CV Joint Grease Failure?

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23,114
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CA
Yesterday, I rebooted the passenger axle’s inner cv boot on a 2008 Camry V6. The inboard CV joint sits very close to an exhaust pipe so the joint sees high temperatures on a regular basis. When the old boot was removed, the grease inside the joint had the consistency of a XW-20 engine oil. The new grease from the Toyota CV Boot Kit had the consistency that you would expect for CV Boot grease. Is there any way to prevent viscosity breakdown in this application? As you may see in the pictures below, there is a small amount of wear on the rollers (bearings), which I attribute to the grease “failure.” Old grease with the consistency of lightweight motor oil: Prior to re-booting: old boot that was seeping grease. Evidence of grease seepage from the cv boot. The grease was slinging onto the engine timing cover and the p/s pump. You can see the wear on the inner cv joint’s rollers (bearings) from this picture. The surfaces were still smooth though. Had to use a 3-jaw puller to separate the slider from the shaft.
 
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4,232
Location
Kansas
Redline Oil has a grease. Archoil does too. Am soil should also. Maybe just need a stouter formula would be my guess.
 
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Messages
25,183
Location
MA, Mittelfranken.de
I have posted this many times on the board, CV joint failure is NOT always accompanied by boot failure. Slight clicking (outer) or roughness (inner) after the car has been sitting a few days or weeks and disappears after a few minutes of being driven is often an indicator of lube failure in a joint. A good sight of this is what appears to be thick oil or thin grease residue around the outside of the boos just beyond the band clamp at the edge of the boot. The boot was not designed to contain oils or thin lubes but grease. Good catch, you fixed it just as you should have. thumbsup
 

The Critic

Thread starter
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23,114
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CA
Originally Posted By: Silk
The genuine Toyota inner joint grease is light brown in colour, and quite runny compared to outer CV joint grease.
The new grease had the consistency of grease; the thickness was similar to grape jelly. The old stuff that drained out reminded me of used 20-wt engine oil. The only possibility I can think of, is perhaps the grease is designed to shear down over time?
 
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25,183
Location
MA, Mittelfranken.de
No it isn't, its called planned obsolescence. I use Redline CV-2 exclusively on CV joints, it hangs in there well over 100K. On most car joints I give them 7oz ea on the outer and 5-7 for the inside and never had a problem.
 

Kestas

Staff member
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It may not be intuitive that bearings with micromotion need light grease. The idea is that you want the grease to reflow under the rollers as they push the lube aside. Heavy grease has a difficult time doing this. These bearings never develop anything near a hydrodynamic film.
 
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25,183
Location
MA, Mittelfranken.de
I suppose that's why the grease has a high 5% moly content. Too thin and its all in the boot and does not find its way back into the joint to any real degree.
 
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434
Location
Ga
Actually you don't have a true CV joint there on the inner side of the axle. What you have is a "tripod ball CV" and the manufacturer (Honda,Audi or whoever) will use an urea grease rather than a high moly CV joint grease/paste. Urea grease works very well in high temp environments. Yes it is watery..which is a good thing with those needle rollers.
 
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517
Location
Canada
Originally Posted By: Kestas
It may not be intuitive that bearings with micromotion need light grease. The idea is that you want the grease to reflow under the rollers as they push the lube aside. Heavy grease has a difficult time doing this. These bearings never develop anything near a hydrodynamic film.
This is a good point. The inner CV uses needle bearings that see micromotion of which a more fluid like lubricant is beneficial. The outer joint is a Rzeppa style of which the balls see sliding motion and would benefit from a high moly lubricant. I would expect the Rzeppa joint to fail before the needle rollers on the inner joint.
 
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25,183
Location
MA, Mittelfranken.de
I had a 08 Subaru inner joint with thin stuff in it and a bad joint, perfect boot though. Are needle bearings in LFL U Joints using lube thin as heavy oil? Most commercial driveshaft builders use GL2 none moly. the needle bearing is only one part of the plunge joint.
 
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7,202
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California
My hypothesis is that GKN/NTN is using thin grease that shears down to flow into the tripod joint and with very little moly or not loaded down with the stuff like most aftermarket grease. Keep in mind Toyota frowns upon on moly in grease unless it's being used in a application with sliding/fretting wear like ball joints and driveshaft splines. In theory, it's quite similar to how trucks and buses use semi-fluid NLGI 0/00 grease to lubricate their axle hubs - it gives the persistence of grease but the flow of oil if a truck operation or transit authority has oil-lubricated hubs but needs endurance. Mobil, Chevron and Valvoline market semi-fluid greases for this: https://www.mobil.com/en/industrial/lubricants/products/mobilith-shc-007 https://hd.valvoline.com/our-products/valvoline-axle-hub-grease http://www.deloperformance.com/en-us/products/Delo-Synthetic-Grease-SF.html
 
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25,183
Location
MA, Mittelfranken.de
An axle hube is a much higher speed bearing. In a plunge CV joint there is sliding and rolling wear taking place. No matter I keep using what I have been using for years that has proven itself and not having any trouble with, others use whatever they want.
 
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