WJ Knuckle Swap, trying a different approach

Status
Not open for further replies.

Team Willys

www.rocksolidfab.com
Location
Chattanooga, TN
So after doing some research on the subject I was quickly overwelmed with a lot of slightly incorrect to straight up wrong information, different ideas and combinations that seemed to work so so, and then ideas that didn't work at all. And of course there were ideas that I wouldn't use on a jeep that was headed to the crusher. I have seen some scary stuff... JKS make a spacer that welds to the knuckle, well, IMHO that's not ideal, but did you know that it also pulls you axle shaft 1/4" out of the carrier? Yep, your seal surface is no longer in the correct spot, and your splines aren't fully engaged either, so that's not good. But did you know that it wasn't needed at all? More on that later. Well what about bolt pattern differences? I read one article that stated you could run a Ford Explorer rotor; but guess what... that doesn't work unless you are ok with stacking washers between your rotor and unit bearing, and even then you have to grind down the bearing b/c it won't fit inside the rotor. This is a very bad idea... So what do you do then? Is there any combination of parts that allows you to keep 5 on 4.5, doesn't require a spacer between the bearing and knuckle, and still allows everything to work correctly?

After doing the swap on a customers rig, I present you with the one and only way to do the swap correctly.

For the purposes of this write up, you should know that 99 is a split year for the unit bearings, so I am going to leave that year out. Let's stick to 98 & older, 00 & newer, and WJ.

First of all, I would like to say that a lot of people made this out to be a lot harder than it actually is, so if you are thinking about doing this, sit back, relax, and take a gander. Tomorrow you'll be gathering parts for your own swap!

I started out at the parts store like most of you guys would. I had them pull unit bearings for a 98 Cherokee, a 00 Cherokee, and an 04 Grand Cherokee.

1026101138.jpg


00 XJ Left, 04 WJ middle, 98 XJ Right

As you can see, the flange height is exactly the same on the 98 Unit bearing and the WJ unit bearing.

I knew right away the correct way to do the swap... bolt the 98 unit bearing to the WJ Knuckle and then re-drill a WJ rotor to 5 on 4.5. No silly spacers or washer stacking required!

To enable me to re-drill the rotor I pressed the hub out of an old unit bearing and then knocked out the studs. The rotor is hub centric so it self centers on the hub.

1026101849a.jpg


I then took a centering punch that fit the stud holes in the hub and used it to mark the rotor where it needed to be drilled.

1026101849c.jpg


1026101849b.jpg


After drilling on a drill press the rotor fits right onto the 98 unit bearing.

1026101850.jpg


Now you can bolt the 98 unit bearing onto the WJ knuckle. The WJ knuckle is thinner than a standard 30 knuckle where the bolts go through. This isn't an issue at all, just don't freak out when the bolts stick through about 3/4 of an inch. They don't hit anything so you can just leave them be.

1031101605a.jpg


Then slide on your re-drilled rotor and install the caliper bracket. As you can see, the rotor fits perfectly in the middle of the bracket.

1031101643.jpg


Now install the pads and caliper.

1031101712.jpg


There you have it! The correct way to do a WJ brake/knuckle swap. Keep in mind, depending on the amount of lift you have and the length of your brake hoses, you may need to grab longer hoses. The banjo bolts are located at the bottom of the caliper instead of at the top like a standard 30. Also, depending on your wheels, you may or may not be able to run 15" wheels. Sometimes you can get away with it, sometimes not. In my case the customer was running 16" Moab Wheels so they fit right on. Rumor has it that if you grind the caliper ever so slightly, a 15" wheel fits just fine.

If you have any questions about this swap, feel free to send me a PM or shoot me an email to [email protected].
 
Re: WJ Knuckle Swap... The CORRECT way!

so since the hub difference began in 99, any hubs prior to 99 will work without the spacer on the knuckle? and im guessing you still used a normal XJ upper ball joint and WJ lower ball joint
 
Re: WJ Knuckle Swap... The CORRECT way!

