Best route for getting 31 spline axles

[PaveBronco]

Wild Horses has 31 and 35 spline axles for small bearing housings.

 

[behemoth]

with the explorer comes a bolt pattern change as well, stock they are 5 on 4.5. Since it is an inch wider than the stock 9 the spacer converter will push the rim further out.

 

[OsideDave]

Thanks everyone for the replies, definitely some good options. For some reason I am not feeling the 8.8 route. Did call and get pricing from WH and Curry and they are pretty similar pricewise for complete disc to disc. Will keep my eyes open for used stuff, hopefully someone is going to a 60 and wants to get rid of their good setup.

Any other suppliers?

 

[Action]

8.8 = no

For me there is no way I would trade my 9" for an 8.8.
Jack

 

[.94 OR]

Any updates on the 8.8?

 

[DirtDonk]

Glad you brought this up. Haven't heard any discussions on 8.8's in quite awhile. Maybe this was the last one from 2015!

We've changed our housing as well since then, as was mentioned earlier in this thread about other brands changing tube size.
The standard truck 3.25" housings are no longer available, so everything is 3" diameter now. Everything else is an upgrade over stock, and with .250 wall thickness, the tubes are still uber beefy.

And it's free shipping this month (still) so that's not a bad way for me to shamelessly promote out stuff once again!;D

Paul

 

[.94 OR]

I am on the small bearing 28 spline axle team.

I am upgrading things with the intent of adding more power in the future, currently '71 302, headers, RV cam, FiTech 400 EFI, NP435/D20 and 3.5 gears on 31" tires.

I am planning to work on the rear axle this spring before summer driving season. Since the vendors sell both upgraded 28 spline axles and 31 spline with small bearings, can anyone convince me that one way is better than the other? I'm tempted to swap out the open diff for something different anyway so I can convert spline count in the chunk at that time.

I have been looking for a large bearing complete axle but I think they outlawed those. Granted the vendors have the naked housing but upgrading to factory style drum brakes is not appearing to be much of an option so discs may be in order. I still run drums on the front so now to change out the rear I may be looking at front discs as well. Can you say "Snowball"?

At this time I was not interested in 4 wheel disc conversion, just a possibly beefier rear axle for future power upgrades.

So, again, upgraded new 28 spline axles or 31 spline small bearing? Explorer 8.8 with disc brakes?

 

[5001craig]

I went with the Wild Horses axles and brakes and really like it. 35 spline for me.

 

[DirtDonk]

I can't argue for, or against the 8.8 option, but it seems like the most finicky for now. Can you do all the work needed to make one fit an Early Bronco, including any housing mods, and axle and brake mods (different bolt pattern), or will you be paying someone to do it?
That answer would definitely effect how cost-effective an 8.8 is going to be.

In keeping with the 9" theme, what is it you will be doing with your Bronco? Casual driving and maybe some wheeling? Some harder stuff, or maybe some adventures in Utah? Road trips to Louisiana mud races or somewhere for fun in the sand dunes?
If you really aren't going to be hard on it at all, save your money and keep the small bearing 28 spline axles. You ever heard in all these years of anyone busting a bearing that wasn't already worn out?
Lots of bearing stories here. But all (or almost all) were from high mileage and/or old age. I don't think I ever heard of anyone with normal size tires (and your 31's certainly qualify as "normal" still today) frying a properly installed bearing.

Axle breakage? Sure, definitely it's a thing. But here again, I bet there aren't many people with open differentials, smaller tires and/or a light right foot that have snapped a stock 28 spline axle.
Adding more power and keeping the 3.50 gears definitely puts more stress on the axles if you like to push the go-pedal, but if you are not changing your habits after all this, you could probably live just fine with stock.
Put a traction aiding device in the rear end though, and all bets are off!

Some companies don't even sell 28-spline traction differentials anymore. Their use is almost certain to result in a snapped axle the first time you look cross-ways at a rock or burn-out box.%).
But for light duty use with an open diff, or limited-slip, nothing wrong with them.
So now you have to decide whether you really even need a limited-slip, locker or spool or whatever. If you do, then just bite the bullet and go with the 31-spline version no matter how light your right foot is.
There, that part was easy, right?

So, let's say intended use, or owner desire says you must add a traction diff. Ok, it's 31 splines and bite the bullet and just buy the 31 spline axles. No matter which housing you use.

