WJ Knuckle Swap

[CobraMarty]

I have all the XJ parts and am still collecting the WJ parts to check and measure but it looks like the WJ knuckle and WJ hub interface diameter is larger than the XJ knuckle and XJ hub interface diameter.

So does anyone know if the XJ hub is loose fitting in the WJ knuckle?
What is the WJ diameter of the knuckle hole?

Just thinking,
If one can use early XJ knuckles and ?late XJ hubs and mount drilled 5x4.5" WJ or Sport trac rotors and WJ calipers, would all this bolt together?

I don't have a WJ caliper yet to measure, but what is the caliper mounting bolt spacing?

 

[CobraMarty]

OK... Another thing, how do you get the JKS spacer located properly to weld it down? I was thinking I would bolt a sacrificial worn-out unit bearing into it to clamp it into place then weld the spacer to the knuckle. Does the JKS spacer only serve to align the U-joint axis with the balljoint axis or does it also locate the smaller-diameter (XJ) unit bearing flange within the larger hole in the WJ knuckle, as I think I read somewhere? If it's the latter it makes me worry that I may slightly misalign the whole thing if I'm not very careful which would result in the inner shaft entering the differential at a slight angle, possibly wearing the splines / side gears faster than otherwise and putting more stress on the inner tube seal then I would like.

This is also what I am concerned about.

 

[NW-ZJ-SCOTT]

the spacer and Knuckle have the exact same size hole for the bearing.

 

[yossarian19]

I just checked out the WJ caliper mount lug spacing vs the early XJ knuckle lugs. Good news and bad news
The good news is that both the WJ caliper and early XJ knuckle seem to be 5 1/4" hole centers (measured with the Mk I eyeball and a tape measure) and they bolt right up.
The bad news is that the depth is all wrong - you could only run a 6" rotor this way. Doesn't work. Easy to build an adapter plate, though.

 

[CobraMarty]

What I was thinking was to use=

Early XJ knuckles, reuse your XJ ball joints and hub bearing, redrilled 5x4.5" WJ 12" rotors, WJ akebono calipers and spacer adapters.
No need for expensive WJ knuckles, spacers, welding spacers to knuckles, WJ lower ball joint, New fabricated steering, New Track bar, track bar mount and sway bar arm modification.

Just another idea for 12 front rotors upgrade without all the other welded spacers, steering, track bar, and sway bar arm mods.

 

[yossarian19]

I'm going to try out 98-02 Crown Victoria rotors on XJ hubs. Same diameter as WJ, same (damn near) depth, correct bolt pattern out of the box. Same reasons. Basically, recreating the Vanco kit on a DIY basis. Labor intensive, but cheaper (hopefully)
Mind you, I'm in no rush - as evidenced by the total lack of progress over the last month or two.

 

[CobraMarty]

Do you know the difference between the Crown Vic rotors and the Sport Trac?

 

[VAhasnoWAVES]

one goes on a crown vic, the other goes on a ranger.

 

[Root Moose]

WJ Knuckles are expensive? Lol I paid $50 for the pair from a car-part.com aligned wrecker and had them shipped to my front door for under $75 all in. If you find that expensive... Well, I don't know what to say.

Early XJ knuckles are pretty mickey mouse things... Not sure why you'd want to retain them.

Spacers are trivial to weld on.

What's the problem you are trying to solve?

 

[yossarian19]

I just checked out the WJ caliper mount lug spacing vs the early XJ knuckle lugs. Good news and bad news
The good news is that both the WJ caliper and early XJ knuckle seem to be 5 1/4" hole centers (measured with the Mk I eyeball and a tape measure) and they bolt right up.
The bad news is that the depth is all wrong - you could only run a 6" rotor this way. Doesn't work. Easy to build an adapter plate, though.

WOW, bonehead move on my part. I realized yesterday that the knuckle I grabbed was the WJ knuckle, not the old XJ. WJ caliper lugs do not match up to old XJ.
Side note... they look a lot alike, and I'm a bonehead.

