Kk diff swap into kj

WhitbyKJ · **Posted:** Fri Jan 30, 2015 11:07 am

Okay,

A little while ago I was talking about tossing a kk diff under my jeep.

The topic kinda got lost.

But I committed, after much measuring and research.

It turns out the following is true.

The cradle is the same dimension, however bracketed is different. At least for the diff.

The lower a arms, however a different style, are dimensionally the same at the bushings. And the bushings themselves are the same.

The bolt pattern that mounts it to the chassis is also the same as is the location Of the cradle with regards to the distance from the edge of the front bumper.

The engine brackets, are also in the same location.

The kk cradle also has a provision for the kj diff bracket on the passenger side, however drivers side doesnt match kj setup what's up with that?

The kj steering rack will bolt right on.

The kk diff has the same inner axle spline dimensions and count as out kjs. The outter cv is a 31? Spline tho?? So I will be re using kj cvs.

I am going to have to think about a drive shaft.... They don't match. My idea is to use and xj shaft (changing the output yoke on tcase of course) and getting a rear axle kj flange from the bone yard and putting it on the end. So far I am 450 dollars ino this and all I need is a driveshaft.

Stay tuned.

Currently 3.5 inch on 32's, crazy mods.

WhitbyKJ · **Posted:** Fri Jan 30, 2015 12:55 pm

I have in my posses the diff and cradle... Cost me 450. Had to cut the kk arms off.

JeepMorrison · **Joined:** Thu Jul 16, 2009 11:34 am **Posts:** 1236

All of this for 4.56s? I have 4.56s in my KJ and didnt go through all of thia crazy stuff.

WhitbyKJ · **Posted:** Sat Jan 31, 2015 8:33 pm

No, not just for 4.56.

There will be a cradle drop, custom upper bj extensions, t case drop, more lift.. End result will either be 35's... Or 33's locked front and rear.

Got three weeks of holidays coming up at the end of March.. So like I said, stay tuned.

I bought a calliper et all, so along with pictures, I will be posting measurements down to the thousandth of an inch.

Not trying to hot rod here or anything or step on toes, etc etc etc..

As you guys may have already guessed, my grammar sucks:.. Guess what? I don't care :p
Lol

I am a mechanic, millwright, welder .: not a lawyer.

Ps

I creep this forum a lot and am totally in love with tiki and mudd. You guys rock.

JeepMorrison · **Joined:** Thu Jul 16, 2009 11:34 am **Posts:** 1236

Sweet....let me grab some popcorn!!!

tjkj2002 · **Posted:** Sat Jan 31, 2015 11:01 pm

WhitbyKJ wrote:

End result will either be 35's... .

Not even going to happen with IFS still,even the KK's diff(and CV's,bearings,and such) just will not hold up to that size.

WhitbyKJ · **Posted:** Sun Feb 01, 2015 12:07 am

So 33's locked?

K, I have been looking real close at these kk diffs.. Essentially all they really are, are jk 30's. Humongous pinions on them. The preliminary move to the kk diff was to establish a hp front d30. From there I intend to "eventually" (heavy quotes) acquire a jk 30 and chop it up... Considering the axle shafts are for kk and jk are both 27 spline on the inside with a diameter of (I believe. They are the same iirc) 1.16 inches.

After doing some cross reference style snooping on rock auto (god I love them) it appears that bearings and races etc etc all have the exact same inside and outside diameters and also in some instances retain the same part numbers between jk wrangler, 1998 xj and 2009 liberty kk, with respect to the d30 seals and bearings.... Therefore I should be able to acquire a jk 30 or other hp30 if need be chop is up and reuse my inner axle shaft. Of course some exact measuring and cutting, perhaps even end milling May be required for bearing races, seals etc in the pass side, but I think it may be possible. Sound familiar? Point in case, I have access to a machine shop and friends that are certified tool makers, so machining is free.

