What happens when you over grease a slip yoke?? (1 Viewer)

[Taco2Cruiser]

Secondly, I did not say the tech was wrong, I only gave my story of how the issue started. I had other users tell me that over greasing was bad, also combined with the humming noise I was getting while I was driving back after over greasing, then the drips of transfer case oil that completely stopped after I relieved the pressure in the prop shaft.

The technician said the leak is unrelated, but I am very confident that the extra pressure put too much load on the bearing and caused some flex that damaged front output shaft seal, possible pushed it too much in and caused it to rub with the bearings or something like that.

Tech said is wasn't related, you said you were confident it was. Not to put words in your mouth, but how else can that be taken?

I said it was POSSIBLE that the over greasing caused damage to the seal, I never said it was definitive.
My experience was provided as a story that could help others who might have had similar experiences put the strings together and form an opinion.

What if desertLC was the kinda guy that then started actively telling people you’ll blow up your cases if you overfill your prop shafts.

Read what I said. "What if desertLC was the kinda guy that then started actively...."

I didn't say you were, I was saying what if someone was like that. It was reflected to radman on the opposing view that he mentioned.

If you pay close attention to the post you will see that the only information given was the story and my personal opinion, I never claimed anything was definitive or as hard fact.

I think you need to exercise your own advice. It looks like you had some criticism directed your way, and you have now become emotionaly defensive. I know you were telling a story, the issue I brought up wasn't that. I was using it as an example that stories can quickly evolve into facts. That is why I said the whole "what if you were like that." Which brings me back to the first sentence in this comment, pay close attention.

This is why it is so hard to actually point issues in public forums, because this happens. A lot of it is because you don't have inflection of tone, and we need to brush off a lot because I highly doubt any of us are malicious toward each other. It's just the limitations of text.

So I say again, I really don't mean to be a jerk. But it's tough to offer opposing views, in a 100% text environment. Which is why I can honestly say that I write, then deleted 8 posts for every one that I post.

 

[OregonLC]

@Taco2Cruiser yeah, don't stop posting and don't be afraid of inserting a corrective point.

I think the key for any of this is to explain the process. That allows for discussion and learning. And if there's debate, it's debate in the context of what is actually happening rather than just 'do this and it will break'.

I will also say that just because you work in a shop doesn't necessarily mean that you're any more or less knowlegdeable than others. I've spoken with Toyota dealership mechanics who are complete idiots. Similarly, there are shade tree mechanics with an engineering mindset who are really, really good at diagnostics and repairs. This is absolutely NOT pointed at @Taco2Cruiser, just a reference that a job title isn't the defacto final authority. Similar with vendors here. Some are good, some are... less than good.

 

[sleeoffroad]

FWIW, we have seen it on more than one instance where the front shaft on a 100 was over greased on the slip and it caused the front pinion on the differential to loose it's preload and eventually the bearings fail. We have also seen it that bad that the front pinion locked up and the pinion actually broke. It is not just hear say, you have to be caareful to not overgrease the front slip.

 

[Taco2Cruiser]

@Taco2Cruiser yeah, don't stop posting and don't be afraid of inserting a corrective point.

I think the key for any of this is to explain the process. That allows for discussion and learning. And if there's debate, it's debate in the context of what is actually happening rather than just 'do this and it will break'.

I will also say that just because you work in a shop doesn't necessarily mean that you're any more or less knowlegdeable than others. I've spoken with Toyota dealership mechanics who are complete idiots. Similarly, there are shade tree mechanics with an engineering mindset who are really, really good at diagnostics and repairs. This is absolutely NOT pointed at @Taco2Cruiser, just a reference that a job title isn't the defacto final authority. Similar with vendors here. Some are good, some are... less than good.

Oh absolutely agree to not trust someone based on their position. Or as the a great line from my last career went, "there's only one person I trust, and that's my mom... but I aint too sure about her."

Story time. I was in college, going green to gold, and got my ASE A1-6 and A8 for fun (never took a class). Because the Army paid for my college (History/English dual major), paid me E-5, and I had another 100% scholarship, I was sitting pretty good. But because I was bored, I went to a dealership to be a tech. 8 months later I was the master tech. That shows you how inept everyone was. So never trust blindly, trust... but verify.

 

[Taco2Cruiser]

FWIW, we have seen it on more than one instance where the front shaft on a 100 was over greased on the slip and it caused the front pinion on the differential to loose it's preload and eventually the bearings fail. We have also seen it that bad that the front pinion locked up and the pinion actually broke. It is not just hear say, you have to be caareful to not overgrease the front slip.

Awesome feedback and based on your experience, I'd like to bounce some ideas off you.

The 100 front diff was pretty crappy from my experience stated above. First with the two pinion design, then when I started seeing 4 pinions "making bad sounds" as a customer stated long ago. I asked Toyota back then and they said that with the upgraded front diffs, there was some production issues with maintaining tolerances during assembly.

