M35 deuce and a half rear axle leaks

Here's a short compendium of answers and then images pertaining to rear axle oil leaks on an M35 2-1/2 ton military truck. These answers are from many different people. Thanks to all the responders on Mil-Veh list and special thanks to Army Master Sargeant Half-Mast at PS Magazine
From: psmag Subject: RE: 424 and 437 (JN-21005/F) To: 'opcom'

Good to hear from you, Sir.

I didn't see anything in PS 424 concerning axle seals in PS 424, but PS 437 does have a similar story to PS 544. The story from PS 437 is attached.

The seal for 2 1/2-ton trucks is currently NSN 5330-00-712-1244, which crosses to several part numbers, as follows:

5X495 (After calling Meritor: This is the insert/key (cork rubber) for the Rockwell C240 drive axle. 3/16" dia. -ed.)
Meritor Heavy Vehicle Systems, LLC 7975 Dixie Hwy Florence, KY 41942, (859) 525-3764

Diamond Reo Truck Co, Somerset, PA 15501

White Motor Co, Cleveland, OH 44100

Hope this helps!

MSG Half-Mast PS Magazine psmag@logsa.redstone.army.mil

I make my own gasket wedges from rubberized cork valve cover gasket material. Easy to do with an exacto knife. Cut the gasket in a sliver that fits tightly width wise and the length of the keyway. Where it ramps up at the end of the threads cut it flush with the top of the axle. Dry assemble the bearing (with a little grease on the mating surfaces to allow you to get it apart easy) and the grease seal and note how long a piece of gasket material you need, and cut it an 1/8th of an inch or so longer, so that when you put it together for real, it will be compressed by the tang on the seal in the keyway and compressed up under the bearing. I used a little silicone gasket material (just a smidge) in the keyway to help the seal. I also put very fine bead on the threads between the locknut and the seal face to cover all bases and a little more in the keyway before I put the locking ring on.

When I pulled my rears due to oil leaks past the inner seals, I found little "rabbit turds" of grease on the top of the axle between the bearings and inside the hub. The 'turds' were created by blobs of grease being rolled inside the hub in the oil inside the hub.The bearings had all of the grease washed out of the outer bearing and not much left in the inner bearing. So, greasing the bearings and leaving the outer seals off seems counterproductive. If the seals could hold oil that well, they wouldn't leak out on the inside of the wheels at all, right? Most common cause of failure of the inner seals is the little piece of cork being left out that goes into the keyway under the outer bearing and is compressed into place by the tang on the outer seal. This allows oil into the hub area in the first place. Again, the devil is in the details....

In 2 of the PS monthlies I've seen, one in the early seventies, and again in the early 80's was a little blurb to the M35 mechs to make sure they made sure they put these cork pieces in to avoid early seal failure. It was also in a multi page MWO or TB that I can't seem to find at the moment (lost in the network hell on one of my machines). Looking a little deeper, I came across this from TM 9-8000 PRINCIPLES OF AUTOMOTIVE VEHICLES section 19-11, Para a) Synthetic rubber seals, "Fig 19-4 illustrates the effect of pressure on lip seals. Internal pressure developed during operation forces the sealing lips tighter against the rotating shaft. This type of seal will only operate effectively against fluid pressure from one direction." This would tend to explain why they use two seals. The inner seal keeps water from entering the hub from outside. The outer seal keeps the oil from reaching the inner seal and leaking out. You use grease on the bearings because it tends to stay put in the hub if it does get flung off. The seals at opposite end of the hub are there only to keep out OUTSIDE water, but this requires the outer oil seal to protect the inner seal. That make sense?