With respect to the kk and jk... Inner splines are 27 and outers are 31. (Keep in mind I am only pulling this information from the top of my head) but there is a serious relationship between these axles that swapping to a kk diff is the first stepping stone to moving onto a steel hp30... And eventually if I shall get so rich, and perhaps maybe so daring... A hp 44, but that would require custom cv middle shaft and inner cup.. Not my cup of tea and it also takes away from the trail sustainability from only needing 1310's and stock kj's cv shafts.

IF, read in a snowballs chance in hell, that I go steel. Then there will be 35s (thank you tjkj for helping me make up my mind). I have considered sfa swap, I have considered a lot of stuff.

What I want to do, is do something nobody has ever done before. I want to do it, and share every aspect of the experience with everyone.

Like I said earlier tjkj, tommudd I love reading your posts and have been doing so for over two years. (Creeper I know right? Lol)

WHERE I NEED HELP

On one of my previous posts, tjkj posted a picture of some contraption he had holding his ending up with a ratchet strap, an engine leveller I believe. Can you please repost the picture?

Otherwise I will have to fab up eyelet bolts that screw into the spark plug holes and use a crane or likewise a vehicle lift.

During the cradle swap I will be rebuilding steering rack, (upgrade ideas are appreciated).

I have determined that kk and kj knuckles are not swappable because the kj and kk lbj's are opposite each other and the kk arm is undesirable due to it being straight(er) (thus a bad bj angle would result from being lifted too far) where as the kj lca has a slight upwards bend, over rules the bad bj design, by providing more articulation. The wheel hub bearing are swappable, as one should physically fit in the knuckle of the other... But kk is 31 spline and kj is the standard 27 spline.

Makes me wonder if the xj wheel hub bearings are a suitable (money saving swap) for non abs kj's like mine?? Only the digital calliper and time will tell. Don't let me forget this.

Last but not least, the two inches of thread on the end of the cv shaft, what the hell purpose is this other to make swapping a cv on the trail a pain in the ^%#*. ? Can I just cut them off and leave 3 threads extra outside nut??

Sorry for the ramble, just trying to build excitement.

WhitbyKJ · **Posted:** Sun Feb 01, 2015 12:10 am

................. Uh oh.

Maybe I was thinking of the non cad xj hp30 ^above.

Either way steel hp30s are 27 spline and kk diff is 27 spline. Parts numbers match etc etc

tjkj2002 · **Posted:** Sun Feb 01, 2015 12:34 am

The KK D30M and JK D30 use the same gears and same carriers.
but even being a HP the D30M will prove a very weak link if pushed hard locked with 33's and does not have much of a chance with 35's.The reason is it's aluminum,granted a better design then the KJ's but still aluminum and still only designed for a 29" tall tire that weighs 40lbs on the rim.Upgrading this and that moves the weak link and trust me you will find it when you start pushing it hard.I deliberately used known weaker locking hubs on my front HP44 so that would be the weak link,lifetime warranty(I do carry spares though) and easy to change on the trail.

It's not my money or vehicle but I still don't understand why some still wish to retain the IFS when looking for 33"+ tires,the cost will be roughly the same(if not more) when the IFS keeps failing constantly.By all means do what you want but gotta ask "is it really worth it?".

WhitbyKJ · **Posted:** Sun Feb 01, 2015 7:10 am

I am doing it just to get the t shirt.

I have been wheeling the snot out of my d30a for some time, on 265/75 lt's with steel offsets from summit racing, I swear they weigh 80 lbs each. Either I have been extremely lucky.. Or the ten years as an armoured crewman has fought me how to wheel properly?? Personally leanin towards the horseshoe in the my butt.

It's just people keep saying that wrt lp and hp 30's that the hp30 is 30% stronger. At least in steel. If the a can take 32's then the m should be able to take 33's.

Either way, we will see

WhitbyKJ · **Posted:** Wed Feb 18, 2015 11:59 am

This project has not lost steam.. Work is busy and holidays start the end of March. Stay tuned.

Liberator4x4 · **Joined:** Mon Aug 13, 2012 12:04 am **Posts:** 29

I love where this is going, keep it up!

