Dana 60 vs. GM 14-Bolt Axles - 4-Wheel & Off-Road Magazine

Enough already. Everywhere we go, we hear the same argument: The Dana 60 is the best rear axle. No, the GM Corporate 14-bolt is best. My full-floater can whip your full-floater. Like to see you try. Fine, let's hit the trail!

131 9902 Dana 60 Vs Gm 14 Bolt rear Axle Photo 31612846

We talked with axle experts all over the country, including those who make, sell, repair, and build up axles, and those who supply aftermarket parts such as lockers, gears, and upgraded axleshafts. We tried to stick to the facts, just the facts, but it wasn't always easy because brand loyalty is fierce even when it comes to axles. Dana 60 rears have served under Dodges, Fords, GMs, Internationals, and Jeeps. GM Corporate 14-bolts, of course, came from the factory only in Chevys and GMCs.

We'll try to separate the beef from the fat axlewise, starting with a couple of general descriptions and then a comparison of the axles component by component. Hopefully, you'll be able to weigh the pros and cons of both the 60 and the 14-bolt for yourself and pick your own king of the hill.

Ratio 60 14-bolt 3.00-3.08 no no 3.21-3.33 no yes 3.42-3.45 no yes 3.50-3.55 yes no 3.70-3.73 yes yes 3.89-3.92 no no 4.09-4.11 yes yes 4.56-4.57 yes yes 4.86-4.89 yes yes 5.13-5.14 yes yes 5.29-5.38 yes no 5.86-5.89 yes no 6.00-6.50 yes no PhotosView Slideshow The Dana 60s and GM 14-bolts we're comparing are both full-floating rear axles. Full-floater rears are easily identified by protruding hubs with a circle of nuts or bolts securing the axle flange. There are also semifloating Dana 60s and semifloating 14-bolts. Semifloat and full-float 60s are similar, but the semifloat 14-bolt is entirely different from the full-float 14-bolt. The semifloat 14-bolt has a 9 1/2-inch ring gear while the full-float has a 10 1/2-incher. For an overview of all the 60s-semifloat, full-float and front 60-see "Guide to Dana 60s," Mar. '97. For this article, 14-bolt means the GM 10 1/2-inch full-floater and 60 means the full-floater rear Dana 60. Also, Spicer and Dana are the same company; Spicer 60 and Dana 60 refer to the same axle design. One huge difference between 60s and 14-bolts is that there is great variation among 60s whereas the 14-bolt has had only one minor change. According to Drive Train Industries' (DTI) Tony Cosslett, the 14-bolt's inner pinion bearing, bearing cage, and crush sleeve were upgraded in 1988. That's it. The housing and other internals were unchanged. On the other hand, Dana made three basic versions of the full-float 60. The most common 60 has 30-spline axleshafts that are 1 5/16 inches in diameter. Heavy-duty 60s with 35-spline, 1 1/2-inch axles are rare in stock 4x4s. Some late-'60s Dodge 4x4s and late-'60s to mid-'70s Ford 4x2s have 16-spline, 1 5/16-inch 60s. Dana made many different variations of the 1 5/16, 30-spline 60 for Dodge, Ford, GM, IHC and Jeep. Many parts don't interchange, so 60s are generally more complicated to shop for and build than 14-bolts. Despite their smaller size, 60s can be fitted with much lower ring-and-pinion ratios than can 14-bolts, according to Reider Racing's information reproduced here. If you want 3.07s or 3.31s in your 60, we've been told it's possible to use Dana 61 ring-and-pinions on a Dana 60 carrier. But we haven't seen it done, so check it out for yourself. The 14-bolt pinion is not only bigger than the 60's, it also rides on three bearings compared with two in the 60. The 14-bolt's extra bearing supports the gear end of the shaft by riding on a shaft extension (arrow). The 60 has no such extension. However, Dynatrac's Jim McGean point out that the 14-bolt's third bearing is necessitated by the axle's design and that the 60's design actually performs just as well with one less bearing in the real 'wheeling world. Dana/Spicer tries to ease identifying 60s (and other axles too) by casting the model number into the axlehousing as shown and stamping the build date and bill of materials number into the axle tube. The bill of materials number can be cross-referenced to a Spicer book that lists all the part numbers and specs for that particular axle. For example, we have the Weatherly Index 094 X510-8 DSD (March, 1990) from Spicer that covers 1967 to 1978. The problem is, not all Dana 60s are actually marked as promised. For example, our '72 Dodge W200's Dana 60 rear has no cast-in model number or stamped bill of materials number.
