Overfilled rear driveshaft with grease: now what? (7 Viewers)

[western flyer]

Was doing the baseline on a 96 cruiser the other night and wanted to force out the old grease... Worked well on the spiders and the front slip joint. Was working as usual on the rear slip joint, then.... POW! .... Grease pours out into the middle of the u-joint. Blew the seal- first time that's happened. Pretty sure that there was some very bad crud in there that prevented the old grease from continuing to come out through the slip joint. Probably still not a bad idea when I want to get water out on a truck I own and know, but I'm gonna alter my baselining procedure for sure.

Now what, indeed...

I had the half dollar-sized steel blank seal blow out on the F driveshaft on my 60 a couple decades back. I had it welded back on at a drive shaft service shop. They also serviced the u-joints and re-balanced the shaft at the same time.

 

[greentruck]

The 80 series driveshafts do NOT have a relief/purge hole in the yoke like most, so surplus grease will either breach the dust seal at the big end or force the shaft length to get longer and longer. This, it becomes a hydraulic ram.

I suspect the difference between OTR semi and other big trucks with a drain hole vs the LandCruiser sealed driveshaft is that you're expected to regularly dip your 4x4 in crud. A semi may get dirty, but rarely needs to worry about getting its lower parts soaked in muck. You don't want your slip joint sanded if you know what I mean

Obviously, another great piece of engineering that the LandCruiser is noted for.

 

[Beej]

How much grease came out (and is slung all over the bottom of the truck?) You may be fine..

Not very much unfortunately. I couldn't get a socket on the nuts though because of the angle and the wrench was trying to slip off.

What do folks use on those??

I assume a 14mm wrench. That's what I tried

 

[bloc]

For the axle end where you need to back up the nub/bolt.. I use two 14mm (actually a 14 and a 9/16" which is almost exactly the same size) combination wrenches, with the box end of each on a nut/bolt head.

Assuming they are 12-point you can arrange the wrenches where the bend on the box end points both wrenches the same direction (in terms of angle), and close enough that simply squeezing hard with a gloved hand pulls the wrenches together.. this will loosen a seriously tight bolt/nut).

For the transfer end I use the 14mm box end of the same wrench. Usually I get the axle end loose first.. then I can turn the shaft to get access to all 4 on the transfer output flange. Instead of getting up and putting the trans/transfer into/out of neutral/park to provide backup, I'll just line up the axle end of the driveshaft and put two of those bolts back through to back up the torque I'm applying to the xfer output nuts.

Sorry if this sounds complicated.. makes way more sense when you get under there with some reference.

 

[4runnerd]

4runnerd: do you mean you blew out that pressed in steel blank about the size of a silver dollar on the slip yolk?

Yep, it was the plug in the middle. I'ts still on the truck (I haven't been driving it), but I'll see if I can get a decent pic of it and post it up.

 

[Howard705]

And tight tolerances in the splines of the LC not just letting it just purge there. If you just pull the zerk and get the rear axle to compress in the easiest way-big bumps etc -it should come out. The driveshaft effectively becomes solid- it would hammer pinion and TC bearings along with ujoints-using all that for bumpstops. I believe that there are bulldozers that use this principle (or used to) of pumping up a hydraulic cylinder to tighten their tracks with grease.

 

[maxamillion2345]

And tight tolerances in the splines of the LC not just letting it just purge there. If you just pull the zerk and get the rear axle to compress in the easiest way-big bumps etc -it should come out. The driveshaft effectively becomes solid- it would hammer pinion and TC bearings along with ujoints-using all that for bumpstops. I believe that there are bulldozers that use this principle (or used to) of pumping up a hydraulic cylinder to tighten their tracks with grease.

Yes tracks on cat dozers work this way.

 

[4runnerd]

4runnerd: do you mean you blew out that pressed in steel blank about the size of a silver dollar on the slip yolk?

So, the driveshaft is still on the truck so I can't get a really good shot of it. But here's the culprit: a piece in the middle of the yoke that appears to be larger than a quarter, and smaller than a silver dollar in diameter. Looks like it blew down at the bottom right of the pic. I'm wondering about the color of the plug- is it made out of brass, or is that rust?

