ORIGINAL: nitroexpress
I have read posts concerning blown diffs in just about every model. The latest I've read concerned the new Mugen MBX6T. From time to time, all diffs are subject to damage. When I first started running my HF, I was blowing diffs much too often. But I learned the right way to build a diff. I have never blown any spyder gears and I can't remember the last time a ring and pinion blew. Point is, don't blame the manufacturer, learn to build a diff correctly. Without doing a step by step, the important things are.
1. shim the pinion close to the diff case. Manual doesn't show shims behind the pinion, but trust me, they are needed for full tooth contact.
2. shim new straight cut ring and pinions ''crunchy''. They will wear in smooth.
3. spiral cut gears from HB can be used. Their smoother from the start so don't go for crunchy, just tight.
4. lube the ring and pinion with a good, thick grease. High pressure wheel bearing grease; works fine.
5. check ring and pinion play from time to time. This can be done in vehicle.
Really, the HF's diffs are no better or worse than other brands. Those that say they are, don't know how to build a diff.
Hellfire uses cast metal gears for their diffs, Mugen uses hardened machined steel...so far on the forums there is 1 guy stripping a diff with a Mugen MBX6T..and honestly IMO if you strip a Mugen diff your either doing something wrong or you got a very rare factory defect..... I had a hellfire and I definitely know how to build a diff and I hate to say this here but they are not overly strong, as apparent by the dozens of not hundreds of people who have stripped them....They are the same diff material used in the Savages, which are horrible for chewing diffs... Sure proper building helps, but when your only working with cast metal there is only so much you can expect.....Machined steel is far tougher then cast metal..which is why RRP upgrades are so popular with the MT's.