So from this write-up looks as though 99.5+ hubs and you will need the JKS spacer, and 99.5- hubs you will not need the spacers.

Very interesting in all the research I've done I've never seen that. Great information!
 
Re: WJ Knuckle Swap... The CORRECT way!

Which ball joints did you end up using??? i have heard mixed reviews on this as well.

uppers from WJ to XJ are the same.. same P/Ns. lowers are different, how much different? i have no idea but the P/Ns are not the same, and i wouldn't wanna take a gamble on something like knuckles.
 
Re: WJ Knuckle Swap... The CORRECT way!

Look at those shafts. That will be an impressive 30. I'm curious about ball joint choice as well.
 
Re: WJ Knuckle Swap... The CORRECT way!

Its funny how companies manufacture and design the spacers when all someone had to do was line the unit bearings up on a counter and take a look. Way to be observant!
 
Re: WJ Knuckle Swap... The CORRECT way!

Chit man where were you 8 months ago?

This should be a great help to members. No more searching through a 15+ page thread with four different ways to do the swap
 
Re: WJ Knuckle Swap... The CORRECT way!

I am stunned. Glad to have you around, bud!
 
Re: WJ Knuckle Swap... The CORRECT way!

since the flange size are different on '98 and '00 hubs, does this mean that axles have different width WMS to WMS ('00+ shorter ) ?
 
Re: WJ Knuckle Swap... The CORRECT way!

Great info! Just a question though...

I remember reading that the purpose for the spacer was so that the u-joint and the ball joint would steer on the same axis when you turn the wheel so no binding occured. I'm assuming you didn't experience this when turning the knuckle? Looking at your pictures it seems that it shouldn't be an issue.

Also, I believe the WJ hub bearing retaining bolts were shorter than the XJ's, so that might be why they go through further (assuming you used the XJ bolts).
 
Re: WJ Knuckle Swap... The CORRECT way!

Great info! Just a question though...

I remember reading that the purpose for the spacer was so that the u-joint and the ball joint would steer on the same axis when you turn the wheel so no binding occured. I'm assuming you didn't experience this when turning the knuckle? Looking at your pictures it seems that it shouldn't be an issue.

Also, I believe the WJ hub bearing retaining bolts were shorter than the XJ's, so that might be why they go through further (assuming you used the XJ bolts).


This would be my question as well. Easy way to tell though. Take the WJ and XJ knuckles and stick a rod through the balljoint holes to get the axis of rotation of the knuckle. Then put a ruler or something flat across the mating surface of the unit bearing and measure perpendicular to this surface to the center of the rod. If both are the same, you are fine. If not, you definitely might get some binding when turning.


That being said, awesome to see someone do a little research on this and figure out a simple way to do it. Still not a cheap swap since you need all new steering and brakes, but definitely a worthwhile one, especially if you go OTK. I think this may be my next big mod.
 
Re: WJ Knuckle Swap... The CORRECT way!

Definitely would be an easy way to tell, I just don't have any D30 stuff anymore.

Was just curious if he (the OP) could add this info to the thread.
 
Re: WJ Knuckle Swap... The CORRECT way!

I have seen this done before. It resulted in broken u-joints.

It will be interesting to see what breaks here. ;)
 
Re: WJ Knuckle Swap... The CORRECT way!

I have seen this done before. It resulted in broken u-joints.

It will be interesting to see what breaks here. ;)


I thought of this too. If things actually don't line up, what will break on the RCV joint? I hope its not in the LS2 XJ.
 
Re: WJ Knuckle Swap... The CORRECT way!

I thought of this too. If things actually don't line up, what will break on the RCV joint? I hope its not in the LS2 XJ.

Depends what is weakest? The joint? the hub? the knuckle? the balljoints?
 
Status
Not open for further replies.
Back
Top