Packing bearings over full

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Originally Posted by JHZR2
There absolutely is a max amount of grease, for example, I found the SKF formula G = DB/10, where G is grease in ounces, D is bearing outer diameter, and B is bearing width. There's something also to be said about the amount of grease for a given speed of the bearing. These never see over 25mph. But I'm not aware of that calculation.
First, on behalf of SKF, let me correct that. That formula is NOT applicable for any tapered bearing or any bearing with removable races and that's ONLY for a "first fill" and to be used ONLY when no other lubrication regime is known. ( that's why when you call me to spec out a lube regime and amount/frequency" I have to plug a lot into the SKF calculator) The reason its "first fill" only is because once grease gets initially worked, the density changes so all those amounts based on "new volume" go out the window. During replenishment, , theoretically" that new grease at a higher density by volume will displace grease at a lesser density but there are a whole lot of variables as to why that often doesn't work. This is why on SKF housings (plummer and PB mainly) you will see a packing "fill line' and various ports depending on the initial fill and relubrication requirements of a specific application. Based on the excellent pictures you have presented- you basically have a primary contamination issue most likely coming from a combination of fitment and tolerance issues allowing ingress and capture of salt water which churns with the grease, combines with it and coats your bearing then disintegrates it until asperities fail then catastrophic failure. I would recommend mic'ing everything to make sure it will hold the bearing tolerance and centerline, beading and coating the inner hubs with insulating enamel (as we do machine castings to form a barrier) and possible upgrade to a finger seal ( rather than a typical garter spring) like a Garlock Klosure, set clearances properly and pack to 100% fill. That's based on your failure account and the pictures provided.
 
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Originally Posted by 4WD
I don't buy boats. I buy a boat, motor, and trailer and it's going to come with Tie Down Engineering spindles or will buy another package elsewhere. The only way to easily displace old grease or contamination in 5 minutes … done
FYI Dexter bought Tie Down (and AL-KO) that might complicate your resolve, although the EZ-Lube system might meet your requirements.
 
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Make sure when you install the hub with new bearings , to tighten it down really good the first time, like 50-60ft/Lbs, then loosen and adjust from there. That tightening makes sure all the bearing races are seated.
 
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JHZR2

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Originally Posted by 4WD
I don't buy boats. I buy a boat, motor, and trailer and it's going to come with Tie Down Engineering spindles or will buy another package elsewhere. The only way to easily displace old grease or contamination in 5 minutes … done
Doesn't always work that way in one step from the third world. Where this boat is, is a far cry from Texas, where there's replicates of everything just one interstate stop away. I agree this is ideal, and some time the trailer will be replaced and specified from a vendor in the States, likely as you indicated.
 

JHZR2

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Originally Posted by ABN_CBT_ENGR
Originally Posted by JHZR2
There absolutely is a max amount of grease, for example, I found the SKF formula G = DB/10, where G is grease in ounces, D is bearing outer diameter, and B is bearing width. There's something also to be said about the amount of grease for a given speed of the bearing. These never see over 25mph. But I'm not aware of that calculation.
First, on behalf of SKF, let me correct that. That formula is NOT applicable for any tapered bearing or any bearing with removable races and that's ONLY for a "first fill" and to be used ONLY when no other lubrication regime is known. ( that's why when you call me to spec out a lube regime and amount/frequency" I have to plug a lot into the SKF calculator) The reason its "first fill" only is because once grease gets initially worked, the density changes so all those amounts based on "new volume" go out the window. During replenishment, , theoretically" that new grease at a higher density by volume will displace grease at a lesser density but there are a whole lot of variables as to why that often doesn't work. This is why on SKF housings (plummer and PB mainly) you will see a packing "fill line' and various ports depending on the initial fill and relubrication requirements of a specific application. Based on the excellent pictures you have presented- you basically have a primary contamination issue most likely coming from a combination of fitment and tolerance issues allowing ingress and capture of salt water which churns with the grease, combines with it and coats your bearing then disintegrates it until asperities fail then catastrophic failure. I would recommend mic'ing everything to make sure it will hold the bearing tolerance and centerline, beading and coating the inner hubs with insulating enamel (as we do machine castings to form a barrier) and possible upgrade to a finger seal ( rather than a typical garter spring) like a Garlock Klosure, set clearances properly and pack to 100% fill. That's based on your failure account and the pictures provided.
I appreciate this and your other previous detailed response. It's fine if I used the wrong formula, the point is they exist. The point initially also was that some vendors define an appropriate amount to use (my Mercedes cars have a larger inner/smaller outer design BTW)... and I've firsthand seen the outcome of more is used - it heats up, oil migrates out and onto the wheel, and there we are... It would make sense to me that there is a max amount because beyond that, the rest is just insulation. As noted, we installed bearing buddies, greased fully with the buddy/gun (after working grease in fully). Thus the curiosity still stands. I can notice that one side is warmer to the touch than the other. Again, this trailer doesn't go further than 5 miles, and doesn't go faster than 25 mph. Both are pumped full.
 

