Rear Differential Carrier ID

[johns_bronco]

This carrier or "lack" there of, is apparently fairly heavy duty. The axles are 35 spline, so it fits for someone that was intending likely full off road. I dont know exactly what it is, but appears to lock both wheels and would be horrible for typical street driving with the occassional off road. What carrier would work best for the typical daily with occassional off road?

 

[EPB72]

This carrier or "lack" there of, is apparently fairly heavy duty. The axles are 35 spline, so it fits for someone that was intending likely full off road. I dont know exactly what it is, but appears to lock both wheels and would be horrible for typical street driving with the occassional off road. What carrier would work best for the typical daily with occassional off road? View attachment 962411

That’s a full spool ,, probably not what you want for your intended use but there people that have no problem running on street ,, depending on 3rd member housing gears a and axles you may get decent return if sold complete , seen complete third member with 31 spine ,, I’d consider a Detroit Tru Trac ( helical limited slip) ) in what ever ratio your looking for as an option speedway has for 1200,$ then would also need axles ,, Or put a tru trac in that housing seems would be 7-8 $ for new carrier than cost of swap over ,,

 

[jamesroney]

You are not going to want to hear this. It requires some background. And some more sleuthing on my part.

But you can't get there from here...

The Ford 9 inch rear axle housing carrier was originally equipped with 2.891 inch carrier bearings. In 1964, those housings were upgraded for some cars to 3.062 inch. The purpose of the larger bearing was to increase load capacity for heavy duty applications. One by-product of the larger bearing was the ability to use a larger diameter axle shaft. Nevertheless, the practical shaft size limitation for a 2.891 or 3.062 bearing carrier is ~1-5/16 x 31 spline. If you wanted to use a heavy duty 1.5x35 spline shaft, you would need a larger bearing. So the aftermarket invented the 3.250 inch housing to allow fitment of a 35 spline shaft into a standard journal with fully supported side gears. The Detroit Tru Trac for a 9 inch in 35 spline requires a 3.25 housing.

The noteworthy exception is the use of a full case spool, which of course has no side gear, and therefore can accommodate a 35 spline shaft thru a "small" bearing. I believe that is what you have.

Based on the picture you posted, and the casting ID...I'm guessing you have a factory housing. I would need to see the casting number that is almost visible in your pic. Just need to see a little to the right. If it is a factory C7AW-E (2.891) or a C4AW-B (3.062) then you can't run the 35 spline true track. If you already have the 3.25 aftermarket housing, that's a win.

I know it doesn't help.

 

[johns_bronco]

That’s a full spool ,, probably not what you want for your intended use but there people that have no problem running on street ,, depending on 3rd member housing gears a and axles you may get decent return if sold complete , seen complete third member with 31 spine ,, I’d consider a Detroit Tru Trac ( helical limited slip) ) in what ever ratio your looking for as an option speedway has for 1200,$ then would also need axles ,, Or put a tru trac in that housing seems would be 7-8 $ for new carrier than cost of swap over ,,

thanks, I agree it may be best to sell of to someone that wants more off road.

 

[Broncobowsher]

As James stated, that is a full spool. Not even a locker, just locked. It is not street friendly.

James knows more about the casting numbers than I do. Pictures of the front. Any other numbers and markings you can find as well. It might be aftermarket?

If it is a small bearing carrier (not to be confused with a big or small bearing housing, completely different bearings) and they have the stock bearing but big spline spool. There are a couple ways to go at this. Either change the carrier to the 3.25" aftermarket carrier and put in a 35 spline limited slip. There isn't much in the 35 spline limited slip (looks like James states a True Trak exists, very good street choice). Most 35 spline applications are lockers.
The other option is downgrade to 31 spline. While that is a downgrade, it is still an upgrade over the stock 28 spline. As many people have survived on 28 spline for decades, the 31 spline is generally the go to option. All sorts of choices for that. Sell the 35 spline axles and spool. Get 31 spline axles and a 31 spline limited slip. Be done with it.

 

[johns_bronco]

You are not going to want to hear this. It requires some background. And some more sleuthing on my part.

But you can't get there from here...

The Ford 9 inch rear axle housing carrier was originally equipped with 2.891 inch carrier bearings. In 1964, those housings were upgraded for some cars to 3.062 inch. The purpose of the larger bearing was to increase load capacity for heavy duty applications. One by-product of the larger bearing was the ability to use a larger diameter axle shaft. Nevertheless, the practical shaft size limitation for a 2.891 or 3.062 bearing carrier is ~1-5/16 x 31 spline. If you wanted to use a heavy duty 1.5x35 spline shaft, you would need a larger bearing. So the aftermarket invented the 3.250 inch housing to allow fitment of a 35 spline shaft into a standard journal with fully supported side gears. The Detroit Tru Trac for a 9 inch in 35 spline requires a 3.25 housing.

The noteworthy exception is the use of a full case spool, which of course has no side gear, and therefore can accommodate a 35 spline shaft thru a "small" bearing. I believe that is what you have.

Based on the picture you posted, and the casting ID...I'm guessing you have a factory housing. I would need to see the casting number that is almost visible in your pic. Just need to see a little to the right. If it is a factory C7AW-E (2.891) or a C4AW-B (3.062) then you can't run the 35 spline true track. If you already have the 3.25 aftermarket housing, that's a win.

I know it doesn't help.

I think i have a picture of what your looking for as far as numbers. I attached what i think is that number, a pic of the housing, and the axles. I do think that this setup is waay to much for my goal of driver. Let me know if these are helpful and I apprecaite everyones input!

 

[johns_bronco]

As James stated, that is a full spool. Not even a locker, just locked. It is not street friendly.

James knows more about the casting numbers than I do. Pictures of the front. Any other numbers and markings you can find as well. It might be aftermarket?

If it is a small bearing carrier (not to be confused with a big or small bearing housing, completely different bearings) and they have the stock bearing but big spline spool. There are a couple ways to go at this. Either change the carrier to the 3.25" aftermarket carrier and put in a 35 spline limited slip. There isn't much in the 35 spline limited slip (looks like James states a True Trak exists, very good street choice). Most 35 spline applications are lockers.
The other option is downgrade to 31 spline. While that is a downgrade, it is still an upgrade over the stock 28 spline. As many people have survived on 28 spline for decades, the 31 spline is generally the go to option. All sorts of choices for that. Sell the 35 spline axles and spool. Get 31 spline axles and a 31 spline limited slip. Be done with it.

Thank you, I really apprecaiate all the input. I believe that selling may be the best option in the long run vs. me trying to "force" some type of fit to save a few bucks. Again, apprecaite !

 

[jamesroney]

C7AW-4025-E or C7AW-E

(The “4025” is silent…)

2.891 small carrier housing. Native to all 67-77 Early Broncos.

The TrueTrac for the 9 inch with 35 spline is Eaton PN 914A690. It requires a 3.25 bearings, and will not fit in that housing.