Front differential slop\clunk

[ClarkGriswald]

Recently aquired an 88 Grand Wagoneer, coolest vehicle Ive ever owned despite the initial repairs Ive been dealing with, among these were replacing one front driveshaft u-joint with no real trouble, and upon discovering my 4wd didnt work ended up with it jacked up on all fours, and tranny in neutral prying the two levers on the trans case apart that were rusted together (mode, and range levers)finally got it to shift but its still stiff and I'm doing it with a big pair of vice grips from under the vehicle. Question: Ive noticed a LARGE amount of play in the front diff that clunks if you turn it back and forth, and when supposedly in 2wd mode i hear it clunking when taking up the "slack" when i change between reverse and drive, or when driving if I release the accel and hit it again. doesnt seem to really be in 2wd? could part of this slack also be in the trans case chain?(np229) but still why would the front axle take up the slack when placed in drive or reverse while in 2wdrive mode?? any info\advice on this would be greatly appreciated, and thanx in advance.. this is a great forum ive read a lot of good info here so far..
thx...

[p.todd]

I've got all the same probs:

1) When in 2 WD (I jacked up the front end to flush the PS sys.) there is slop in the front wheels while turning the front drive shaft back and forth. This is also noticeable with the windows down and coming to a quick stop (or while parking) I'll hear a "clunck" from the front end as the FSJ comes to rest. Maybe the front bearings need lube and adjustment?

2) 2WB mode, shifting into rev. from drive I hear a hefty "clunck" from underneath. Checked it out today (installing new PS hoses & pump, with front end raised) and it seems to be from the xfer case (NP 229) not the differential.

3) in 2 WD mode on the highway, if I rapidly accelerate then take my foot off the gas I'll feel the slop in the rear drivetrain. My mechanic says case #2 is the rear U-joints, but, they are rock solid when shaken, pushed back-and-forth by hand. Xfer case again?

Anyone gone through this before?

there was this discussion on the FSJ-list afew weeks ago, but, the cures were all over the place: use Ford spline grease, no it's the U-joints, or there's a gear inside the TF727 tranny that must flip over when in reverse and that the "clunk" is normal.

Anyone out there have a definate idea of this prob?


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-P. Todd
'91 GW "The Swank Tank"
360/727/229/+2" lift

[This message has been edited by p.todd (edited July 07, 2000).]

[bignblue]

I've both experienced and read about this problem, and from what I've been able to gather the source is multiple. First off, some of the clunking DOES come from the U-joints. They may be rock solid to the touch, but an engine produces much more torque than a human hand. They're cheap, so why not replace them? Secondly, an article in Peterson's recommended lubing the splined area of the driveshaft as it enters the transfer case. Under acceleration, the rear diff moves back and down (I think--going from memory and faulty logic here) producing some potential slack. When you stop, or shift or whatever that potential is realized: the diff moves forward and up. The clunking noise is coming from the splines slapping up against each other as they're forced together by the motion of the driveshaft, which is being pushed/pulled by the differential.

Again, I'm going by memory so I may have is bass-ackwards, but the theory is the same. Some clunking is to be expected.

[rm126]

I had the same problem. Turned out to be a combination of slack in the driveshaft u joints, the front axleshaft u-joints, and LOTS of slack in the t-case chain. REplaced all the u-joints first, there was still some clunking, did the t-case, and that seems to have taken care of it.

[Brown Bear]

Clunking just tells me that The Minnow is working

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1984 Grand Wagoneer
bone stock
P235/75 R15 Daytona Stag XT

[scotty]

remove both driveshafts. you can check the differentials simply by moving the pinion gear around.there should not be much(if any at all)rotational movement. if you can twist the yoke any noticeable amount,or move the pinion gear back and forth,in or out,or up or down,that is bad.in otherwords,it should be nice and tight.

put the t case in 4lo.in theory,the center diff is now locked and not a factor.grab the front output yoke and rear yoke and twist one or the other.any amount that one yke turns before turning the other is slop in the chain. some is to be expected.alot is bad.definately bad.very,very bad.

do you get any less clunking in 4wd? awhile back i read on another forum that the 229 produces 2wd by locking something to the viscuos coupling,but not connecting it to the front output.i cant remember exactly hhow it worked,but,the moral of the story was that when the viscuous coupling goes bad,you hadve no 2wd,you have to put it in 4wd to move. maybe some of the clunks youre hearing are coming from the viscuous coupling or its "2wd making mechanism thing" however it works.

my advice:replace all u joints,replace t case with a 208. replace pinion bearings or ring/pinion gears as needed. no more clunks.

good luck.



