EZ Lube axles/hubs

mike-s wrote:

Cummins12V98 wrote:

falconbrother wrote:
After lots of research I have decided that I'm going to service the EZ lube axles like the factory video says regardless of what the guy at CW said. There's no way pressure can build up in an EZ lube axle and blow out a seal.

It would blow the rubber plug in the cap first!

LOL. You're joking, right? Because how are you going to pump that thick grease in through the zerk without removing the rubber plug?

And yes, you have to pump it, because it does take pressure to push that thick grease through the bearings and back out. That's when it's trying to push past the seal, not afterwards when you're going down the road with the rubber plug in place.

"There's no way pressure can build up in an EZ lube axle and blow out a seal."

This is the part I was concentrating on.

I was a victim of the infamous Lippert greasy brakes. They are EZ lube axles. I decided to hand pack the bearings five months after the warranty was up and found two brakes covered in grease and the seals starting to leak on the other two. When I called Lippert they asked whether I used the EZ lube system. No. They then asked if I had repacked them before. No. I was then told the manual said they had to be repacked every 12 months so I was out of luck. After a bit of a struggle and contacting Grand Design they agreed to send me new parts but wouldn't cover labour.

IMO, EZ lubes are a useless trap, if you use them and have trouble they will say you didn't do it properly and caused the damage. What's the point in them if a manufacturer specifies repacking every 12 months anyway.

They are also a waste of grease, only about 20% of the grease you pack into the hub is actually lubricating the bearings.

Hi Guys,

Let me add some technical findings to the issue. I have been around machine building all my of my career and I'm now retired. You can build a shaft and seal to run true and hold back lots of psi of oil or grease pressure. They do it all the time on hydraulics. We are talking 1,000's of psi here.

But we are not talking heavy duty industrial in this case. The seal leaking we are talking about in on an RV...

Let's look at some of how the problem on leaking grease comes about.

See this pic of out of our camper. It was bought used like that and we drove to PA to get it. Yes, a state that inspects trailers. At that time it had Alko axles and no EZ lube axles. When I brought it home, I went through the brakes when I changed the axles that were out of tolerance to know what I had. Sure enough, here is one drum



This is non EZ lube and a standard hand pack by whoever did it and by who ever did the 2 years of PA inspections. This is the first time I had the wheel off.

How did the grease come out? It was not the EZ lube as it did not have it. Well, they could have nicked the seal during an inspection, it could of been cheap grease with a low temp rating, there is heat involved from long distance towing that creates grease expansion pressure and there is centrifugal force of the grease flying around and it could of been the mechanical setup. It could be any of them or a combo. On a standard hand pack that was not that heavily packed, the grease had enough pressure/flow to works itself out of the seal that may have been compromised or had parts issues.

Hold that thought, let's look how a trailer axle spindle and brake setup is made.

If you have ever changed rear axle seals on a 3/4 or 1 ton truck and you go to the parts place, be ready to drop a $50 to $100 for 1 of those special rear axle seals. The rear axle casing is vented so it is not pressure seal, so why such a good expensive seal? Well, they do not want it to leak. When you go to get a trailer seal, the cost can be from $3 for a cheapo one to $7 for a Dexter double lip that works with their EZ lube https://www.easternmarine.com/dexter-2125-id-grease-seal-010-010-00

Why 10 to 50 times more cost for the truck rear axle seal then the trailer axle seal?

Next, is the manufacture of the housing the seal is mounted in. If you ever look up the design spec's of the type of seals used in trailers, the seal and shaft are supposed to run true to each other within a small tolerance. See here when they talk about "runout" http://www.skf.com/us/products/seals/industrial-seals/power-transmission-seals/radial-shaft-seals/coaxiality-and-runout/runout/index.html

Runout in this case means the seal needs to be running true to the shaft within about 0.004" to 0.005" TIR (total indicator reading) or else the lubricant can work it's way out the eccentric clearance between the seal and the shaft. I came up with that tolerance off the SKF chart since a trailer wheel of 27" (ST205/75R15) dia spins at around 685 rpm doing 55 mph. Larger tires spin a little slower, smaller tires a little faster. And a CRW5 and CRWA5 seal is close to what is used on our campers. SKF CRW5 The runout chart SKF Runout chart

Granted there is a garter spering to help keep the seal lip against the shaft. But in time, the seal lip will wear more/deteriorate more the larger the runout is and inertia is always at work.

So how good do trailer wheels spin? Well in my experience not very good.

See my post from when I converted my manual adjust brakes to Dexter Never-Adjust Dexter Self Adjusting Brakes (long W/pics and details)

I had one Alko original brake drum with 0.028" TIR runout. I called Dexter after I bought 4 new drums and their spec is 0.015" TIR. And 1 of the 4 drums was outside that.


