Wheel bearing grease

mdoyle · #1 10-31-2006, 11:12 AM

I know there is a special aviation wheel bearing grease, do I really need to buy it or will any high quality wheel bearing grease be adequate?
There has been much discussion about the superiority of the Michelin Airstop inner tubes, are they so much better that I need to not use the Van's supplied tubes and purchase the Airstops?

Low Pass · #2 10-31-2006, 11:52 AM

Quote:

Originally Posted by mdoyle

I know there is a special aviation wheel bearing grease, do I really need to buy it or will any high quality wheel bearing grease be adequate?
There has been much discussion about the superiority of the Michelin Airstop inner tubes, are they so much better that I need to not use the Van's supplied tubes and purchase the Airstops?

Answers -

1. Only if you like spending money unecessarily! I'd recommend something from a major brand supplier with EP additive.

2. Only if you like having to add air every 2-3 weeks. I have the air stops and add once every 3-4 months.

N916K · #3 10-31-2006, 12:11 PM

Quote:

Originally Posted by Low Pass

2. Only if you like having to add air every 2-3 weeks. I have the air stops and add once every 3-4 months.

I have the Vans tubes and tires. 18 months and 245 hours later, I have only added air twice. Once was to increase the air preasure when I went from a nose wheel to a tailwheel plane. I'm not sure why people are having so many problems with the Vans tubes. Possibly the cores are cheap and leaking.

az_gila · #4 10-31-2006, 12:51 PM

Quote:

Originally Posted by mdoyle

I know there is a special aviation wheel bearing grease, do I really need to buy it or will any high quality wheel bearing grease be adequate?

My Grumman Maintenance Manual calls for MIL-G-25760 grease for the wheel bearings.... similar Cleveland wheels.

This is easy to get at any aviation supply place as AeroShell #16 grease. I would personally stick with the aviation stuff....

gil in Tucson

RV6_flyer · #5 10-31-2006, 01:31 PM

I use an automotive high temp EP wheel bearing gease that I used in a car years ago. I was too cheap to go buy a new grease. If you need to buy grease, purchase the Mil spec grease that is called out by the manufacturer.

The tubes supplied needed air once a month when inflated to 40. At 30 days, they would have only 20 psi in them.

The 'Air Stop' tires are ran at 30-35 psi and only add air (typically 5 psi addition) about every 3 or 4 months.

I now have over 1,964 hobbs hours after 9 years.

What ever grease you use, stick with it else you need to wash the bearings out with solvent. I only regrease the bearings about every two years or every other tire change.

az_gila · #6 10-31-2006, 02:08 PM

Well I replied too soon, and didn't follow my own advice and check what the manufacturer actually says.... I'm guessing this is a later product than my 1977 era Grumman Manual...

Parker has their Technical Service Manual here...

http://www.parker.com/ag/wbd/cleveland/pdf/Wbtech.PDF

It calls out a later MIL-Spec, equivalent to AeroShell #22.

The Parker web site is here for aerospace products....

http://www.parker.com/ead/cm1.asp?cmid=349

UPDATE

I would disagree with Gary S. on not completely cleaning the old grease out and re-greasing each condition inspection. You need to fully remove the old grease to perform a good inspection....

A good reference on wheel bearings is here, describing the process....

http://www.sisuservices.com/Bearings.htm

It is item e(7) in FAR 43 - Appendix D

(7) Wheels--for cracks, defects, and condition of bearings.

How can you check the bearing condition when it is full of old grease?

gil in Tucson - don't act like Tim Allen....

RV6_flyer · #7 10-31-2006, 06:25 PM

Quote:

Originally Posted by az_gila

How can you check the bearing condition when it is full of old grease?

gil in Tucson - don't act like Tim Allen....

If there is something wrong with the bearing, you can see it, and hear it when you put the airplane way.

I have replaced TWO bearings on my airplane. Without cleaning the old grease out, I could see SPOTS on the bearing rollers and races.

I left the airplane in Sacramento and flew home commercial due to weather (RAIN). I got sick and it was too weeks till I went back to get the airplane. At the next condition inspection, I found SPOTS on the bearings. I assume that it was from the rain. They were smooth but I replaced them anyway. Yes I did clean them to examine closer but they did not need cleaned to find the potential defect.

I had several OLD TIMERS look at the bearing and tell me that I am wasting my money by replacing them.

cytoxin · #8 11-01-2006, 08:10 AM

bearing can fail several differewnt ways, inner races (need to be clean to inspect), outters no cleaning neccesarry and rollers..wellll careful as abrasive step wear on the end of the roller is some times difficult to detect. if youve got them apart for repack and they are at the threshold of failing. you wont see that on greasy bearings. whats another few minute to do the job right.those water marks mentioned earlier are problay harmless. people get away with less than standard bearing service because so few miles are accumulated on these bearings. use any good high temp extreme pressure (EP) lubricant and you'll be ok. jmho

ctbecker · #9 06-06-2007, 06:10 PM

Vans suggests Aeroshell #5. Is there really any reason not to use a high quality semi-synthetic automotive wheel bearing grease? Its a long drive to the airport and a short trip to the AutoZone!

dan · #10 06-06-2007, 06:25 PM

Quote:

Originally Posted by ctbecker

Vans suggests Aeroshell #5. Is there really any reason not to use a high quality semi-synthetic automotive wheel bearing grease? Its a long drive to the airport and a short trip to the AutoZone!

The party line used to be...those automotive greases aren't intended for flight level temperatures. Coldest I've ever seen at normally aspirated altitudes was like 9F, though. Not like we're flying up to FL400. Even so I still use A/S #5 on my wheel bearings & tailwheel fork & what not.