealing with an alloy material with steep gradients in carbon content, hardness, tensile strength, and microstructure from the surface to the center of the axle, the primary design consideration is the type of application an axle will be used in. Most project cars fall under the street/strip umbrella, and those particular applications require an axle that has a good hard Rockwell rating for longevity, but too deep of an induction hardening process can make the shaft brittle. This is one area where my dad's experience running a forging company for all those years paid off. He had contacts with multiple forging companies all across the country along with teams of engineers at his disposal, which he used to develop the proprietary material that we use today. There is a big reason why we still work closely with a local forging company and do our own heat treating and rough and final machining. With all of the imported products coming into the market these days, it is critical to have complete control over the entire manufacturing process. Moser Engineering prides itself on only using U.S.-made and designed steel forged in U.S. plants using Moser-designed dies and tooling."
At some point, Bow Tie horsepower will get to a level where a locker or a spool is a must. Not many people are hardcore enough to give up a limited-slip differential in a street car, but fortunately they've come a long way in terms of strength in recent years. "There are a lot of great limited-slip units being made, and probably one of the best is the Detroit TrueTrac," Moser explains. "We have seen some incredible power numbers go through this Posi unit, but any failure with this type of differential is going to be related to launch rpm and torque loads. With some finesse and experienced control, you can see these in a street tire car handle 800 hp reliably."
Flex in a housing assembly can be one of the most detrimental forces on a rearend. According to Moser, a common problem with stock 10- and 12-bolt rearends is gear deflection. In simple terms, this is when force delivered by the pinion gear pushes against the ring gear and tries to push it out the back of the housing. The purpose of the main caps is to transfer the climbing force exerted on the ring-and-pinion into a horizontal force to the side gears, which in turn rotates the axles. When grip and torque exceed the capacity of the main caps, they can break or stretch, resulting in ring and pinion failure. "Rear covers add a kind of doorstop to the caps by giving them extra leverage against these forces and allow the rearend to handle a greater torque load," says Moser.
Another common problem is the flexing of the axle tubes. "Wider rearends impart more leverage and stress on the housing and centersection. Increasing horsepower and vehicle weight also increases the likelihood of rearend flex, misalignment, and subsequent failure of internal parts. Securing the tubes to the housing with a back brace dramatically increases the strength of the housing and will afford greater consistency when running at the track."
One of the benefits of running a 9-inch rearend is the myriad configurations in which they can be arranged. When it comes time to select a case, the options are either a standard cast, nodular iron, or aluminum third member. Moser says that a standard cast iron case is good for applications of 400 hp or less. While you may be able to get away with more power, the pinion support is prone to failure with high-rpm launches and sticky tires. Nodular and aluminum cases are a big step up in strength, but choosing between the two depends on vehicle weight. "If a car is a daily driver with a full interior, then you might as well save your money and just go with a nodular case. If it is a stripped-down car and you're trying to save every ounce of weight, then an aluminum case might be a good choice," he says. "The one thing to look out for with an aluminum cases is that you really should have a through-bolt design on the main caps. Without a through-bolt design, the case can flex and cause ring gear deflection. We only offer our aluminum cases with through-bolts, and they're good for some very serious power."
Stock vs. Aftermarket Housings
Although they may be hard to spot with an untrained eye, aftermarket rearend housings incorporate several improvements over their stock counterparts. All of Moser's housings are manufactured from all-new housing centers and feature new brackets, housing ends, and larger axle tubes that are always welded to the center. "On our new 12-bolt rears we have increased the main cap size and use larger Allen-head bolts to secure the caps," Moser says. "The casting itself also has more ribbing to reduce deflection. Likewise, our standard 9-inch centers are new stampings that are much stronger than a stock piece."
C-Clip Eliminators and Housing End
If the thought of your wheels, tires, and axles ejecting themselves from the rearend housing is a bit unsettling, C-clip eliminators or weld-on housing ends are a cheap insurance policy. Moser says that C-clip eliminators are generally for cars that are being slowly converted to a full drag race setup. They work by acting as a safety hub with sealed, press-on bearings. In the event that an axle breaks at the spline, C-clip eliminators will keep them safely in the housing. However, they do have some drawbacks. "They weren't really designed with street driving in mind and can sometimes allow gear lube to leak through them," explains Moser. "We have made a number of design changes to our C-clip eliminators through the years to help eliminate this issue. The next step up from C-clip eliminators is weld-on housing ends and the conversion to press-on axle bearings. The weld-on housing ends obviously provide the safety needed for racing and can also handle the side loads of a street vehicle."