The 14-bolt is more massive than the 60 in almost every way. The 60's ring gear is 9 3/4 inches in diameter (left); the 14-bolt's is 10 1/2. In two major ways, the 14-bolt is actually more comparable to the Dana 70 than to the 60. Both the 14-bolt and the 70 have 10 1/2-inch ring gears, and the 70's normal axleshaft diameter is 1 1/2 inches, which is close to the 14-bolt's 1 9/16 inches. So why not compare 70s and 14-bolts instead? Because when you look at a 3/4-ton 4x4, you're looking at either a 60 or a 14-bolt. The 70s ran on 1-tons and very rarely on 3/4-tons and are less common. There are also fewer lockers and gears available for them. The 14-bolt's bigger pumpkin provides less ground clearance than the smaller 60's. And 60s are available in high-pinion versions too, whereas 14-bolts are not. High-pinion 60s were used as front axles and are custom-built to work as rear ones. The high-pinion design, in which the pinion shaft enters above the axle centerline, becomes important to correct driveline angles in some short-wheelbase 4x4s with short driveshafts. The 60's have one big advantage over 14-bolts when it comes to traction-adding devices. You can get an ARB Air Locker for your 60, but there's not one currently available for the 14-bolt. Detroit Lockers and Lock-Rights are available for both axles, but you can't get a Detroit Tru-Trac posi or an Auburn unit for either one. Here's where the bigger-beef argument really tachs up. The 14-bolt axleshafts (left) are 1 9/16 inches in diameter and have 30 splines. The majority of 60 shafts are 1 5/16 inches in diameter with 30 splines. That's the same size shafts that are found in rear Dana 44s. Heavy-duty 60s have 35-spline, 1 1/2-inch shafts (same as Dana 70s), but on the used market they're as scarce as truth in Washington. And contrary to some opinions, the Dana 61 is not a heavy-duty 60. According to Dana's reference book, full-float 61s ran only in mid-'70s Ford 3/4-ton 4x2 pickups and vans. They all had 1 5/16-inch axles, not 1 1/2-inch. The major difference was their higher gear ratios (3.07, 3.31) compared to stock 60s. We've heard tales of retrofitting 1 1/2-inch axles into 60s that came with 1 5/16-inch shafts, but we've never seen it done and Dynatrac's McGean is skeptical. He cautions that the spindles would have to be bored out so much that they'd be too thin and weak to bear the weight of the 4x4 and the stress of tough trail work. But custom-axle companies, such as Moser Engineering, can supply 1 5/16-inch super-beef alloy replacement shafts that match or exceed the strength of stock 1 1/2-inch axles. Both DTI's Cosslett and Dynatrac's McGean report that they see very few shock-related failures (such as heavy application of 'wheeling torque) to either 60 or 14-bolt diff internals. Due to the shim setup used to set the ring-and-pinion in 60s, older 60s tend to wear the thrust surface in the case. If the wear gets bad enough, it can cause excessive ring-and-pinion play, leading to more problems or failure. Sometimes 60 cases must be remachined to repair the thrust surface. This is only a concern when looking at high-mileage, used axles. The same sort of thrust wear occurs in the 14-bolt, but it wears against the lock ring, which can be adjusted to compensate.
One big problem with salvage-yard 14-bolts and 60s is that most of them served under work trucks and were severely thrashed before they were retired. However, Boyce Equipment sells primo used and rebuilt 60s and 14-bolts from government surplus. And Dynatrac offers all-new Dana 60s (44s and 70s too) in high-pinion or standard versions. All Dynatrac 60s (as shown here) are fitted with new 35-spline, 1 1/2-inch axleshafts and feature Dana-70-spec spindles, wheel bearings, and wheel hubs. They can be fitted with disc brakes as shown and five-, six-, or eight-lug patterns. Dynatrac axles carry a 12-month warranty. Both 60s and 14-bolts came factory-equipped with big (and very heavy) drum brakes. Aftermarket disc-brake conversions are available for both axles from companies such as Dynatrac (60 and 14-bolt), Off Road Unlimited (60 and 14-bolt), and T.S.M. (14-bolt). Discs save considerable unsprung weight and increase stopping power.