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Please try this with your XJ and tell me results?

soyjer

NAXJA Forum User
Location
California
1999 XJ, 98K easy (street-only) miles, 4.0L, AW4, Chrysler 8.25

With your XJ at a standstill, please try shifting into Drive from Reverse both WITH a pause in Neutral and WITHOUT a pause in Neutral, and let me know which gives you a smoother (even slightly) shift into Drive?

I (and several professional XJ and transmission experts) have now spent over a year trying to diagnose my XJ's "clunk/lurch when shifting into Drive at a standstill" problem (see below link if you want the gory details), and I now believe that the key to knowing whether it is the transmission or differential lies with whether or not "normal" XJ's make this shift smoother WITH a pause in Neutral or WITHOUT a pause in Neutral.

Mine makes this shift very smoothly if I do NOT pause in Neutral, but if I DO pause in Neutral then the clunk/lurch into Drive is comparatively rather violent.

The only explanation that I can come up with for this behavior would be that, when in Neutral, the input half of the transmission rotates freely at approximately the rpm of the engine, whereas when in Reverse, the input half of the transmission is held stationary by the stationary rear wheels on the ground, and so when in Neutral the input shaft has rotational momentum that causes the clunk/lurch when shifted into Drive, whereas when there is NO pause in Neutral then there is NO rotational momentum, and so there is no clunk/lurch when shifted into Drive.

But in order for this theory to be true, then ALL XJ's at a standstill must ALSO shift from Reverse into Drive smoother (even just a little bit) WITHOUT a pause in Neutral than WITH a pause in Neutral.

If ALL XJ's behave this this way, then my transmission is functioning 100% normally, and it is merely a loose differential that is amplifying this behavior in my XJ.

On the other hand, if pausing in Neutral does NOT result in a slightly harsher shift in normal XJ's than not pausing in Neutral, then my theory is bogus, and then that casts suspicion back onto my transmission, on which a complete professional rebuild didn't solve the problem.

If I could get the answer to my question here, and if it confirms that ALL XJ's behave this way (only to a lesser degree), then I will just have to assume that all of the experts were wrong about my differential, and pay one of them to look inside of it, even though they are saying that doing so is a waste of time.

https://www.naxja.org/forum/showthread.php?t=1146705&page=3
 
At the back of the transfer case/transmission there will be a slip joint under a black rubber boot. Removing the driveshaft and greasing the splines of this slip joint can eliminate a lot of clunks that might be attributed to a transmission or rear end.
 
At the back of the transfer case/transmission there will be a slip joint under a black rubber boot. Removing the driveshaft and greasing the splines of this slip joint can eliminate a lot of clunks that might be attributed to a transmission or rear end.

Some clunks as described happened on my jeep, greased it well, and clunks went away.


good luck
 
Couple of points here....

1. When diagnosing a problem with a vehicle, it is advisable to compare the condition to a like vehicle, I.E. same year, make, model, engine, transmission, etc. With an XJ, you're talking about a vehicle that was made, I dunno, what for 15 years with the last ones rolling off the line almost 20 years ago? LOTS of variance there in terms of parts, mileage, maintenance, etc.

2. Things are relative and subjective. This one kinda bit me in the butt when I used to work as a professional wrench-monkey. See, I'm used to old, rolling crap piles like XJ's. Never leased or taken out a loan on a vehicle in my life. When you drive old iron like that, you get accustomed to their... quirks. And when you get accustomed to it, you might just dismiss problems on a nicer, newer vehicle. For example, when I worked as a wrench-monkey at a shop, I took a job where the customer was complaining of a "whining" noise from the front of the vehicle (vehicle was a used Caddy Escalade, but still probably worth $40K or $50K) Took it for a spin, and it was hard to tell with my bad hearing, but it sounded like front wheel bearings. Got it back to the stealership shop and sure enough, both were starting to go out. The point here is, what you describe as a "violent shift," somebody like me might just chalk up to tired U-joints and put it on the long-term "to-do" list.

3. And for the record, I tried this on my POS '89, probably 5 or 6 times. I wouldn't describe any of the shifts as "violent" once the trans had some fluid pumping through it. (see point #2) Clunky, which indicates to me that the U-joints need some TLC and this tired old Dana 35 needs go back to the scrap pile of the foundry to be made it something better, but not "violent."
 
According to the AW4 manual, starting with the shifter in neutral moving it to reverse should have a maxiumum engagement time of 1.5 seconds, and moving to drive should have a maximum engagement time of 1.2 seconds. It also identifies the primary cause of harsh engagement as an improperly adjusted throttle-tranny cable. Have you adjusted that properly?
 
Original post explains extreme measures already taken to diagnose problem, including complete transmission rebild, etc.

