8 3/4 leaking - advice needed

[66 Sat]

Hi, I recently noticed a small leak on my driver's side - there was oil running down from the back of the drum and onto the rear tire. I was hoping it was a brake cylinder but when I've pulled off the drum to have a look it all seems dry there, and it seems to be coming from the axle. There's oil and crap all over the inside of the drum and on the shoes which I'll have to clean off (rubbing alcohol?).
Anyway, the question is which seal usually causes the leak - the inner seal or the outer seal? The reason I ask is I can get the inner seal locally in Australia, whereas the full seal kit and bearings I'll have to get from Dr Diff which means the car will be off the road for a few weeks with shipping times etc.
If I do the full job is this the right kit from Dr Diff https://www.doctordiff.com/tapered-axle-bearing-package.html
I'm leaning towards doing the whole lot anyway - I haven't pulled the axle out yet to have a look at what's going on - will it be obvious once I get to that stage?
I've done a bit of research on here and think I can handle the job, but I'm just looking for advice from you guys that have done this for 50 years on whether it's standard practice to do the whole lot (inner seal, outer seal, bearings) or just to replace the shot seal (if that's the case). I don't know the history of the rear end - all I've ever done is change the diff oil.
Cheers

 

[cheeseburgerhead69]

I would replace the outer and monitor it for continued leakage... you can always replace bearings and do the complete rear end if it doesn't fix it.

 

[R/T Boy 67]

The inner seal is the main oil seal. If it is doing it's job then the outer seal just keeps the bearing grease out of the brakes. If the bearings are good I would repack them and replace the inner seal and keep an eye on it. If you don't have one, get a service manual

 

[Fran Blacker]

I would replace the outer and monitor it for continued leakage... you can always replace bearings and do the complete rear end if it doesn't fix it.

The outer a harder fix, need to remove axle bearing. See RT boy67 post.

 

[493 Mike]

The outer acts as a dust seal, the inner as stated above is the grease seal. 8 3/4 axle bearings must be repacked occasionally. They should not get differential lube. You can cut a new foam gasket from foam shipping material.
Mike

 

[66 Sat]

Thanks guys, I'll pull the axle out this afternoon after work and see what's what. New inner seal and repack the bearings sounds like the way to go then, assuming the bearings look decent. I've got 2 service manuals - a '66 manual that came on a disk, which was a scanned pdf document and isn't that clear as a result, especially the illustrations, and luckily a real hardcopy '69 manual that I bought 25 years ago when I had my Barracuda, which is indispensable.

 

[sloinker]

The outer acts as a dust seal, the inner as stated above is the grease seal. 8 3/4 axle bearings must be repacked occasionally. They should not get differential lube. You can cut a new foam gasket from foam shipping material.
Mike

Hmmm. I know very little about 8.75 rear ends but have had my hands on a few others over the years and I have the distinct understanding that the gear oil supplants the grease over time and unless you develop an issue it is plug and play for life. I need to look at the service manual and see the re-greasing interval now. Thanks a lot.....

 

[66 Sat]

So I pulled the axle out and there's a few notches in the collar (as per photos). Maybe the hit it on instead of pressing it on? Does this need to be replaced in this condition? Also regarding the bearing cup and cone - are these meant to have a lot of free play, both in and out and up and down or should they be a tight fit to the shaft? In the bottom 2 photos below you can see how much they move in and out. Someone has tried to fix this before, there was black silicone sealant all round the retainer.

 

[Demonic]

Does this need to be replaced in this condition? Also regarding the bearing cup and cone - are these meant to have a lot of free play, both in and out and up and down or should they be a tight fit to the shaft?

The retaining collar is likely fine, just got whacked or installed with something that left a mark. New assembly is usually done in a press.

Yes, the tapered roller bearing has a good bit of play without the flange bolted to the axle. Like Fran said in post 4, there's an outer seal pressed into that flange, under the bearing. It's important for keeping oil off the brake shoes. Otherwise, you're replacing shoes twice. The bearings need to be well greased - and NOT over greased where it pushes past the seal- when they go in. Silicone isn't needed with good seals. The downside is if you need an outer seal, you need new bearing also. Can't remove them without destroying them. If they're old or may have ran without enough grease, the choice is easy. A bad axle bearing has a distinctive sound, usually noisier when weight is on that side of the car.

Your brake shoes may be soaked with grease or gear oil. Buy new ones, as it's hard to get oil out of the lining.