So i've also seen my fair share of 100 front diffs fail too, but I've seen very few diffs fail outside of that and some rear 06-08 8" e-lockers that Toyota said was the same situation for failure.

Now with the fact that the rear prop shaft can also compress from the live axle making it worse to suddenly crush the crush sleeve more, but I didn't see many of those fail.

Have you seen a situation where everything was perfect. Someone over greased a prop shaft, and then it blew a diff immediately?

Or were these situations where a customer comes in, the diff is bad, and... well, I don't know how you could trace it back to the prop unless maybe there was grease everywhere and the customer thinks that was what did it. I mean, a properly greased prop still requires the zerk to be removed, and a pry bar to compress the shaft and kick enough grease out to clear the studs. So not like that would be an indicator. Side note, do you guys do routine maintenance? Like oil changes, brake jobs?

I don't know if you guys build your own diffs, or if you once did, or you still do. But we both know that it takes a LOT to crush a crush sleeve.

But I've sure had a bunch of seals fail, because Toyota doesn't make the best seals in my opinion. Example, Marlin Crawler had to make EcoSeals to fix Toyota issues.

 

[OregonLC]

FWIW, we have seen it on more than one instance where the front shaft on a 100 was over greased on the slip and it caused the front pinion on the differential to loose it's preload and eventually the bearings fail. We have also seen it that bad that the front pinion locked up and the pinion actually broke. It is not just hear say, you have to be careful to not overgrease the front slip.

Does the front behave different from the rear because there's no articulation to push the grease down the shaft? And whatever pressure is there ends up being trapped forever until it relieves itself by forcing the pinion bearing to fail.

 

[DesertLC09]

there is a large number of land cruisers where I live, speaking in terms of percentage of cars on the road. The tech said it was very uncommon for that seal to leak. The leak started on the same day of overpumping the grease and three months later the seal failed. I still see a correlation of the two events. Thats why I was very confident, and still am, that they are related.

 

[bloc]

@DesertLC09 I’m not disputing your experience, but I don’t see how a seal could be made to fail without the bearing also being trashed. For the front output shaft to be pushed into a position where the seal would fail, surely the bearing would be damaged.

And yet, a new seal fixed it.

Either way.. I think we can all agree this board is a mix of OCD offset by ignorance, with some carelessness spiced up by epic attention to detail and mechanical aptitude.

I totally see how overfilling a rear shaft then sharply compressing the suspension *could* damage things, due to the physics involved, but haven’t dealt with it myself. I still think it is good practice to warn people of the potential danger of doing this wrong. Should someone immediately rebuild their transfer case and diff if they made this mistake? Not necessarily.. but the point still needs to be made that this should be avoided.

 

[Taco2Cruiser]

Either way.. I think we can all agree this board is a mix of OCD offset by ignorance, with some carelessness spiced up by epic attention to detail and mechanical aptitude.

 

[sleeoffroad]

The 100 front diff was pretty crappy from my experience stated above. First with the two pinion design, then when I started seeing 4 pinions "making bad sounds" as a customer stated long ago. I asked Toyota back then and they said that with the upgraded front diffs, there was some production issues with maintaining tolerances during assembly.

Most breakages we see if from shock loads where the pinion gears break / or teeth are broken off the ring gear and strips the pinion bearing.

Now with the fact that the rear prop shaft can also compress from the live axle making it worse to suddenly crush the crush sleeve more, but I didn't see many of those fail.

We have never seen that on a live axle. Either because the pressure is not constant or the compression force of the driveshaft is enough to force the grease past the seals on the slip.

Have you seen a situation where everything was perfect. Someone over greased a prop shaft, and then it blew a diff immediately?

Not immediate but happened on a road trip right after owner did maintenance on the truck and greased the driveshaft's. On discussion on how it was done, it was stated "greased until the shaft expanded a little".

Or were these situations where a customer comes in, the diff is bad, and... well, I don't know how you could trace it back to the prop unless maybe there was grease everywhere and the customer thinks that was what did it.

Those cases are mostly breakage when they don't know what happened. Not pinion bearing failures.

I mean, a properly greased prop still requires the zerk to be removed, and a pry bar to compress the shaft and kick enough grease out to clear the studs.
So not like that would be an indicator. Side note, do you guys do routine maintenance? Like oil changes, brake jobs?

DIY mechanics that are used to old school greasing of shafts does not do the above.

I don't know if you guys build your own diffs, or if you once did, or you still do. But we both know that it takes a LOT to crush a crush sleeve.

Yes, we do 100's off diffs and I agree on the crushing of the crush sleeve. What happens is there is so much pressure transfered to the inner pinion bearing that it either starts spinning on the pinion or the rollers lock up. Once this happens and metal is ware away the diff looses it's pinion preload. Now changes of this happening is probably less on a brand new bearing vs. something that has 100k miles on it and probably pitted or has some wear on it.

