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Thread: Modding a ZJ F.A.Q.

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    Modding a ZJ F.A.Q.

    So you bought a ZJ and want to modify it. Lots of questions will pop up and I hope I can provide some answers. I had the same questions, through trials and tribulations I found most of the answers I needed.

    First thing I'll touch on is some general info about the ZJ, what to look for when buying one, and some options they came with.

    ZJ grand cherokees were made from 93-98. For the most part the chassis went without any revision. The trucks were OBD1 until '96 and OBDII after that.

    ENGINES

    Engine options were from the begining either the AMC 4.0 HO or a 5.2 318ci Dodge engine, in '98 there was the option for the 360ci Dodge engine. No mater what engine you have consider, relocating the intake. Stock location is behind the left headlamp and if wheeled eventually will take on water with devestating consequence.

    Transmissions for the zed are as follows.

    4.0 AUTO

    93-93.5 the auto for the 4.0 was the AW4, a near bullet proof auto IMHO should have remained throughout production. In 93.5 the AW4 was replaced with the Dodge 42RE which remained until the end of production. The 42E was horribly unreliable.

    4.0 MANUAL

    For the first two years of production the AX-15 manual 5-speed was an option in base trim grand cherokees. A roubust light duty 5 speed and a twin to those offered in the YJ and Cherokee. (xj)

    V8 AUTO

    The V8 only was offered as an automatic. The starter on the Jeep version of the transmission is on the passenger side while the 46RH used in Dodge trucks was on the driver's side. in 1996 they switched from the 46RH to the 44RE behind the V-8, except for the 1998 5.9L which got the bigger 46RE. The only difference between the RE's and RH's is that with the RE's more things were being done by the computer.


    AXLES

    The front axle in the grand is a Dana Spicer 30 model with a low pinion housing. The D30 is decent axle that can be run quite reliably with a 33" tire. A great low buck upgrade for the D30 low pinion is to exchange the axle for a high pinion Cherokee D30. It is a direct bolt in swap.

    The rear axle was a Dana 35, while later in production an aluminum Dana 44 was offered. The D35 can handle 33"s with some upgrades. The aluminum 44 is poorly supported and prone to failure with costly repairs, not to mention the aluminum center doesn't get on well with rocks.
    Last edited by C.C.; 11-18-2009 at 09:47 PM.

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    What to look for when buying.

    Remember when looking for a ZJ the last one was produced over a decade ago, it will have typical old car problems.

    Of course you best bet is to take a potential purchase to a trusted mechanic or Jeep Guru.

    Look at all of the vehicle fluids for signs of corrosion or debris, scale in the coolant, condition of the transmission fluid ETC.

    ZJ floors are typically good, with rust forming in the rocker panels, tailgate, door bottoms, and sometimes around the control arm brackets.

    Look for worn bushings, U-joints, and steering components.

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    The first steps 2" BB

    The 2" Budget Boost lift, is a set of four 2" tall polly spring spacers that will increase overall ride height.

    The BB should be used with a new set of shocks, and extended brake lines.
    If you don't install new longer shocks the factory length shocks will top out during articulation and leak. Brake lines likewise will be stressed during full flex. '95 YJ stock lines fit the bill perfectly or a stainless steel set of extended brake lines from any any of our sponsors.

    The front and rear axle will be slightly jogged to the side over stock height but do not affect overall driveability.

    Of course as with any suspension modification an alignment will be required. Your ZJ will also become more prone to the dreaded death wobble if there are any worn steering or suspension components.

    31" tires will fit with some light bumper trimming. You may require a shallower backspaced rim so the 31's don't rub on the lower arms during full lock turns. Proper cost will be $500. without installation
    Last edited by C.C.; 11-17-2009 at 11:37 PM.

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    The 3.5"-4" short arm kit.

    To lift to 3.5-4" you'll of course need springs either from a lift kit or from the legendary F>R swap.

    Let's first cover the lift kit. Springs and lower adjustible control arms should be included at the very least. Extended shocks and brake lines will be needed along with longer swaybar links. Now is a great time to add front swaybar disconnects. I found a 2" drop pitman arm brought the steering back to respectable angles. The Ideal soloution of course would be a high steer or inverted T setup over the Jeep factory inverted Y.

    Some kits will come with raised track bar brackets. Don't waste your time. Toss em out. The increased leverage on the axle brackets will tear them off the axle with any real use. Adjustible track bars are the only perminant answer.

