Comparative Results
So far, we've discussed numerous differences between the two packages featured in this story (one of them being the state of completion each axle assembly is shipped in). But we also decided to do a bit more detective work to compare and contrast the two kits even further. Though by no means an apples-to-apples comparison-remember, each of these companies offers several different rear-axle assembly packages compatible with 4th-gen F-bodies-we'd like to give you, the readers, as much information as possible in hopes of steering you in the direction of the "right" axle assembly for your application.
First off, there is the issue of mass. Though aftermarket axle assemblies are far stronger than the F-body's stock 10-bolt, the added meat required to support this strength does incur a weight penalty. More weight to drag around means reduced acceleration; plus, an axle assembly is unsprung weight, so a more massive one will affect suspension behavior. With that in mind, we decided to weigh the stock rear and compare it to the Strange and Moser units. With all rears at the same stage of assembly-no brakes and no fluid, torque arm variations not factored in-the breakdown is as follows (keep in mind that these are dry weights, so differing fluid capacities can factor in to actual running weight):
| TABLE OF REAR-AXLE ASSEMBLY WEIGHTS: |
| Rear | Dry Weight | Change from Stock |
| GM 10-bolt | 154.6 lb | - |
| Strange S60 | 222.8 lb | 68.2 lb |
| Moser M9 | 205.6 lb | 51.0 lb |
Secondly, one thing you may not think of with regard to added mass is that it can also come into play in power loss. More massive axles and gears require more energy to get up to speed, adversely affecting rear wheel horsepower. Other factors, like internal friction, play in as well, of course. This friction may be attributable to bearing properties, along with axle fluid viscosity and flow behavior, and can also be influenced by geometric concerns like the diameter of the ring gear (which is intertwined with the properties of how the ring-and-pinion mesh). Though the physics involved may merit a full-blown engineering discussion in a future issue, for now we decided to do before-and-after testing of both of these project cars on TTP's Dynojet for a quick comparison. Our results are:
| TABLE OF REAR-WHEEL HORSEPOWER/TORQUE CHANGES: |
| Car | Rear | Old HP/TQ | Rear | New HP/TQ | % Loss |
| Jensen Camaro Stock | 3.42 | 412.5/390.0 | Strange S60 | 3.73 397.9/376.0 | 3.5/3.6 |
| Werner Trans Am Stock | 3.42 | 441.2/432.3 | Moser M9 | 3.70 436.6/428.6 | 1.0/0.9 |