tech topic Dukw wheel bearings, seals, grease, speedy sleeves, axle upgrade

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tech topic Dukw wheel bearings, seals, grease, speedy sleeves, axle upgrade

Post by fahtal » Wed Nov 06, 2019 7:52 am

So we are playing around with some different types of grease over the last few years.

First normal grease but that was a disaster with water proofing(we use axle sleeves and they work great)

Later on we used maritime grease. worked a little better but still with water it becomes soapy and after a year the bearings show corrosion and also allot of water leakage along the shafts.

Now we use a new grease eurol-cs2. on purpose we skipped big maintenance for one year and after 2 years no water in the axles! and no corrosion or wear on the bearings. everything looks great! but... all metal parts looks black now! the grease is still yellow, on some wheels it is more brown(more contact with water?) On the spots where the grease could contact the metal, the metal is black also the grease a little bit. On the spots where it is metal on metal the metal is silver...

It doesn`t look like heat because everything is black also the bearing nuts and the axle. and there are no blue or yellow colours.

So on the water proofing and wear and corrosion we are very happy. but the black colour leaves us wondering....

We will send 1 bearing with grease to the manufactors lab so they can check what is happening...

So what do you use?

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W. Winget
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Re: What grease do you use on dukw wheel bearings

Post by W. Winget » Wed Nov 06, 2019 10:04 am

Haven't had the joy of floating mine yet (or anytime in the near future) I was intending on boat axle bearing grease as it's made for limited water exposure. Short of doing maintenance that the Army had time and bodies for of stripping everything down after a swim.... I too would like some longevity and protection.
The black color might be phosphorus, like you would see using a rust removing chemical like Evaporust or such. This would appear to be harmless, but any bearing surface is being affected at the micro level if it is changing the colors of the metal where there is no metal to metal contact in the phosphorus coating, i think it would be depositing onto the metal, providing protection, and hopefully not add to wear as it is removed in use.
I thought anything with molybdenum in it would suffice, perhaps just because it sounds scientific :lol:
Will be interesting to see what your company comes back with.

Have you tried just dropping an old cleaned then 'lubricated' bearing (or other steel) in a bowl of water for a few months VS not maintenancing the DUKW?
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Re: What grease do you use on dukw wheel bearings

Post by jeffl » Wed Nov 06, 2019 11:00 am

In the first 6 months with our new DUKW this year I have just been using a marine grease. The main cabin of the DUKW takes on less that 2 gallons of water in a 1 to 2 hr run, most coming from the center drive shaft tube area into the cabin so pretty tight now.

I had to rebuild the rear axle due to water intake (at least a gallon plus each run). I believe most was coming in the input pinion shaft and the right inner axle seal. Ring and pinion had corrosion so this was going on for some time. Right side bearings were bad, actually wearing the tire abnormal. No outer seals for either side of the axle flanges were installed.

I put new bearings on right side, bearings on left were nice (likely replaced shortly before I got the DUKW and no water was found in there so inner seal must have been fine), pinion seal and other inner and outer axles seals. I don't get any water in the axle now other than one time after 40 plus hours in the water (maybe 15 trips). I will inspect this winter to see if water has been entering the bearings by pulling axles. I guess it could get in there but now not make it to the inside of the axle because I have the outer seals installed

Center axle started to drip on right side a month ago and would get about a cup of water in the axle from being in the water for an hour plus. My drive shaft tube fills with water during the run so the water is coming in there or the right axle. I did see water come out from the bad gasket when I removed the axle (could be inner seal). There was not an outer axle seal on this axle either? The bearing cage has some light rust but rollers and races look great. This might be from the runs this summer because the first half of the summer the grease looked clean and then changed as water was emulsified into it. I will finish this side and the do the other. side over the next week. I may or may not use new bearings and just pack them with the marine grease. I will install all 4 axle seals.

At this time I don't want to learn how to drop the drive shaft tube to change the pinion seal. I will see how clean the gear oil stays in the axle once I have the new seals installed. This should help me to determine if water is entering from the drive shaft pinion.