Years ago when I was doing my first seal installation, I stopped in to our local National Guard motor pool to ask some questions. What a learning experience! They pack the bearings with plain old chassis grease, the yellowish stuff, on the initial installation, then leave the outer seal out so the gear lube takes care of the bearings. I still pack the bearings with blue or red grease and install both seals. I'm not so sure that the inner seal would hold up very long against the light (compared to grease) gear lube. Joe Young www.joeyoung.com

Ron: assuming these are Rockwell axles? 6.72:1 ratio? If so, parts are still made and available from any truck parts house that handles Rockwell Axles. Are you using grease to lube bearings?-if NO- use "RED" Synthetic High temp. Replace the cork tapered grove plug with one cut out of a rubberized/cork valve cover gasket [Chevy] using a sharp razor blade and make it 1/8 longer than necessary to seal better when compressed. Also wipe some silicone sealer on this wedge shaped piece and bearing axle surface before assembling. It helps to seal inside of bearing/axle surface. While disassembled --clean out/up oil slinger and Oil singer holes in brake drum with a drill bit and spray brake cleaner. Put it back together very, very, very clean. Change oil in axle to 140 weight when finishing all these procedures. Also run it 3/4 inch below filler hole to allow for expansion when hot as these axles run very hot [double reductions] ... the problem with the axle leaks will stop and will not return if you do it my way. I've spent too many hours repairing/redoing others mistakes...I learned these procedures by watching/discussion/drinking tea with a veteran military mechanic while he was making/teaching/joking about these repairs when ANG units can't keep their axles from leaking. He now is retired from Rockwell and lives in Fla. Do you need the new numbers- if so- write back and I'll go to the river/shop and get them late tonight-and will send another e-mail very late tonight

Memphis sends NOS stuff packaged in the 50's. wrapped in cosmoline ick! get new seals they don't shrink Oil slingers HELP to keep the 90 wt. off the brake shoes by flinging it away from the internal parts inside the hub as you will see when you get the hub off. Keep the holes clean and they work rather well. If they get muddy/clogged the shoes get oil soaked. If you do use grease on the bearings, if it should overheat, it will not end up on the shoes. Theoretically that is! .....geof

The vehicle is a 1968 Kaiser M35A2. The axles are as shown in both the 209 and 361-34P manuals. This will be the first time the wheels are off by me. This is the first large truck that I have had to maintain. I just went out and crawled under the truck and used carb cleaner to clean the paint off the tag on the axle. Worked too well. Took paint off the tag too. There appeared to be a company symbol on the upper left corner of tag, like a large black "W". I don't know how to identify a Rockwell axle from another type by looking at it. Axle ratio will have to wait till the truck is up in air and drive shafts disconnected to get ratio. If this sounds like a Rockwell, any numbers would be appreciated, but no need for special trips, since parts stores up here won't be open until Monday, and I won't get to pulling things apart until Wednesday or so. When you get a chance will be fine. Do the oil slingers and holes redirect the oil back into the axle away from the brake drum or oil that has leaked past the seals out away from the brake drum/shoes and out to atmosphere? It is these tid bits about oil wt., grease type and cork replacements that you have garnered by listening to people who had to actually maintain the equipment versus the folks who wrote the manuals that are invaluable and are much appreciated by those to whom you pass them on to. ith many thanks for your inputs, Ron

Seals and gaskets:
pinion seals...Federal Moguls #410101N
pinion seals... CR [Chicago Rawhide] -#23695

National also makes some dual lipped-can't find the number now but crisscross the other numbers. Grease the seals and surfaces well before mounting the seal...

gaskets.... use silicone rtv blue or copper on any surface that requires paper gaskets let dry for 20 minutes and torque as usual...also on axle shims [metal] behind the pinion seal

axle seals...[inside]....
Meritor # A- 1205 - Z -650 or 550 [2 ea.in box]

and outside

Meritor # A- 1205-Q-667 or CR # 7061230 [or] 8
(I can't see well enough to tell- it's one or another....)

Meritor and Rockwell are the same Company now-they will always make these seals/gaskets because these axles are still used in off-road equipment and are also used by Ford on some of their 4X4 and 6X6 utility trucks with different hubs/brakes and for different rims.

Your outer seal is bad. I order mine from memphis equipment. They're not that expensive. While you are at it order a new lock washer.

You don't need a wheel dolly. Jack up one axle like you were removing the wheel and then pull off the wheels (one at a time). Then you can break loose the 8 bolts that hold the axle on. Inside there you will find a puddle of oil. Be sure to have a coke can to catch it in to keep the mess to a minimum.

