What size rear axle 2900 or 3300 lb for 74’

[Gas Pig]

Trying to get rear wheel cylinders for my 74? Autozone computer was asking if the axle was 2900 lb or a 3300 lb. Honestly I don’t know… I thought of it as a big bearing or small bearing axle.

I know it’s 4.11 factory lock and I’m pretty sure sure it’s a 10” drum with a big bearing.

In the past I was never asked that question before when buying rear wheel cylinders. There is a big price difference between the two different size axes, I just want to buy the right stuff the first time.

 

[LUBr LuvR]

Hey Jeff,
Here’s some pics of the wheel cylinder dimensions where it come thru the backing plate of a ‘74 with 3:50 ls and 10” drums

Lmk if you want any other pics or dims.

 

[Viperwolf1]

Trying to get rear wheel cylinders for my 74? Autozone computer was asking if the axle was 2900 lb or a 3300 lb. Honestly I don’t know… I thought of it as a big bearing or small bearing axle.

I know it’s 4.11 factory lock and I’m pretty sure sure it’s a 10” drum with a big bearing.

In the past I was never asked that question before when buying rear wheel cylinders. There is a big price difference between the two different size axes, I just want to buy the right stuff the first time.

There were 3 axles available in '74-'75. Light duty was 10" brake and small bearing. Medium duty was 10" brake and big bearing. Heavy duty was 11" brake and big bearing. All had their own unique backing plates and axle shafts. Sounds like you have the Medium duty.

 

[DirtDonk]

Trying to get rear wheel cylinders for my 74? Autozone computer was asking if the axle was 2900 lb or a 3300 lb. Honestly I don’t know… I thought of it as a big bearing or small bearing axle.

We only show two model rear wheel cylinders for the '74 and '75 model. Either 10" or 11" brakes. Maybe they use the same cylinder depending only on the brake size.
Wheel Cylinder Page

In the past I was never asked that question before when buying rear wheel cylinders.

On Broncos also? Different years perhaps? Or maybe they changed how the computer listings were formatted.

There is a big price difference between the two different size axes, I just want to buy the right stuff the first time.

Hmm, interesting. Ours are all the same price no matter what the model.
I don't think that was always the case, but at least it is currently.

Paul

 

[Rsmith]

Trying to get rear wheel cylinders for my 74? Autozone computer was asking if the axle was 2900 lb or a 3300 lb. Honestly I don’t know… I thought of it as a big bearing or small bearing axle.

I know it’s 4.11 factory lock and I’m pretty sure sure it’s a 10” drum with a big bearing.

In the past I was never asked that question before when buying rear wheel cylinders. There is a big price difference between the two different size axes, I just want to buy the right stuff the first time.

Were you able to figure this out? I just went to Autozone and got stumper by the same question. I was going to guess that the 2900 pound would be the 10” brake and the 3300 would be the 11” but decided to do some research. Mines a 75 and they did come with both 10 and 11 in drums. I might just order the cylinders from WH. They offer the 10” for a 75, which is what I have. I would have ordered the whole kit from them but the weight of the drums caused shipping to push me to a local parts store.

 

[Gas Pig]

Were you able to figure this out? I just went to Autozone and got stumper by the same question. I was going to guess that the 2900 pound would be the 10” brake and the 3300 would be the 11” but decided to do some research. Mines a 75 and they did come with both 10 and 11 in drums. I might just order the cylinders from WH. They offer the 10” for a 75, which is what I have. I would have ordered the whole kit from them but the weight of the drums caused shipping to push me to a local parts store.

Sorry this is taken me so long to get back to this. Just today I open up the Autozone packing and compared to the originals.

Anyways the two I bought are wrong for my axle. I believe the ones they gave me was actually for the 11” brakes… which I would guess it’s 3300 lb. axle.

If you notice the part of wheel cylinder that comes through the brake backing plate is smaller on my original wheel cylinder then the ones that autozone sold me. I took them back but Autozone was out of the other version. So I ordered a pair of cylinders from O’Reilly Auto Parts. They are supposed to come in tomorrow. I’ll keep you posted if they are correct or not.

Thanks Jeff

 

[DirtDonk]

Do you have a Marti Report? Do you still have the Warranty Plate on the glovebox door or Certification Label on the driver's door B-pillar?
I thought the label listed the GAWR for front and rear. But maybe not. But certainly a Warranty Plate or Marti would.
And frankly, one of the VIN gurus here should be able to tell you what you have based on information from the glovebox door.

Paul

 

[Waldo]

I found this to be the easiest way to determine which of the 3 versions (10" w/small bearing, 10" w/ big bearing or 11" w/ big bearing) you have installed.
Sandpaper the backside of the drum plate to get rid of dirt/rust...doesn't have to be shiny clean. Then rub a bright colored crayon on the area you want to read, rub it off, and then take a picture of it with your phone. Don't bother trying to read it, directly. Once you have the number, refer to the chart and voila, you know what you have.
In addition to the number chart I attached, I've included what mine looked like doing this process. I had 10" drum with large bearing on my 75.
Good luck!

 

[Viperwolf1]

I found this to be the easiest way to determine which of the 3 versions (10" w/small bearing, 10" w/ big bearing or 11" w/ big bearing) you have installed.
Sandpaper the backside of the drum plate to get rid of dirt/rust...doesn't have to be shiny clean. Then rub a bright colored crayon on the area you want to read, rub it off, and then take a picture of it with your phone. Don't bother trying to read it, directly. Once you have the number, refer to the chart and voila, you know what you have.
In addition to the number chart I attached, I've included what mine looked like doing this process. I had 10" drum with large bearing on my 75.
Good luck!

This is a little more complete.
Bendix 319130L or 317363L = '66-'75 big bearing/11"x1 3/4" brake , driver side
Bendix 319130R or 317364R = '66-'75 big bearing/11"x1 3/4" brake , pass side
Wagner FF55264 or L55264 = '66-'75 small bearing, 10" brake, driver side
Wagner FF55265 or L55265 = '66-'75 small bearing, 10" brake, pass side
Bendix 80174L = '74-'75 big bearing/10" brake, driver side
Bendix 80175R = '74-'75 big bearing/10" brake, pass side
Bendix 3203097L = '76-'77 big bearing/11"x2 1/4" brake, driver side
Bendix 3203098R = '76-'77 big bearing/11"x2 1/4" brake, pass side