 

[yossarian19]

Do you know the difference between the Crown Vic rotors and the Sport Trac?

The Crown Vic rotor is .41" larger diameter (12.42"), .02" less hat height, .08" thicker. Same hub register and pattern. Crown Vic rotor lists a 0.61" bolt size vs the Sport Trac's 0.63, but it fits on the XJ hub like it's supposed to be there.

Thinking now that, with 15" rims, I might be better served by using the Sport Trac rotor. I can *just* get a WJ knuckle & brake caliper stuffed in with a an inch-and-change worth of wheel spacer. 12.42" is probably too much rotor unless I want to buy 16s.

 

[CobraMarty]

Costs, that's the problem to solve.

Start to finish, including everything needed to do a 'WJ' front brake swap can be nearly $1000+.
WJ knuckles, spacers, welding, WJ lower ball joint, calipers, pads, rotors, hub bearing, steering and track bar DOM, offset TRE, higher sway bar arms, modifying track bar mount.
OK you upgraded the steering and track bar, but what if you only want to upgrade to 12" front brakes and don't need or want the OTK steering etc.

 

[yossarian19]

Yep.
The knuckles themselves aren't the expensive part.
It's all the stuff to make them work properly on an XJ.
Not everyone wants / needs the steering changes which are a necessary and expensive part of the WJ swap. Sure, you could run stock steering and track bar with WJ stuff if you don't mind bump steer. You still wind up putting in new lower ball joints & buying a couple new hubs and some spacer rings. You can figure a lot of this is just preventative maintenance, or you can figure "screw this, I can come up with another way to do it..."

 

[CobraMarty]

Got a WJ passenger side knuckle.

Measurement of caliper mounting lugs-
WJ- 5.15"
Early XJ- 5.50"

 

[kastein]

If you don't want the steering upgrade, AFAIK you can bolt XJ steering right onto the WJ knuckles, you just ignore the second arm for the drag link on the passenger one.

The weld-on spacer is necessary to make the XJ unit bearing plus stub shaft align the center of rotation of the ujoint with the kingpin axis. Else, your axleshaft "bend point" won't line up with the kingpin axis and the axleshaft will both plunge and move side to side within the axle housing as the steering is turned.

The choice of 91-99.0 or 99.5-01 XJ unit bearings depends entirely on what rotors you intend to run.

 

[CobraMarty]

WJ 12" Rotor and caliper swap/upgrade. Not using or needing WJ knuckles.

Almost finished putting together my 12" rotor upgrade. I still have 2 XJs with 15" wheels and need better brakes.

No welding, no drilling, no hub spacers, no WJ lower ball joint, no cutting, no fab work, no new steering or track bar required, no sway bar arm modification.
All bolt on.

Using early XJ knuckles which bolt on to all stock D30 XJs, re-use all the stock XJ ball joints, hub bearings, stub axles, steering and track bar.
12" sport trac rotors and WJ dual piston calipers.
Just need to grind corner/edge of hub flange slightly and use an adapter/spacer bracket.

Now this hasn't been done before, once or a million times.

 

[rav]

just curious how many xj's do you have?

 

[CobraMarty]

3, all 2 doors.

'98 with the Sprintex SC, '98 33MTRs long arms (no SC) and '99 'RaceXJ' with M62 SC.
The 2 '98s are red with 15" wheels, the '99 is white with 18" wheels.

 

[rav]

3, all 2 doors.

'98 with the Sprintex SC, '98 33MTRs long arms (no SC) and '99 'RaceXJ' with M62 SC.
The 2 '98s are red with 15" wheels, the '99 is white with 18" wheels.

what do you do for a living if you don't mind me asking? I am always broke with just one, I can't imagine how much money you must have poured into three...

BTW you have one XJ that's not supercharged might as well give that one a go too with the new side kit?

 

[CobraMarty]

what do you do for a living if you don't mind me asking?

I collect XJs for a living.:roflmao:

BTW you have one XJ that's not supercharged might as well give that one a go too with the new side kit?

Already thought about it, Don't tempt me any more than I already am.