Updated warning on greasing the rear drive shaft
- Thread starter IdahoDoug
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As I see it the main issue is the use of heavy greases such as the synthetics. Good old bearing grease travels right up the tube and out the splines lubricating everything. Why else do you think there is a zirk on there in the first place.
The synthetics have worked out great as a fluid but as a grease I think there are issues with it's heavy nature.
The synthetics have worked out great as a fluid but as a grease I think there are issues with it's heavy nature.
flintknapper
Apparently, some have a seal that fits so tight that it will not allow grease to pass by, (barring any dried grease etc. in the splines) and others like mine will. I don't know what to attribute this to but I think the idea that it could cause a problem with the T-Case or the diffs. is a very real possibilty.
Personally, if mine do not allow the extra grease to escape around the seal then I will disassemble the driveshaft and cut a few small slots in the seal until it does!
The benefits of having an "ultra-sealed" driveshaft are quickly outweighed by the potential damage to the other members of the driveline. Just my thought.
sjcruiser said:
Apparently, some have a seal that fits so tight that it will not allow grease to pass by, (barring any dried grease etc. in the splines) and others like mine will. I don't know what to attribute this to but I think the idea that it could cause a problem with the T-Case or the diffs. is a very real possibilty.
Personally, if mine do not allow the extra grease to escape around the seal then I will disassemble the driveshaft and cut a few small slots in the seal until it does!
The benefits of having an "ultra-sealed" driveshaft are quickly outweighed by the potential damage to the other members of the driveline. Just my thought.
- Thread starter
- #25
Rod, did you mean to say your shaft will spit grease out of the zirk - out of the fitting you're pumping into? Just curious.
I agree that its ridiculous to have a zirk fitting, yet have to disassemble the part to find out what's going on. But I have to say I'm glad I did.
Since posting my results, the shaft has been happily spitting a bit of fresh purple grease out the splines. So, it may well be that the grease at some point hardened up in that fibrous "hairy" seal and prevented subsequent grease from getting through properly. It now seems to be working as designed though I completely agree with the comment by sjcruiser regarding the potential damage of a seal being too weather tight.
I'd have to check my log, but somewhere around 48,000 miles my transfer case began making a very faint high pitched noise that I recognized as a bearing going. Before you all fall over with coronaries, it is not the typical 80 whirring/high pitched whistling that they all make. I've driven literally dozens of 80s and they all make a very different characteristic "big gears in oil" sound. Anyhow, there was a very good Toyota Master Mechanic in town at the time and I had him drive it and he could not hear it. Being the stubborn type, and having connections at Toyota I had the transfer case replaced as a warranty item and am glad I did. The mechanic cracked it and found a bushing or bearing on the rear shaft output was damaged and overheated, plus discovered micro cracks in the aluminum case around the rear output shaft.
When he told me this, I immediately flashed to the clicking sounds I'd sometimes heard as I pumped the rear shaft full of grease, and the time I had trouble getting the truck out of Park after I'd greased the shaft. Why I never made the connection is a mystery, but clearly the rear shaft on my truck has always been too tight and/or the grease in the spline seal dried early on. I am the owner who first revealed this issue on 80'sCool many years ago and this adventure is why I started advising caution on greasing the rear shaft.
Removing the rear shaft is obviously fairly simple, and it will be revealing for those of you who also cannot seem to get grease to come out the seal like you'd expect. Since my truck is totally stock, I figure you all have the identical shaft and seal, so there's every reason to believe you have the same issue.
As to the question above by Rod and his damage on the Rubicon - may I speculate and guess that you greased your shaft shortly before departure? If so, lots of rear compression and bouncing may well have been the culprit if the splines were unable to shed grease. Or, even if they were as you'll presently read. A hand grease gun can generate extremely high PSI. Add to that the extreme leverage (guessing at 10:1) the rear suspension movement exacts on shaft length and it's anybody's guess how much pressure you're putting on the transfer case bushings and bearings.