    A short arm lift will add stresses to the body that it was simply not designed for. Under most circumstaces it will hold up just fine BUT it has happened to a couple of our members the stresses fatiuge the metal to the point of shearing off the control arm mounts. Rot can also play a factor aswell with a vehicle of this age. In my own experience I have never had a problem.

    The F>R

    Take the front springs and put them in the rear, Buy front 3.5" lift springs, That's the magic. You will still need shocks, brake lines, swaybar links, track bars, and so on. You get away from the aftermarket control arms, and cost of the rear springs.

    With either lift you may need a t-case drop, it wasn't my experience but be aware some find they do. A slip yoke eliminator or hack 'n tap is a good idea at this point.

    Some people try to get 6" on a short arm lift by retaining the BB with the new lift. It is so not recommended it hurts. Poor driveline and steering angles will occur without enough room for adjustment, not to mention the road manners become unstable and the truck rides like a cinder block.

    with the 3.5 - 4" system 33's can be stuffed in with some minor bumper, and fender trimming. Cost will be $1500 - $2500 depending on kit and options without install.
    Last edited by C.C.; 11-17-2009 at 11:38 PM.

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    Longarms 4"+

    Many different longarm setups are available from store bought right to custom made. It's a little harder then just bolting up square tube to the chassis. Look for a well designed system. If you're at this point you should of course understand all of the incidentals that go along with it. You have to truss the rear axle so now would be a great time for an axle upgrade.

    To long arm properly you'll be looking at $3,000 and up.

    See Joel's writeup below. I went a different route and am not familiar firsthand of all the incidentals.
    Last edited by C.C.; 11-18-2009 at 02:18 PM.

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    Bumpers

    Aftermarket bumpers cost around $1000.

    ZJ's have a dirty secret. The frame will fit a steel 2x4 almost perfectly. The 2x4 can be drilled and tapped to be used as frame extensions to build a bumper and winch mount from. If you have a little fabrication / welding skill a decent looking bumper can be had for far less then a KOR or ARB unit.

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    stock:

    2in BB with 31s

    3.5 inch lift with stock tires:

    3.5inch lift with 31s

    6.5 inch lift with 35s

    6.5 inch lift with 37s


    8.5 inch lift with 37s (too tall)


    if anyone has questions, take it from people who have done it.


    some good reliability mods:
    external trans cooler and guage (http://www.mallcrawlin.com/forum/showthread.php?t=7801)
    kevin offroad, steering box brace (http://www.kevinsoffroad.com/zj/zj_s...gearbrace.html)
    kevin offroad radiator cradle/tow point (http://www.kevinsoffroad.com/zj/zj_rad_support.html)
    electric fan(http://www.mallcrawlin.com/forum/showthread.php?t=2912)
    Track bar conversion. normally comes in a kit with a front track bar, removes the trackbar tie rod type joint and replaces with something stronger and allows more articulation (http://www.kevinsoffroad.com/tbconversion.html)
    Last edited by JoeL; 11-18-2009 at 10:47 AM.

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    long arm = A PAIN IN THE ASS

    but it is also so worth it, better flex, better ride better everything.
    i went with clayton long arms, really the only tried and true long arm manufacture for ZJs. it required cutting and welding so make sure you know what your getting into, there is no going back from this point without a lot of work.
    heres a quick parts brake down of the absolute minimum you will need in addition to a long arm upgrade kit
    skyjacker front and rear extended brake lines
    pro comp rs9000 shocks (part number 929500)
    still using my original KOR track bar conversion
    ORO u-turn steering
    i went with rock krawler 6.5 springs (not made anymore)

    with the U-turn steering you dont need a drop pitman arm and there is no bump steer at all at 6.5 or 3.5 inches of lift. it is also very easy to adjust for alignment.

    before going to long arms i replaced the bushing in my track bar and all my tie rod ends as well as ball joints and unit bearings to make sure it would hold up to it all better.
    i also copied Clayton offroad's skid plate which adds a lot of rigidity to the body.
    ()
    this is also a good point to swtich axles since most likely you will be going to a tire size that will be too big for the d35 or 44a

    i went with a custom 9 inch :

    you need to cut the top mounts off of whatever axle your using and weld on a truss so why not go to a new axle.

