 |
Jay Miller at 4 Wheel Parts pulled the diff cover and checked the backlash of our ring-and-pinion prior to disassembly. It turned out to be a little sloppy, probably from wear. The gears get worn in a pattern and if it is changed it will more than likely cause gear whine. For this reason the backlash should be returned to the same setting when reassembled with the new spool. |
The Dana 60 in this Jeep had been built with 35-spline shafts. On this vehicle it borders on overkill. Some believe a spool will decrease the stress placed on the shafts, especially on the street. The occasional jerk and bang from an automatic locker can fatigue axleshafts. Others feel that the constant twisting stress of a spool is more likely to snap a shaft. Small shafts with low spline counts and spools (or lockers) dont mix well. If your vehicle is a heavyweight, has lots of horsepower, or is abused regularly, consider upgrading the shafts at the same time. |
Removing the carrier from a Dana axle requires the use of a case spreader or a long prybar. This is because the bearing preload (and backlash) is adjusted by the use of shims under the bearings. |
Miller chased the threads of the ring gear with a tap before cinching it down to the spool. Thread locking compound from the original installation can sometimes gum up the threads. The bolts were then coated with fresh thread locker and torqued to spec. |
This contraption makes pulling the case bearings off a snap. Even with this tool they can sometimes be damaged. It is a good idea to change the bearings when doing a gear or carrier swap. We used new bearings on our spool but the original shims were pulled and measured to give an idea of which shims to start with when setting the backlash. |
The case bearings can be pressed on as shown or a hammer and bearing race-installer will work. We ordered a complete install kit for our Dana 60 from Summit Racing. The kit included carrier and pinion bearings, pinion seal, pinion nut, shims, ring-bolts, gear marking compound and a gasket for the cover. |
Thread-locking compound is used on the bearing cap retaining bolts and they are torqued to spec. The Summit diff cover has feet that are adjusted to pre-load the bearing caps. This keeps the housing from deforming under load and can increase the life of the gears and bearings, especially in trucks that tow heavy loads. The covers are available for GM 10-bolt and 12-bolt, Ford 8.8, and Dana 60 axles. The 60 cover will also work on a Dana 70. |
The cover is made from aluminum so it dissipates heat better than the original steel cover. It also holds more gear oil and has a drain plug. Worries about breaking the cover on a rock vanished when we saw how thick it was. Silicone is used to seal the cover and the bolts are torqued to 30 foot-pounds. The bearing cap preload-bolt-threads are coated with silicone to prevent leaks and cinched down to 10 foot-pounds. |
Maybe we've gone insane, or maybe we were never sane to begin with. The popping and clicking of automatic lockers and the complexity of selectable lockers has pushed us further over the edge.
Simplicity, that's what we want. Something so simple that there is no way for it to fail, and no way for it to clunk since it has no moving parts. We're talking about a spool. This wonderful but feared component replaces the carrier with one solid piece that holds the axleshafts together...no matter what. Many have said that spools shouldn't be used on the street because of adverse handling, and some believe that a spool will make it difficult to turn. We found otherwise. Our Jeep with a Detroited Dana 60 rear axle proved to be a handful on the road. Shifting the manual transmission also meant involuntarily shifting lanes at times.
Automatic lockers have up to a one-quarter turn of slop at the pinion built into them. This is needed for them to function properly. It causes a clunk when you hit the gas from a coast and another clunk when you let off. A lurch to one side or the other usually accompanies the clunking. Predicting which way the vehicle will jerk becomes a difficult and tiresome game, especially in a lightweight short-wheelbase vehicle.
The Detroit also causes the tires to chirp in tight quarters (U-turns, and parking lots) under throttle. Don't get us wrong, the Detroit has worked flawlessly, but we were ready to try something else.
We called Summit Racing to get a spool, a complete installation kit and a cool aluminum diff cover that pre-loads the bearing caps. We had all our parts installed at a local 4 Wheel Parts Performance Center. Spools are normally sold to the racing crowd for their strength, durability, and reliability. We wanted one for the same reasons, plus less clunking and few lane changes. We traveled more than 2,000 miles with the spool in the Jeep and we found that it handles much better on the highway and in traffic (no automatic lane changes).
However, driving through the neighborhood with a spool will get you more than a few sneers. When making tight turns the tires squeal since a spool allows no differentiation. This can be kept to a minimum by the use of aggressive mud-type tires. Off-road the spool performed no different than the Detroit.
Some believe a Detroit will let the vehicle turn sharper since it can release. But if you are on the throttle, the Detroit will stay locked--just like a spool. Spools are available for Ford 9-inch and 8.8, GM 10-bolt and 12-bolt, Chrysler 8-3/4, and Dana 60 axles. They are much cheaper than limited slips and lockers and stronger than welded diff gears. So is a spool the ultimate locker? That depends on if youre willing to put up with the slight acceleration in tire wear and chirping. For us, the answer is yes.