I have this posted up on Highlifter, will lots of great feedback. Hope Ya'll find it usefull.
After my 2nd BF750 front diff failure, I figured I would share some of my knowledge. I can't take 100% credit here, another member here on Highlifter gave me the idea, I simply put it into action and made a write up.
The basic problem with the front diff is the spider gears. The spider gears ride on a cross shaft in heart of the front differetial. The issue is the clearnace between these gears and the cross shaft. There is next zero tollerence between the shaft and the gears (no, there are no bearing, its metal on metal). Under general riding condition this is not an issue, but with big pwoer, big tires, and watery crappy conditions, this can cause a failure. Bascally, the gears will seize onto the shaft due to lack of lubrication and overheating. This failure be as minor as having the front end in a permanant diff lock, or as serious as an actual differential explosion. I've scene both.
In order to correct this problem, we need to modify the cross shaft to allow oil to flow in between the gears, and the shaft. This can be done with either an angle grinder or a dremel. You just need to notch or grind the shaft slighly to allow oil to flow between the gears and the shaft.
This 1st picture shows happens to the cross shaft when the spiders seize up on it. you can see just how hot the shaft got before sezing
The 2nd pic is the diff torn down on the bench. The spider gears I'm referring to are the smaller ones
The 3rd pic is the fresh new shaft in the vice. Not the greatest pic, but you can see my cut. By the way, the cross shaft and new pins came to a grand total of $13
And finally the shaft cut out (last pic), and the spider gear in place. You can see, the basic idea is just to allow some oil to make its way in between the two. I cut the notch in both sides to be safe. Enjoy!
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