The Stovebolt Site Forums The Shop Area Driveline 1946 1/2 ton rear wheel seal leak

I have gear oil on my rear brake pads. How do I replace the axle seal? What has to come off and what are the steps.

you should find the details in the shop manual, section 4: 'rear axle' - if you don't have a manual, see the 42-47 manual here

Bill

How old is the oil in the differential? When it gets old, it get thin. Many rear axle seal leaks have been remedied by just changing the oil! No guarantee, but if you are up for it try it, the seals may leak a little until the new oil softens the old seals, so I would try it for just a few miles, then if the leak persists, change the axles seals. You needed to change the rear end oil anyway!

While you're at it.....make sure the vent tube is clean/not blocked.

You've got to pull the rear axle by removing the cover off the rear end. Shop manual will show you the steps to remove the axle shaft spacer, which lets you take the horseshoe retainer loose that holds the problem axle in place. Sounds scary, but it's pretty easy (I've pulled axles on the side of the road before).

Once you get the axle out, you'll see that the seal is probably leaking, it's not an unusual problem. In the 30 years I've owned my '46 I've probably done them 3 times. I use a 3-jaw slide hammer to pull the old seal. Be careful that you put the slide hammer on the SEAL and not the bearing!! The old seal will be trashed in the process. Here's what an old one on a '51 GMC looks like - they're pretty much the same for a long stretch on Chevy/GMCs:

http://s456.photobucket.com/user/bl...ogress/DSC_1244.jpg.html?sort=3&o=10

Inspect the bearing and the race on the axle shaft while you've got it apart. Replacement seals can be gotten from NAPA, about $14 last time I did one.

You'll notice that the seal is actually countersunk a bit into the axle housing - important that you get the new one countersunk as well. Put a little gasket sealer around the outside of the new seal before you install it - I rub on a thin coat with my finger. Tap the new seal in place by gently tapping around its perimeter with a small hammer until you get it level with the housing. To get the countersink I use a PVC pipe joint that is just a tad smaller then the OD of the seal. I took the seal to an Ace Hardware and found one for $1.29. You can pound on this pretty well since you're not hitting directly on the seal. Once the seal is in snug, I spread some fresh gear lube on the bearing, the axle race and the rubber ring on the ID of the new seal.

Gently slip the new axle in. Reassemble the horseshoe lock and axle spacer. Refill the rear and you're done. Sounds like a bear, but, like most things, once you've done it once it isn't bad. I can do one start to finish in about an hour.

Good luck,

David

I second Victor's comment about checking the axle vent. Do that first as it is so easy to do. On my '51 I had gear oil on my brake shoes on one side. With a blocked vent, driving causes warming of the differential, leading to increased air pressure, pushing gear oil past otherwise intact seals. I cleaned the vent, cleaned the shoes and drum and several years later no problems without ever changing the seal.
Kent

Hi David,
I looked up the info you posted a while back on how to remove the seals and bearing on the rear axle. I'm a little stuck on removing the horseshoe retainer. Ive pushed the shaft as far in as it will go, and with a flat head screwdriver leveraged in also as far in as the shaft will go but the horseshoe retainer still doesn't seem to have enough clearance to come out. Am I missing something? How do you usually push those out? Thanks for any help you might have.

A little update, I hadn't gotten to the right side shaft, this one was very easy to take off as soon as I took the wheel and hub off. It gave me more than plenty of space/clearance to take the horseshoe retainer out. The left side is another story. Could the fact that the bearing ran out be the problem? I have about 1/4 of an inch up and down play on my shaft from the bearing wearing out. Could that have an impact? Thanks for any help. All I need is about 1/8th of an inch more clearance to get the horseshoe retainer out.

That definitely is abnormal. I wonder if you can tap the axle back in a bit. It sounds like the bearing has shifted.

The shaft has about 1/4 inch play left to right but its not enough to get it off. I imagined it wasn't normal, especially by how easy the other side was to get off. I'm going to have to start pounding on it a bit. Maybe its catching on a groove the worn bearing made on the shaft. If anyone has any more ideas, they will be welcome. Thanks

There should be almost no play up and down? That would be a bad bearing. I had pitted axles at the bearing. I had a 1/2 inch spacer made and moved the bearing out farther in the axle housing. The new seals were thinner than the old leather ones and it worked out fairly well. I have some photos in photobucket. None for the axle removal.

