Five Questions With QA1 About Carbon Fiber Driveshafts

It’s nothing new: enthusiasts have always been about the latest technology whether they needed it or not. When cross-drilled, slotted rotors first hit the average street car, you could find them on vehicles that probably didn’t need them, but they looked pretty cool nonetheless, and people just had to have them.

Carbon fiber is another product that has had enthusiasts drooling over for quite some time now, and we’re seeing it on everything from vinyl wraps to genuine carbon fiber body panels. To make a stronger driveshaft, QA1 has created the REV Series of carbon fiber driveshafts that come out to nearly half the weight of their steel counterparts, and are considerably stronger.

QA1 showed off the REV Series carbon fiber driveshaft at SEMA, with more applications added to the lineup.

As we’ve been making changes to Project Track Attack, one area that has grown on us is the length of the driveshaft. Initially we started with a steel driveshaft of about 3-inches in diameter. But as we made changes to our drivetrain, the need for a longer driveshaft arose and we had to bump the diameter up to 3.5-inches. That steel driveshaft was quite heavy at 25.8 pounds.

The last change to the car was a Moser Engineering M9 rearend to go along with our new Control Freak coilover suspension. We swapped out a Mopar 8.75-inch to a new Ford 9-inch, and as you might guess, that meant we added another couple of inches of distance between the transmission and the rear yoke – time again for a whole new driveshaft. You can sometimes shorten an existing steel or aluminum driveshaft, but if it needs to be longer it needs to be a new shaft.

The problem with steel driveshafts in a racing environment is that one failed joint and your driveshaft can become a projectile. Carbon fiber is stronger than the steel, but when things break, it shatters instead of opening the floor pan like a can opener.

QA1 Brings Carbon Fiber To The Track And The Street

We’ve already been fans of QA1 for this project, and have graduated from single adjustable shocks to double adjustable coilovers. So when it was time for the new driveshaft we decided that even though we needed a longer one, we wanted to go lighter than the existing steel driveshaft.

QA1’s lightweight REV Series carbon fiber driveshafts fit many applications, from dirt track to street to strip. Unlike typical steel or aluminum driveshafts, however, there’s some pretty trick things going on at QA1 with regards to driveshafts, and how they’re made.

While there are many specific applications for the REV Series driveshafts, ours was a complete custom order that joined a 4L60E yoke to a driveshaft mated to a Ford 9-inch rearend with 1350 u-joints at each end, all made to our specifications.

The technology behind building a carbon fiber driveshaft is much more than just wrapping carbon fibers around a buck. There are matrix resins, nano silicas, binding angles, and tension winding to build these driveshafts. to name a few of the many processes. We reached out to our friend Dave Kass to ask five questions about carbon fiber driveshafts, and this is what he had to say.

Is there a recommendation for care/maintenance on a carbon fiber driveshaft, anything that is above and beyond what one would do for inspecting a standard driveshaft?

Dave Kass: A carbon fiber driveshaft does not require extra care/maintenance, but with any driveshaft, we recommend periodically inspecting it and cleaning it with soap/water. Keeping everything clean helps when doing visual inspections of the drivetrain and will help to see any potential problems.

The 11-step process for bonding the carbon fiber to the yoke is something that QA1 keeps confidential. All we can tell you is that they work with 3M matrix resins and nanoscale silicas for a bond that has proven stronger than the driveshaft itself.

We’ve seen videos where a carbon fiber driveshaft has splintered and blown apart, what typically causes something like this, is it just brute power that does it?

If a carbon driveshaft fails and blows apart it is due to damage to the exterior of the shaft or failure of another component in the drivetrain. This can be caused by the shaft making contact with the chassis from excessive suspension movement, a broken linkage, or lack of clearance. Also,  if you use a driveshaft that isn’t designed for the power of your engine it can cause a torsional failure with splintering.

This is one of the most important benefits to carbon fiber. They typically don’t generate catastrophic damage like alloy driveshafts do and are less likely to hurt the driver.

The SFI rating is something that needs to be checked off during ordering, as it’s an additional process that each driveshaft must go through.

