recomer Posted May 18, 2014 Share Posted May 18, 2014 Moses, Here's an odd one for you. Referencing the attached picture what is the purpose of the 3 screws on the brake drum? This is on a AMC Model 15 axle on an Eagle. They appear to only attach the drum to the hub but why? Figuring the lug nuts and wheels would be doing just a fine job without those. I've read one other place that they were there for assembly purpose at the factory to keep the drums from falling off when the cars were overhead on the assembly line and really aren't required. You thoughts? Thanks, Rich Quote Link to comment Share on other sites More sharing options...
Administrators Moses Ludel Posted May 19, 2014 Administrators Share Posted May 19, 2014 Recomer...This is a traditional way to secure drums after service work and, yes, during vehicle assembly, too. Some manufacturers find it expedient to use push-on spring washers that get installed once, become a chore to pry or break off, and prove impossible to find on a Sunday at any auto parts retailer! I buy these push-on brake drum spring washers in bulk through Dorman sources, sized for wheel bolt studs. Typically you get a box of 25 (minimum). AMC apparently had an ulterior motive with these three screws. Note that the screws are not 120 degrees apart, so they index the drum in a specific position. If you install these three screws, the drum will always mount in the same position on the hub—and likely for good reason. See the balancing weights attached to the brake drum? Did AMC balance these drums with the hubs attached to get a true hub/drum balance? (This could account for the extra stamina and centering effect of these three screws versus spring washers.) The screws assure installation of the drum in the "correct position". This would be useful when balancing the wheel/tire assemblies, either off the car or on the vehicle, using a floor balancer. During wheel/tire rotations or a wheel rim replacement, the brake drum and hub would always be in balance. The tire/wheel, if also balanced correctly on a tire/wheel balancer machine, could be installed in any position on the wheel studs with reasonable balance assured. This is conjecture but sounds good, right? The obvious AMC aim was to get the brake drum on the hub in the same orientation every time. Moses Quote Link to comment Share on other sites More sharing options...
recomer Posted May 19, 2014 Author Share Posted May 19, 2014 Moses, A few of the other Eagle guys have replaced their drums with aftermarket ones (kind of hard finding OEM drums for this car anymore) and some have holes some don't (and weights on the aftermarket drums are non-existent). Problem I've noticed with these screws as I've replaced the wheels with ones from a Jeep Cherokee and they need to sit flat against the drums. With these screws there, the wheels are not flat against the drum. Factory AMC Eagle steel and aluminum wheels have indents for those screws. Rich Quote Link to comment Share on other sites More sharing options...
Administrators Moses Ludel Posted May 19, 2014 Administrators Share Posted May 19, 2014 Wheels must always fit flat against the drum and hub. Sounds like the AMC Eagle wheels have reliefs for the screws, likely cut at five positions to match the space between each of the wheel studs and these brake drum mounting screw points. As you share, these three screw heads do not sink below the drum surface. Perhaps screws with shallower heads are available, or these OE screw heads could be milled. If milled, would there be enough "bite" to secure the drum properly? An option would be "relieving" the XJ Cherokee alloy wheels to match the reliefs on the original AMC Eagle steel and aluminum wheels. To do this properly would require a milling tool operation. As a labor sublet to a machine shop, you need to see what this could cost. Guess it's a matter of how much you want Jeep XJ Cherokee wheels to fit—or the scarcity of replacement wheels for an AMC Eagle. Moses Quote Link to comment Share on other sites More sharing options...
recomer Posted May 21, 2014 Author Share Posted May 21, 2014 Moses, Just a follow up on this. Looked through the factory parts manual and they don't even list or show brake drum retaining screws. Service manual mentions removing them for servicing the brakes but no mention of replacing them nor are torque specs listed for them. Looked for comparison on the AMC 20 Axle and it shows the retaining screws on them but they are flush mounted heads. Rich Quote Link to comment Share on other sites More sharing options...
Administrators Moses Ludel Posted May 21, 2014 Administrators Share Posted May 21, 2014 Recomer...If the Model 20 axle hub/drum screws are available, will they fit flush on the AMC Eagle axle hubs and drums? Moses Quote Link to comment Share on other sites More sharing options...
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