So now you've gone with the 31 spline differential of your choice. No waste of money because you can carry that over to any 9" housing you care to upgrade to in the future. If you even go there in the future, which is still up in the air at this point.
One of the least expensive options for most are the big bearing 31-spline axles. But your small bearing axles do complicate the decision by adding another 80 bucks or so to the tab. But only slightly more complicated.
If you do buy 31-spline, small bearing axles now, then decide sometime down the road to upgrade to a larger bearing housing because you're carrying a lot more crap in the back than you ever thought you would, or just want the cool stronger housings, you could sell your small-bearing 31-spline axles in a heartbeat to someone going through the same process as you are now. And recoup much of the cost of the new, less expensive big-bearing axles.

You're not ready to go with rear discs at the moment it sounds like (price-wise?), so you're really not anchored into one bearing size or the other. Right now you have all your existing brake stuff to use and that's fine for now. For drum brakes with big bearings though, they exist no problem. We have fully assembled big bearing, big brakes (the really big '76 and '77 style) ready to go if you do decide on the big bearing housing from the get go. No need to go disc if you don't want to. But obviously you have that option and price-wise there is a difference (almost double) but you can still decide to spend the extra if you want.
Right now drums are $340, discs are $695 (or $875 including axles, bearings, brakes and all that, but for a specific housing end, so more finicky)
So some, but not much advantage to sticking with drums in some cases.

If you opt for big bearing and drums, you simply substitute '76/'77 31-spline axle shafts for your new housing. Voila! Big bearings and brakes.
You can make the rear brake decision whenever you decide ultimately which housing ends you're going to end up with.

And yes, to complicate things, even the 28-spline aftermarket axle shafts are stronger than stock. So yes, you could keep the 28-spline differential and work with that in mind. But at that point, you would not even need to change the axles, so why would you, right? Unless you were just going for stronger. IN which case you're right back to the 31 vs 28 decision.

If you're trying to go best bang for the buck, it ultimately just comes down to how are you going to use the Bronco. Just like pretty much every other decision we make.
If you aren't going to be doing anything different from before, and it has lasted the last 48 years without much complaint, you just have to decide how much work and money is worth what you're trying to achieve.

Simple, right?;D

Paul

 

[toddz69]

Paul - really bummed that you guys don't sell the HD Currie housing anymore. That was a neat piece and so nice compared to many of the other housings on the market these days.

Todd Z.

 

[DirtDonk]

Which one are you referring to Todd?
We still sell two styles of housings. The #8689 Super-9 heavy-duty version of the stamped 9-inch similar to the Currie, and the fabricated #8657 XHD similar to the one we used to have made by Ruff Stuff.

Is there one I'm not remembering? The #8689 is pretty sweet, without being quite so exotic as the fabricated housing. Still immensely strong compared to a stock one.

Paul

 

[Jedeka]

Check with Quick Performance for your axle and axle shaft needs.

 

[fordguy]

Check with Quick Performance for your axle and axle shaft needs.

I have been seeing them pop up on my google searches. I sent them and email and they responded within a day. They were the ones offering the explorer disc setup for small bearing 9 inch housings.

 

[toddz69]

Which one are you referring to Todd?
We still sell two styles of housings. The #8689 Super-9 heavy-duty version of the stamped 9-inch similar to the Currie, and the fabricated #8657 XHD similar to the one we used to have made by Ruff Stuff.

Is there one I'm not remembering? The #8689 is pretty sweet, without being quite so exotic as the fabricated housing. Still immensely strong compared to a stock one.

Paul

Here it is, Paul. I had to dig back through a surprising number of catalogs to find it.

Todd Z.

 

[Crush]

I acquired a trac-lock diff out of a full size with 31 spline and plan on ordering the wild horses axels with bearings already pressed on and a rebuild kit for the trac-lock and some 4:56 or 4:88 gears. This is likely the least expensive way to build an axel. Prolly can buy one already set up used for considerably less though

 

[DirtDonk]

Here it is, Paul. I had to dig back through a surprising number of catalogs to find it.

Todd Z.

Hah! Yeah that's going back a bit.
But we do still offer the "same thing" basically. But different.
When Currie could no longer get the truck-style center housings assemblies, we were told we could no longer get housings. They do have their custom setup using the smaller tubes and less stout center, but I don't remember being given that option at the time. Or maybe we just didn't want to go there yet.
So we had to go to Plan-B and found someone to make the housing we now carry.

The good news to my mind about that, even though we no longer have the Currie name, is that they have billet ends and the drilled and tapped breather bolt hole is in the stock Bronco location, rather than higher up where Currie put them.
Still with the V-notch (fish-mouth) but on the slightly narrower center housings with the 3" tube size vs the old truck 3.25" tubes. Same wall thickness though, at .250 inch.
Along with that stuff, they have the billet ends instead of just the "regular" large heavy duty ones (at least I don't think the Currie version was using the billet?).
So it was basically the loss of any truck housings that precipitated the change.