When I inspect the rebuilt rear axle over the winter I will report back on what I see.

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Re: What grease do you use on dukw wheel bearings

Post by W. Winget » Wed Nov 06, 2019 11:38 am

Have you considered pressurizing the axle housings to around 2-3 PSI to keep water out? I had read of this previously. Obviously if the shaft tubes were sealed, you wouldn't get water entering an pinion seal, perhaps a small suction tube/hose (2mm) to a 12volt electric bilge pump could be run through the transfer case side holes back to the rear most area of the axles where they drop down while swimming.

Here we would jokingly say "Flexseal it" a aerosol spray on sealant where a guy sprays a boat he's cut in half back together and floats it.
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Re: What grease do you use on dukw wheel bearings

Post by jeffl » Wed Nov 06, 2019 1:55 pm

W. Winget wrote:
Wed Nov 06, 2019 11:38 am
Have you considered pressurizing the axle housings to around 2-3 PSI to keep water out? I had read of this previously. Obviously if the shaft tubes were sealed, you wouldn't get water entering an pinion seal, perhaps a small suction tube/hose (2mm) to a 12volt electric bilge pump could be run through the transfer case side holes back to the rear most area of the axles where they drop down while swimming.

Here we would jokingly say "Flexseal it" a aerosol spray on sealant where a guy sprays a boat he's cut in half back together and floats it.
V/R W Winget
Very similar thought, the upper axle tube for the rear axle drops down into the bottom axle tube for the center axle. Putting in a T there would allow a bilge to keep the axle tube dry. In talking with Steve it is possible i have a leak behind the axle tube brace where I can't see it and this allows the small amount of water to enter. I might further explore putting in a T to drain the tube at that joint. While the pinion is lower than the tube entry it would relieve some pressure and tell me if that is where the water is entering.

For your idea the axles are vented with the vent pipes coming up into the cabin. I would guess pressuring the vent could accomplish keeping water out of the axles if they are pretty tight to begin with.


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Re: What grease do you use on dukw wheel bearings

Post by W. Winget » Wed Nov 06, 2019 3:37 pm

From memory you want just enough pressure to equalize and cancel water pressure so your not pushing seals or oil out.
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Re: What grease do you use on dukw wheel bearings

Post by fahtal » Thu Nov 07, 2019 2:12 am

we have heard of people trying to pressurize the axles and the result was the oil went out instead of the water in...

When we swim it is alway 1 or 2hours. sometimes 4. we don`t make enough water for the pumps to work. I think the mean leak is the rudder axle. and maybe the tubes.

Our axles after 30 hours of swimming this year are water free. we just tapped the oil and no water. that was a first for us.(in 30 years of swimming with dukws...) So the grease works great en still looks great. So if your grease gets influenced by water... then maybe have look at the type we use.

Today i will get a visit of the oil company to look at the black stuff.. The phosphorus theory also came to my mind. We still have to try to remove with some scotchbrite or something.

In the end I think we will reassemble everything and check it next winter what the wear is. If we can do 3 years with the same bearings that would be a record for us. And would mean allot less maintenance than before.
pictures of the 2 year old bearings 30 to 40 hours swim
Image
Black... only the surface of the rollers are silver. no big signs of wear


Image
see the silver look where there is no grease

Image
left the axle sleeve. i would recommend to use this to upgrade your waterproofing.
Look at the black colour.

Image
underside. look at the silver spot where the outside bearing gets pushed to the axle by gravity.

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Re: What grease do you use on dukw wheel bearings

Post by fahtal » Thu Nov 07, 2019 6:51 am

some more pictures.





Image
old bearing 1 year old used with marine grease. see the corrosion spots...

Image
Speedysleeve, we made a "reversed lathe machine" on old wheel bearings and machined the axle so we could fit the speedysleeve with loctide.
Image
Image
Moderne seals instead of the original leather ones.

