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9” axle: Changing oil

raleigh_bronco

Bronco Guru
Joined
Sep 25, 2002
Messages
1,448
Quick questions:
1. What is the P/N of the axle gasket located inside the brake drum? Fel-Pro?
2. Do you recommend a gasket or just use Permatex on the housing surface when removing and re-installing the 3rd member to drain the oil?
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
1. Did you already bugger yours up? If not then you probably don't even need one. I don't think they were changed very often because they rarely needed it.
Though I have heard more and more talk of them lately, and they are available I believe. Just don't know anything about it.
You'll just need to know if you have a big or small bearing, or a "medium" setup to get the correct part.

2. With a paper gasket i always use sealer. Especially if your surfaces are not pristine. For theoretically better sealing without chemistry though, one of the newer "Lube Locker" or o-ring or steel core type gaskets might be the way to go.
I don't know if sealer is recommended with the steel core gaskets or not.
Lot of 9" gurus hereabouts though, so someone should know all that stuff.
Here is our listing: https://www.wildhorses4x4.com/category/Bronco_Rear_Housing but I did not see any instructions. Seems like the steel one would benefit from sealant as well.

This the '69 you're working on? Original rear end setup?

Paul
 
OP
OP
raleigh_bronco

raleigh_bronco

Bronco Guru
Joined
Sep 25, 2002
Messages
1,448
1. Did you already bugger yours up? If not then you probably don't even need one. I don't think they were changed very often because they rarely needed it.
Though I have heard more and more talk of them lately, and they are available I believe. Just don't know anything about it.
You'll just need to know if you have a big or small bearing, or a "medium" setup to get the correct part.

2. With a paper gasket i always use sealer. Especially if your surfaces are not pristine. For theoretically better sealing without chemistry though, one of the newer "Lube Locker" or o-ring or steel core type gaskets might be the way to go.
I don't know if sealer is recommended with the steel core gaskets or not.
Lot of 9" gurus hereabouts though, so someone should know all that stuff.
Here is our listing: https://www.wildhorses4x4.com/category/Bronco_Rear_Housing but I did not see any instructions. Seems like the steel one would benefit from sealant as well.

This the '69 you're working on? Original rear end setup?

Paul
Appreciate this Dirt!
 
OP
OP
raleigh_bronco

raleigh_bronco

Bronco Guru
Joined
Sep 25, 2002
Messages
1,448
68. I really like that Lube Locker gasket with the bead. I’ll pull the outer gasket carefully and inspect. I’ve never looked but assume it is the small bearing due to the year - 68
 

billtammy

Jr. Member
Joined
Mar 24, 2014
Messages
78
I CHANGE MY OIL 2 TIMES A YEAR ( CHEAP INSURANCE ) JUST TO SEE WHATS GOING ON INSIDE. I USE HARD LINE LIKE ARB HOSE AND PUSH IT THRU THE FILLER. START A SIPHON AND LEAVE IT OVERNIGHT TO DRAIN. IF YOU WANT USE A CONTAINER TO MEASURE AND YOU WILL SEE ALMOST ALL OF IT WILL COME OUT.
 

bax

Contributor
Old Member
Joined
Aug 22, 2005
Messages
14,491
Easier way is to pull the front pinion support and suck it out. Not like that you sick bastards.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
68. I’ve never looked but assume it is the small bearing due to the year - 68
Nope. Doesn’t work that way. Big bearings were available every year from 66 to 77 and beyond.
They were all 28 spline axles from the factory, but the bearings came in two flavors.

Next time you’re under there look for a couple of clues. Brake diameter and the telltale flare at the end of the tube behind the brake backing plate.

If you have 10 inch brakes then most likely you have the small bearing. If you have 11 inch brakes most likely you have a big bearing.
If you look on our website under drivetrain, rear axle, axles and bearings, you’ll find a little write up showing what the end of the housing looks like. If the tube goes straight all the way out to the brake plate it’s a small bearing.
If about an inch before the backing plate it flares out slightly it’s a big bearing.
 

jamesroney

Contributor
Sr. Member
Joined
Sep 11, 2007
Messages
1,667
Loc.
Fremont, CA
I CHANGE MY OIL 2 TIMES A YEAR ( CHEAP INSURANCE ) JUST TO SEE WHATS GOING ON INSIDE. I USE HARD LINE LIKE ARB HOSE AND PUSH IT THRU THE FILLER. START A SIPHON AND LEAVE IT OVERNIGHT TO DRAIN. IF YOU WANT USE A CONTAINER TO MEASURE AND YOU WILL SEE ALMOST ALL OF IT WILL COME OUT.
I have NEVER changed my gear oil in any Bronco that I have ever owned. Unless it was submerged in water above the vent line...which is a full 32 inches above the ground. I have driven my 9 inch, Dana 44's 60's, 70's and my AAM axles at least a million miles, and never changed the gear oil. Gear Oil does not wear out. It can only get contaminated. I have drained original gear oil from 50 year old axles that was as good as it was when new.

