Over greased drive shaft (1 Viewer)

[kwelhand]

My buddy just brought a new to us 14 LX570 w/ 120K.

Yesterday, he tired to grease his rear drive shaft, and according to him he pumped his grease gun about 100 times before he got tired (no joke).
I think I've seen somewhere that you must not over grease your drive shaft, otherwise, it will damage your vehicle or something.
Should I tell him to remove the grease fitting and let the grease spilling out while he drives?

Does anyone know any pic or website with all proper grease points for our truck and also how many pumps to inject your favorite grease?
Many thanks in advance.

 

[CharlieS]

Zoinks. I do five or six when I grease mine. If it was me, I'd mark the orientation, remove the shaft, take it apart and rectify the situation.

 

[Sandroad]

There are 6 grease fittings. One on each of the 4 spider joints at the front and rear of both propeller shafts and one on the slip joint of each shaft. 100+ pumps in the slip joints is way too much. Removing the fitting and letting that much grease go could make a mess. So, what @CharlieS said. Lots of threads on greasing.

 

[kwelhand]

Thanks guys... @CharlieS @Sandroad
We might have to remove the shaft to deal with this over grease issue... hope it's a DIY job

 

[bloc]

On a LX it’s very easy to fix it.

Remove the zerk, put the truck in low. That sets it on the bump stops and effectively shortens the shaft as much as it will go in normal operation.

Any grease that comes out was too much. Clean it up, reinstall the zerk, done.

 

[kwelhand]

On a LX it’s very easy to fix it.

Remove the zerk, put the truck in low. That sets it on the bump stops and effectively shortens the shaft as much as it will go in normal operation.

Any grease that comes out was too much. Clean it up, reinstall the zerk, done.

Excellent advice! that sounds a lot easier than what I thought.
I will repot back with the result!
Thanks for sharing @bloc

 

[bloc]

Excellent advice! that sounds a lot easier than what I thought.
I will repot back with the result!
Thanks for sharing @bloc

Any time. I'm curious how much grease comes out.

Just to double back, yes it being overfilled can put huge forces on the transfer case output shaft and front diff pinion bearing when it can't shorten during suspension cycling. Due to the type of bearing it is, the front pinion bearing is probably fine with these forces.. but the transfer output shaft is not.

 

[kwelhand]

Any time. I'm curious how much grease comes out.

Just to double back, yes it being overfilled can put huge forces on the transfer case output shaft and front diff pinion bearing when it can't shorten during suspension cycling. Due to the type of bearing it is, the front pinion bearing is probably fine with these forces.. but the transfer output shaft is not.

Exact info I was looking for… thanks!

 

[tominboise]

Your buddy needs some mechanic lessons before he works on his car again.

 

[kwelhand]

Your buddy needs some mechanic lessons before he works on his car again.

LOL~ I concur!

 

[East100Cruiser]

Could this cause the front diff to vibrate violently under acceleration?

 

[bloc]

Could this cause the front diff to vibrate violently under acceleration?

Possibly.

There aren’t any quick suspension tricks to push extra grease out, but you can pull the zerk and see whether grease comes rushing out. And even if it doesn’t, go for a short drive, if you believe the slip joint got overfilled at some point. Anything extra should come out. Then button it back up and pay attention to any differences with the vibration.

Personally I’d be checking that all the front diff mounting hardware was in place and tight.

 

[East100Cruiser]

Thanks. I replaced all the front diff bushings thinking that was the issue. I’ll check the drive shaft tomorrow and see what I find. It isn’t terrible to get out.

 

[bloc]

Thanks. I replaced all the front diff bushings thinking that was the issue. I’ll check the drive shaft tomorrow and see what I find. It isn’t terrible to get out.

If you haven’t already, while you have it out you can drive the truck with the center diff locked to confirm it is front driveline and not something else.

 

[East100Cruiser]

Thanks- I’ve done that- definitely in the front. I am not sure what too much grease looks like though. The front driveshaft seemed very hard to compress when I took it out. It had to slip enough to clear the front diff. That’s about as much as I could get it to slip. Thoughts ?

 

[bloc]

Thanks- I’ve done that- definitely in the front. I am not sure what too much grease looks like though. The front driveshaft seemed very hard to compress when I took it out. It had to slip enough to clear the front diff. That’s about as much as I could get it to slip. Thoughts ?

Might as well take it apart and scoop out extra grease. Then smear some on the splines and reassemble (obviously making a mark so it can be indexed back to stock). Then see how difficult it is to compress, starting from a known good condition.

