With years of competition testing and multiple top place finishes, Spidertrax 40 Spline Ultimate Axle Shafts have quickly become the #1 front axle shaft among top rock crawling and rock racing teams. Stub Shafts are the outer shorter part of a front shaft assembly. These Stub Shafts are made using a single piece billet design manufactured from 300M and are heat-treated after machining. Unlike the 35 spline version, the 40 spline is retained into the unit bearing using a cap and bolt which are supplied with each stub shaft. Please note that Spidertrax 40 Spline Ultimate Stub Shafts are designed and intended to be used with Spidertrax Ultimate and Pro Series Knuckles and 40 Spline Ultimate Unit Bearings. These shafts are designed to be used with Dana 60 style universal joints, Gigglepin offer CTM and Branik and these can be found here. Overview Aerospace Quality We don’t use the term Aerospace lightly. Yes, the Pro Series Stub Shaft is manufactured out of the finest domestic military grade 300M on the planet, but there’s much more that makes it Aerospace worthy. We follow the strictest AMS Aerospace standards for our heat treatment, complete with double tempering, snap tempering, and cryogenic treatment procedures. Parts are sampled to ensure proper grain structure is achieved up to 0.0003″ 0.008mm from the surface, that’s a depth 1/10 the thickness of a human hair! In summary, you’re getting the best material and the best heat treatment on the market. Locked Turning 40° is impressive, but our axle shafts can turn 50°. It’s insane really, Ultra4 racers would often appear broken by the sharp steering radius, and it truly makes the difference when in tight conditions. However, when turned that tight, keeping the shaft happily in the centerline of the knuckle becomes difficult. On our Pro Series Stub Shaft, we’ve solved this problem by positively locking the shaft to the Ultimate Unit Bearing with a billet aluminum cap and cap screw. Keeping that stub shaft tightly secured not only helps with driveline vibration, but helps with overall strength of shaft and u-joint. 40 Splined A bit obvious, but the Pro Series Stub Shaft is 40 splined. It’s a size that makes perfect sense, especially when running properly paired inner axle shafts. When sized with the same shaft diameter as inner shafts, stub shafts end up taking the full punishment in your front end. The stub shaft should be stronger than an inner axle because unlike an inner axle, stub shafts have little room to twist, making them more prone to failure. An added bonus: with many drivers running 40 splined rear Ultimate Unit Bearings, having the same unit bearing up front makes for better serviceability and part simplicity. Manufacturing Perfection Spidertrax pride themselves on holding the tightest manufacturing tolerances in the business. They take their in-house manufacturing & engineering very seriously, and never cut corners for the sake of saving a few dollars. The Pro Series Stub Shaft is no exception to this rule. Shafts are manufactured, heat treated, and then returned to the manufacturing table to ensure those high tolerance dimensions are perfect. After heat treatment, we bore the holes for the u-joint caps in one single operation, and in that same setup fly cut the insides of both ears to ensure proper u-joint spacing.