Not A Build Thread (Oh How Things Change!)

[DirtDonk]

My goal is to get my small bearing 9" as strong as possible without replacing axles.

My reasoning is I want to get this thing back together and will be going with a traction device in the future so trying to keep costs down at this time.

I'm correct in picking the 2.89 carrier bearing size if I'm keeping the stock case right?

If that's the size yours has now, then yes.
I think we talked about it before, where we've seen Broncos with both the small sizes. We don't know if they're from the factory originally all these years later of course, so the only way to know is to take it apart and find out.

Since it's not driving yet, and it IS in fact already apart, I assume you've already measured yours?

The next option. (If it is worth it in strength gain I would rather go with this)

They are definitely stronger. But the center section is very rarely the weak link in a 9" that's used in moderation. They fail under hard use of course, but I can't remember the last time someone said theirs failed under anything even approaching normal use.
Racers and those running HUGE tires or HUGE engines break stock ones all the time.

Is the HD version worth it? Depends on what your criteria is. From a fitting 31spline axles eventually and going to the ice-cream store with the kids standpoint, not really.
From a peace-of-mind standpoint, probably worth it, just like are the 31spline axles with an open diff. Overkill, but you can sleep at night if you think you might get crazy someday. Or just believe in spending a little more up front and doing everything just once? Sure.
From a simple bang-for-the-buck upgrade standpoint, absolutely!

It looks like I need to do the conversion axles with this setup right? You can select a 28 spline axle for the case on the summit website but I don't see how that would work.

Do you mean the small bearing 31 spline axles? You do not "need" to do the conversion axles with any center section. Since you're not changing the carrier to the limited-slip or locker at this time, and the new bearing kit does not look like it includes new side gears (the part with the splines in them) then new axles are not required.

Since your plan is to put stock axles and stock bearings back into this newly reconditioned center section (just bearings and gears) then it looks to me like the parts you're listing should all work together.
Hopefully someone with more diff building experience will take a closer look.

So your only real choice, other than where to buy this stuff, is whether to purchase the new nodular housing now, or just wait until later. All of your other choices are pretty much decided.
Only the housing and which size bearings it needs is still up in the air.

Basically there's nothing requiring you to go either way. You can get the stronger housing later when you do the traction diff, or you can do it now and run it with your old axles.

As said, the stock ones are pretty robust already, which is one part of why the Ford 9" has such a stellar reputation and is used in custom builds to this day like no other axle assembly.
Adding a torquey engine, a limited-slip, or perhaps even locking differential, 35" tires, and an unknown set of conditions on the trail someday, I'd say there's nothing holding you back from spending a few hundred dollars extra and buying a nodular center section.
It's just the do-it-now, or do-it-later bit that's still up in the air for you to decide.

Paul

 

[Okie69]

Since it's not driving yet, and it IS in fact already apart, I assume you've already measured yours?

Wellllll, I do have the third member out sitting on the bench but I haven't measured anything. Up until a little while ago I was under the impression "small bearing" was just referencing the bearings on the axle ends.

To measure the carrier bearings I assume I'll have to remove a spanner nut to get to it?

Overkill, but you can sleep at night if you think you might get crazy someday. Or just believe in spending a little more up front and doing everything just once? Sure.

I'm correct in thinking that the HD carrier upgrade will fit if/when it's time to go to a full large bearing housing, 31 splines etc?

Since your plan is to put stock axles and stock bearings back into this newly reconditioned center section (just bearings and gears)

I was under the impression that the kit I linked had replacements for all wear prone parts?

As said, the stock ones are pretty robust already, which is one part of why the Ford 9" has such a stellar reputation and is used in custom builds to this day like no other axle assembly.

It seems like you're leaning towards the "change the gears and put in a rebuild kit and don't do burnouts" advice. (which is what you've already said. I'm just trying to get all my ducks in a row.)


One more question...I was going to say one last question, but lets be real.

Besides smaller outside diameter bearings at the axle ends and possibly smaller outside diameter carrier bearings. What are the other differences in the small bearing as compared to the large bearing?

Thank you sir.

 

[DirtDonk]

Wellllll, I do have the third member out sitting on the bench but I haven't measured anything.

;D

Up until a little while ago I was under the impression "small bearing" was just referencing the bearings on the axle ends.

About 90% of the time that's exactly what's being talked about in the Bronco world. But now you're digging deeper than most, so you're getting into deeper discussions.
The 3rd member bearing sizes (carrier bearings) do come up now and then, but not near as often as the wheel/axle bearings do.

To measure the carrier bearings I assume I'll have to remove a spanner nut to get to it?

Good question. And no idea!
Maybe you can just measure the outside diameter of the threaded collar.
Anybody?

I'm correct in thinking that the HD carrier upgrade will fit if/when it's time to go to a full large bearing housing, 31 splines etc?