 

[john-9]

your inner seal is done -- it keeps gear oil off the bearing (which is packed with grease) and your brakes -- if i was you i would replace the 50 year old bearings and the outer grease seal ( in the bearing retainers ) -- your seal surface on the axle looks rough ,, clean it up as any rust / pitting will not allow the inner seal to do its job -- if it the seal surface does not clean up a stainless steel repair sleeve ( speedy sleeve ) is available and can be installed so you have a smooth surface for the new seal to run on.--- make sure when you install the new inner seals you get them deep enough into the housing so your axles will seat -- there is a stop lip in the housing end the seal will bottom out against -- yes the bearings have that amount of play that is why you have an adjuster on the passenger side to set the end play on the axle bearings (.008-.012 )

 

[493 Mike]

So I pulled the axle out and there's a few notches in the collar (as per photos). Maybe the hit it on instead of pressing it on? Does this need to be replaced in this condition? Also regarding the bearing cup and cone - are these meant to have a lot of free play, both in and out and up and down or should they be a tight fit to the shaft? In the bottom 2 photos below you can see how much they move in and out. Someone has tried to fix this before, there was black silicone sealant all round the retainer. View attachment 973148 View attachment 973149 View attachment 973150 View attachment 973151 View attachment 973152

I imagine someone used silicone to replace the foam gasket I mentioned earlier. There should not be any gear oil in the bearing cavity. When repacking, wash all the old grease out and pack in the new grease (I use two fingers to work it in between the rollers).
Mike

 

[Mick56]

Check the vent on the axle housing. If it gets plugged with dirt, pressure can build up inside the housing and force grease past the seals.
I have had some vents that slightly pop when removed, due to the pressure inside.

 

[mopar jack]

Any time I pull an axle I always add grease before I reinstall. very easy to do with a couple of grease gun attachments.

 

[66 Sat]

Well I think I'll just get 2 new inner seals and see how I go. Car can be back on the road in a few days instead of weeks/months. Parts I ordered from the US in March didn't arrive for 6 weeks due to the covid-19 debacle so I'll take the easy option for now.
I will order the full Dr Diff kit as well and when it arrives just keep it safe for the future.
I'm going to try to clean up the brake shoes and give them a light sand - the shoes don't seem as absorbent as disc pads are so they might be ok.
Many thanks for all the advice.

 

[66 Sat]

I've ended up ordering the Dr Diff full kit with the Timken bearings and paid for priority shipping which apparently will arrive within 5 days (we'll see).

The local bloke wanted $45 each for the inner seal, when Dr Diff sells them for about $5.70 Australian Dollars. It pissed me off so much I thought I'd just get the whole lot and do the job properly and if it takes a few weeks so be it.

 

[sloinker]

I've ended up ordering the Dr Diff full kit with the Timken bearings and paid for priority shipping which apparently will arrive within 5 days (we'll see).

The local bloke wanted $45 each for the inner seal, when Dr Diff sells them for about $5.70 Australian Dollars. It pissed me off so much I thought I'd just get the whole lot and do the job properly and if it takes a few weeks so be it.

Probably a sound decision. Do it right once.

 

[rrTor-Red]

I've ended up ordering the Dr Diff full kit with the Timken bearings and paid for priority shipping which apparently will arrive within 5 days (we'll see).

The local bloke wanted $45 each for the inner seal, when Dr Diff sells them for about $5.70 Australian Dollars. It pissed me off so much I thought I'd just get the whole lot and do the job properly and if it takes a few weeks so be it.

You'll be glad you got the whole kit from Dr. Diff in the long run. I had to change the pinion seal and axle seals and got them from DR. He knows his stuff. But, I have the green bearings on mine which made it much easier. Cheers!

 

[Gary Gaz]

I'm in New Zealand and hear your pain, did this recently
I got all my axle bits from Rock Auto, better price and way better freight to downunder
You will need to replace all your brake shoes to, ( both sides) once they have oil or grease on them they are buggered.
Couldn't press of the retaining band and had to use a Grinder to get of. cut a line in it then use a cold chisel to brake it, we had 60 Tonnes of pressure and it wouldn't budge.
get all the parts and replace all bearings and seals. its worth it in the long run,

 

[threewood]

I would replace the outer and monitor it for continued leakage... you can always replace bearings and do the complete rear end if it doesn't fix it.

If it is leaking gear oil the inner seal is compromised. Those rear bearings are greased. The gear oil could wash the grease out and wreck them. Replace the inner at minimum. And check the shiny metal surface on the axle where the seal rides for grooves.

 

[threewood]

So I pulled the axle out and there's a few notches in the collar (as per photos). Maybe the hit it on instead of pressing it on? Does this need to be replaced in this condition? Also regarding the bearing cup and cone - are these meant to have a lot of free play, both in and out and up and down or should they be a tight fit to the shaft? In the bottom 2 photos below you can see how much they move in and out. Someone has tried to fix this before, there was black silicone sealant all round the retainer. View attachment 973148 View attachment 973149 View attachment 973150 View attachment 973151 View attachment 973152

Hit the shiny surface of the axle above the retaining collar with fine crocus cloth and inspect for wear.