Here's a very simple test that will take you 5 minutes. Take a wrench and unscrew the zirc fitting in question while you're truck's unladen and sitting on a level surface. If grease comes out under pressure then you've got your answer - grease is not getting down the splines well. I did this almost a week after greasing and the 'tail' of grease that came out was about 4 inches long. That's why I opened it up.
It's a strange situation. If you have a basic understanding of hydraulics, you'll understand when I asked the questions at the end of Post #5 above. To wit: If the splines are full of grease, and the cavity (the cylinder, if you will) is full of grease, the shaft (the piston) cannot move in EITHER direction very far before the incompressibility (or the opposite) stops it - fractions of an inch at best before force rises dramatically. I left an air cavity in there which is easily compressible and can also be a vacuum when the shaft elongates. And I'll never grease the shaft via the zirk again as it will displace the air and I'll essentially have a solid shaft again.
How do custom shaft makers handle this issue - they are designed to go through far more travel, right?
Your mileage may vary.
DougM
I agree that its ridiculous to have a zirk fitting, yet have to disassemble the part to find out what's going on. But I have to say I'm glad I did.
Since posting my results, the shaft has been happily spitting a bit of fresh purple grease out the splines. So, it may well be that the grease at some point hardened up in that fibrous "hairy" seal and prevented subsequent grease from getting through properly. It now seems to be working as designed though I completely agree with the comment by sjcruiser regarding the potential damage of a seal being too weather tight.
I'd have to check my log, but somewhere around 48,000 miles my transfer case began making a very faint high pitched noise that I recognized as a bearing going. Before you all fall over with coronaries, it is not the typical 80 whirring/high pitched whistling that they all make. I've driven literally dozens of 80s and they all make a very different characteristic "big gears in oil" sound. Anyhow, there was a very good Toyota Master Mechanic in town at the time and I had him drive it and he could not hear it. Being the stubborn type, and having connections at Toyota I had the transfer case replaced as a warranty item and am glad I did. The mechanic cracked it and found a bushing or bearing on the rear shaft output was damaged and overheated, plus discovered micro cracks in the aluminum case around the rear output shaft.
When he told me this, I immediately flashed to the clicking sounds I'd sometimes heard as I pumped the rear shaft full of grease, and the time I had trouble getting the truck out of Park after I'd greased the shaft. Why I never made the connection is a mystery, but clearly the rear shaft on my truck has always been too tight and/or the grease in the spline seal dried early on. I am the owner who first revealed this issue on 80'sCool many years ago and this adventure is why I started advising caution on greasing the rear shaft.
Removing the rear shaft is obviously fairly simple, and it will be revealing for those of you who also cannot seem to get grease to come out the seal like you'd expect. Since my truck is totally stock, I figure you all have the identical shaft and seal, so there's every reason to believe you have the same issue.
As to the question above by Rod and his damage on the Rubicon - may I speculate and guess that you greased your shaft shortly before departure? If so, lots of rear compression and bouncing may well have been the culprit if the splines were unable to shed grease. Or, even if they were as you'll presently read. A hand grease gun can generate extremely high PSI. Add to that the extreme leverage (guessing at 10:1) the rear suspension movement exacts on shaft length and it's anybody's guess how much pressure you're putting on the transfer case bushings and bearings.
Here's a very simple test that will take you 5 minutes. Take a wrench and unscrew the zirc fitting in question while you're truck's unladen and sitting on a level surface. If grease comes out under pressure then you've got your answer - grease is not getting down the splines well. I did this almost a week after greasing and the 'tail' of grease that came out was about 4 inches long. That's why I opened it up.