WhitbyKJ · **Posted:** Mon Mar 16, 2015 11:00 pm

START THE COUNT DOWN!!!!!

4 days till three week holidays. I got 21 days of wrenching coming my way!!

Parts are in, consumables are in, I am pumped, Libby is pooped out... It's overhaul time boys!!!

Teaser: looking into maybe Nissan or ford double cardan for the rear... A double cardan will be going into the front. (250 dollars for two cv joints or 75 dollars for three ujoints that won't blow a boot???? Duh no brainer there)

Need to make a decision quick:

Input needed. Cradle drop is set at 2.5 inches. Not changing.

Do I drop the engine and trans to lower CoG or proceed with modification to my kk cradle where I will move the engine bracket up 2.5 inches to compensate?

Un-ryAnified (that's a term my wife uses lol) version: is 4 - 5 inches.of lift a centre of gravity/tip over concern?? I am running 265/75 on 4 inch bs.. And plan on going bigger.

I would extra appreciate input from anybody that has rolled a kj, and also need input from those that haven't, near miss etc etc.

Ps
Remember how I praised lost members for their hard work?

Today you saved me and my daughter. Got into a stupid today. Totally my fault.

I tried to climb the side of the trail, mossy grass, wet, snow etc etc, 7 feet up, on like a 60 degree angle. I went up on a 45 one wheel at a time, which was fine until I got stuck, then as my father describes it (he was following behind) the rear pSsenger tire was three feet off the ground and bouncing like a basketball.

I kicked the daughter out before trying to get out this whoopsy, and I could hear the noises coming from all the joints and bushings. They were really pissed... But everything survived and I drove it home, daughter in tow lol. I am almost certain that if I didn't heed warning and just haul off and lift the snot out of my jeep without consideration to bj angles... My kj would be in a wrecking yard tonight no fault of its own, but it's not.

Instead she is all covered in mud and tucked in safe and sound at the foot of my driveway

Hats off to you LOST. Thanks for helping me build a tank.

Now as soon as I can figure out how to put up movies and pictures I promise you a show you will never forget.

cuz I'm funny on camera and swear a lot. Lol jk.

4 days. Let the count down begin.

WhitbyKJ · **Posted:** Mon Mar 16, 2015 11:08 pm

Question #1,000,002 : can I cut the extra threads off the darn cv half shaft already?

KJWildman · **Posted:** Tue Mar 17, 2015 4:03 am

You will probably need to lengthen your steering shaft also with a 2.5" cradle drop. I went 1" and was able to make it work, any more. ..... no.

WhitbyKJ · **Posted:** Tue Mar 17, 2015 5:20 am

I was anticipating having to do something with the shaft.

What about centre of gravity? Leave it or move it?

Mountainman · **Posted:** Tue Mar 17, 2015 12:12 pm

No reason why you can't cut those extra threads off. They are a pain with just a little rust even with my air ratchet... I'm no metallurgist, but I imagine that you'd use fluid and cut it off slow to not weaken the steel with the heat? Just curious.

Those extra threads are slightly handy in getting the nut started though...

tommudd · **Posted:** Tue Mar 17, 2015 1:31 pm

WhitbyKJ wrote:

Question #1,000,002 : can I cut the extra threads off the darn cv half shaft already?

Why?

WhitbyKJ · **Posted:** Thu Mar 19, 2015 10:19 pm

Because every time I go to take them out usually three times a year.. It's a pain in the butt trying to wrestle the lca down and get the darn cv out. If the threads were shorter, I could see swapping a cv on the trail inside of twenty minutes.

I know you guys may not agree with me, but a tried and tested lesson from the days in the armour (tank) corp was to be prepared. Anything I can do now, to make life easier down the road is the difference between being totally f@&$ed, and emerging victorious from less than desirable circumstances.

And I see that little inch and a half of "extra" shaft being a pain in the you know what, when it lets go and I am in the middle of tucktiucktuck with minimal tools.

WhitbyKJ · **Posted:** Thu Mar 19, 2015 10:24 pm

"Tried and true" excuse my typo.

Kk diff swap into kj

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