This all together with the new grease made our axles waterproof. still only the black colour remains a mystery. The used grease is of to the lab. You can remove the black colour but it is stubborn;)

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Re: What grease do you use on dukw wheel bearings

Post by jeffl » Thu Nov 07, 2019 10:33 am

I like the speedy sleeve idea. What part number did you buy and how did you work down the original axle sealing surface for it?

The new seal looks narrow, do you bottom it out or make it flush with outer edge?

All summer with no water is fantastic.

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Re: What grease do you use on dukw wheel bearings

Post by fahtal » Thu Nov 07, 2019 10:48 am

Skf 99313 speedy sleeve.

We put a small air pressure grinder on 2 old bearings on the axle. Mcgiver style...

Image

Picture of the seal in the hub.

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Re: What grease do you use on dukw wheel bearings

Post by jeffl » Mon Nov 11, 2019 6:21 am

I will have to give that some thought to grind.

When rebuilding the center axles we had a 3.200 and 3.196 measurements on the seal surface. Just used standard seals and lot of interference to "pull them on" with axle nut. Bearings had light corrosion so we cleaned and repacked. Just used standard marine grease again from Tractor Supply.

We pulled the rear axles to inspect. Right side was dry but left was wet. We though we were done for the day. Pulled it all apart and found the rubber on the inner seal was eaten up. We had it in Lake Erie for an event and there was sand in the grease. After polishing the seal surface and repacking everything we reassembled. What we didn't like was the hub pushed right on. The sealing surface measured 3.175. The 0.025" smaller must have been just too much wear. It likely slid on easy in the spring when I did the rebuild on the rear axle but I did notice it then or know as much then.

I likley need to take this off in the spring before water use and address with a speedy sleeve. How far did you work the diameter down too for your part number. My measurements were don with PI tape.

I moved to the front axles on Sunday and the left front had the same appearance of ground rubber with black being seen and water in the hub. I have to measure these this week.

Image

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Re: What grease do you use on dukw wheel bearings

Post by jeffl » Mon Nov 11, 2019 6:45 am

I was looking up the sleeve you used. Seems diameter would need to be ground to just below 80.01 mm or 3.150 in where I would still have room to go.

If the speedy is 0.28 MM thick, total of 0.56 mm then 80.01+0.56 is about 80.57 mm or 3.172 inch and your seal showed 3.189 in. I don't work with seals much but that seems like a greater inner diameter than the speedy sleeve. What am I missing or did I calculate something wrong.

I guess this off the grease topic but I found your information great to my task at hand.

Thanks

Image
Image

Added seal picture from above as reference

Image

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Re: What grease do you use on dukw wheel bearings

Post by fahtal » Tue Nov 12, 2019 6:02 am

Sorry my bad. The seal i photographed was for the front axle... I will let you know what we use for the different axles.

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Re: What grease do you use on dukw wheel bearings

Post by fahtal » Tue Nov 12, 2019 12:25 pm

So did some research(because it was 12 years ago and I didn't do the axle job) the front axle seal surface was clean and we put the modern seal from the picture on.

The rear axles were worn down and we modified them to put the speedy sleeves on.

The seals have 2 lips. One for dirt and the other to keep the greas in and water out.


Today we got an update from the Eurol lab.

The grease was still in good condition. There were some elements of silicium aluminium and iron. So a little wear and some sand. Nothing scary. If we wanted we could be using the same grease for another year... 3 years in a row!!.

If you want you could do some tests...

Put a dot of grease and put it on a white paper. Then wait a while. 10 to 30 minutes. If the paper gets soaked around the dot of grease. Like it is spreading.. Then the grease can t hold itself together.

Another test . Put it on a metal plate put some sand and a bit off water and mix/swirl it around with your finger with some pressure... If you hear scratching noises.... the this is what happens in your axles....

The grease that we use doesn't spread on paper. Doesn't scratch or mix with water.

It is darn sticky and won't come off your fingers or tools.... that is the negative side. Haha

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Re: What grease do you use on dukw wheel bearings

Post by fahtal » Tue Nov 12, 2019 12:27 pm

Still no clue what the black colour is. Maybe from a combination of electrical current water and the grease....

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