Here's an idea. The next time you plan to change your gear oil...just send me a check for $50. I will hold your money for the next 30 years. If you have a ring gear or bearing failure due to lubrication in the next 30 years, I will fix it for free. In 30 years, I'll have $3K, and you will still have a perfectly good set of gears. If I could just get a couple hundred people to sign up...I could retire. (again...)

Lately I've started re-using my gear oil. Drain, filter in a paint strainer, and re-use.

Save the planet. Stop wasting gear oil.
 

Speedrdr

Contributor
Learning Member
Joined
Nov 27, 2017
Messages
1,134
Loc.
Paris, MS
I had to change the gear oil a time or two in the ‘72 I once owned. Wouldn’t have changed it those times except for the axle bearings going out…or the axle breaking. It was a stinky mess having to add the friction modifier (read: whale oil) to the rear housing.

Randy
 

lars

Contributor
Been here awhile
Joined
Jun 29, 2001
Messages
3,041
Loc.
NorCal flatlands
I have NEVER changed my gear oil in any Bronco that I have ever owned. Unless it was submerged in water above the vent line...which is a full 32 inches above the ground. I have driven my 9 inch, Dana 44's 60's, 70's and my AAM axles at least a million miles, and never changed the gear oil. Gear Oil does not wear out. It can only get contaminated. I have drained original gear oil from 50 year old axles that was as good as it was when new.

Here's an idea. The next time you plan to change your gear oil...just send me a check for $50. I will hold your money for the next 30 years. If you have a ring gear or bearing failure due to lubrication in the next 30 years, I will fix it for free. In 30 years, I'll have $3K, and you will still have a perfectly good set of gears. If I could just get a couple hundred people to sign up...I could retire. (again...)

Lately I've started re-using my gear oil. Drain, filter in a paint strainer, and re-use.

Save the planet. Stop wasting gear oil.
This is the best rant I've read all week. My statistical sample is smaller but I haven't changed the oil in my rear axle since I installed the assembly in 2005, other than to replace the drippage due to stupid-me induced disassembly. And even then I collected most of it and reused it. Not only that, I drained as much oil as I could out of the previous axle and reused it. Gear oil never gets close to being overheated unless something is seriously wrong, and if it does (the only thing that could cook it) you have major other problems.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
As far as “cheap insurance“ goes I changed mine every 50,000 miles. Just in case…
And as you can tell by what the others have said, that was still likely more often than needed.
But in that case it did fall in the category of cheap. Changing it twice a year kind of changes the cheap aspect.

I had the oil in my manual transmission go bad before that, but I couldn’t really confirm from memory that it had been gear oil and not something different like motor oil.
Although when I topped it off I used gear oil, whatever was in there before was unknown.
 
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OP
raleigh_bronco

raleigh_bronco

Bronco Guru
Joined
Sep 25, 2002
Messages
1,448
Nope. Doesn’t work that way. Big bearings were available every year from 66 to 77 and beyond.
They were all 28 spline axles from the factory, but the bearings came in two flavors.

Next time you’re under there look for a couple of clues. Brake diameter and the telltale flare at the end of the tube behind the brake backing plate.

If you have 10 inch brakes then most likely you have the small bearing. If you have 11 inch brakes most likely you have a big bearing.
If you look on our website under drivetrain, rear axle, axles and bearings, you’ll find a little write up showing what the end of the housing looks like. If the tube goes straight all the way out to the brake plate it’s a small bearing.
If about an inch before the backing plate it flares out slightly it’s a big bearing.
Thank you Dirt. I really appreciate the thoroughness of your responses. I would love to fly you out to NC and help with my new crate motor / install. :)
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
Would be fun!
But I’d probably have to drive and do a parts delivery run at each stage along the way. Might not get to your place for a month, but if we plan it right it could still work. :)
 
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