But I've sure had a bunch of seals fail, because Toyota doesn't make the best seals in my opinion. Example, Marlin Crawler had to make EcoSeals to fix Toyota issues.

Not sure what those seals are, but we sold Marlin's HD seals for the front of the 80 axles and had a bunch of failures so we stopped selling them. We would have to agree to disagree on seals. Most seal failures we see on truck is either mud / water crossing related due to "grinding paste" on the seals when owners don't properly clean the underside of the truck, or insufficient maintenance on differentials / transfer cases where the fluid is contaminated.[/quote][/quote]

 

[scottm]

Have you seen a situation where everything was perfect. Someone over greased a prop shaft, and then it blew a diff immediately?

Yes. Meticulously maintained low-mileage 80, actually cracked the transfer case casting pulling out of the driveway, after greasing the driveshafts to extension. Since then he and I have dropped our driveshafts to grease the splines. If you've ever watched a frame machine bend a truck frame, notice how small those hydraulic pistons are. About the size of our driveshafts, which become hydraulic cylinders when filled with grease.

100 driveshaft was backwards from the 80, required a lot less greasing to get grease into the splines, less chance of filling the cavity with grease, so I just gave it a few pumps every oil change. I did drop the shaft and look inside a couple times to be sure. I haven't crawled under my 200 yet, my house is under construction and I don't have a garage at the moment to get out of the snow. But I'm worrying about that first oil change and what might be damaged by a dealership mechanic.

This kind of debate is exactly what worries me, even experienced mechanics insist they can just blast the grease into that slip joint. Two of my 4 Cruisers were damaged by dealerships during oil changes, one got a new engine, the other a new torque converter (long story).

 

[Lester did that]

Not a mechanic. And while the info about greasing all of the the different drive shafts from the past 30 years is interesting, and led me down a rabbit hole of the evolution of the driveshaft, I don't care about a 80 or 100 series but if I am ever on Jeopardy and that is a category I'm good now.

So exactly how much grease is too much?

What is "over greased"? If the joint moves 1/128" is that too much? 1/16" or 1" too much? Till it squeezes out? What is the point when you know it's enough? When the full tube is empty? The mechanics of it seem very simple. If you look at the diagrams or tear one apart it just seems you would really need to put a lot of grease in beyond common sense to cause any damage. OCD and or Waddington effect yes. It just does not make sense to me why any manufacturer would dial in a grease zerk that has to be filled with such precision and can not be measured. They ain't transmissions.

 

[Taco2Cruiser]

Yes. Meticulously maintained low-mileage 80, actually cracked the transfer case casting pulling out of the driveway, after greasing the driveshafts to extension. Since then he and I have dropped our driveshafts to grease the splines. If you've ever watched a frame machine bend a truck frame, notice how small those hydraulic pistons are. About the size of our driveshafts, which become hydraulic cylinders when filled with grease.

100 driveshaft was backwards from the 80, required a lot less greasing to get grease into the splines, less chance of filling the cavity with grease, so I just gave it a few pumps every oil change. I did drop the shaft and look inside a couple times to be sure. I haven't crawled under my 200 yet, my house is under construction and I don't have a garage at the moment to get out of the snow. But I'm worrying about that first oil change and what might be damaged by a dealership mechanic.

This kind of debate is exactly what worries me, even experienced mechanics insist they can just blast the grease into that slip joint. Two of my 4 Cruisers were damaged by dealerships during oil changes, one got a new engine, the other a new torque converter (long story).

Sucks. I guess since this conversation keeps coming up, I will just say that any front prop shaft is pushing on a t-case in a "twisting motion" while it pushes rearward. If you over fill the rear prop shaft, it will push in line with the entire driveline, so it would be much harder to crush the rear of a t-case inward. But pushing the front prop shaft output on the t-case backward, well... much easier to crack something. With an IFS truck, compression of the front prop shaft is obviously much less than on a solid axle truck.

I'm not advocating to grease shafts until they blow grease out of them, I personally pump grease until I see it move a millimeter, then I stop and i've never blown a prop shaft ever. Which is also how the Toyota FSM, and Toyota Certification Program states it the proper way.

I've seen literally hundred of early trucks ('79-95 pick ups) pump grease in their front shaft to excessive levels, then go pound rocks. Working for a bit in a Toyota dealership where everybody is clueless, customers to techs, never even heard of an over greased prop shaft breaking a diff or t-case. The only way front prop shafts broke anything was a rock bending them, in my experience. That was a few wheeling groups in the southeast and we ran Tellico a majority of the time.