 

[nukegoat]

Yup overfilling makes your drive shaft a hydraulic locked ram. Made the mistake of over greasing before hitting the trail one day. Collapsed the pinion crush sleave in the rear 3rd and had to replace ring and pinion gears

I sort of doubt this unless you really didnt set up the gears right in the first place

 

[Malahki]

I sort of doubt this unless you really didnt set up the gears right in the first place

It was factory gear set. Never had previous issue. Diff was fine on the drive to the trail, then howled on the way home and had pinion slop. Driveshaft was locked up solid with grease when removed. Do you have a better explanation??

 

[nukegoat]

It was factory gear set. Never had previous issue. Diff was fine on the drive to the trail, then howled on the way home and had pinion slop. Driveshaft was locked up solid with grease when removed. Do you have a better explanation??

Id be curious to know how the tapered roller bearing in your diff lost the axial loading battle against the regular ball bearing in the xfer case... your rear diff was likely having issues already

 

[Malahki]

Id be curious to know how the tapered roller bearing in your diff lost the axial loading battle against the regular ball bearing in the xfer case... your rear diff was likely having issues already

It is possible that was just the straw that broke the camels back. But is it not the factory crush sleave that is the weak link in terms of axial loads. Not the tapered roller bearing. Hence the reason people upgrade with solid spacer crush sleave eliminators. If over torquing a pinion nut is enough to compress the crush sleave and ruin a gear pattern then surely cycling a suspension offroad with a solid driveshaft could do the same

 

[nukegoat]

It is possible that was just the straw that broke the camels back. But is it not the factory crush sleave that is the weak link in terms of axial loads. Not the tapered roller bearing. Hence the reason people upgrade with solid spacer crush sleave eliminators. If over torquing a pinion nut is enough to compress the crush sleave and ruin a gear pattern then surely cycling a suspension offroad with a solid driveshaft could do the same

When you overtorque a pinion nut you are literally clamping the two opposing tapered roller bearings together. In your scenario even if you hit the end of the pinion super hard and flattened the outer pinion bearing into a little steel donut youd just dislodge the inner tapered roller bearing from the race.

Make sense?

 

[mmml4]

Yep, it was the plug in the middle. I'ts still on the truck (I haven't been driving it), but I'll see if I can get a decent pic of it and post it up.

I'm no expert but it seems to me that if if the grease pushed the plug out then either the plug is suspect or the grease could not get past the splines and the seal/wiper. The seal /wiper has to let the old grease out so the new can get in if not it will be rigid as has been suggested.

 

[4runnerd]

I'm no expert but it seems to me that if if the grease pushed the plug out then either the plug is suspect or the grease could not get past the splines and the seal/wiper. The seal /wiper has to let the old grease out so the new can get in if not it will be rigid as has been suggested.

That's exactly what happened. This truck was not maintained well; the grease that came out of the u-joints was the worst I've ever seen (and you should have seen what came out of the transfer case- wow....). At various points there was grease that had become liquid, separated, solidified... It was bad. The old grease started to push out between the splines, and then it just stopped. The hydraulic pressure at a certain point just became too massive for the plug and it popped- but I think that is why the plug is there, instead of just being solid. It did what it was supposed to do and popped out in order to save the driveshaft. I've got the oil pump cover to do this weekend (you know how that is), and then I'll drop the driveshaft and see what I find inside and out. Hopefully I'll have time to do both. I'll post pics for everybody when I do.

The more I work on these, the more impressed I get with just how robust these things are. I've worked on 4Runners for years and love the way that the 1st and 3rd gens were built (the 2nd gens.... not so much....). But Toyota really outdid themselves with these trucks- it's really no exaggeration to assert that these are simply the best 4wd vehicles ever to roll out of a factory.

Ugh.... Like I needed another vehicular love affair....

 

[4runnerd]

Ok. So I got the driveshaft off, and the problem was that somebody had put what appears to be white lithium grease into the slip joint, and this clogged up the works.....
Anyway, I got it all cleaned up and this is what it all looks like.
First pic is inside the slip joint, then I took two pics from one side of the u-joint (one looking a little to the right and one a little to the left, if that makes sense), then two from the opposite side. The weird thing is that the plug looks ok, and when I was cleaning the inside of the tube out with carb cleaner, none leaked out. Put it back together and everything was good. I'll have to take a look at it again at some point because I discovered that the spiders could use rebuilding....