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Unit Bearing tech/interchange - Help me add to this

flatlander757

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Doing a lot of spreadsheets on planning to do stupid things with stupid axles ended up forcing me down the rabbit hole of comparing 1 ton unit bearings. My plans will be revealed once I figure out exactly WTF I'm doing, but figured I'd share this to start some discussion so people with parts and actual vehicles already in progress could add to it.

I built this up using SKF's online lookup plus Rockauto for applications/etc.

Here is a link to the spreadsheet:



1 Ton Unit Bearing Reference.JPG



Things that stick out to me:

GM 99-06 HD unit bearings are 8x6.5, 33 spline, and same 4-bolt pattern as the 99-04 Super Duty stuff. Thanks to a post by Tech Tim either here, or on the old board, his post about dropping a GM unit bearing right into a Spidertrax knuckle was what got me to thinking about doing this.

Ram 2009+ unit bearings are all 8x6.5 and either 33 or 35 spline, with 33 spline available in 9/16 or M14 studs, and 35 spline available in M14. What is interesting to note is that 2wd/4wd were different applications up until the 2013+ stuff (where 2wd/4wd interchange). I was not originally sure if this was a cost cutting measure (not having to spline it), or because the 4wd bearings would come apart without the stub axle (like on TJs and most 1/2 ton and FWD car bearings). My guess is that there may be ABS differences on some year splits where dimensions are unchanged otherwise. I did look up Mopar part numbers as well and they do not have the 12/13 2500/3500 having different year splits... that is only SKF. Not sure what to think of that. 12 or 13+ is when the AAM axle went from 4 link to radius arms up front... did the 3500s get that one year sooner? If so that may be the difference? On that same note, no idea what changes exist on the 2019+ bearings.

Back on topic... Ram 14-18 unit bearings have the same 4 hole pattern as the 05+ Super Duty bearings. This could be huge if 35 spline is good enough. What is hard to find is how far from the KNUCKLE FACE to the center of the u-joint is it? I'm sure one of the two bearings can probably go one way but not the other, with the other one requiring a spacer potentially. I could swear I've seen someone selling an overpriced kit to run F350 bearings on Dodge/AAM knuckles, but cannot find it now.

Depending on how far off one bearing/knuckle vs the other is, it could be as simple as a custom stub shaft being made up to keep the u-joint pivoting within the steering axis.

Brake rotor hat offset is the other issue if you're trying to adapt to a truck, but whatever I'm doing will be all custom (lighter weight) stuff so that's not a big deal... BUT being that all the hub offsets are with ~3/8in of each other... simple spacers either between the hub and knuckle (if putting Ford hub on Ram) or between the caliper bracket and knuckle (if putting Ram hub on Ford) to keep a factory (redrilled) rotor. I haven't bothered looking into brake rotor thicknesses and offsets yet, but I'm sure that's another option too.

Hopefully this gets some gears turning, :beer:
 

stan1688

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I'm very interested in your findings. I have a super duty 60 sitting at home. I'll see if I can measure what you're needing.
 

flatlander757

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Good stuff Flatlander.

Somewhere I have a full Timken UBH catalog. If I come across it, I'll post it up.

I'm very interested in your findings. I have a super duty 60 sitting at home. I'll see if I can measure what you're needing.

Thanks guys. These are the dimensions that are needed to see how compatible one bearing or the other may be with the other as far as just slapping in and calling it good (with regards to the ball joint axis at least). Brake rotor offset/spacers/etc may be necessary if you are wanting to keep them stock.

When measuring stuff like this, I prefer to set things on a bench straight up and down, and use a self-leveling laser adjusted to the appropriate heights where I'm wanting to measure. Then you just hold a tape measure straight up and down with the laser shot right over it.


AXLE SHAFT DIAGRAM.JPG



UNIT BEARING DIAGRAM.jpg
 

A_G

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Good stuff Flatlander.

