buckz6319

what causes this nut....
on the rear companion flange to come loose even though it is staked from the factory?...I have asked this question to many transmission shops and searched this forum for the answer but haven't come across a legit answer.I would like to know because this nut was loose on my 95 4runner A340H transmission and the nut was still staked from the factory......I also would like to know what type of damage can be done to any of the components of the tranny or drive shaft when this nut comes loose and stays loose for a long time until it is discovered
Thanks for any input

corax

I've heard of this happening (though rare) to a few other people . . . I couldn't even begin to guess the why or how of it though. As long as the splines that the flange are installed on are OK, there should be no internal damage.

My suggestion -> reinstall with a new nut and use some loctite on it

buckz6319

thanks for the reply...I had this happen on my tranny and was just curious about why this nut came loose.I think the P.O. who I purchased this 4runner from didn't know this nut was loose either.I only discovered it being loose after dropping my rear drive shaft to replace the u joints and there was the nut I just put my finger on it and it wiggled and was almost off the shaft.I'm just wondering if the transmission problems I'm dealing with were a result of this nut being loose for a long time?

akaphilly

is that photo the before or after picture? maybe they didnt hammer the notch correctly from the factory. since u could move it by hand i would assume that. i doute it would do cause any tranny problems.

buckz6319

thanks for the reply.....the pic is from a donor tranny before I disassembled it.....but the nut on the rear companion flange of my 4runner tranny looked exactly like the one in the pic above and didn't appear to have a defective dimple..and I really don't know if this nut being loose causes some transmission damage?...... it is possible I think, but to what extent i'm not sure...

corax

maybe the nut itself was not loose, but the shaft the flange slides onto had too much endplay due to internal trans problems?

buckz6319

corax...thanks for the reply...and I think your on to something with that comment!...I have not considered that but you may be right....I had internal transmission problems before I found the loose nut and maybe the nut being loose was because of the transmission problems I'm having internally and I do have a lot of slop in the transmission when rotating the companion flange from side to side by hand also when putting the transmission in the O.D. off position letting on and off the gas I can feel a lot of slack like something not tight inside the tranny

tc

Because your output bearing is toast. The nut is still in the same position it was from the factory, but there isn't as much pressure on the backside any more.

I just discovered mine is the same, not looking forward to doing the bearing replacement.

Matt16

Lol, that is so simple, why did no one (myself included) think of that?

buckz6319

tc thanks for the reply please explain why my output bearing is toast?,,,this is the bearing you are talking about?
I know that I thought the same thing so I replaced it and even the one I took out that I though was bad looked ok no signs of heat damage or worn or pitted areas that what's so puzzling after changing out that part I have discovered my tranny hydraulic section planetary gears may be going bad

tc

Well, because that's the only thing it can be. The nut didn't turn, and I doubt you crushed the companion flange, so the only thing left is the preload on the bearing.

How hard was it to replace the bearing? Can you do it with the tcase in the truck?

buckz6319

tc just to answer your question about the bearing you have to remove the rear drive shaft from the companion flange and remove the speed cable then un stake the nut (30mm) then remove the nut and thick washer then unbolt the front t-case section and the bearing is installed in it's own race kinda like a wheel bearing except the bearings are much larger and I think the bearing is ther just to support the rear shaft or the shaft just rides on it, there is no preload on that bearing but I'm no expert on this kind of stuff so if I'm wrong some one please let me know.Here is a link to my tear down
https://www.yotatech.com/forums/f116...t-case-156307/
I hope the link works for you?

abecedarian

shouldn't there also be a bearing on the other end of the shaft?
inner and outer, so to speak?
is that bearing tapered or flat (I think that would answer the other questions)?

drew303

Couldnt it have to just not been torqued on from day one and staked?

95RunnerSR5

well mine was simply loose. how i don't know but it definitely backed off some because where it was staked was not lined up in the groove on the splines.

buckz6319

here is a pic of the front t-case section notice the bearing around the rear output shaft
if I remember correctly it's a flat bearing not tapered....and notice the size and shape of the bearings they are not round sphere like they are long and round if that makes ant sense.. and this is a pic of the back side of that case

I don't have a close up pic of the back side but I'll try to take a pic of it tomorrow if I get time

abecedarian

it may well be straight (needle-ish) bearings. but if the output shaft is held captive in the trans, I'd be willing to be there's a bearing in there too. It may well rely on the cut of the gears to thrust the shaft towards the rear and thus not need tapered bearings, only thrust washers or similar.
I'm not much of a transmission man, so I may well be wrong.

buckz6319

you know this is a good subject and I'm enjoying the comments and hope that we'll be able to find the reason for this nut coming loose and so far I think we are just beginning
could that nut possibly loosen if some one mistreats the tranny?....

buckz6319

well I have a question ....sense there are course threads on that 30mm nut could vibrations cause it to loosen because there maybe some clearance between the inside threads of the nut and the outside threads of the shaft?
but I know the reason the stake is in the nut is to keep it from backing off but for some reason it does back off even being staked

Hypoid

Interesting, I had the companion flange on the front section of my two piece rear drive shaft that is held on with a staked nut, be loose and cause a nasty driveline clunk. I thought it was the carrier at first, had to dissasemble and drop the driveshaft to see what the problem was. (The carrier was also on the way out.)

Beats me why *that* was loose.