Question about WJ swap

[garr]

Resurrection, but...
I think the JK 27 spline stub shaft will work. It's 0.19" longer. I haven't gotten my hands on all of this to verify, but the JK stub looks to me like the winner for going 5x5 on Dana 30 knuckles.

That .19" should be enough to fit the washer that will not fit if you use XJ stup Shafts with WJ unit bearings.
JK stub 6.3
TJ/XJ Stub - 6.1
Can someone out there Please verify this?

 

[foxwar71]

You guys realize the JK's use a different u-joint right? Its something like a 1350-sized joint if I recall.

 

[XJLI]

You guys realize the JK's use a different u-joint right? Its something like a 1350-sized joint if I recall.

44s, yea. Pretty sure the jk30 is a standard 760x size.

 

[yossarian19]

Yep, JKD30 uses a 760 joint - according to Rock Auto, same as the 84-01 Cherokee. Stub is 27 spline, too. I mean, no guarantees - but it darn well looks like it should work. Doesn't eliminate need for the weld on spacer but does get you a 5x5 unit bearing with no machine work.

 

[garr]

Yep, JKD30 uses a 760 joint - according to Rock Auto, same as the 84-01 Cherokee. Stub is 27 spline, too. I mean, no guarantees - but it darn well looks like it should work. Doesn't eliminate need for the weld on spacer but does get you a 5x5 unit bearing with no machine work.

Why would you need the spacer?
If you use WJ unit bearings the extra .19" should give you the room you need for the washer behind the bolt ?

 

[yossarian19]

The spacer goes between the knuckle & the hub to pull the u-joint further outboard, so it aligns with the ball joints. Both U-joint and ball joint need to pivot on the same axis to prevent bad judju.
The axle shaft will suck in to the back of the bearing just the same wherever you position the bearing. Longer stub shaft matches the longer bearing of the WJ - regardless of which knuckle you put the whole mess onto, spacer no spacer, whatever.
I've been making a hobby of brake / knuckle / bearing / stub swap-ology lately. Gotta hand it to Blaine - that guy has gone to the great beyond & returned with some good Dana 30 tech.

Also, for anyone that's interested, the S10 truck guys that go SAS have found a way to put a 5x4.75 S10 unit bearing into a Dana 30.

 

[garr]

The spacer goes between the knuckle & the hub to pull the u-joint further outboard, so it aligns with the ball joints. Both U-joint and ball joint need to pivot on the same axis to prevent bad judju.
The axle shaft will suck in to the back of the bearing just the same wherever you position the bearing. Longer stub shaft matches the longer bearing of the WJ - regardless of which knuckle you put the whole mess onto, spacer no spacer, whatever.
I've been making a hobby of brake / knuckle / bearing / stub swap-ology lately. Gotta hand it to Blaine - that guy has gone to the great beyond & returned with some good Dana 30 tech.

Also, for anyone that's interested, the S10 truck guys that go SAS have found a way to put a 5x4.75 S10 unit bearing into a Dana 30.

I think the JK axle stub may be the key to the puzzle here.
I asked this same question in another thread Years ago, Here is the question.

Not that I would want to do this,
If you used WJ unit bearings with WJ CV axles in WJ knuckles all mounted on an XJ (without the JKS welded on spacers) would everything work?
or is the spacing screwed up?

Here is the answer I got.

everything would work except for the inner CV shafts, the WJ is a wider axle and they would be too long to fit in an XJ housing. If the WJ was U-joint, this whole issue wouldn't exist, we'd just use XJ inner shafts and WJ outer shafts... at least I would.

The JK outers may just do it, I have to look for a JY set of WJ Unit bearings & JK Axle stubs to test the theory, This would eliminate the spacer & give us the Much Bigger stronger WJ unit bearing.

 

[yossarian19]

I'd thought the same thing but talked to an expert and found out different. The WJ hub / JK stub combo would work, but you'd still need the spacer & to adjust the caliper spacing
Think about it this way...
The stub shaft has two important length measurements. One is how long is the splined / threaded section from the tip of the threads to the flatt part where it bottoms out on the back of the hub. Two, is how far from that flat portion to the U-joint centerline.
The JK stub shaft is longer on measurement 1 by 0.19". It will go through the deeper unit bearing. Good so far.
Measurement two, though, I think is the same as XJ stuff. That's a problem for the WJ swap because the U-joint centerline needs to be 1/4" or so outboard of where it will land without the spacer.
So, you add the spacer to move the U-joint centerline. 1/4" will do it. JKS sells the ring - great.
Now that the JK stub is playing with your WJ unit bearing and the U-joint centerline is in the same place as the ball joint centerline, we've created another problem.
The rotor is now 1/4" outboard, too. The caliper needs to be spaced that same 1/4" to remain centered. This could be done with no real-world consequence, provided it is done with care. You'd want a single machined flat "washer" 1/4" thick and, once the bolts were torqued down, you'd want to weld it to the knuckle.
Now, the reason the late model XJ / TJ hubs don't need any caliper spacer is that the late model hub is actually (roughly) 1/4" shorter than the WJ or mid 90s XJ hub. Even with the 1/4" spacer underneath it, the late model Xj / TJ hub comes to the same height as the stock WJ hub. So the rotor is in the same place (close enough anyway) and the caliper sits (darned near) where it belongs.
I think at one time I'd understood this then forgotten. It's a lot of dimensions & details to keep in mind over the years I've been geeking out on this stuff. Mr Blaine schooled me on it over the phone a week or two ago. Real helpful guy.