It's a strange situation. If you have a basic understanding of hydraulics, you'll understand when I asked the questions at the end of Post #5 above. To wit: If the splines are full of grease, and the cavity (the cylinder, if you will) is full of grease, the shaft (the piston) cannot move in EITHER direction very far before the incompressibility (or the opposite) stops it - fractions of an inch at best before force rises dramatically. I left an air cavity in there which is easily compressible and can also be a vacuum when the shaft elongates. And I'll never grease the shaft via the zirk again as it will displace the air and I'll essentially have a solid shaft again.
How do custom shaft makers handle this issue - they are designed to go through far more travel, right?
Your mileage may vary.
DougM
Landtank, you saying that synthetic wheel bearing grease would go into which of your categories? Synthetic or bearing grease? I've been using amSPOIL red wheel bearing grease on my d-shaft, so am now curious.
In response to IdahoDoug's questions-
Yes, when I lubed the rear drive shaft (overlubed more like) I had a spaghetti stream of grease coming out of the zerk fitting. By the time it quit is was probably a foot long (though obviously it broke multiple times in the process). And yes, I lubed up everything the night before I headed up to the Rubicon (
), so that is likely what caused the leak in the xfer tailstock. I have repair parts, including a new bearing, on the way from Cruiser Dan, so I should know a bit more about what damage might be there fairly soon. After reading previous posts I removed the zerks from both drive shafts yesterday morning before heading to work. No grease came out and there was about 1/4 of grease visible on the exposed portion of the male spline on both driveshafts. I've taken special care to exercise the suspension over available speed bumps (and the occassional curb) and have noticed that the bump/clunk on starting and stopping has nearly disappeared, though I can get it to occur sometimes. I'll put the zerks back in tomorrow morning to see if has any effect on the noises. And if time permits this weekend I will pull and disassemble both driveshafts to see if I can tell what is going on. Hopefully I haven't damaged anything more than the rear xfer seal..... 
Yes, when I lubed the rear drive shaft (overlubed more like) I had a spaghetti stream of grease coming out of the zerk fitting. By the time it quit is was probably a foot long (though obviously it broke multiple times in the process). And yes, I lubed up everything the night before I headed up to the Rubicon (
), so that is likely what caused the leak in the xfer tailstock. I have repair parts, including a new bearing, on the way from Cruiser Dan, so I should know a bit more about what damage might be there fairly soon. After reading previous posts I removed the zerks from both drive shafts yesterday morning before heading to work. No grease came out and there was about 1/4 of grease visible on the exposed portion of the male spline on both driveshafts. I've taken special care to exercise the suspension over available speed bumps (and the occassional curb) and have noticed that the bump/clunk on starting and stopping has nearly disappeared, though I can get it to occur sometimes. I'll put the zerks back in tomorrow morning to see if has any effect on the noises. And if time permits this weekend I will pull and disassemble both driveshafts to see if I can tell what is going on. Hopefully I haven't damaged anything more than the rear xfer seal..... 
subscibe bump, 2 many step #6's to understnad now 
There are two "bumps" I've noticed, one on stopping and one on starting. The stopping bump occurs just after the vehicle has come to a stop. I originally thought it was a loose caliper but those checked out fine. After I lubed the driveshafts the stopping bump pretty much went away. As suggested elsewhere it could be driveline wind up releasing.
The starting bump occurs about a second after accelerating from a complete stop. A relatively slow acceleration does not seem to induce it. It feels like a hard shift but it occurs before the shift to second (I've kept it in first to verify this and it still occurs). It just occurred to me that it also could be driveline wind up releasing. I'll try to pay attention today and see if there is ever a case where I get both a "stop bump" and a "start bump". If so, it's probably not driveline wind up.
The starting bump occurs about a second after accelerating from a complete stop. A relatively slow acceleration does not seem to induce it. It feels like a hard shift but it occurs before the shift to second (I've kept it in first to verify this and it still occurs). It just occurred to me that it also could be driveline wind up releasing. I'll try to pay attention today and see if there is ever a case where I get both a "stop bump" and a "start bump". If so, it's probably not driveline wind up.