Yes.
The wheel bearing size has no bearing on the carrier bearings as far as overall fitment of the assembly is concerned. Has no bearing on how the chunk fits the housing in other words.
The HD center-section is the same size and has the same number of bolts as your original does, and will fit into either your existing housing or any aftermarket big or small bearing housing.

The housing's all have the same number of bolts and the same size hole that all the rest do, so any 9" 3rd member will fit no matter what the brand, the metallurgical makeup, or the size of their carrier bearing saddles.
Look at the last two pics on this page: https://www.wildhorses4x4.com/category/earlybroncothirdmember and then your own, where your smaller bearing version, then the ones with 3.062" and 3.25" bearing saddle sizes, all look the same where the circular-ish outer mounting flange area is. Same size, same number of bolts, same gaskets, same bolts/studs.

The "carrier" is the actual differential, and the part that the ring & pinion bolt to into, and the side bearings are pressed on. It will be either an open diff like you have now, a limited-slip, a locker, or a spool. And they are all basically the same fitment except for the number of splines in the side gears where the axles slide into, and the size of the bearings that interface with the case.
Hence the difference in carrier bearing sizes. To accommodate the different diameter axles and combinations of parts.

I was under the impression that the kit I linked had replacements for all wear prone parts?

Yes and no. A "wear prone" part can be subjective, and new side gears are not normally part of a rebuild kit because every brand of differential is different and most have multiple choices in spline counts. If they included side gears too, they'd need 40 or 50 more "kit" part numbers to fit all possible combinations of differential assemblies.
So you do not normally find side gears or spider gears in a rebuild kit

You don't really need new ones for your old diff unless something is wrong with yours that won't allow them to work anymore.

It seems like you're leaning towards the "change the gears and put in a rebuild kit and don't do burnouts" advice. (which is what you've already said. I'm just trying to get all my ducks in a row.)

Kind of. Well, pretty much...
But only because you've indicated many times that you need to build this in stages. Frankly, because it's not even running yet the normal recommendation is to just build the whole thing new during the process and have what you need as soon as you're ready to drive.
But do what you want and buy as much as you feel like or can budget in right now. I don't know your budget of course, but since we've be having this conversation for a long while now, it's easy to assume you can't just throw down $3grand to buy it all right now and call it done.

Circumstances can dictate otherwise, but it sounds like just bearings and gears is still at least one reasonable option. You can buy as many new parts as you want now, or you can save your money because something isn't absolutely necessary yet.
An open diff, 28-spline small bearing axles, and even with 35's it's not going to be the housing or the case that break!

But let's hear from an expert that can confirm you can even bolt up a stock, small bearing carrier into the new case. There would have to be an available bearing and race that can allow them to mate up.
I assume there is, but there it is. I'd only be "assuming" and you know where that leads. A completely different rabbit hole!
If there is not, then while you're using your stock open diff, you're stuck with your stock 3rd member.

One more question...I was going to say one last question, but lets be real.

;D
Yeah, not gonna happen!

Besides smaller outside diameter bearings at the axle ends and possibly smaller outside diameter carrier bearings. What are the other differences in the small bearing as compared to the large bearing?

Just that. The diameter of the carrier "shank" where the bearings press on and axles slide in, and the diameter of the saddle bore of the 3rd member where the bearings sit.

You're asking legitimate questions, but about stuff that normally does not even come up because most do not bother with trying to come up with the combinations you have asked about so far.
If you put your new gears and bearings on your old stuff, there's nothing to worry about now and just worry about matching all the new parts later.
If you start mixing and matching odd combinations ahead of time (such as a nodular big bearing 3rd member with small bearing 28-spline carrier and axles, the questions start multiplying!

The good news? Someone will know for sure what works and what (if anything) does not.

Paul

 

[Okie69]

Hey guys, I stumbled across this np435 locally and am wanting to make sure it is the correct one for an EB swap. I’m not quite ready to start working on the transmission swap but it seems like a pretty good deal. He’s got it listed for 150$

 

[Okie69]

Here’s the description from the listing.

“Have a np435 4 speed transmission. Came out of a early 70s dodge with a divorced transfer case setup. I thought I could convert it to a married setup but found out it wont work for a np241. Shifts good and tight, has good fluid. Asking 150 or will trade for a 80 to 93 4wd np435. Just transmission and shifter.”

 

[Okie69]

;D

About 90% of the time that's exactly what's being talked about in the Bronco world. But now you're digging deeper than most, so you're getting into deeper discussions.
The 3rd member bearing sizes (carrier bearings) do come up now and then, but not near as often as the wheel/axle bearings do.

So after measuring (I think I measured the right area) and making certain that everything on my rear end is in fact small bearing I've decided to just ditch it and go with a large bearing setup to just "do it once, do it right" kind of thing

I think I'm going to go with the HD WH housing and Probably just a complete drop in as well. Blowing the budget but it will give me some peace of mind.

