Just as with Kleenex and Scotch tape are interchangeable with “facial tissue” and “transparent tape,” so too has the term “CVDs” come to be synonymous with the unique bell-shaped universal joint design that has become ubiquitous since it was first released in 1991. While “CVD” is now shorthand for all driveshafts with the bell-shaped look, the only genuine CVDs are manufactured by MIP. Strong, efficient, and easy to rebuild, MIP CVDs are the gold standard for RC driveshafts. MIP’s wide line of CVDs now includes lightweight Race Duty shafts, and at the other end of the spectrum, the topic of this review: the X-Duty heavy-duty driveshafts, currently offered for Traxxas VXL models, Slash and Slash 4X4 (as tested here), and the Vaterra Twin Hammers.
Every part of the X-Duty shaft is hardened steel. The 3/8” joints and 3/32” cross pins are shared with MIP’s 1/8 scale shafts.
Constructed entirely of hardened, high-carbon steel, the massive X-Duty shafts feature deeply splined telescoping sections and 5/8” joints with 3/32” drive pins, parts shared with MIP’s 1/8 scale shafts. The splines themselves are involute, which is worth Googling if you feel like nerding out, but the main thing to know is that involute splines are stronger than “square” or parallel-key splines. Not that the X-Duty shafts need the extra strength—they are Stout. The capital “S” is not a typo. Assembly and installation is simple and fast. I took my time and had the job done in 45 minutes. No modifications are needed to replace the stock Traxxas axles, the MIP parts simply take their place. In addition to their strength, the CVD design also offers the benefit of keyed stub axles, which eliminate the need for cross-ins to secure the drive hexes. MIPs steel hexes slide over flats on the axles and are secured by a setscrew. They’ll never slip or sheer a pin (since there is no pin), yet the hexes are easy to remove when needed. MIP supplies flangeless axle nuts with the kit, but I decided to re-use my 4X4’s stock flanged, serrated nuts for maximum grip.
Assembled. This is a front shaft, note the stepped stub axle.
The stock Slash 4X4 shafts are quite strong as far as not-failing goes, but the plastic parts can take on a visible twist that does not help their efficiency. Needless to say, the MIP shafts do not twist. Power delivery is instantaneous, and despite their considerable heft (85 grams per complete axle assembly versus 20 grams for a stock assembly), I noticed no difference in acceleration or “punch.” The laws of physics are immutable, so there’s a penalty somewhere, but I couldn’t detect it. After much running with the X-Duty shafts, both with 3S LiPo and the stock Velineon power system as well as Mamba Monster power, I can report no problems with reliability or durability. Frankly, none were expected, just as no one expects a tank to get door-dings. The only thing not to like about the X-Duty shafts is the price: depending on where you shop, outfitting the Slash 4X4 with a set of X-Duty shafts will run you $120-$150 dollars. Not cheap, but you get what you pay for with top-shelf materials, fully machined construction, and asteroid-proof durability. And what is made-in-USA worth to you? Cue the Lee Greenwood.
That’s the stock Traxxas axle on top, MIP X-Duty CV below. The black finish makes it easy to confuse the MIP shaft for plastic, but when you feel its heft you’ll know it’s solid steel.
Installed. Looks tough!
– Burly hardened-steel construction
– Easy to assemble and rebuild
– Looks hardcore
– Not cheap
Price (varies with dealer): $75 (pair)