![]() ![]() Here is a copy/pasted the email from Chase.ĭennis, flow the chart and monitor the oil temp on your D60 and use 85w140 Lucas oil I have also installed a digital temp gauge to monitor the oil temperature. It will be interesting to learn if any R&P gear makers are using it / recommend doing it, and so on.Īfter I received the Dana 60 from ESGS, Chase’s shop, he also emailed the flowing charts for gear oil change intervals. The above is just my initial take after looking into it today (and my general background in machine design). Ring and pinion gears are made in matched sets, so any shape change after manufacture would tend to make them not match anymore. As noted by others above, the OP's failed gear looks like a brittle failure (a brittle fracture tends to be shiny in the fracture face because it separated all at once), not a fatigue or wear failure (which would occur over time, and would tend to have little "wave marks" in its fracture pattern, or have dull areas which rubbed for a while until the rest broke free).Īlso, after most other heat treating processes, a gear face must be re-machined to eliminate the shape changes which naturally occur during the material property changes. It seems its main use is for increasing wear durability of surfaces. He got 5+ years on his last r&p? And considering an upgrade to a larger aftermarket axle would more worth it since there's strict testing and improvements over OE units for the intended offroad use.Ĭryogenic metal hardening (cool to -300F, then heat to +300F to stress relieve) - reading up on it, some of the remaining austenite (softer) is converted to martensite (harder), but most of the articles talk about doing it to gear cutting tools, not to the gears themselves, as while the resulting material is harder it also tends to be more brittle than the original (easy to deal with in a cutting tool, not as easy to deal with in a gear transmitting loads). ![]() I would say with the way drives, considering a cryo treated r&p would be worthwhile. We can adjust our driving until some unfortunate situation happens. I can make some similarities to the track when I think of the trail 4x4 guys gaining the experience on driving: choosing lines, proper acceleration control, left foot braking. Things naturally ensued and breakage occurred As I moved on to road racing, it became, "spend more on track time and less on parts." When things did break, both parties would eventually upgrade to the proper equipment. Up to a certain threshold it works fine, but they got bolder and bolder as their confidence level went up. My friends that drag raced (not play dress up :wink::browsmiley have cryo treated their transmissions in the past. Not like anything that could ever happen to an FJ when rock-crawling over a white-knuckle section. Note that many different types of failures are attributed to shock-loading, where a spinning wheel on a big-rig suddenly gained traction. It's written for heavy-duty rigs, but is 100% applicable to automotive failures. Here's an interesting failure analysis guide for differential gear teeth, transmission and axle shafts, etc. If you end up rebuilding this axle, make sure that the axle housing is VERY THOROUGHLY cleaned out to remove all metallic debris from the failure. If you had a metallurgist look at the fracture surface and take some Rockwell hardness measurements it would be possible to determine if improper heat treating was a factor. If the gear mesh and bearing preloads are not setup correctly when the diff is initially assembled, excess load can be applied to the outboard end of the ring gear teeth, leading to fatigue fracture. A gear tooth that is too hard will be susceptible to chipping, and a gear tooth that is hardened all the way through will be susceptible to fracture. A properly hardened gear tooth will have a very hard carburized outer layer, with a slightly softer, tougher inner core. A failure of the oil film will result in scoring and galling of the gear tooth faces, not broken teeth.īroken ring gear teeth are usually the result of shock loading, overloading, improper gear mesh setup, and/or improper heat treating.
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