Somewhere I have a full Timken UBH catalog. If I come across it, I'll post it up.
Have you seen this ?


timken bearings by vehicle
by vin
by size
by application
cross reference
 

stan1688

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Here’s what I measured:

Backside of mounting flange to axle shaft seal surface: ~1.0234”

Ujoint center to where the axle shaft makes contact with the inner bearing race (I couldn’t get a good picture): ~4.5625”

I realized after I measured that the second one might not be what you were looking for, but hopefully still useful.


F77ACF8B-83B5-47A1-A492-AA2E0F2C4F50.jpeg



9CB36504-6300-4E5A-94C7-61AE38644A49.jpeg
 
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TrailTamer

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I’ll like to see Jeep sized unit bearings added to the spreadsheet.

Last I checked I’m unable to find good data on dimensions for JL/JT unit bearings. I know for fact their unit bearings are considerably larger than predecessors as some JL/JT come with 1410 wheel u-joints from factory. I’d imagine it won’t take much work to get standard D60 1480 wheel joint to fit through the hole.
 

stan1688

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Looks almost like you could slap the late model dodge UB on to a superduty to get 8x6.5 instead of redrilling

That was my initial thought, too, but after looking at some pictures of the Dodge unit bearings, I'm not sure it would be that easy. The Superduty unit bearings have a large cavity for the lockout hub that the Dodge unit bearings don't. If it did otherwise work, not having a lockout would be a dealbreaker for me.

It also looks like the unit bearing mounting flange to the wheel mount surface may be different, as well. I'm not sure if that would matter as much, though.


Ford
FordUB.JPG


Dodge/Ram
RamUB.JPG
 

Bebop

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Looks almost like you could slap the late model dodge UB on to a superduty to get 8x6.5 instead of redrilling
And loose the massive 2"+ 32sp outer shaft possibilities in the process.

Doesn't sound that great of an idea to me.
 

YotaAtieToo

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And loose the massive 2"+ 32sp outer shaft possibilities in the process.

Doesn't sound that great of an idea to me.

Or on the other side of the spectrum, loose the selectable hubs.

I also would be curious about jeep sized stuff.

I'd like to see a kit to put 99-04 ub's on a jk knuckle. The options to gain selectable hubs on the jk axles are a step backwards imo.
 

TrailTamer

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And loose the massive 2"+ 32sp outer shaft possibilities in the process.

Doesn't sound that great of an idea to me.
Ok but why?

Have you ever seen a stub shaft (the ones with big nut) break? I have not. It’s always the either yokes, u-joint or inner shaft that fail, never the stub shaft’s shaft itself.
 

flatlander757

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Here’s what I measured:

Backside of mounting flange to axle shaft seal surface: ~1.0234”

Ujoint center to where the axle shaft makes contact with the inner bearing race (I couldn’t get a good picture): ~4.5625”

I realized after I measured that the second one might not be what you were looking for, but hopefully still useful.

Thanks! Any chance you could also get a distance from the u-joint centerline to the fat flange? I'm not necessarily looking to make a direct bolt on... I'm looking for a hub bearing that bolts in place, and has sufficient room to have a custom stub shaft built so that it's otherwise off the shelf consumables (and 8x6.5 ideally). Personally, I also really like the simplicity of the Dodge style unit bearings, no lockout hubs, drive flanges needed, etc.

I’ll like to see Jeep sized unit bearings added to the spreadsheet.

Last I checked I’m unable to find good data on dimensions for JL/JT unit bearings. I know for fact their unit bearings are considerably larger than predecessors as some JL/JT come with 1410 wheel u-joints from factory. I’d imagine it won’t take much work to get standard D60 1480 wheel joint to fit through the hole.

Done. No data for JL/JT that I could find though. Will add if/when I stumble upon it.


That was my initial thought, too, but after looking at some pictures of the Dodge unit bearings, I'm not sure it would be that easy. The Superduty unit bearings have a large cavity for the lockout hub that the Dodge unit bearings don't. If it did otherwise work, not having a lockout would be a dealbreaker for me.