JHZR2

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That's definitely in the cards as the leaf springs are showing some rust. It's a 19' boat, 150hp engine, 75 gals of fuel, etc. I suspect it's 3000# or so.
 
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Originally Posted by JHZR2
I appreciate this and your other previous detailed response. It's fine if I used the wrong formula, the point is they exist. The point initially also was that some vendors define an appropriate amount to use (my Mercedes cars have a larger inner/smaller outer design BTW)... and I've firsthand seen the outcome of more is used - it heats up, oil migrates out and onto the wheel, and there we are... It would make sense to me that there is a max amount because beyond that, the rest is just insulation. As noted, we installed bearing buddies, greased fully with the buddy/gun (after working grease in fully). Thus the curiosity still stands. I can notice that one side is warmer to the touch than the other. Again, this trailer doesn't go further than 5 miles, and doesn't go faster than 25 mph. Both are pumped full.
Thank you, I would like to address those key points highlighted basically for the masses as they may apply to many here "Generically" it probably applies to 90+% of all trailer application hubs out there so it may address some mysteries others may have. This is specifically addressing the hub/bearing design because if this is "wrong" then nothing in the way or lubrication will do anything beneficial except buy some more time. Your Mercedes I'm sure has a documented history of engineering, stress analysis and somewhere an engineering review and a stamp on the design (as one would expect and that's the realm I operate in industrially) I would expect a much higher level of engineering and precision as well as quality specified components on that than on a generic "brand X" axle set probably selected on cost alone for a trailer builder so it may be somewhat of an apples to oranges comparison. Utility trailers most likely use a calibrated eyeball or just copying a previous design. USDOT doesn't require it- they mainly focus on tongue weight, welds and stuff. Not axle bearing loading. I personally wouldn't count on having a truly properly engineered and matched set of hubs for any utility or boat trailer. (ask a trailer sales guy for the engineering calcs and FEA/FEM on the hub set and see what they say) Here's why this is important- each one of these plays a significant determining factor in the life of any hub bearing. The remaining question is "How much does each play in your specific application"? (results will vary) First is the bearing themselves Look at the second digit on the bearing number (usually a 3)- that denotes a dimensionless (and meaningless because it's not a recognized standard) "medium" strength recipe for the bearing (auto grade usually). When one designs this for an application you need to know wheel geometry and thrust (centerline) as well as tire size (it usually sits load centered between bearings). When people vary tire sizes this gets overloaded really quick. (many makers just put what looks good or go by the tire load rating- not the axle geometry) A lot of times the bearing itself is of the most inferior steel, quality and load requirements right out of the box. ( just because they fit do NOT mean that are adequate for the load) All of these stress angles quickly overload small bearings. Then they use different sizes. That's two different RPMs with two different SFPM's turning. (which is why there's an immediate temperature difference even with no other mechanical or load contribution) That design will work but it builds in enormous stress during turning and inertial thrust on that smaller outboard cone and will damage it quicker- if its under designed and under lubricated and even set wrong- it may not last but a few thousand revolutions. So, for a properly designed and installed bearing for the spindle/hub (which is highly unlikely in the first place without a stamped set of prints to verify the criteria the bearings were specified against)- just the running loads ( inertia, wind, cargo loading, alignment to center axis and TURNING) is going to stress these bearings incredibly because tapered bearings will handle axial loading but ONLY when properly set and lubricated. If the design contact angle is exceeded, they will polish then start to Brinell at best. (usually on the obtuse aide of the angle relative to tapered centers) Then the failure cycle starts Now to the sump (inner hub) Most designs like for the shaft to turn and the sump not because gravity and vibration (slumping) help keep the grease close to the bearing so it can wick and do the boundary thing. In hubs the opposite it true- The bearing and grease is getting centrifuged. That's bad enough but now the thixotropic qualities are being affected because oil that would normally recombine is being slung away from where its needed most and it can't crawl back there on its own. This is why its always best to pack it full. Heat it beyond that then you add another set of problems. Heat- the real truth There's a difference between heat generated from a mechanical issue (which no lubricant will ever overcome or mitigate) versus the normal heating by application of grease. In that case, the normal build up is NORMAL and doesn't hurt anything. It's the norm to allow for this cycle to happen as grease initially gets worked and distributes itself along with the inherent qualities of the application. Now if there's heat from excessive loading, improper tolerance, insufficient lubrication- that's a different animal. All that to say that heat (in and of itself and up to the limits of the grease and bearing) are not hurtful- it is normal. Don't let thousands of badly worded, factually incorrect and overly misleading internet articles lead one astray. A lot of well meaning people have "weaponized" this because they really don't understand the concept. On lubrication (and that formula) I helped develop and write a lot of these standards and procedures over the years and certify lube professionals with the full range of certs so let me tell you the facts (not the media hype) and can validate what I say at any level. There is no such thing as "over greasing" a bearing. (assuming this is defined as volumetric displacement of voids internally in a bearing) You have a dimension (defined as races, cage, media) and whatever left is "space"- once you fill 100% of that void- there is no room for any more so over greasing is impossible. Once that bearing has gone one revolution- it self remedied that and pushed excess grease to the side to be picked up later. What they talk about is too much grease by volume in the HOUSING (often jacking a seal, spilling into a winding or other undesirable "stuff") or over ADMINISTRATION (pumping in too fast either shocking a bearing thermally or mass induced, creating grease whirl, shock cracking or other effect resulting in bearing damage). ( technically that's over greasing the application or housing- not the bearing) This also has been "weaponized" to the point that now UNDER lubrication is the major problems because "precision lubrication" uses these formulas WRONGLY and often starve the bearing.( that's a different story altogether) This is really critical in Couette flow such as online motor lubrication where new grease (dense) passes through a running bearing (changes density due to horizontal mechanical shear) as Howard Primrose goes into in great detail in his work. There are times one needs to consider this, but a hub/axle isn't one of them. Pack it full, preload to squeeze while setting clearance- spin it a few times to distribute and go fishing. The grease that's squeezed out is not going to get angry and jump back in ( especially when being centrifuged out)- you actually need that full packing to make sure enough oil eventually gets to that bearing or the "shinier it gets" (textbook lack of proper lubrication- yet often in a hub full of grease) Those formula (as on various sites) were originally designed to help set intervals on central lube systems and injectors (horizontal/vertical and leading/lagging and W groove scenarios) to ensure proper online lubrication. They were never intended to guide offline or manual lubrication. They are just used for that because there is nothing else. The "clue" would be in more detailed reading and asking oneself how can I relube at 60% of a bearing fill in an environment where I can't see anything? (nobody can, that's for an injector on a times cycle- not a human with a grease gun) Contamination All that flexing and heat will compromise the average lip seal in short order, and nothing can be done to stop it without a re-design. Once raw water gets in- it's not going to evaporate significantly- it will sling/drain and emulsify with the grease to some degree. Then it will coat the surfaces and speed oxidation. (put grease in a blender and demonstrated this too many times- find some videos) Newer grease is more resistant to this effect- worked and overheated grease, not so much. Hope that may answer some people's questions but most of these problems stem from the fact that in many applications there is a generic axle pack (not specified to anything) with random wheels (tangential stresses above the load) combined with an unknown geometry and load plan. In that case its very possible to start off with a scenario where the bearings will fail due to overloading sooner than a normal L-10 life regardless of the lubrication selection and regime. If that's the case, then the only solution is a different application properly matched. There are many factors affecting utility trailer bearing life and many (probably most) go beyond the selection and application of a particular grease. I recommend looking at all of them to get the most reliable service at the best cost. There's a lot more to hub lubrication with grease than what's briefly touched on here but this might help solve some chronic problems for a few.
 