Hello Mr. Wirth, that's the reason I'm taking the drive shaft out. The bearing pretty much disintegrated I imagine. There should be absolutely no play in the drive shaft to my knowledge. I hadn't thought of using a spacer, though I already bought the bearing and seal. I imagine the most cost effective option, if the shaft is worn, would be to buy another shaft. Thanks for the info, good to know

Well I finally took it off. I had to remove the inner bearing support. That's going to be fun putting back together. One question for anybody that might have experience having done this. Is it worth it going from 4.11 gears to 3.73 gears? Will my truck still have decent low end torque? I guess it would be worth it for the higher top end speed.

The shaft is out, needed to use a slide hammer. Bearing and seal came off. The bearing was completely gone, ate into the shaft pretty good so ill have to have that replaced. Good news is, after the shaft was out, the inner axle bearing was not too hard to put back together, lucked out on that one.

Not to ruin your day but I contacted axle companies all over the usa. No replacement axles exist that I could find. Best of luck.

I guess its the hunt that makes owning a classic exciting, hehe. I think I might have found a company on ebaymotors that carries them, if worse comes to worse then I imagine the drive axle could be machined down a bit where the bearing rides and have a race put on, then it would be good forever. Theres plenty of parts trucks out there also. I hope to take some pictures of the work soon so that whoever comes after me with the same question can have an idea what they are in for. It turned out to be a pretty simple job but for the stuck drive axle.

Can you find the Original GM part number

of your damaged axle ?

I'll see if I can find one GM NOS.

I found GM NOS axles for David Bush.

George
'54 3600

Good day George,
I really appreciate that. I couldn't find any parts number on my axle, I looked it all over. Could it be behind the backing plate that is pressed on with the studs? I might have some luck with these guys on ebay, their company is rpm-motorsports. They seem to deal in older car parts and have many later model axles. But the NOS is definitely the way to go if I can get my hands on one. So have you ever heard of an axle being machined down to accept a race or a sleeve where the bearing can run? I don't see why it couldn't be done. Here are some picture of my truck and the axle.
Close up axle
whole drive axle
New Rims or Old Rims?
Engine problems

let's get this correct. You have a 1946 1/2 Ton.

Please just go to the online parts manual & look up

your axle part #. Please post it here.

What do you need ? Right or Left or both ?

If you have a '46 1/2 ton.....I've already found

GM NOS axles. I'd suggest replace both axles. Along

with inner & outer bearings on each axle along with

seals.

George
'54 3600

Hello George,

Mine is a 1946 1/2 ton. I only need the left one, the right is in good shape. I installed both sides bearings and seals but not the inner ones, they're in good shape.
The shaft is 17 tooth, a little over 29 1/2 inches long and it's the 6 lug. I'll have to look up the part number. Thank you for all your help. Where can I purchase this axle?

1946 Chevy 1/2 ton truck

Rear Axle - GM NOS - Availability

LEFT axle - GM # 5.420 - GM # 3652341

28 & 3/4 " O.L. - stamped # 3652341

Why is your measurement of O.L. different then

stated in the parts manual ? You state, a little over

29 & 1/2 " .

Right & Left axle lengths on your truck are NOT the

same.

as shown in Chevy Parts manual
@
photobucket

http://i669.photobucket.com/albums/...xle%20LEFT%20and%20RIGHT_zpsdxmlv7c9.png

&

http://i669.photobucket.com/albums/...AXLE%20GM%203652341/AXLE_zpsarlwd2yw.png


Dan's Obsolete GM Parts
Chinook, Montana
phone: 406-357-2615

Dan's has ( 4 ) GM # 3652341 in stock

He will want EXACT measurements of your old axle.

He may even request photos. So , get prepared.

He does not like to send out a part & then get it

sent back.

Last fall he sold this axle for $75.00 plus shipping.