I'm sure we are on the same page of how to properly do something. Anything I've said above was more like, "yeah you shouldn't, but I haven't seen an issue." I've just had a different experience than you, but I will take your experience and add it to my list of "you shouldn't" things I tell people.

(this next paragraph is not intended to discredit you, far from it. I absolutely believe everything you are saying). Honestly, I spend most of my time these days, when it comes to fixing, fixing what other shops and DIYer do to their truck on an electrical or simple bolts not tightened focus. I've replaced a 200s t-case from it cracking in half, but that was from an ARB skid that bolts to the t-case itself. That truck hit a rock just right and the force cracked it since the t-case itself was the mounting point. Replaced a few timing tensioners, fixed some spark plug tube leaks, not the o-rings at the top, but where the tube is pressed into the block. Bunch of starters, radiators, and brake jobs, but as preventive/routine. And a good amount of inner tie rods. But i've yet to see a prop shaft issue. Maybe I'm lucky, or maybe customers are?

 

[kcjaz]

Getting ready to lube the drive shaft and other chassis components so I read the FSM and searched the forum and found this thread. Good info. I've always believed, based on what I have been told that it is possible to over grease a drive shaft and potentially something could break or get damaged if over done. I also know that no grease is no good either. So even after reading this thread, how much grease is too much is not crystal clear to me. Based on what the FSM says, and knowing that there are 1000s of 4x4 vehicles that get greased or not greased at quick lubes and dealerships where technicians may or may not know what they are doing yet examples of damage seem to be few (not zero), IMO the range between not enough and too much is very large. If precision was necessary, the FSM would be more specific.

So, my plan is to hit the u-joints with one pump and the middle one with a couple pumps in the middle looking for movement on the sliding part (like the FSM says). Then drive it and look for grease sling and clean up.

It does make sense to me to drop the prop shafts, remove the zerks and use a pry bar to compress them to clear the old grease and make sure you don't have to much new grease but I would guess that this is almost never done and most of the time, its OK. Who (besides @Taco2Cruiser) does this or verifies their mechanics do? I'm sure there are a few.

 

[bloc]

Getting ready to lube the drive shaft and other chassis components so I read the FSM and searched the forum and found this thread. Good info. I've always believed, based on what I have been told that it is possible to over grease a drive shaft and potentially something could break or get damaged if over done. I also know that no grease is no good either. So even after reading this thread, how much grease is too much is not crystal clear to me. Based on what the FSM says, and knowing that there are 1000s of 4x4 vehicles that get greased or not greased at quick lubes and dealerships where technicians may or may not know what they are doing yet examples of damage seem to be few (not zero), IMO the range between not enough and too much is very large. If precision was necessary, the FSM would be more specific.

So, my plan is to hit the u-joints with one pump and the middle one with a couple pumps in the middle looking for movement on the sliding part (like the FSM says). Then drive it and look for grease sling and clean up.

It does make sense to me to drop the prop shafts, remove the zerks and use a pry bar to compress them to clear the old grease and make sure you don't have to much new grease but I would guess that this is almost never done and most of the time, its OK. Who (besides @Taco2Cruiser) does this or verifies their mechanics do? I'm sure there are a few.

You'll need more than 1 pump in the spiders. There is really no risk in overgreasing them other than making a mess, as they don't compress during normal use. Keep pumping until you see clean grease coming out of the seals after the old/dark stuff. Then wipe it as clean as you can. I use a screwdriver and medical-gloved finger to get most of it off.

For the yoke.. I'm about as OCD as they come and see no need to pull the shafts and compress them, personally. Your mention of millions of prop shafts running around just fine without this step supports my method, at least in my head. I'm pretty sure this method will get me to the 400k mile target that I have for mine.

 

[radman]

I agree. Go nuts on the spiders, and be patient for the prop movement.
I was watching the prop like a hawk while I was pumping, but then it moved a lot at once. I would mark the current location of the prop with blue tape and then do 2-3 pumps of the grease gun - then wait several seconds before you continue (or even a minute if you’re really ocd).

 

[Lester did that]

It does make sense to me to drop the prop shafts, remove the zerks and use a pry bar to compress them to clear the old grease and make sure you don't have to much new grease but I would guess that this is almost never done and most of the time, its OK. Who (besides @Taco2Cruiser) does this or verifies their mechanics do? I'm sure there are a few.

If your up for it is the way to go especially if you have higher miles (120k+) or questionable service records. But if you are actually greasing the prop on a regular interval, not beating it like some or constantly submerging it in water it's a touch of overkill to remove the shaft every time you grease it. Unless you want some alone time in the garage.

I wouldn't get too OCD about overfilling it. Just pump till it moves a bit. If nothing happens for a while and then it jumps 1/2"-3/4" don't sweat it. It will be fine. Now if you pump pump and pump and grease starts coming out of the slip junction your going to have a problem. You really have to put a lot in and not use common sense to over do it.