F-Body Torque Arm
"Moser Engineering is now offering a performance chrome-moly adjustable torque arm for '82-92 F-bodies. The new unit fits existing 75/8-inch rearends in addition to stamped 9-inch and 12-bolt housings from Moser and many other manufacturers. One of the nice things about being a rearend manufacturer is that we've seen lots of different torque arms and suspension upgrade kits, which gives us an excellent perspective on how to create the best torque arm design. Our torque arm was patterned after the same type of setup used in Pro Mod cars and is intended for cars running 10s and quicker. Features include 11/4-inch chrome-moly construction, TIG-welded joints, and a sliding front mount to prevent bind and maintain excellent handling."
When flipping through the drivetrain section of a parts catalog, the difference in pricing between street and race ring-and-pinion sets is dramatic. So what's the difference between the two? "A street/strip gear is generally made from a harder 8620 material, while a race gear is made from a softer 9310 alloy," explains Moser. "In a race car, the softer compound is designed to absorb the shock load from a high-horsepower launch without fracturing. Most manufacturers advise against running race gears on the street because they wear much quicker than street/strip gears and cost almost twice as much. Generally, the launch characteristics of a car that requires a race gear are not going to translate to a car that will be driven on the street anyway."
M9 Fabricated Housing
For cars that have enough power and hook to flex and distort a standard stamped steel 9-inch housing, a fabricated unit may be the answer. They're made from a single piece of triangulated 1/8-inch laser-cut steel and feature internally welded gussets, bulkheads, and a 3/8-thick faceplate. "We have actually used the M9 housing design as the basis for our new full-floater housings that are being used in classes like Pro Mod and Top Dragster, where guys are going over 215 mph," says Moser. While fabricated rearends were once exclusive to full-tilt racecars, Moser offer its M9 housings in bolt-in form for street cars as well. "Not only do they function extremely well, but they also look great under the back of a street car. Even if you don't really need it now, it does lay the foundation for the future needs of the car as the horsepower grows. The M9 housing is priced so that there isn't a huge difference between it and a standard stamped housing, and if you add a back brace it makes for a very rugged setup."
12-Bolt or 9-Inch?
No interview with a driveline manufacturer is complete without stacking the best from Chevy and Ford against each other, so here is Moser's take on the matter. "The 9-inch is a bit stronger than a 12-bolt, has a larger ring gear, can accept 40-spline axles for extremely high-horsepower applications, and is easier to work on due to its drop-out center section," he explains. "However, the 12-bolt is about 2 percent more efficient, usually a little lighter, and more compatible with late-model GMs that have ABS. In most cases, both rearends are more than capable and it is really a matter of personal preference. While this debate will never end, the most important issue is that both designs are still being updated. Fabricated 9-inch housings are now available in bolt-in form for street cars, and it's now possible to fit 35-spline axles in a 12-bolt."
Company Race Cars
Racing has always been a big part of the Moser tradition. There is always a stable of in-house race cars to assist the company in parts development. "In our industry, you don't want any surprises, and being at the track on a weekly basis enables us to put our current products through the rigors of racing and to test new product designs quickly and efficiently. That way, we're testing our products in real-life circumstances, not just on a test stand in a perfect environment," Moser explains. The shop currently competes with three in-house Super Comp dragsters driven by Moser, his son Justen, and R&D manager Tim Irwin. "Many of our employees are avid racers. Kip Hayden, our VP of operations, races a company-owned 10-second '87 Camaro, and some of our other drag cars include a 10-second '87 S-10 truck, a '94 Camaro, and an '88 Firebird."
"We're constantly updating our product line, and there are several new items that we're very excited to announce. Moser's new economy disc brake kit is going to give customers the ability to have disc brakes at a price point that's lower than most new drum brake kits. It utilizes an 11-inch vented rotor with a single piston caliper, and a parking brake is optional. Best of all, the setup will work with just about any 15-inch-and-larger rim combination.
"Our new M9 full-floater rearend was designed to be the best design of its type on the market. Its high-strength chrome-moly housing is perfect for Pro Mod, Top Dragster, and Top Sportsman classes in addition to any application where a racer wants the safety you gain with a floater unit. Moser uses its premium alloy axle shafts, hubs, and 4130 alloy spindles in this setup. The hub assemblies can be built to accommodate a standard 5x5 or a 5x4 3/4 bolt circle. Other features include premium 31/2-inch chrome-moly axle tubes and the option to choose from a full range of 9- or 9 1/2-inch competition centersections.