I have another source if Dan's does not work out.

Please keep us posted on your progress.

George
'54 3600

Thanks George,

I will definitely keep you guys posted. Its strange the left drive axle is shorter by one inch than the right side. I wonder what that is due to. In any case, I had measured the left side one and it is 29 1/2 almost 29 3/4 inches long. I wonder if whoever had the truck before me put the wrong one and if it had anything to do with its wear. Ill be calling Dan's on Monday with some pictures just to make sure. Thanks again for your input and help. Glad theres guys like you out there helping us out. Take care

Sorry to have been out of this discussion since I went through this whole process a few months ago. Life intrudes, ya know?

It is not strange that the axles are different lengths, that is correct for your truck. Be sure you're IDing the axles correctly: left and right are based on you perspective from behind the wheel - left is driver's side, right is passenger's side.

Group # - 5.420
Left 28 3/4" OL Part # 3652341
Right 29 3/4" OL Part # 3652342

As far as I can tell, these axles are specific to 40-46 COMM only.

Dan's is where I got my replacement axles. Before you install the new ones you'll need to go to a machine shop and get your studs pressed in. THIS IS IMPORTANT: there is a metal oil deflector plate that is held on by the studs when they're pressed in. There MUST be a gasket installed under the plate before you press the studs in - I put some gasket sealer on both sides of the gasket first, then pressed in the studs. You also need to install another gasket between the axle flange and the brake drum when you put it back on. These gaskets are available through most old truck parts suppliers - I think mine came from Jim Carter. You DON'T need to put sealer on this one or you'll play hell getting the drum off again.

It's been my experience (owned the truck over 30 years) that the oil seals seep a bit. Notice that the deflector has a channel in it to point any seeping oil out through the hole in the axle flange and then through the hole in the drum. Be sure you align these holes! Without the gaskets, even with a pretty good oil seal, you'll frequently see just a bit of oil getting through to the inside of your brake drums.

Hello David, thank you for the extra info, it will come in handy. I called Dans and am awaiting a response from him. Hopefully soon he'll get back to me. I'm quite sure I measured this drive axle right, it measures a little over 29 1/2 inches long, so, either the previous owner put the wrong side in, or as Dan told me, sometimes they're just not the correct length. I wonder if it makes that big of a difference? I'll make sure to put the correct one in though. Perhaps that was the reason for the premature wear. I'll keep updating till its done. Thanks again for the info.

Gabe

It's pretty much impossible to put the axle in the wrong side, so that's not it. It just won't fit if it's the wrong length. The axles I got from Dan were great - NOS in original GM packing. Good luck with your project. Thanks again to George ('54 3600) for the connection to Dan's. These axles are HARD to come by!

Yeah, I'm glad to get one, he's asking $100 now, which is understandable since they are getting harder to find. So here's the question I've asked a few times and no one seems to have an answer. What does one do when there's no more drive axles to be found? Short of changing the whole rear end for a later model one? Do the 47-54's axles or whole rear ends fit an earlier model truck? I'm wondering if I should keep my old axle? Has anybody ever had one machined to accept a sleeve or race where the bearing would run? It can't be that expensive and you would have an axle that would work in theory, forever .What are your thoughts?

Finally got my shaft delivered after a months wait, it was a while coming but worth the wait. It took me literally about 10 minutes to put it back together, I guess that shows how much I went through it in my mind. Here are the pictures of the parts back together now. Thanks for everybody's help, I hope this info helps others with the same job.

Shaft NOS

Part Slip

Gasket in between Oil Deflector and Shaft

Oil Deflector Hole and gasket

Thank you for the update. Those photos were great. Jeffrey

This is how she looks now with its newly painted artillery wheels. These where supposed to go on my 47 fleetline but I went to big on the wheel and will now have to use them on my truck. The seats in the back are from my fleetline, will be getting upholstered soon. Its time to use it now for what it was meant for. More pictures to come in duty

Finished Front

Finished Rear

Finished Side

Good job! Glad to see her back together - beautiful truck!

Thanks David, im glad to have it running again too. I appreciate all the help. Greetings from Eureka California