STRONGER, MORE EFFICIENT GEARBOXES

We make gearboxes and diffs stronger. Precision machining and setup, advanced processes including shot peening and isotropic super-finishing (ISF), and in-depth know-how lead to the strongest, most efficient drivetrains in Australia.

FAQ

What is shot peening?

Shot peening is a cold work process, where a workpiece such as a gear is bombarded with small spheres of metal in a controlled environment. When done properly (i.e. to recognised international standards), shot peening adds a uniform compressive layer to the surface of components, and in doing so drastically reduces the possibility of crack formation on a surface.

Shot peening has been proven to increase gear fatigue strength by 30% and in some cases 49%. Neat Gearboxes offers shot peening to SAE J2441 standards as part of our upgrade package, which along with our Isotropic Superfinishing (ISF), seriously improves the fatigue strength of transmission internals.

Check out our short video

What is Isotropic Super-Finishing?

ISF (often referred to as REM, although this is a proprietary name of a similar process) is another industry proven method for improving the fatigue-resistance of gears.

By chemically finishing the surface of metals down to extremely low roughness levels in specialised vibratory finishing machines, the workpiece is left with a non-directional mirror finish. This incredibly uniform surface reduces the likelihood of stress risers (re)occurring. SAE investigations have proven that ISF-treated gears last exponentially longer than those that have not been ISF treated. ISF can be used as a stand-alone process or ideally in conjunction with shot peening of gears.

Due to the very fine surface finish, gear friction is also greatly reduced, meaning your gearbox produces less heat and thus transmits more power to the wheels.

Neat Gearboxes are proud to have specialised ISF machinery in-house.

What causes gears to break?

Without wanting to sound too classroom-ish, what is important to understand when talking about gear strength is that almost without exception gear failure occurs due to fatigue cracks, not an inherent lack of overall strength (ultimate tensile strength). What this means is that improving fatigue strength and preventing cracks should be the main concern, or first step, when upgrading transmissions.

There are many contributing factors to the formation of metal fatigue cracks,  but by far the most common would be stress risers. Stress risers are almost always related to manufacturing process or inherent design weaknesses. They are the “weak link” in what otherwise may be an extremely strong component, and act as a catalyst for crack formation and amplify metal fatigue. Some examples of stress risers include surface disruptions such as casting flashes, forging seams, sharp edges left by machining processes, and other imperfections in the surface of metals from, for example, honing or grinding. Stress risers are more often than not the first point of crack formation and one of the most common reasons for gearbox component failure.

Factory-standard gears can be made remarkably strong by simply eliminating these stress risers. removing sharp edges, deburring forging seams, and polishing imperfections all reduce the likelihood of crack formation. How this is done, though, is extremely important. Some shops "polish" the gears with a die grinder or flapper disc. Based on in-depth research, this has been found to be counterintuitive. While there is occasionally a place for this before other processes, it should never just be left as-is. This is because the very act of grinding and deburring can penetrate the case hardening of the gears, and introduce more stress risers. Where necessary, Neat Gearboxes remove significant forging flashes etc, but only before shot peening and ISF so as to eliminate the possibility of the repair turning into a stress riser itself. The best ways to uniformly ensure that stress risers do not occur are through shot peening and ISF.

Another reason why gears break is when bearings fail. This can happen from misalignment, lack of lubrication, overheating or a combination of all of these factors. This is why we check critical dimensions such as case alignment and shaft runout in the course of our rebuilds. A transmission case that is even slightly misaligned will lead to excessive strain on the gear train and premature failure. We also pay careful attention to lubrication and make improvements to oil feeds and tracks to ensure that your gearbox is adequately lubricated. We can make recommendations in regards to temperature control, including Thermal Dispersant coatings, external oil coolers and pumps. We use and recommend only the best components and fluids.

Finally, Gears can break because of contaminants in the oil. Small metal particles that build up in gearboxes and diffs will eat through the hardened surface over a period of time. Filtration is very rare in standard gearboxes, so that is why we strongly recommend the use of Dimple magnetic drain plugs. We also recommend regular gear oil changes: once a year/20,000km for a street drive vehicle, and shorter intervals for motorsport applications.

