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Replacement rear bearings

muskrat

Bronco Guru
Joined
Aug 21, 2008
Messages
1,503
Well I've figured out my 74 has the medium duty large bearing set up. My glove box tag indicates that I have the 2780lbs axle.

When I purchased my replacement bearings from my local auto parts vendor they showed two axle ratings, 2780 and 3300. I looked at my diff housing near the backing plate and it was not a small bearing profile.

I installed the new large bearing and it fit no problem. I guess I'm just confused and lucky when I bought the large bearing replacements.

Can a 2780lbs axle be a big bearing medium duty bearing?
 

Gerbow

Sr. Member
Joined
Jul 24, 2011
Messages
775
Loc.
Jacksonville
I dont know how to get quotes or links from other threads or anywhere else for that matter, but if you type in "rear axel question" in the search this thread, go to that thread by 70 steed and there is a little info there for you that helped me.
As far as bearing size....
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,312
Well I've figured out my 74 has the medium duty large bearing set up. My glove box tag indicates that I have the 2780lbs axle.

When I purchased my replacement bearings from my local auto parts vendor they showed two axle ratings, 2780 and 3300. I looked at my diff housing near the backing plate and it was not a small bearing profile.

I installed the new large bearing and it fit no problem. I guess I'm just confused and lucky when I bought the large bearing replacements.

Can a 2780lbs axle be a big bearing medium duty bearing?

The '74-'75 medium duty axle used large bearings and small (10") brakes.
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
The standard ball bearings are permanently lubed with grease from the factory. The bearing itself is sealed to keep the grease in. The axle seal keeps the axle oil inside the housing.
 

Timmy390

Bronco Guru
Joined
Jan 1, 2011
Messages
5,609
Loc.
Conway, AR
Well I've figured out my 74 has the medium duty large bearing set up. My glove box tag indicates that I have the 2780lbs axle.

When I purchased my replacement bearings from my local auto parts vendor they showed two axle ratings, 2780 and 3300. I looked at my diff housing near the backing plate and it was not a small bearing profile.

I installed the new large bearing and it fit no problem. I guess I'm just confused and lucky when I bought the large bearing replacements.

Can a 2780lbs axle be a big bearing medium duty bearing?

Ran into the same issue this past summer. Glove box stated axle rating of 27 but those bearings wouldn't fit. The 33's were just the ticket. I'm just glad I took one of the old bearings wtih me to the parts store and compared old to new before I bought them else I would have pressed them on and been like WTH....

Tim
 

Timmy390

Bronco Guru
Joined
Jan 1, 2011
Messages
5,609
Loc.
Conway, AR
There are just two sizes of bearings. Large and small. The Medium duty refers to the axle weight rating. Medium duty has the 10x2 1/2" brake shoes, as mentioned by Viperwolf1.

I think it's the parts stores confusing everyone as they ask for the weight rating and the "computer" tracks to the small bearings for the lighter axles.

They can only look up parts via the standard questions, year, make, model, engine size, etc. They'll then ask axle weight.....You go in there and say big bearing and they have no clue......

Tim
 
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