Bend the tabs of the lock washer back up and away from the nut. I think it's about 3" but you'll want to get the right socket so you can tighten it up again properly.

Remove the outer nut, the washer and the inner nut. Look at for wear on the seal. Look at the hub where the seal contacts it. If it's worn the hub will have to be re-machined (or replaced) or it will leak again. Check to make sure the bearings have grease in them. If not pull the hub off and repack the bearings. Put the hub back on and then the seal and then the inner nut. Tighten the inner nut till the wheel begins to bind then back off 1/8 turn (one flat on the nut). Align the nut with the tabs on the lockwasher and place the (new) lockwasher on the spindle. Install the outer nut and tighten very tight (150 lb-ft or so but check the manual to be sure). I don't worry about the gaskets around the axle flange. Just use form-a-gasket or rtv or something and be sure to wipe off the excess when you tighten down the axle bolts.

Re-install the wheels (remember to check for left hand threads, you'll find them on one side of your truck). Lower the wheel to the ground and move on to the next one. You can do the rears in an afternoon with no problem.

Get a Budd impact socket for the wheels

That's socket-s as on two, one hex and one square. A mechanic freind has tried the combo sockets and says that he does not like them. As memory serves the two that you need are a 1-1/2 hex (deep) and a 15/16 square but verify before you go buy anything. Of course your also going to need a 3" 8 point axle nut socket as well. All are common from truck type places and tool companies (Snap-On Mac, etc.).

One other thing I could mention. If you take out the axle shaft, you will get some oil from the front side of the outer seal but if you take the axle nuts off to try to get at the outer seal then listen to some advice...... Unless you want to clean one hell of a slimy mess out of the brakes, DO NOT remove the second nut and let the hub pull out or even drop down. If the outer seal has failed then the entire hub and bearings will be full of oil/grease and you will dump all that slimy stuff past that inner seal and it goes right into and all over the brake shoes. If you need to take the second nut off or you need to change or get at the seal, have someone push back on the hub or clamp it somehow. I did it. once. What a mess. Now if your planning to redo or clean the brakes anyway then no matter.

If they are a stock US bearing which I believe they are, you should be able to get the numbers off of them. Try Eastern Bearings in Manchester or Londonderry NH by the airport. I use them a lot and for seals too...

Memphis has the seal, but instead of cork, it's a little wedge of rubber for $0.50 each. It looks like a wide letter "L". NSN is 5330-00-348-8365 and it is detailed in the 361 parts and maint manuals.. FWIW....I contacted 13 vendors ( 8 responded)concerning the items needed in a hub tear down ( cork "wedge", hub gasket, lock washer, outer seal, inner seal, inner and outer bearings and wheel cylinders and brake shoe sets) and only Memphis had everythimg in stock. Boyce, Murray and Antelope had everything but the "wedge". SECO didn't have the lockwashers or the "wedge". The others only had one or two items each.. Prices varied widely on the same parts ( ie NSN). I was warned that I would get NOS cosmolined parts from Memphis, but received New manufacture parts from Korea and Japan. All parts are clean with nice new synthetic rubber. Next step is to hit some Bearing Supply houses and Truck stores and see if they can match up with American parts. But the Offshore stuff doesn't look shabby at all and I will probably use them.

When I checked around to several truck dealers to do my 4 leaking rear wheels, it varied between $1000- 1300 and I had to supply the parts----good excuse for me to do it and buy tools instead of giving someone else the money....Plus if your gonna own big toys ya gotta get the tools or you'll go broke real fast, cause they break something every time they sit for a week or 10 days.

You can do the job yourself, just follow the -209 series manuals for basic instructions and the -361 series for the torque numbers etc and take your time. Plus there is something Zen like in packing bearings that large by hand.

