I spent the last couple of days working on installing my Wavetrac differential and wanted to post a bit of information on what I found. While we can debate the merits/deficiencies of the Wavetrac against a clutch type diff, this post is only intended to note installation findings. This is due to a lack of any real installation instructions available from Wavetrac, either in the packaging or through phone conversations.
The package contained the differential and one shim and a disclosure recommending the use of the stock gear oil and a warning that using an incompatible oil would result in a warranty cancellation. Motul Gear 300 and Motul Gear Competition were the only non stock recommended oils. The intended use of the included shim is not noted anywhere and a phone conversation with tech support did not answer my questions.
The stock diff had a shim between the bearings and the bearing faces on both sides. These shims were carefully noted from which side of the ring they came from to reuse on the Wavetrac in the same position.
After removal of the stock diff, I wanted to determine the differences, if any, between the stock diff and the Wavetrac as far as critical dimensions. These dimensions are the distance from the bearing stop opposite the ring gear mounting face to the ring gear mounting face in addition to the distance from the ring gear mounting face to the bearing stop on the same side.
Determining these dimensions with sufficient precision would be difficult without some high end tools. I have access to a precision granite measuring table and a Mitutoyo QM-Height 350 precision height measuring system that is repeatable and precise to 0.00001”.
To measure the stock diff I placed the differential on the bearing face opposite the ring gear face on top of some precision machining blocks that were sitting on top of the granite table. Using the Mitutoyo, I then set as my zero datum the ring gear mounting face and then measured to the bearing face on the same side of the ring gear.
Noting the final height measurement, I removed the stock diff from the machining blocks and placed the Wavetrac on the blocks and measured it. The Wavetrac differed from the stock diff datum by 0.001” and -0.07” from the ring mounting face to the bearing face on the same side.
The one shim included in the package measured 0.07” and it was then clear it needed to be installed in addition to the original shim between the bearing face and the bearing on the same side as the ring gear mounting surface.
Re-measuring with the shims placed accordingly show the same 0.001” datum difference with a 0.0002”difference from the ring gear mounting face to the bearing/shim face on the same side. Seeing that I decided it was precise enough to not change backlash and bearing preload enough to require additional shimming so I installed the bearings and differential into the transmission. After installation into the transmission, everything feels really good.
The machine quality and finish of the Wavetrac is really good with my only complaint being the total lack of installation information.
A couple of pics;
Linear Mode