The grease and dust seal is tight enough for the inner chamber to act as an air spring. Meaning at first it shouldn’t be very difficult, but the more you compress the more the spring rate increases. It’ll be quite hard to compress further as that volume reduces.

And that is one issue with too much grease.. the air volume goes down, so your spring rate goes up. To some extent excess should slowly sling itself out of the slip yoke, but that can only happen so quickly.

The vibration has been there since you got the truck?

 

[TeCKis300]

With excess grease in there, it would border on hydraulic locking the shaft and putting extreme strain on the transfer case, diff inputs, or u-joints. Not just increased spring rate. I wouldn't presume taking out the zerk and putting AHC low would be enough. The suspension can and does compress even lower than low position in use. Hope he didn't do much or any driving like this, as with that many pumps was probably jacking up the car by the driveshaft.

Probably best to disassemble or take the zerks off the drive shaft for some number of miles and let it clear most of the excess grease.

 

[bloc]

With excess grease in there, it would border on hydraulic locking the shaft and putting extreme strain on the transfer case, diff inputs, or u-joints. Not just increased spring rate. I wouldn't presume taking out the zerk and putting AHC low would be enough. The suspension can and does compress even lower than low position in use. Hope he didn't do much or any driving like this, as with that many pumps was probably jacking up the car by the driveshaft.

Probably best to disassemble or take the zerks off the drive shaft for some number of miles and let it clear most of the excess grease.

My comment about spring rate was in response to @East100Cruiser noting difficulty removing his front driveshaft. I didn't specifically say it, but yes turning the slip yoke into a hydraulic cylinder is exactly what would make the extreme forces I referred to earlier, and is the big risk with the condition OP posted trying to resolve.

Zerk out, AHC low, will remove enough grease to make the car safe to drive for normal use. Then it is lifted back up, and the volume in the yoke displaced by the male portion of the splined section will fill with air. As it is driven further the excess will work it's way out through centrifugal force spreading it all out into the splines, then normal driving compressing and extending the driveshaft in a smaller range causing shear stress (in the fluid) that works the grease out slowly, as well as a little air-spring driven positive displacement pump on suspension cycling to push grease out as well. This will have happened by the time the suspension is fully compressed, unless the truck was being prepped for an off-road trip. In that event.. removing the zerk and driving wouldn't hurt. I don't think it's necessary though.

For those wondering how grease will "flow" like a fluid into and down the splines, assuming the splined section of our driveshaft is about 1.5", at 75mph there are roughly 225 times the force of gravity. that will make a thick fluid, even non-newtonian as our driveline grease is, flow really well.

The air-spring effect, hydraulic lock, whatever it is called, is why I've always been uncomfortable with toyota's published method of pumping grease in until you see the shaft move. They are basically instructing you to push grease in to the point that the pressure in the slip yoke turns the driveshaft into a ram, spreading it and putting force on the transfer output. This can't be a small amount of force.. plus.. the force required to move things will depend on whether the shaft is straight like our front one, or flexed like the rear. Or the height of the rear suspension. As you mention, yes, you can even lift the vehicle by pressurizing the driveshaft. To me their instructions are too subjective, so I do what I and thousands of others have and throw an amount in that feels right, and keep driving. Toyota shafts almost never wear out the slip section, so it must be working.

 

[East100Cruiser]

No, not since I purchased it. Recently, this is what I’ve done:

4.88 gears
Diff drop
Spc upper a arms
New front diff bushings

When I put it back together, I adopted a new vibration at low speeds. Moving the upper ball joints all the way out helped the vibration, but still there. Lowering the preload on the torsion bars helped,
but still vibrating (verified it was front diff via GoPro)

I take the front driveshaft out and the vibration is gone.

I’ve cleaned and refreshed it and will try to reinstall and report back later this evening.

 

[bloc]

No, not since I purchased it. Recently, this is what I’ve done:

4.88 gears
Diff drop
Spc upper a arms
New front diff bushings

When I put it back together, I adopted a new vibration at low speeds. Moving the upper ball joints all the way out helped the vibration, but still there. Lowering the preload on the torsion bars helped,
but still vibrating (verified it was front diff via GoPro)

I take the front driveshaft out and the vibration is gone.

I’ve cleaned and refreshed it and will try to reinstall and report back later this evening.

Despite your username I wasn’t aware this is a 100.

When you check the driveshaft make sure it is indexed correctly. It’s a little complicated to explain, but basically as long as the yokes on the center section are aligned, and all 3 of the zerks pointing within a roughly 90 degree arc, it should be correct. If the zerk on the u joint for the short section is pointed the opposite direction as the others, it got put together incorrectly.