Is there any kind of market in the EB community for a small bearing 9 with 3.50s and the 10 in drums or should I just throw it on one of the sale sites and try and get a hundred bucks or so? I'd rather it go to someone trying to do a factory resto or something like that if possible.

 

[DirtDonk]

I'm not sure about the transmission. I thought we needed a Ford version no matter what?
That way it's just an easy bolt-on to the bell housing and only the output shaft may need to be modified.

I think there's a market still for the old SB 9" setups. Especially with housing and all.
You're right that most looking for it might be restorers, but if the size is right even the car guys can use it.
More than enough strength so they don't need big bearings (except under extreme conditions, maybe...) and the small bearings are better at higher speeds than a big bearing anyway. Less "surface speed" or whatever that condition is.

You probably don't want to hang on to it forever so a quick sale is good for the budget and garage pile-O-parts corner, but there should be someone out there somewhere.

Paul

 

[gick70]

Proper bolt pattern I think you need the 2wd version!!

 

[.94 OR]

The 2wd and divorced units should be one and the same. The married unit 4WD's don't match up though.

 

[Nothing Special]

I don't think you want a divorced transfer case in a Bronco. To do that you'll need to fabricate a transfer case mount strong enough to hold about 17 times as much torque as the engine will put out, and shorten your rear driveshaft by about a foot (maybe a little more).

 

[unimogger]

I don't think you want a divorced transfer case in a Bronco. To do that you'll need to fabricate a transfer case mount strong enough to hold about 17 times as much torque as the engine will put out, and shorten your rear driveshaft by about a foot (maybe a little more).

To use the adapter that bolts up a dana 20 transfer case, the 2wd / divorced NP435 is the easiest to install. Just cut the threads off the output shaft, and it fits the 20 transfer case
But: I heard conflicting info on using a dodge/ chevy NP435, some said to wouldn't work. Maybe someone can answer that. $150 is a fair deal

 

[EPB72]

Your old rear end could be usefull to the" rat rod guys" I've had a couple occasions some one stopping by when I'm out front asking,, They like the width and narrow spring perch locations,,,As far as the np435 not sure about the newer adaptors but the old advance adaptor needed the square tail housing bolt pattern NOT the A-pattern and the tailshaft will need to be trimmed down ,,,this is from memory so ?.

 

[Okie69]

interesting, I was thinking a NP435 was a NP435 and the only differences were 2wd vs 4wd output shafts.

So I need to be looking for the Ford 2wd version?

 

[Okie69]

Also while I’m here (famous last words I know) I’m going to do new body mounts. I don’t really want a body lift, but a lot of people seem to recommend it.

With an NP435 swap will I appreciate a 1” body lift or can I get by without it?

 

[EPB72]

I went 25 years 351 np435 no body lift -there 2 knubs on drivers side of trans top/shifter cover you will probilly have to trim /cut off ,pretty much all of the center tunnel top flat area an 3-4 inches up into the fire wall including center floor brace will have to be removed,,,,Now currenty 1 inch body lift new front floor sections and tunnel cover Your still pretty much have to cut out about the same maybe a little less towards the rear of the tunnel area..I just cut out most of it left about 5/8 flange with weld nuts to underside and fabricated a tunnel/ shifter cover from 1/8 plate as low profile as I could.. Now with out a body life the stock shifter makes a 90 degree bend (the heater box floor vents will most likely need trimming and depending how tight you get the shifter bent it might contact the bottom of dash when in 1st gear,,,another option look up gear banger shifter

 

[EPB72]

Here's a pic of the cover I made.

 

[Dave's1971]

So, about the NP435... this will likely start a fire but I could not wait to get rid of that tranny. Ok it is a great off-road tranny but I more wanted hwy speed. I sold mine and refit a AX15 and could not be happier. This 5speed with 4.11 diffs and 35s, I'm turning 2400rpms and 70mph. Shifts smooth and actually just made the whole rig better!

 

[unimogger]

As far as the np435 not sure about the newer adaptors but the old advance adaptor needed the square tail housing bolt pattern NOT the A-pattern and the tailshaft will need to be trimmed down ,,,this is from memory so ?.

My adapter (advance adapters, bought used) was drilled for both bolt patterns. The top two holes are the same, but there are 4 holes on the bottom to fit either pattern

 

[.94 OR]

I put a 2WD NP435 in mine with the appropriate adapter after cutting the threaded end off the output shaft. No body lift. It is tight but can be done. I took my time bending the shifter and it doesn't hit anything.

If money were no object I'd likely have gone with a fully synchro'd 5 speed for easier driving. The 435 is a tough gearbox but shifts really slow.

 

[Okie69]

If money were no object I'd likely have gone with a fully synchro'd 5 speed for easier driving. The 435 is a tough gearbox but shifts really slow.

Like the 4500 or 3550? I haven’t made a decision yet and I’m not on that part of the build so I’ve got time, just saw that one locally and thought I might save a few bucks. I’ve also been looking at the 3550. It looks nice having the shifter farther back, but that’s a lot of coin.