It also looks like the unit bearing mounting flange to the wheel mount surface may be different, as well. I'm not sure if that would matter as much, though.


Ford


Dodge/Ram

I know it will definitely not be a direct drop in. You'll be screwing around with mix and match axle shafts and/or just have custom outers made entirely.

The flange to the knuckle mount surface by eyeball in the photos only appears the Dodge larger "lip" of the two is about the same as the Ford bearing. Comparing distances from flange to bolt hole edge, vs bolt hole diameters and drawing an imaginary line from bolt hole to bolt hole. See here (note the Dodge has two steps, it APPEARS the F350 knuckle pilot bore may be roughly the same as the Dodge. If I have to guess, maybe Dodge cuts away part of the bearing so keep those things from getting stuck in the knuckle as easily? I know I've destroyed the shit out of one at work trying to remove a long time ago. :laughing:

F350 UB knuckle pilot vs bolt holes.jpg Ram 3500 2016 UB knuckle pilot vs bolt holes.jpg


And loose the massive 2"+ 32sp outer shaft possibilities in the process.

Doesn't sound that great of an idea to me.

For MY purposes I will have zero need for anything like that, ever.

Comparison of later model Ram and Superdooty rotors.

Awesome, thanks! Once we can confirm bearing interchange and sort out the axle shafts, rotors will be the next step!

Or on the other side of the spectrum, loose the selectable hubs.

I also would be curious about jeep sized stuff.

I'd like to see a kit to put 99-04 ub's on a jk knuckle. The options to gain selectable hubs on the jk axles are a step backwards imo.

Added Jeep stuff to the spreadsheet link. :homer: You're not going to be putting any 4 bolt unit bearings on a JK knuckle (which is 3 bolts). The JK stuff is on a 4.5in bolt circle (for the mounting to the knuckle), and the 99-04 is on a 5.1in bolt circle. The overall hub depth is pretty similar, so short of added a few inches for a LARGE spacer, I don't see it as feasible but would love to be proved wrong.


I also added a few Dodge/GM 1500 applications... which looks like they'll nearly interchange. Same 3x4.96 hub bolt pattern to potentially swap from 5x5.5 to or from 6x5.5. Both 33 spline.

Edit again: Also just added the hub bearings for the 2011-2019 Grand Cherokee(WK2? I can't keep it all straight). It wouldn't surprise me one bit if these are recycled for use in the JL/JT. Slightly larger and IF FCA are a bunch of cheap bastards like I know them to be, they actually could potentially interchange for the 33 spline GMT900 6x5.5 or the Ram 1500 5x5.5 hubs. Someone will have to verify.
 
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YotaAtieToo

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Ok but why?

Have you ever seen a stub shaft (the ones with big nut) break? I have not. It’s always the either yokes, u-joint or inner shaft that fail, never the stub shaft’s shaft itself.

He's talking big boy parts. Like Rockwell sized rcv with 40-47 spline inners, so at that point, yes you will definitely break the 33-35 spline stub.

Personally, I don't like the short ass UB type stubs unless they are over sized, no room for twist.

But, I don't think anyone using 05+ stuff and big bell rcv's, is going to be afraid to just redrill the ub for 8x6.5.
 

TRINDU

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I have nothing to add, but 99-04 ford UBs fit 99-07 dodge axle like a glove, vice versa. Still need to measure for stubs.

20201206_162543.jpg
 

flatlander757

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I have nothing to add, but 99-04 ford UBs fit 99-07 dodge axle like a glove, vice versa. Still need to measure for stubs.

It's funny you mention that, I LITERALLY just added the 94-99 Dodge Ram hubs and at least according to SKF's catalog, they have the same bolt pattern as the 99-04 Super Duty hubs. But you say 99-07 Dodge... can you double check the year? Because their catalog shows a 4.377 4-bolt circle, vs a 5.500 4-bolt circle on the 99-04 Ford and 94-99 Dodge stuff.

I will say, strictly eyeballing their stock photo for a 2006 Ram 2500 hub here: SKF It does not appear that the 4 bolt circle is over 2in smaller in diameter. Pure speculation on what could be an incorrect photo though.
 