Why is heat bad in a gearbox or diff?

Heat is a product of friction between meshing gears and is inevitable in a gearbox or differential. Maintaining heat at stable levels is crucial for a number of reasons. Most importantly, a correctly assembled gearbox or diff has finely adjusted preloads and clearances, which allow for the metal components to expand and contract. These tolerances are critical for normal bearing operation.   If components (and the gear oil) get hotter than they should; that is, hotter than the preloads and clearances allow for, parts may expand to the point where rotating components are no longer sufficiently separated for an oil film to form. This problem is amplified when the heat rises outside of the operating range of the gear oil being used. Metal rubbing against metal in most situations is not a good thing. Too much heat can cause massive damage in a gearbox or diff and this sort of damage will always require major repair and probably replacement of many expensive components, such as bearings, gears, pinions and hubs.   Another critical reason why heat is bad is because it actually robs power. Energy from the engine is transferred through the driveline (gearbox and diff) to the wheels. When the gears intermesh they create heat. That heat requires energy – and takes it from the kinetic energy of your engine. This is part of what is called driveline loss, and is one of the reasons why vehicles have more power at the crankshaft than the wheels.   Excessive heat is a symptom that your driveline is sapping too much power. The only real way to control this is to lower gear friction.

How can I control the temperature of my gearbox or diff?

By Isotropic Super-Finishing (ISF) your gears: Smoother surfaces create less friction. Heat in a gearbox or diff is a product of friction from intermeshing gears. Therefore, smoother gear surfaces create less heat. Simple. ISF is the best and most economical way to reduce heat output from gears, period. Neat Gearboxes offer ISF as one of our core services - nothing makes gears smoother.

By using quality gear oil and changing it regularly: Gear oil plays a crucial role of heat transfer and friction reduction in your gearbox and diff. There is a difference between good oils and bad, and there are different applications for those good oils. Neat recommends a range of quality gear oils for different applications, and recommends changing gear oil every 20,000km/1 year for road use. Vehicles used for racing applications may require gear oil changes much more frequently. Contact us if you are unsure of intervals.

By using a Thermal Dispersant (TD) coating on the housing: This helps the gear oil to transfer heat into the atmosphere via the housing/casing. See “What is Thermal Dispersant (TD) and why do I need it?

If your gearbox or diff is still running too hot after these modifications, the best way to control excessive heat is through using external gear oil coolers. They are a surefire way of preventing the excessive expansion of components in your gearbox, by keeping gear oil temperature within the specified operating range. Neat Gearboxes are currently working on putting together a number of gear oil cooler packages for popular makes.

What should I send you for the Peen and Polish Package?

While items vary between gearboxes, a general list may include:

• all gears including clusters
• all shafts
• hubs and sleeves
• shift rails
• forks (steel/iron only)
• shifter ends
• crown wheel
• spider gears and shafts
• shifter barrels

We only process ferrous materials - we don't peen or ISF brass or aluminium.

How should I package my gears for shipping?

This is crucial. We take a lot of care in packaging customers' gears for return shipping, but we often see them just tossed in a box and sent to us without much thought. Who knows what damage occurs during shipping - it may be the case that chipped teeth and cracks have occurred at this point.

We recommend wrapping everything in multiple layers of newspaper so that the components cannot knock against each other in transit. Then choose a box in which everything fits snugly, and fill up the voids in the box with more scrunched up newspaper or other filling material. Usually the parcel is relatively heavy for its size, so use plenty of masking tape to keep the box from coming apart. Often inserting another layer of cardboard inside the packing box is helpful if it seems a bit flimsy.

While you don't need to thoroughly clean the items (we hot tank and thoroughly clean them as part of the package), it's best not to send them dripping in gear oil, which might seep out into your cardboard box and weaken it, along with annoying the poor courier by stinking out her shiny new van.

How do I purchase parts and services from Neat Gearboxes?

We're moving towards an online purchasing experience, but for now you simply need to contact us and we can forward payment options to you, and inform you of stock availability.

Thank you for your patience while we develop this site.