So a 5x5 WJ hub is doable but takes more than the JK stub, and still doesn't get rid of the spacer ring.

 

[dasbulliwagen]

I dont think Im fully understanding why you would need the spacer if youre using a WJ knuckle, WJ hub, and presumably a WJ U-joint stub. These all being made to work together from the factory would put the U-joint turning radius in the same plane as the WJ and thus the XJ ball joint plane, would it not, thus making the spacer not needed. This is what we are trying to get at.... a bolt on upgrade to use with the newer wheel bolt pattern. And wouldnt the same go for a JK Dana 30 knuckle? Or is there something different with the ball joints on those that make it so they wont bolt to an XJ Dana 30?

 

[yossarian19]

If you got an export model stub shaft, that shoudl work. The only WJ Ujoint shafts I've seen are XJ stubs on WJ inners. Sorta works for a WJ but no good for us.

 

[VAhasnoWAVES]

your seriously over complicating this...

 

[yossarian19]

your seriously over complicating this...

I've been accused of that before.

 

[garr]

comparing wj to xj unit bearings, the WJ ub is about taller, looks awfully close to the .25 spacer thickness.
Does anyone have the jk stub shaft & wj ub so we can compare?

 

[ocean_jet]

VAhasnowaves... your PM inbox is full...

 

[CobraMarty]

The stub shaft has two important length measurements. One is how long is the splined / threaded section from the tip of the threads to the flatt part where it bottoms out on the back of the hub. Two, is how far from that flat portion to the U-joint centerline.
The JK stub shaft is longer on measurement 1 by 0.19". It will go through the deeper unit bearing. Good so far.
Measurement two, though, I think is the same as XJ stuff. That's a problem for the WJ swap because the U-joint centerline needs to be 1/4" or so outboard of where it will land without the spacer.
So, you add the spacer to move the U-joint centerline. 1/4" will do it. JKS sells the ring - great.

That being said, can the XJ stub shaft ''flat portion' be machined 'lower/down' .19-.25" to allow the XJ stub shaft to go that much more into the WJ hub and then the ball joint/U joints will line up?

 

[yossarian19]

I don't know.
I'm pretty damn far from an engineering degree.
I have to wonder if weakening that face where the stub mates to the back of the hub is going to affect conditions in the bearing or strength of the stub shaft in general.
I don't see how it would, exactly, but that only means again that I don't know.

 

[CobraMarty]

Yeah, IDK. Weld a reinforcing ring around?

If it was strong enough, would it all align up? No spacers or washers.

XJ axle--XJ stub axle(machined shorter)--WJ knuckle--WJ hub bearing(drilled to 5x4.5")--WJ disc(drilled to 5x4.5")--WJ caliper

 

[VAhasnoWAVES]

its deffinantly an idea... but reverse engineering to a problem that (many can argue) doesnt exist. personally, i think it could work. with the access to the tools, it can be done quite easily. i think if you started with a chromo shaft itd be quite strong. i find the weak part of D30 shafts, especially stockers, and ESPECIALLY on the outer, tends to be the ears.

but hypothetically... unless the donor parts came off of a good, running and driving WJ, id want new calipers/pads/rotors, minimum. if your XJ is like 95% of them, your buying new unit bearings regardless... it isnt equipped with the correct ones. WJ bearings, '99.5+ bearings, your getting new ones. or rather, i would. now... the cost of machining stub shafts probably isnt any more than having someone weld on the spacers. but every reasonable jeeper has at least one friend with a welder willing to do it.

but wait, you can just have 2 turned, best idea is probably to have at least one, probably 2 spares made. now what happens on the trail? your spares are useless to a buddy in need, or worse? you forget your custom parts and are very SOL... and if you ever need more or want to upgrade your axle shafts, your looking at more work.





as cool as custom parts are (ive machined my own custom knuckles and spindles), im a believer that one should try to stay away from custom "consumable" parts... such as axle shafts... especially D30 axle shafts...

 

[garr]

Found this Photo & info on another site.
WJ on the Left XJ on the right. I think it will work with the JK D30 outer shafts without a welded spacer!

You can see how the TJ/XJ unit bearing would sit much deeper in the knuckle, positioning the end of he stub shaft and U-Joints closer to the C than the WJ hub. As the WJ Knuckle doesn't extend as far as the TJ Kunckle from the inner C, its my understanding that the spacer is used to keep the U-Joints located between the ball joints by moving the bearing out further, while keeping the same bolt pattern. With the WJ hubs, I think we could get away without it.

 

[VAhasnoWAVES]

the important measurement isnt the depth of the bore fitment into the knuckle...

its the retaining surface from the end of the unit bearing to the edge of the bore fitment. but thinking about it simply... i would guess that the WJ unit bearing would properly center the Ujoint and still provide the right hat height for the rotor. that is assuming that the JK knuckle is the same (dimensionally) as the WJ one. i understand they use the same BJs, but youd really need to compare the JK and WJ knuckles. at the very least... the unit bearings. if they are identical, then its possible?

but im still failing to see the gain... with the addition of a $25 spacer, you now have 5on4.5... meaning no need for new wheels or to address the rear bolt patter.