Talon2006

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I dove deep into this when I had my 2nd gen.

I had a 2005+ford Super duty 60 for a while, and looked at the factory unit bearings. The stub shaft between the dodge unit and the ford unit were different, and this would prevent it from working. If I remember correctly the ford stub shaft was farther back. Ultimatly the swing between the stub shaft and the steering knuckle would not agree. The U joints were all the same size, as long with the ball joints. I think this information is also in the DIY dodge freespin kit on the old site.

Also, the tone rings are different between ford, and Chrysler products. I think Artec makes a conversion unit bearing for the ford super duties for JKs. It is a "ford" unit bearing with the JK tone ring. For some reason the numbers 52, 55, and 57 are in my head but I do not remember what fit what.


I was looking at putting the ford superduty under my dodge so I could get locking hubs, but came to the conclusion that it would be cheaper just to buy the free spin kit.
 

TRINDU

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It's funny you mention that, I LITERALLY just added the 94-99 Dodge Ram hubs and at least according to SKF's catalog, they have the same bolt pattern as the 99-04 Super Duty hubs. But you say 99-07 Dodge... can you double check the year? Because their catalog shows a 4.377 4-bolt circle, vs a 5.500 4-bolt circle on the 99-04 Ford and 94-99 Dodge stuff.

I will say, strictly eyeballing their stock photo for a 2006 Ram 2500 hub here: SKF It does not appear that the 4 bolt circle is over 2in smaller in diameter. Pure speculation on what could be an incorrect photo though.

The photo posted is my personal 2002 Dodge 2500 with a 99-04 ford UB. I actually converted it using TTB parts. Which is why I said 99+ as the <98 have different knuckles. I believe the dodge 2nd/3rd gen UB are similar considering the free spin kits available are the same. I tend to stay away from ~2010 Fiat trucks.

Theres actually a guy/company who sells ford UBs for dodge trucks to make them 'free spin'.
 

TrailTamer

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flatlander757
You was talking about this guy?


The video was hard to watch. Guy seemed miserable and clumsy. But looks like stock dodge stub shaft thread got cut off and a spacer, like what we do with WJ knuckle swap? (I’m deaf so I don’t know what he said)
 

Projectjunkie

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I mixed and matched gmt800 parts to make a 4wd van

1500 and 2500 half shafts have the same splines into the bearing, you can un bolt a 2wd 2500 bearing and bolt on a 4wd 2500 bearing, but you'll need a 1/4" spacer under the rotor, or maybe under the bearing, for rotor hat/ caliper issues

Btw 1500 6 lug gm is all 3 hole, it would be sweet to find a 3 hole 8 lug unit bearing... initial search showed a 94 ram, but there was no speed sensor, and some other fitment issues IIRC, maybe spline count, etc
 

Bebop

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Ok but why?

Have you ever seen a stub shaft (the ones with big nut) break? I have not. It’s always the either yokes, u-joint or inner shaft that fail, never the stub shaft’s shaft itself.
On what 05+ OEM unit bearing have you seen a stub shaft with a big nut ?
 

Bebop

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:laughing:

Dodge Ram HDs
I'm talking about 05+ F250 and up unit bearings that offer the opportunity to put big outer shafts. 40sp+
Removing these and replacing them with the crappy dodge shit would be a mistake IMO.

And if you've never seen the outer shafts on these break, I guess it's awesome, but on my end I see 40sp shit break from time to time so less than that I'm not even considering.
 

Adamwende

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This is 94-98 dodge UB, on 99 style Ford beam axle. Which is the same as the 4x4 axles. Those parts are for sure interchangeable.

I run dodge unit bearings on my 4 banger rear steer rig, with good results.

Dodge stuff doesn’t need hubs, and doesn’t need high steer. They’re high steer already. I’d love to get my hands on the late model ram stuff. The stubs are bigger, and stronger than the 33 spline stuff I run.
 

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