>> ... see if there is ever a case where I get both a "stop bump" and a "start bump". <<
That reminds me, I need to lower my bump stops.
-B-
That reminds me, I need to lower my bump stops.
-B-
flintknapper
yeah, everybody will point and say...what a zerk off!
e9999 said:
yeah, everybody will point and say...what a zerk off!
- Thread starter
- #33
Heh....
If the grease is coming back out the zirk fitting, then it should be replaced as the ball isn't maintaining pressure as it should. This assumes you weren't putting enormous pressure on the grease so that it somehow overpowered the little ball valve in the zirk, though I really don't think this is possible. Get a new one. I'll be interested in what you find in the TC, and carefully examine the TC case itself for hairline cracks. Also, I agree you shouldn't drive around without the zirks in place.
DougM
If the grease is coming back out the zirk fitting, then it should be replaced as the ball isn't maintaining pressure as it should. This assumes you weren't putting enormous pressure on the grease so that it somehow overpowered the little ball valve in the zirk, though I really don't think this is possible. Get a new one. I'll be interested in what you find in the TC, and carefully examine the TC case itself for hairline cracks. Also, I agree you shouldn't drive around without the zirks in place.
DougM
Just to add another vote, not that I've ever pulled the shaft to look at the splines or the seal, and not that I know anything else about it than this, but my shafts seem to allow grease to get through each and every time, they seem to have lotsa longitudinal travel, and they seem to start super soft clunking right around 3000 miles which is when I replace oil and lube anyway. The clunking only comes like when I come to a fastish stop, and then go to a fastish takeoff right after and it really is a super soft clunking that goes away as soon as the shafts are lubed again. Anyway, I use M1 synthetic grease, pump four pumps each and every time, I always wipe any grease off from the travel areas of the shafts, and I always have some fresh gease goo out within a short soft drive which I also always do right after greasing. (Ever since my dad showed me since I was twelve or so, I've always assumed that taking an aggravatingly slow spin around the block several times right after oil and lube was part of this process. In fact I still remember sitting too short to touch the floor and watching him creep around corners touching the throttle softly then the brakes softly over and over while he says " Wait, you hear that, ahh never mind, its nothing! " Pretty funny really. Then we check for oil plug and oil filter leaks, wipe the fresh grease on the shafts, make sure ball joints etc are good ( I know, none here). Anyway now many moons later I do the same thing, just with out the " you hear that's? ". I'm hoping that the crammed up seal that ID has is rare, I'm also hoping that the fact that my driveshafts act this way does not mean they are worn. For me at least, the zerk seems to do what it's supposed to do, the driveshafts accept an amount of grease, release any excess rapidly, travel with lots of longitudinal travel, and within about 3000 miles, need another four squirts. Like I started, just another vote to go with this cool thread. Thanks.
So I killed my t-case 
I added grease to my rear drive shaft and woundered why there was no grease comming out the splines. Soon after my t-case would over heat and the VC would lock.
I should of went with my assumptions and replace the rear output bearing. I had ordered and received the bearing. But a tranny repair shop said that if one bearing was bad they all would be bad.
I went with a new t-case.
I spent $2000 when a $50 bearing could of solved my problem
Even worse, had I took the driveshaft apart cleaned and lubed I would on not had a problem at all.
OR
The PO could of done it as the VC would only lock when it was hot outside.
I dot the 80 in the spring whan it was cold out. It was summer when it went bad.
Two others had the same t-case problems when the weather was hot out.
I seen no damage to the output shaft on my old t-case but maybe I took it apart before there was too much damage.
I added grease to my rear drive shaft and woundered why there was no grease comming out the splines. Soon after my t-case would over heat and the VC would lock.
I should of went with my assumptions and replace the rear output bearing. I had ordered and received the bearing. But a tranny repair shop said that if one bearing was bad they all would be bad.
I went with a new t-case.
