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I agree this makes the most sense. Watching the vision the installation of the Clutch shaft and Needle bearings, they apparently would drop into the case, but it seems like the shaft would have to come out quite far for that to happen. In any case, there are no bearings in the case, so that is not the cause of the noise.If the needle bearings in the input gear pilot got loose, they would end up inside the transmission and probably be stuck to the magnet. There is no way for them to get outside without a big hole in the tranny case. The 420 is reasonable easy to work on, but I wouldn’t assume it is responsible for the noise If there is no obvious loose metal inside
Good comments. I appreciate it. I can take the scolding and will try try to avoid writing anything offensive in the future. I didn’t mean to be hurtful., it’s just that we aren’t all at the same skill level. I do more than I should…. Sometimes it gets me in trouble. Sometimes it works out. Things like a transmission are not a trivial item to experiment with, especially at my age. It’s too much work and expense if you screw up!I too would defend Pig, Onur, Steve and anyone else on here. Help, help diagnosing the MYSTERY noise ????? I will offer that my sm420 which has been used, rebuilt, used some more, behind 2 different engines, I've rebuilt it, & my tcase alot all by myself, not speaking down to you just offering that I have seen, felt, fixed the particular unit you have myself and if you are confident none of the roller bearings fell out then it is a mystery at this point. Given your descriptions it is odd but if it is running then time will tell. My 420 did this once in 20 years, after a long hard day in low range I pulled into the stage area at Rubicon to air up, put truck in Nuetral, got out to unlock hubs, heard same odd rattling sound, looked at my daughter, said " you bump the shifter ?" she says no, huh ?, as rattle gets louder I notice truck trying to move, shut it off. Never figured what caused it, never duplicated it. I honestly think there is just a wierd spot that if the shifter gets too it puts the collar between input & output shaft in a spot that it bounces off the dog teeth as they just barely rub , other than that I got nothin. The input and output bearings can wear and let the gap where that collar rides increase and there are some spring clips in the 420 little planetary thingy that goes under the collar that if not put in right will cause the collar to drag causing same noise. I forget what oil you said you were running , IMO put 90w in a 420. After hours long freeway runs you should smell the 90 wt and maybe see a little up out shift tower, and as I said before the shifter will rattle in 3rd never did it in neutral but if I recorded my shifter rattle and played it with your eyes closed I bet youd say, "Thats the noise I heard ".