74 rear axle bearing size

[BrownDog]

I am trying to figure out what bearing size I have. 28 spline 10 in drum and the axle bolts have 9/16 nuts. I spoke with Toms bronco parts yesterday and was told some of the 74’s had small drums and big bearings. Is there any way to know other than pulling one axle to measure the bearing?

Also this is my first post. I have enjoyed the forums very much. I inherited my bronco from my uncle who bought it new. I actually have the original window sticker and build sheet.

Thanks for everyone’s help

Scott

 

[langester]

Welcome to the site! Try this link maybe it will help you determine what you have.


http://www.wildhorses4x4.com/category/bronco_rear_axle

 

[BrownDog]

Thanks. Looking at that and comparing my axle it looks like a small drum large bearing. Also looking at the build sheet it has order cod 201 4500 gvw Package along with decoding my axle tag that shows it being a 3300 lb rear axle.

 

[DirtDonk]

Great story BrownDog! Now we just need to see pictures of your family-Bronco!
When you get a chance of course...

Your 3300lb rear axle should be the heavier duty model, with the big bearings.
Timken says so too, which makes your seal the #51098 and the bearing a #514003P
If you're buying locally, they should all have the crossover numbers to whatever brands they carrry. The Timken numbers are usually fairly standard though (plus or minus the "P" that I've noticed sometimes) so they should be easy to find.

We keep them in stock, and any local auto parts store worth their salt should have them as part of their regular bearing supply as well.

Paul

 

[Viperwolf1]

Thanks. Looking at that and comparing my axle it looks like a small drum large bearing. Also looking at the build sheet it has order cod 201 4500 gvw Package along with decoding my axle tag that shows it being a 3300 lb rear axle.

Whats on the axle tag? Whats the rear GAWR on the door tag?

 

[BrownDog]

WFR-B2 is on the axle tag. The door tag shows 4500 GVW. Thanks for the info Dirt Donk

 

[BrownDog]

Viper the door tag says 2900 for the rear but the tag decodes to 3300 and the order/ build sheet says 3300 rear and that goes with the tag on the rear axle

 

[DWALKER]

Ok. I’ve been down this road. In 1974 Ford offered a medium duty rear end. That was big bearing and 10x 2.5 drums. All other big bearing rear ends have 11x1.75 shoes.

 

[Viperwolf1]

Viper the door tag says 2900 for the rear but the tag decodes to 3300 and the order/ build sheet says 3300 rear and that goes with the tag on the rear axle

2900 GAWR is the heavy duty, large bearing, 11" brake axle. It was an option with the 4500 GVWR in '74. The difference between the 2900 lb and 3300 lb is the weight of the axle, wheels, tires, etc.

 

[frenchy]

Dirt Donk, are those sealed bearings or tapered with a race? Seems the bearings I got with my new 31 spline axles were tapered with a race even though stock was a sealed for my 77.
Thanks

frenchy

 

[BrownDog]

Thanks everyone. So I will order a new third member and axles this week. 10” drum with large bearings. Is it worth changing to 31 spline from the stock 28? Also is the true track worth the extra over the traction lock?

 

[Viperwolf1]

It's odd that everything says you should have the HD axle yet you say you have 10" brakes. Maybe someone swapped the axle in the past. Maybe the assembly line put the wrong one in. I would take a good look at the backing plates and make sure someone didn't do something to squeeze the 10" brakes on, like drill out mounting holes or use 3/8" bolts in 1/2" holes. There is also a brake offset difference between the heavy and medium duty axles so make sure of what you need before ordering.

 

[BrownDog]

Viper - some 74 and 75’s had small drums and big bearings. I have the paperwork for everything ever done to this bronco. My uncle was a Colonel over a fighter Maintenance squadron. I have documentation for everything all the way to the date and mileage for every oil change ever.

 

[DirtDonk]

Dirt Donk, are those sealed bearings or tapered with a race?

Stock replacements. Sealed ball bearing and an inner axle seal.
No Early Bronco ever came with the Set-20's tapered rollers from the factory. Only full-size trucks had those.
And only the sealed ball type will fit the stock axle shafts properly. Aftermarket axles are another story...

Seems the bearings I got with my new 31 spline axles were tapered with a race even though stock was a sealed for my 77.

That would be correct. Stock was sealed, even in '77. But many aftermarket heavy duty axles use the heavier duty Set-20 tapered roller style bearing as part of the strength upgrade.
It's just a choice the manufacturers make when creating a new axle shaft. Go with the stock setup, or give it an added value of working with the stronger bearing setups.

Personally I feel that the stock sealed ball bearings are plenty strong for most of use, but since the manufacturer's can't really know what the owner is going to put on those axles (37 or 40 inch tires maybe, plus a plethora of heavy off-road goodies on top?), it can be better to err to the stronger side.
Hence the tapered rollers on most 31 and 35 spline upgrade axles.

Paul

 

[BrownDog]

Dirtdonk - when I order a set of axles from y’all will they include seals?

Thanks again
I tried to post a picture of my bronco but could not get it to work I will have to figure it out

 

[DirtDonk]

If you order 28-spline axles they come with the bearing installed, but you have to order the seals separately.
If you order the 31-spline axles they come with the tapered roller bearing and integrated seal already installed. The seal is part of the outer race and installs all at once WITHOUT an inner seal.

The standard seal is to keep lube inside the housing and away from the bearing. The Set-20 tapered bearing seal is there to keep it all in the housing still, but allow the gear lube to reach the bearing rollers to keep them lubricated.

Paul

 

[DirtDonk]

If you're replacing the whole 3rd member, as it sounds like you're doing, definitely specify 31-splines for the differential to match the 31-spline axles.
I figure you knew that already, but would have hated for you to have gotten some mis-matched parts after all this!

Paul

 

[DirtDonk]

To upload an image directly from your device to your discussion thread, you need to become a contributor for 12 bucks a year.
You can still upload images for free to your "garage" and "gallery" locations accessed in your User CP, but if you get the chance the 12bucks is totally worth it!

You can also use online image hosting sites and link the pictures, such as SuperMotors like members like Steve83 does. To me that's a big hassle if you're just going to do a few photos, but he's got reams upon reams of pertinent information on his SuperMotors pages.
Just don't choose PhotoBucket! Unless they've changed their ways, they buggered a lot of people with their newer policies.

Paul

 

[frenchy]

Dirt Donk thank you for the info. I ordered the 31 spline and they came with the tapered
bearing. Cleared up all my questions.
frenchy

 

[DirtDonk]

Great.
As an additional installation FYI, if these are going into your old housing, it might not be a bad idea to add a slight bead of silicone sealer around the seal area. You can do this before the install like you would normally think to do it, or you can do it after the install, and simply lay a bead with your finger around the perimeter.
The point is to help the seal do it's job in a possibly not to pristine environment like an old used outer housing end.
But look at yours. If they are perfect and have zero nicks, scratches, blemishes or surface rusted areas, you should not need additional sealant.
But if they look like they're coming up fast on 50 years old, a little dab'll do ya I say.

Even if you're going to put sealant on the seal itself, I would test-fit everything first so you know it fits all the way in and you won't have to pull them out again to get something to cooperate. Kind of a common thing when limited-slips and lockers are involved, since it sometimes takes a few tries to line up all the splines.
This test-fitting and verifying a final product is also good practice with powder coating and painting things as well!

For me, this is a good argument then for using sealer after it's installed.
Enjoy the new stronger parts!

Paul