What processes need to be in place in order to get an SFI rating on your CF driveshafts?

There is an extensive test system in place in order for a driveshaft to be certified to the SFI 43.1 specification. Fortunately, we have worked with SFI and are authorized to perform our own certification in-house. To have an SFI certification on a driveshaft the customer would need to select the SFI box on the custom driveshaft order form or select the SFI driveshaft part number for any vehicle specific shaft.

Please explain in some detail how you wind shafts differently for different applications and why.

Many factors are considered when winding a driveshaft. Whether it be a Dirt Late Model or a 2000HP drag car, the torsional stiffness of the shaft needs to be optimal for traction while being strong enough to handle the power of the vehicle – and to have a high enough critical speed for the RPM range of the driveshaft.

We tailor each shaft for its specific market a number of ways; we can alter the fiber count of the carbon fiber itself, we have multiple resin systems that are better suited for different temperature ranges, and we can completely change the layup of the tube (the actual carbon structure).

Depending on how and where the driveshaft is used, the winding process involves angles and tension that help contour the torsional stiffness of each driveshaft for maximum performance.

This gives us an almost infinite number of combinations to choose from which allows us to fine tune the overall weight, temperature range, ultimate strength, and torsional stiffness. For example, a 32-inch dirt modified driveshaft is 2.25 inches in diameter and is designed to be relatively soft in torsion to help hook the car up on extremely slippery dirt tracks.

This same driveshaft design would not work in a Pro Mod, so we have a different diameter tube (larger), a different tube layup to resist torsional twist, and sometimes use a different resin depending on temperature.

We realize you don’t want to discuss proprietary info on the bonding process, but is this something that will last a lifetime, or is there a point where the bond might weaken?

Our bonding agent was developed for extreme torque capacities and has been cycle tested without failure in extreme weather and racing conditions.

Dropping from 3.5 inches to 3.2 inches in diameter, we won’t have any problems with our REV series carbon fiber driveshaft handling horsepower from our upcoming engine build.

Is Carbon Fiber Too Much For The Street?

We’ve talked with QA1 about this topic before, and the short answer is ‘no’ because even for a street machine we’re always looking for ways to shave a few pounds and add strength. But the benefit for us is that we’re not just shaving a few pounds, we went to a smaller diameter carbon driveshaft, which opened up some room around our exhaust again.

When we upgraded last time to a 3.5-inch driveshaft, it was considerably close to the exhaust system. Needing an even longer driveshaft meant upgrading to aluminum or carbon fiber, or adding a few more pounds for another steel shaft. And then there was the possibility that we needed to increase the diameter, as well.

Not only were we able to drop our existing driveshaft down to 3.2 inches, but we shaved more than 11 pounds from the overall weight.

With various diameters and winding processes, the REV Series carbon fiber driveshafts benefit in both strength and durability, all while reducing weight and increasing performance at critical speed. To say that you’ll notice the difference between the two is something that is difficult to measure by seat-of-the-pants measures, but from a performance aspect, the benefits are many.

Is a carbon fiber driveshaft too much for the street? That’s almost like asking if a high quality, lightweight billet wheel is too much for the street. We want the best for our musclecars, and we want products that will perform as well as they look, with strength to match. When confronted with the need for a longer driveshaft our question was simple, and QA1 had the answer.

It’s almost like the saying, “too much horsepower is never enough” – because too much technology is never enough, either, at least not where performance is a concern. A good solid steel driveshaft shouldn’t give you any problems, but a REV Series carbon fiber driveshaft will out perform both steel and aluminum.

It’s a tight squeeze, but a great fit and a lot easier to install than our previous steel driveshaft.

You can find out more technical information about the REV Series carbon fiber driveshafts at the QA1 website, complete with benefits, engineering and manufacturing processes, and test results.

Article Sources

About the author

Michael Harding

Michael is a Power Automedia contributor and automotive enthusiast who doesn’t discriminate. Although Mopar is in his blood, he loves any car that looks great and drives even faster.
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