A differential can be externally visible as a unit consisting of one mechanical unit, but a number of smaller parts are internally involved to conduct power between the wheels. Differential repair or rebuild can include replacement of worn or damaged internal gears or other components. Here is where a nest kit can come in handy, i.e., internal nest kits.
Internal nest kits are also available in the automotive aftermarket, primarily in applications of a specific differential and are often linked to the non-positraction or non-limited-slip carriers. Their contents and compatibility precisely rely on the design of the axle, as well as the differential.
What Is an Internal Nest Kit?
An internal nest kit is usually created to substitute internal differentials gear components chosen instead of the whole differentials gear set.
A kit can include spider gears, side gears, thrust washers, cross shafts or other minor items depending on the application. Differentiated designs can differ greatly in the contents.
As an example, there are internal nest kits listed as aftermarket to fit certain applications of Dana and GM differentials, with some kits specific to certain spline counts, axle setups and non-posi carriers.
This renders distinguishing the differential prior to ordering so crucial.
Why Internal Components Wear
The gears within a differential are working under recurring loads whenever the car accelerates, turns or has heavy loads. In the course of time, the normal wear may apply on the gear teeth, thrust surfaces and other internal parts.
Wrong lubrication, or pollution or undue stress in the drives can also be a cause of internal wear.
A broken internal gear can result in the following symptoms: clicking, knocking or an abnormal sound of the driveshaft, but other parts can cause similar issues. An accurate check is thus handy before making a decision on what parts should be replaced.
Internal Nest Kit vs. Complete Differential
It is not the same as replacing a whole differential, but only an internally-gear kit.
Provided the size of the housing, carrier, and large components can be serviced, a replacement of particular worn-out internal components can be relevant to the repair. A full different assembly, however, substitutes a considerably bigger fraction of the driveshaft.
This option would be determined by the state of the existing parts, the nature of the damage and the cost and complexity of reconstruction of the unit.
A technician can easily check the carrier, gears, cross pin, bearings among others and decide whether it is worth making a sense to do in-house repair.
Fitment Is Extremely Important
The particular error that most people make when buying internal nest kits is to think that differently named yet similar-looking differential components can be used interchangeably.
Different axle families can use different gear dimensions, spline counts, carrier designs and internal arrangements. Even vehicles using the same general differential family can have variations based on model year, drivetrain configuration or axle specification.
The present parts lists reflect the specificity of certain categories of these kits. Some GM kits, such as axle sizes, spline numbers and non-posi are listed.
The axle model, type of differential, number of splines and usage must be checked before the ordering.
What Else Should Be Inspected?
Distributing the new inside gears is not always the solution to all issues inside a differential.
The technician can also check the bearings, races, pinion, ring gear, carrier and cross pin, thrust washers and seals during a rebuild. In case these parts are overly worn, it can be a partial solution to replace the internal gears only.
Checking lubricant to find out if it is having metal particles or other internal damage should also be done. Discovery of debris in the differential oil might be a sign that more parts require scrutinizing.
Choosing the Right Parts for a Rebuild
A parts replacement with the internal wearing component in the internal gear can be offered by the appropriate internal nest kits, which would require less replacing the entire assembly.
Nevertheless, the important thing is correct identification. To be sure of what to buy, check the differential model, axle usage, spline design and the vehicle is an open, non-posi or limited-slip design.
An inspection can then be carried out on whether an internal gear kit would be suitable or a more costly complete overhaul on a differential would be needed.
Since the way the overall differential functions depends on small internal components, the choice of the correct kit and its installation based on the respective specifications are significant as well in a successful repair of the driveshaft.