    a few other things that will need to be considered will be a longer drive shaft front and rear. i have yet to do this on mine as im waiting on putting in a new front axle. a longer drive shaft might as well accompany a SYE kit, either a hack a tap for the 242 or tom woods SYE or swap tcases to something like a 231 or whatever where SYEs are easier to come by. 35s would have been the perfect size for 6.5 inches of lift with minimal trimming, 37s are quite big and i had to add spacers to my front axle to match the ford 9s 5x5.5 bolt pattern, this has increased my scrub radius (http://en.wikipedia.org/wiki/Scrub_radius) to where it contacts the firewall. (the new front axle will fix this)

    alot changes with a long arm kit, but its fairly straight forward, and will ride better and work better on and offroad. my girlfriend's sister in law thinks my zj rides better than her Pontiac vibe, lol. you are opening a can of worms tho, almost nothing under my jeep is stock, everything needs to be changed to hold up to the stress. theres the obvious but also the small things, like in the rear the spings will come off the spring posts when you flex it out. longer spring posts should be on your list too. bump stops and limiting straps are also a great idea.

    call up clayton offroad and ask them any question you have they are very helpful.
    Last edited by JoeL; 11-18-2009 at 11:11 AM.

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    Here's the pic of the busted control arm point you can toss in your edu-macation information there. I'll have to get some pics as I mentioned of the underside of the truck where it broke. I've still got the shell hangin' around. The upper control arm on the axle broke off from the added stress after this picture. Ended up using a ratchet strap to my front rad support/tow point. (Just don't buy the tow point I sold to C.C., it's cursed I tells ya!)



    And a shot of it on the 4.5" Rubicon Express kit with 33's:



    My personal opinion is that if you want to do any serious kind of wheeling with a ZJ, long-arm it. Otherwise buy something with a frame. Not everyone agrees with this but when you're stranded deep in the woods overnight limping a truck out with ratchet straps for suspension you gain a new perspective on unibody strength.

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    yes the manufacturers recommend longer brake lines yes its better braking and will not limit your flex if they are extended. saying that, i didn't upgrade or more my mounting bolt or anything until 3.5 inch lift with arms. they stretched under flex and i started to get worried about busting one so i got longer stainless steel ones.

    its one of those upgrades that is highly recommended but if your on a tight budget can wait a bit
    Last edited by JoeL; 11-18-2009 at 01:48 PM.

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    Quote Originally Posted by JoeL View Post
    before this turns another tech thread to a pissing match, like alot of jeepkings threads:

    yes the manufacturers recommend longer brake lines yes its better braking and will not limit your flex if they are extended. saying that, i didn't upgrade or more my mounting bolt or anything until 3.5 inch lift with arms. they stretched under flex and i started to get worried about busting one so i got longer stainless steel ones.

    its one of those upgrades that is highly recommended but if your on a tight budget can wait a bit
    Well put.

    The thread will not become a pissing match. I will edit and revise as I see fit. It's a beginers information thread and opinions are welcome @ssholes are not.

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    Quote Originally Posted by C.C. View Post
    It's a beginers information thread and opinions are welcome @ssholes are not.
    I see how it is. I guess i'll just leave then.

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    The rad support Nine-t-one refers to is cursed. It cost 3 ZJ's in varying degrees, 2 engines and a lower control arm. It will never be sold again. It's been welded all perminantly to the snapper.

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    Nice thread, I've always liked the ZJ's. One minor correction however, in 1996 they switched from the 46RH to the 44RE behind the V-8, except for the 1998 5.9L which got the bigger 46RE. The only difference between the RE's and RH's is that with the RE's more things were being done by the computer.

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    ^ corrected with a little help. Thanks Tealj

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    what a great write up!
    Thank you for this

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    Quote Originally Posted by NINE-T-1-RENEGADE View Post
    And a shot of it on the 4.5" Rubicon Express kit with 33's:

    that's bad-ass...black and gold just like mine....got any more pics?
    1995 ZJ Limited, 5.2, 46RH, 249, D30/D35, stockish, his....
    2004 WJ Overland, 4.7HO, 45RFE, NV247, D30/D44, stock, hers...
    Quote Originally Posted by Beerfest
    "It's $10 for a BJ, $12 for an HJ, $15 for a ZJ..."
    "What's a ZJ? "
    "If you have to ask, you can't afford it."

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    man this is a good read! a WJ one would be awesome too, but beggars cant be choosers i guess hahah
    young kid learnin the hard way
    90 YJ 4.2L, howell TBI, 4L head, 4"lift with 31x11.5s. broke it, welded it, broke around the welds, welded it again, sold it
    99 grand cherokee, 4.7L. 2" BB, 245/75R16

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    ^ I'm just starting with the WJ let me work on one. LOL

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    Quote Originally Posted by GONRACIN View Post
    that's bad-ass...black and gold just like mine....got any more pics?




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