Made to specifically to our request, quality is every bit as good, no new brake lines should be needed (but I have not tried it myself yet), our ability to stock them because manufacturing volume is up, and the price has stayed steady.

I like Currie and still buy stuff from them. But I have no problem recommending our housings at all. For price and quality and features.

Paul

 

[68ford]

http://9inchfloater.com/CompleteRrEnd/CmplteRrEnd_28_31.htm
This is always the best bang for your buck. Brand new housing with all hubs, bearings and spindles. Brake rotors and 31 spline axles for less than 1000 buck. Put your 3rd member in and buyb2 calipers and your entire rear end is new with disc brakes.

 

[.94 OR]

I was working on the assumption that a 31 spline small bearing setup was a regular 31 spline axle with a different low profile bearing. If so, the bearing could be swapped to a standard profile large bearing if a large bearing housing was sourced. If not, is it a special 31 spline axle that is specific to this application?

I have had my Bronco for 30 years. Issue is, I think it had at least 7 owners prior to me in the first 18 years of its existence and I doubt any of them were easy on it. I drove it for 2 years then it got T-boned hard and I rebuilt it. I likely have only put 5000 miles on it in the 28 years since. Sad I know. I was always told that the axles will continue to twist with use but I don't remember the rule of thumb on how much twist is acceptable before replacement is recommended. My axles do have some twist with no breakage so the 28 splines seemed to have survived likely considerable abuse in their early years. I thought I would only be driving it to A&W for root beer floats, but living 2 hours from the Oregon dunes where there are summer Bronco functions and 30 minutes to the Cascades where there are opportunities for snow running I think beefing up the rear a bit would be a good step.

 

[DirtDonk]

I was working on the assumption that a 31 spline small bearing setup was a regular 31 spline axle with a different low profile bearing. If so, the bearing could be swapped to a standard profile large bearing if a large bearing housing was sourced. If not, is it a special 31 spline axle that is specific to this application?

Unfortunately, it is my understanding that the axle shaft is also a "custom" smaller shanked shaft.
Obviously the business end at the differential is identical to any 31-spline 9" setup, but is necked down where the bearing mounts. Possibly even below the 28-spline version's size, but I don't have the dimensions memorized.

I was always told that the axles will continue to twist with use but I don't remember the rule of thumb on how much twist is acceptable before replacement is recommended.
My axles do have some twist with no breakage so the 28 splines seemed to have survived likely considerable abuse in their early years.

As far as I know, the rule-of-thumb for twist is zero, zip, nada. Any twist has weakened the shaft already. Any more twisting is just getting it closer to that snapping point we all want to avoid.
In the real world however, a twisted shaft, whether an axle, or a steering box sector shaft, can live long and prosper under moderate use.
But if heavy use is expected, OR you just want the safest most reliable setup, you replace any twisted shafts at the first opportunity.

There is an official specification for wear on the face of the splines as specified in the manuals, but even that seems to have a very low tolerance for what we find as normal wear and tear. I've seen axles that were worn beyond their book spec and never give up. But they are nevertheless weakened beyond what Ford (and the other manufacturers) deem acceptable.

A little shiny face with slight indent is acceptable, but just. Once that indent becomes more pronounced (probably still measured in the thousandths though) you're supposed to replace the shaft.

I traded a 28 spline diff to a Mustang guy for a 31-spline setup with axles. Turned out the axle shafts were cut down and machined full-size axles, which was not a big issue for me as people had done that forever.
Unfortunately I was blinded in my excitement and overlooked the obvious twisting of the splines. VERY TWISTED in fact. A 10 year old could have seen them if they were actually looking.
But hey, I was going to run them for awhile anyway until I could justify buying some. I have a very light right foot but was going to be very extra careful anyway.
And that, in addition to all the worrying about it would have taken a lot of the fun out of the swap.

I thought I would only be driving it to A&W for root beer floats, but living 2 hours from the Oregon dunes where there are summer Bronco functions and 30 minutes to the Cascades where there are opportunities for snow running I think beefing up the rear a bit would be a good step.

Totally agree with all the logic. They can live through a lot of abuse. But who wants to be "that owner" that gets to collect on all the back pay-back built up by the previous crew?
Not me!

Good luck. (while still having fun of course... )

Paul

 

[sykanr0ng]

What I have seen in other places about twisted axle splines is that if the splines are twisted to the point where they line up with the next spline over on the untwisted part then the axles MUST be replaced.

In racing axle spline twist is expected, axles are considered a consumable wear item.