It gives you an excuse to buy two sets of truck jackstands, the 3/4' air impact and Snap-On budd socket, the special 3/4' drive lock nut socket so you can torque the axle nuts properly with your new 'click' sears killer torque wrench. Don't forget the wood for cribbing and the 7 ton bottle jacks. Forget the wheel dolly....just take the wheels off one at a time and be ready to move the hub-drum combo off the axle onto a strategically placed wooden box to avoid placing them onto the ground. You want to borrow a BIG pair of truck brake pliers (I paid $103 for my set) because a standard car pair will almost do the job, but I almost took an eye out when the pieces of pipe I was using slipped of the 'normal' size ones I was using. A company on ebay named molinestud (search for the name on eBay) was selling mil surplus ones for $15 each at Gilbert, PA last weekend. Keep a roll of HD aluminum foil to cover axle ends and ziplocks to put bearings in as soon as you take them off and after you've cleaned them.

Not difficult work, but bull work for sure. I put together a spread sheet listing the prices of the parts from all the vendors I contacted but while one guy had this cheaper than another, it turned out that Memphis Equipt was about $10 bucks more expensive when you figured all of the shipping from the different guys for a 2 piece shipment here and another there. But they send you the wrong "wedge" when you give them the NSN for it. But everything else comes in one box which is a big plus. Order one extra inner and outer seal when you order, so if you screw one up, your not dead in the water.

From: dennis.gilliam@riomail.maricopa.edu 7:21 AM Subject: Rockwell axle sealing To: opcom@vmsone.com Hi Patrick, I've a half-dozen large tacticals (2.5 & 5 tons), and when I have to service wheel bearings, I use either good used or new seals. As to the spindle slot, I get the hub bearings all tightened up and just fill the slot with silicone seal. It works fine in keeping oil from migrating, and is easy to remove next time. I got this tip form our local guard CSMS. The corks are a pain to get through supply. Dennis Gilliam MVPA 3675

These are unusual parts. I bought Rockwell inner seal part # 1205Q650 and outer seal part # 1205Q667 as well as the rubber/cork key and the lockwasher from Memphis Equipment. Best to get them ahead of time, and take them with you to the diesel shop if you are having a machanic do the work. Memphis Equ. (901-774-0600) will know exactly what you are talking about when you call to buy the parts.


My own M35 had to have the outer seal replaced, and the cork insert should always be replaced. I decided to also replace the inner seal and the lock washer.

The image shows the truck jacked up slightly and the left rear axle shaft removed. A jack stand was put in place after the image was taken.

The image shows the outer surface of the outer seal, as well as the outer nut, lockwasher, and inner nut. An old jug caught the small amount of oil present.

The image shows the view with the outer nut and the lockwasher removed. The groove in which the small cork insert/key fits is plainly visible. The seal extends from the axle tube to the iner diameter of the hub. It is designed to keep grease in, and dirt out. It is not designed to keep differential oil out of the bearing space. That is the job of the little cork insert.

The image shows one of the wheel bearing adjusting nuts, the lock washer, and axle bolts. The lockwasher is beat up from being re-used before, and will be replaced.

The image shows the outer axle seal being removed. The nuts and lockwasher are already off. The outer bearing can be seen.

The image shows the inside of the hub with the outer bearing removed. Most of the axle grease has been washed out by differential oil. Fortunately, the bearings are ok. In the groove or keyway, what's left of the cork insert can be seen.

The image shows the axle tube and brakes, as well as the inner bearing, and the inner grease seal which is behind it. Notice that only a few globs of grease are still present. If the truck were taken for a long trip on the highway, the bearings would overheat and fail. It was suggested that the bearings be converted to oil bath, but the inner seal is not designed to keep oil in (thus the leak!) and so it's not a good idea. Additionally, the oil level in the differential is too low to let the bearings bathe in oil.

The image shows the inside of the hub and brake drum. It's pretty nasty all right. The whole wheel assy was cleaned. The brake shoes didn't seem to be too oily, so they were cleaned up, and they will be fine.

The axle tube assembly has been thoroughly cleaned up, as have the brakes, brake drum, hub assy, and all parts. Cleanliness is of utmost importance in a job like this!.

I thought a more complete cross-section of the hub would be useful to those first timers trying to understand this job. The manuals really don't illustrate how and why the insert works, and where the differential oil enters the bearing area if the insert is bad.