Basically the seal bore runs true with the brake lining surface. But the seal does not run true with the bearing bore. This is a machining setup issue but it doesn't matter as the spec is so wide open a lot of this is in spec.

I asked Dexter, why can't these drums run more true like automotive does? Getting a seal bore to run true in automotive in less than 0.005" TIR is done all the time and 0.0005" TIR on disk brake rotors too. He said no one rides in a trailer and the vibration is acceptable where in a car it is not. He did not tell me it was to save cost, but in the machine shop world precision costs more $$$.

Have you ever adjusted the manual brakes on your camper? Spin the wheel and you hear, skip, skip, skip of the drum only touching for a portion of the drum revolution. Why? The drums runout out that bad.

Point: Yes, a "good" seal, on a "good" surface shaft, with a brake drum that spins "true", has "good" high temp grease has a chance of lube not coming out.

The reality is this is an RV.... the seal is cheap, the brake drums do not spin true, shaft finish has issues, the grease type is unknown in some cases. Then with EZ lube we pack that seal side solid with grease right up to the seal edge trying to force grease through the bearings. And when that packed grease warms up from towing long hours, it can thin, expand and works its way out towards the brakes due to the runout issues and or a poor seal quality setup.

I'm not trying to convince those that have had good luck with EZ lube to change their ways. Yours might be in the better machined side of the tolerances. Just pointing out how the trailer setup we have can fail. Do you really think these RV's are built to tight tolerances?

Hope this helps

John

Mike-s wrote:
And yes, you have to pump it, because it does take pressure to push that thick grease through the bearings and back out. That's when it's trying to push past the seal, not afterwards when you're going down the road with the rubber plug in place.

The Dexter axle manual that came with my trailer requires Lithium base grease,(NLGI#2)to be used in the EZ Lube axle. On the grease viscosity chart #2 is mid-range, and in my experience flows easily through the outer bearing.

mike-s wrote:
These are RVs. What's "good" got to do with anything? :D

Do what you want, but there are lots of people who ended up with grease on their brakes after trying to use an EZ-Lube type system. Whenever it's time to replace the grease, it's also time to inspect the bearings. Do you plan to skip that step?

FWIW there are instances of people who have ended up with grease on their brakes, and they didn't have EZ-Lube. Of course there are the people who have had issues with their hubs right after a "service", so maybe there's something to be said for "If it ain't broke, don't fix it".

mike-s wrote:

Cummins12V98 wrote:

falconbrother wrote:
After lots of research I have decided that I'm going to service the EZ lube axles like the factory video says regardless of what the guy at CW said. There's no way pressure can build up in an EZ lube axle and blow out a seal.

It would blow the rubber plug in the cap first!

LOL. You're joking, right? Because how are you going to pump that thick grease in through the zerk without removing the rubber plug?

And yes, you have to pump it, because it does take pressure to push that thick grease through the bearings and back out. That's when it's trying to push past the seal, not afterwards when you're going down the road with the rubber plug in place.

Yes, it can, and did happen with my first enclosed snowmobile trailer. More than once, I noticed after a long haul, that the rubber plugs were partially pushed out, and spewed grease on the outside of wheel. I think part of the problem was the trailer loaded to max, causing very cold bearings and hub to heat and build pressure. I have a 7x23 enclosed snowmobile trailer now, double axle, and never the same issue. This one has a 3,800 lb CCC, so never over loaded.

btw, truck&trailer were new, when pic was taken

Jerry

These are RVs. What's "good" got to do with anything? :D

Do what you want, but there are lots of people who ended up with grease on their brakes after trying to use an EZ-Lube type system. Whenever it's time to replace the grease, it's also time to inspect the bearings. Do you plan to skip that step?

"That's when it's trying to push past the seal, not afterwards when you're going down the road with the rubber plug in place."

But a seal that is in good shape with no nicks, and a good sealing surface will increase the sealing force against the sealing surface as more pressure is applied to the sealing side. So the more pressure to try to push by it increases the sealing pressure to resist. That's how a good seal works.

Cummins12V98 wrote:

falconbrother wrote:
After lots of research I have decided that I'm going to service the EZ lube axles like the factory video says regardless of what the guy at CW said. There's no way pressure can build up in an EZ lube axle and blow out a seal.

It would blow the rubber plug in the cap first!

LOL. You're joking, right? Because how are you going to pump that thick grease in through the zerk without removing the rubber plug?

And yes, you have to pump it, because it does take pressure to push that thick grease through the bearings and back out. That's when it's trying to push past the seal, not afterwards when you're going down the road with the rubber plug in place.

falconbrother wrote:
After lots of research I have decided that I'm going to service the EZ lube axles like the factory video says regardless of what the guy at CW said. There's no way pressure can build up in an EZ lube axle and blow out a seal.

It would blow the rubber plug in the cap first!