I spent $2000 when a $50 bearing could of solved my problem
Even worse, had I took the driveshaft apart cleaned and lubed I would on not had a problem at all.
OR
The PO could of done it as the VC would only lock when it was hot outside.
I dot the 80 in the spring whan it was cold out. It was summer when it went bad.
Two others had the same t-case problems when the weather was hot out.
I seen no damage to the output shaft on my old t-case but maybe I took it apart before there was too much damage.
- Thread starter
- #36
I still haven't gotten my question addressed directly, which is how a drive shaft full of grease can extend and retract?
Look at it this way. The male splined part of the shaft is the piston. The other part is the cylinder. Because the cylinder is packed solidly with grease, you've got the exact same situation as a hydrolocked engine cylinder (an engine that's ingested water) - the piston cannot move as it's against something incompressible. Now you hit a 4 inch high rock ledge with the back tires and the suspension cycles up and down in less than a second. How did the driveshaft move? It didn't squirt grease along those long splines that quickly on the compression stroke.
BTW, I loved the reminiscing about your Dad and car care. That's a lost art and we're the last generation this was passed down to in any significant numbers. My Dad is the same way (what a surprise, eh?)
Anyhow, what say ye about the shaft movement? The way I just set mine up with the greased splines and air pocket is the only way I can see unfettered movement taking place.
DougM
Look at it this way. The male splined part of the shaft is the piston. The other part is the cylinder. Because the cylinder is packed solidly with grease, you've got the exact same situation as a hydrolocked engine cylinder (an engine that's ingested water) - the piston cannot move as it's against something incompressible. Now you hit a 4 inch high rock ledge with the back tires and the suspension cycles up and down in less than a second. How did the driveshaft move? It didn't squirt grease along those long splines that quickly on the compression stroke.
BTW, I loved the reminiscing about your Dad and car care. That's a lost art and we're the last generation this was passed down to in any significant numbers. My Dad is the same way (what a surprise, eh?)
Anyhow, what say ye about the shaft movement? The way I just set mine up with the greased splines and air pocket is the only way I can see unfettered movement taking place.
DougM
Kurt,
Was there a question in there somewhere?
Do you also hear voices when you're not on the meds?
Was the brain surgery to help with "talking to yourself" problem?
-B-
Was there a question in there somewhere?
Do you also hear voices when you're not on the meds?
Was the brain surgery to help with "talking to yourself" problem?
-B-
Beowulf said:
-BB-
I was responding to post #25
<I'd have to check my log, but somewhere around 48,000 miles my transfer case began making a very faint high pitched noise that I recognized as a bearing going. Before you all fall over with coronaries, it is not the typical 80 whirring/high pitched whistling that they all make. I've driven literally dozens of 80s and they all make a very different characteristic "big gears in oil" sound. Anyhow, there was a very good Toyota Master Mechanic in town at the time and I had him drive it and he could not hear it. Being the stubborn type, and having connections at Toyota I had the transfer case replaced as a warranty item and am glad I did. The mechanic cracked it and found a bushing or bearing on the rear shaft output was damaged and overheated, plus discovered micro cracks in the aluminum case around the rear output shaft.>
If you read all the posts (even the long ones
) you would see I am on topic.Greasing the driveshaft:
What I would do is remove the driveshaft, take it apart and clean it and grease it real good before assembly.
Put a couple squrits of grease in and move the shaft back and forth to make sure it can move fully without bottoming out on your grease.
When I took mine apart I had to remove the zirk as there was so much suction or vacuum that the shaft would not slide out. Now it slides back and forth with ease.
My piont from my killing my t-case comes from me probly overgreasing the driveshaft.
I may never know what the real reason was but the overgreased driveshaft makes cents to me.
Conclusion!!!
Don't over grease the driveshaft. Look to see grease on the splines. If not remove and clea it.
If I am still way off topic, I may have to go back to the brain surgeon for an adjustment
