True, ive never seen a koyo bearing failure, Though I have broken trail jizz bearings. I had 25 year old koyos in my old rig on 40's, never beat on it too bad, but it made it though some of the harder trails in AZ without issue. BUT, I used a trail jizz rebuild kit in my 85's front axle, after 1000 miles and 6-7 medium trails on 35's the drivers upper bearing was broken and the TG tie rod ends were worn really bad for such little use... I now have marlins 25mm kit, arms, and rod ends on both rigs.
Anyone that I have seen in person break a trunion bearing was due to trail jizz bearings or steering arms, only seen one guy break an allpro 17mm pin, but he was running jap bearings and he BEATS hit rig... 250hp turbo motor and 37in sticky crawlers...
I am that Koyo bearing failure. Random as can be too. I went up to recover a budy who was stuck in snow on a fairly easy trail. one truck maybe 25ft in and then my buddy was 50 or so feet in. I put the thing in 4wd and rolled 5 feet and hear this weird sound. A friend of mine walking next to the truck said it was coming from the driver front axle. I told him to unlock the hubs and went in with 2wd(to give you an idea of how easy of a trail...no locker even needded and didnt air down) I pull both trucks out and coming back down the dirt road leading up to the trail is when i notice it. Driver top bearing distroyed. The noise we heard was the bearing pins rubbing the birf cause they fell in.
I got lucky and it only scratched the birf but driving the truck at a crawling pace down to where it could sit and go get a trailer it had smashed all the backing plate for the knuckle, tore up everything in side, took my tire from maybe a summer left to smooth and the passenger front almost the same....IDK if the bearing was the cause but it distroyed a tierod and broke part of the hub gear(not sure how that happened either) the truck had about 6,500-7k miles on the rebuild with all new parts. I daily drive it and am still learning the truck so i have been going really easy on it. most of the trails i had run were pretty close to stock friendly. Im on 37'' old mtr's btw
I picked up my kit yesterday. The parts look pretty good, Rebuild kit was a huge bonus, shipping times were great. I weighed my options putting this thing back together and took that plunge for a little piece of mind. Got my locked 3rd set up saturday, 30splines yesterday, new wheel bearings, the T.B.E kit and arp studs through out.....Now i need the hub gears and im set. Fingers crossed its a step in the right direction.