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scott
85 grand wagoneer
258/904/twin stick dana 300/dana 44/amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd

[ClarkGriswald]

WOW.. thanx for all the great answers, hehe. I swear I've found almost every problem that I am dealing with on my own FSJ, right here on the list and forum's. Most of your answers seem to confirm the same things, my 229 is probably beat to death as well as a lot of front diff slop. I talked to a mechanic from a jeep dealership yesterday that told me to open up the front diff cover and hold on to the different parts and observe that the slack is a combination of the R&P as well as the other spider gears and such in there and even the splined ends of the axle shafts where they insert into the diff.. so I will probably just have to throw some new parts at that front axle. I like the idea of locking it into low range and checking the backlash in the transfer case chain.. gonna do that soon..
Thanx again for the good info folks this list rocks!..

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88 Grand Wagoneer
D44's front\rear
AMC 360
TF 727
NP 229 (Funky)
Bone Stock (for now)
NO RUNNING BOARDS!

[p.todd]

Thanks for all the interest and good ideas (like puuting the T case in 4 lo and twisting).

BignBlue do you remember what issue of "Petersons" that article was in?



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-Phil
'91 GW "The Swank Tank"
360/727/229/+2" lift

[Marc_01]

If replacing the chain and gears in a x case a hard job? IE, can you do it at home with basic tools?

[bignblue]

Marc--the tech section has an article on replacing the chain in the Quadtratrac t-case. Seems like it's about a five-hour job, and while you CAN do it with one person two are really needed. I went the easy way and had my mechanic do it: Alabama summer days are kicking around the 112 degree mark right now, and I don't want to melt on my driveway.
P.Todd--I don't remember which issue it was, but I probably still have it here around the house. I'll look for you and maybe try to post a "Reader's Digest" condensed version if I can figure out how it's done.

Happy Jeepin'!

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'78 Chero WT
401/4bbl/TH400/QT
44s F&R
"Jeep: the toughest 4-letter word on wheels"

[ClarkGriswald]

OK<<<<< VICTORY!! Tonight i took my big pair of vice grips and crawled underneath my beast and shifted my 229 into 4wd all the way.. then got rolling and popped her into low range.. after some joking around and acting like a tractor, i pulled in my buddies garage over a pit.. chocked all four wheels and unhooked my rear driveshaft from the trans case.. and lifted one side of my front axle and with a big pair of channel locks on the rear yolk of the trans case, observed a LARGE amount of play\slack between the front and rear . so my chain is wasted.. (scared yet?, should be cause in the process i dropped one of my ujoint caps into the pit full of oildry, and with much luck was able to recover ALL the needle bearings with a shop light and a magnetic pickup tool and clean and relube\reuse them. Second time in my life that Ive had that happen to me in the same shop.Whew!)But now on too the good new's.. Now that I had a buddy helping me out.. I started her up and had him flip the 2wd\4wd switch and my vacuum actuator was in fact working. I hooked it back up, and with its help was able to FINALLY shift it into 2 wheel drive mode.. (first time in the 3 or 4 weeks I've had this truck) my only comment's?? Night and DAY!!! finally I can have a fair judgement of how powerfull the 360 is. Sufice to say I had a fun drive home getting sideways around every corner of a twisty dirt road. first time Ive gotten it to break the rear end up and get sideways.. Quite fun!.. So in conclusion. Lots of slop in my front diff which I need to address, but Definatly a old\bad trans case chain. I am very intersted in how to change this, Ive rebuilt a half a dozen or so smallblock chevy's so mabye I can handle this task I hope.. . Thanx for the good test idea's about lockin her into 4low. mabye I'll save myself much money and headache's by fixin my chain before it breaks.. . Good luck all and thanx..

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88 Grand Wagoneer
D44's front\rear
AMC 360
TF 727
NP 229 (Funky)
Bone Stock (for now)
NO RUNNING BOARDS!

[p.todd]

the otherday I did as scotty said above:

put the t case in 4lo.in theory,the center diff is now locked and not a factor.grab the front output yoke and rear yoke and twist one or the other.any amount that one yke turns before turning the other is slop in the chain. some is to be expected.alot is bad.definately bad.very,very bad.

After a few minutes of twisting back and forth I measured the play by scratching a reference mark where the front output yoke meets the front of the NP229 Tcase. Then twisting my front yoke the opposite direction (and still holding the rear yoke stationary) I measured the play: 1/16th of an inch. Enough for a "clunk" to be heard, but, I don't think enough for me to think the T case chain needs service.

Anyone think this amount of play is unacceptable?

I'm hoping a good lube of all the U joints will reduce the clunk.



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-Phil
'91 GW "The Swank Tank"
360/727/229/+2" lift

[ClarkGriswald]

When I did my "4low slop test" i unhooked my rear driveshaft, and jacked up one front tire.. so everthing was free.. while watching the front yolk to see when it moved.. and turning the rear yolk with a really large pair of channel locks, mine probably moved and inch or more mabye inch and a half.. and a goodly clunk. now that its in 2wheel finally, the clunk is just the normal amount from the rear axle engaging.. My chain is real loose. so im a bit scared of it.. looking for a 208 i think.. before i have problems with this one..