Dodged a $$$$ bullet (1 Viewer)

[Godwin]

I had the small bolt that holds the tab that secures the idler shaft break at some time in the past and I have no idea when. This of course allowed the idler shaft to back out and that must have happened over many miles until last week when internal pieces were set free within the transfer case.

The issue became manifest with a nasty grinding noise with no load on the gears and strong vibration. At first I thought bearings in the transmission had gone bad but a quick look under the Cruiser revealed the problem. Luckily I was near home when this happened and drove the Cruiser there.

The forward thrust washer dropped and was crunched by the input and idler gears with the chipping of some teeth.

 

[Godwin]

Unsupported gears scored a couple of spots inside the rear half of the t-case. Also when the idler shaft dropped out of the front of the t-case most of the transmission oil flooded the t-case.

Over the past two weekends I pulled the t-case apart, replaced gaskets and o-rings, replaced the idler gear set, and put it back together.

Since I caught this early and did not drive far the transmission suffered no damage that I can tell. I've put > 80 miles on it and the transfer case is working fine. Because I had to reuse the input gear with chipped teeth and swapped in a replacement idler gear I'm getting some gear noise when coasting, otherwise no problems.

Dodging the $$ bullet. This did cost some money for gaskets and oil but in comparison this could have been very pricey with a transmission and transfer case replacement.

Had a little trouble reinstalling the hi/low gear set but by hanging a set of vice grips off the shaft I could manipulate the collar that the gears mesh with to get the gear set stabbed in.

 

[cruisermatt]

Ooof. Mines been making a horrible racket in neutral on deceleration for the past six months or so, and I drove it 300 miles today. Got the rebuild kit in hand, maybe it’s time to quit ignoring it and dig into mine too

 

[3_puppies]

good catch, I've seen the results when the shaft comes completely out, the idler was spinning and broke the big half of the case as the gear set hit the bottom.

 

[g-man]

I was wondering what you would find. Lucky in a way.

 

[Godwin]

The 2F has had a bit of an oil leak for a while and the oily residue plus sand and dirt accumulated on the skid plate. When the bolt broke and the retaining tab fell it dropped onto the gunked up skid plate and stayed there.

 

[g-man]

So now the million dollar question... how or why did the bolt break? I imagine if you over torque it ..that it would simply strip the aluminum threads in the housing and not wring the bolt. Was it the original bolt?

 

[cruisermatt]

So now the million dollar question... how or why did the bolt break? I imagine if you over torque it ..that it would simply strip the aluminum threads in the housing and not wring the bolt. Was it the original bolt?

That break does not look to me like it was over-torqued, I actually would guess that it was loose (or the threads were tight but the head wasn't holing the tab tightly enough) Possible it is not the original bolt and too long, bottoming out just before fully clamping the idler shaft retainer? Or missing a washer? That could do it. I see residue differences indicating a washer on the tab, though.

 

[g-man]

If the retainer was not tight to the housing then it could turn to a point that one of it's corners jammed against the idler shaft causing the retainer to put pressure on the side of the bolt. Have images of the imprint of the retainer on the housing?

 

[Godwin]

So now the million dollar question... how or why did the bolt break? I imagine if you over torque it ..that it would simply strip the aluminum threads in the housing and not wring the bolt. Was it the original bolt?

That is the question. This is the original bolt at 33 yrs old and 435,xxx miles. I rebuilt this case at about 200K, then a second time at ca. 400k or ca. 30k miles ago. This second round I installed FJ62 gears.

Bolt was not over torqued nor did it seem to be overly loose. I was able to extricate the stub with vice grips.

 

[Godwin]

That break does not look to me like it was over-torqued, I actually would guess that it was loose (or the threads were tight but the head wasn't holing the tab tightly enough) Possible it is not the original bolt and too long, bottoming out just before fully clamping the idler shaft retainer? Or missing a washer? That could do it. I see residue differences indicating a washer on the tab, though.

Original bolt and washers. Perhaps it did loosen some over time. I did not use locktite on it when installed and I'm thinking a little of the blue stuff might be a good idea.

I still have the broken bolt. Want to see it? I can drop it in the mail.

 

[cruisermatt]

I’m going to put some medium strength threadlocker on mine for sure now.

 

[cruisermatt]

I still have the broken bolt. Want to see it? I can drop it in the mail.

As much as I’d like I don’t have x-ray vision (I wouldn’t be looking at bolts if I did )
There are labs you could send it to that just look at broken bolts all day, I have no idea what sort of expense comes along with that process though. Most likely not worth it.

 

[g-man]

Is it possible the idler shaft bearings seized on the shaft causing the shaft to turn? What kind of shape were they in? Any damage to the shaft? I can imagine a shaft turning under great pressure from the gears would break that bolt and push the retainer off.

 

[cruisermatt]

Is it possible the idler shaft bearings seized on the shaft causing the shaft to turn? What kind of shape were they in? Any damage to the shaft? I can imagine a shaft turning under great pressure from the gears would break that bolt and push the retainer off.

Idler shaft looks fine in 2nd/3rd pics in first post.

 

[Godwin]

Idler shaft and bearings in good condition. I've put ca. 200 miles on it so far with no problems.

 

[Spook50]

Ouch. Eventually I want to rebuild my tcase and put in a McNamara gear for the sake of preventative maintenance (no infamous "clunk" when shifting into and out or reverse, but almost 300K miles on it either way). I'm not looking forward to that task.