4WD

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IIRC … Dexter bought Tie Down Engineering … so that is what I have used trouble free since 2006. One way you can over grease is with Bearing Buddy … that's a closed system and a grease gun can create enough pressure to damage the rear seal … not a good thing on a boat trailer … As for bearing replacement … a coated hub, fully grease packed and new bearings installed is just $49 in my size … By the time I need bearings … that "coupon" on my aluminum trailer is done for good …
 
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There is also the thermal effect of backing hot or warm hubs into cool water, in this case as it's a boat trailer. I think thats why most recommend yearly inspection. That's why I think ez lube Dexter axles would work well here. You can give a shot of grease after every immersion, and that pushes out contaminated grease from the inner races vs bearing buddies, which do not do that. .
 
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Originally Posted by JHZR2
I'm sure a heavy boat on a single axle trailer in severe terrain doesn't help. Especially the severe terrain. Both grades and turns. But I also think the seal isn't working. The back side of the spindle is corroded and not smooth. So it can't seal.
Boat trailer wheels submerged in water when putting the boat in or taking it out of the water is a killer if the seals are allowing water in. If it's still failing with a bearing buddy with regular greasing, then there's a lot of water getting in. That photo of the new seal on the rusty spindle obviously won't last long if the spindle isn't polished out. I had a bad spindle seal (lip was rolled over upon install when the truck was built) on a 4x4 truck that never was driven in deep water, just heavy rain, and enough water still got in the wheel bearing to make it start going out.
 
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