Experts are stumped, so now I am just trying to follow my best "clue", which is simply that pausing in Neutral causes a harsher shift to Drive than not pausing in Neutral.
If my theory about input shaft momentum is correct, then this should be true for ALL AW4 transmissions, regardless of condition or age. The only difference would be the DEGREE OF NOTICABILITY between pausing and not pausing. On XJ's with tight drivetrains, it should be HARD to detect the difference, whereas on XJ's with LOOSE drivetrains, it should be EASY to detect the difference, if my theory is correct.
If I had a 2nd XJ here...preferably one with a loose drivetrain, then I could answer my own question, but I don't know anyone here with a Jeep of any kind, and so I'm trying to get an answer or two from this forum.
If my theory is correct (ALL AW4's behave this way, only to varying degrees), then all of the professional mechanics saying it's the transmission are wrong, and it is just my loose drivetrain that is merely AMPLIFYING the normal behavior of the AW4.
On the other hand, if my theory is bogus, then the transmission shop that rebuilt/replaced my transmission/torque converter managed to somehow accomplish that without fixing the clunk/lurch problem.
Either of the above would require that multiple experienced, honest, reputable, professional mechanics somehow were ALL wrong in their diagnoses of this problem, which is also hard to believe.
 
On my 96, going into D quickly from R causes a huge lurch/shock to the driveline, and stopping in neutral can eliminate it sometimes. I greased the slip yoke which helped slightly, however the issue I believe is wear and tear on the original driveshaft/pinion/axle/slip yoke over 200k miles. lots of little things with a tiny bit of play add up once you count every component.

I removed the driveshaft and drove it around in 4wd and the situation improved 90% very little lurch, the rest I'm guessing just a worn front driveline.

I'm totally guessing here, but once I do a SYE, replace driveshafts, do my axle swap, the problem will go away entirely.
 
Thanks for the doing the test for me... your results would seem to indicate that my transmission is behaving in the exact opposite manner to a normal AW4.
The real mystery is what could possibly cause it to be doing this, and how did the transmission problem "survive" a complete professional transmission/torque converter rebuild/replacement? The transmission mechanic even, out of desperation, finally replaced the transmission CASE...and (of course) that didn't fix the problem, either. :-(

On my 96, going into D quickly from R causes a huge lurch/shock to the driveline, and stopping in neutral can eliminate it sometimes. I greased the slip yoke which helped slightly, however the issue I believe is wear and tear on the original driveshaft/pinion/axle/slip yoke over 200k miles. lots of little things with a tiny bit of play add up once you count every component.

I removed the driveshaft and drove it around in 4wd and the situation improved 90% very little lurch, the rest I'm guessing just a worn front driveline.

I'm totally guessing here, but once I do a SYE, replace driveshafts, do my axle swap, the problem will go away entirely.
 
these issues are common on an XJ. I'd just deal with it the way it is. they're starting to show their age now and will have little quirks like this.

do you have 4x4? get underneath and pull the driveshaft. it's not difficult. then stick it in 4x4 and drive around cautiously in a parking lot at low speed. go into r/d/n. see if the problem goes away. if so, there's slop in the rear end driveline.
 
Probably already been done... But how do the motor mounts look?

How does it respond to the initial P to R? And P straight to D?
 
Driven a lot of xjs that exhibit this. Never once thought it was bad to address. A lot of the problem I notice too is worn/soft springs. In reverse the axle rotates down, effectively flattening the springs (and the axle trying to move rearward from reverse) and slightly lowering the vehicle. Going to drive the opposite happens and the springs unload slightly, giving a little bit of clunk/lurch. Seems worse cold when the idle is high as it's exaggerated slightly.

Wouldn't be bad to make sure all your suspension is in good order.

I totally agree tho, one person's horrible clunk is another's...eh.
 
these issues are common on an XJ. I'd just deal with it the way it is. they're starting to show their age now and will have little quirks like this.

do you have 4x4? get underneath and pull the driveshaft. it's not difficult. then stick it in 4x4 and drive around cautiously in a parking lot at low speed. go into r/d/n. see if the problem goes away. if so, there's slop in the rear end driveline.

I have no doubt that the clunk/lurch would totally disappear without the rear drivetrain connected, because anytime that the XJ is rolling at or above the speed that it would normally be traveling at idle rpm in Drive, then the clunk/lurch does not occur, whether I pause in Neutral or not. It's like striking an anvil with a hammer...no anvil, no clunk.

The clunk sound DOES sound as if someone is hitting the differential ring gear with a hammer, which may well indicate that ALL OF THE EXPERTS ARE WRONG and the driveline somehow has excessive play, but even if it does, that doesn't explain why MY transmission shifts smoother without a pause in Neutral, whereas seemingly all other AW4's shift smoother WITH a pause in Neutral. That fact is the ONE SOLID clue that I have that my XJ is different than a normal XJ, and that is why I am pursuing that first.

What I need is for fellow AW4 owners to just try the test that I am requesting (takes about 10 seconds) and report the results, so that I can confirm that MY AW4 prefers NO pause in Neutral whereas everyone else's AW4 prefers a pause in Neutral.

So far only one reader here has done this test, and I would feel more confident if I heard it from more than just one AW4 owner before I pay $2000+ dollars to have my transmission rebuilt (again!).
 
Probably already been done... But how do the motor mounts look?
How does it respond to the initial P to R? And P straight to D?

I paid a reputable shop here $90 to SPECIFICALLY look at the entire drivetrain, all mounts, etc., and they said that it all checks out OK and "it's the transmission".
Additionally, the transmission shop had it INSIDE of their shop for 9 weeks, completely rebuilt the transmission, replaced that torque converter, even the transmission case, etc., and didn't even charge me a penny for the normally $2200.00+ job (because he said that he doesn't charge for work that doesn't solve the problem)! It's hard for me to believe that they would have invested that kind of time and money into the transmission without even looking at the rest of the drivetrain, mounts, etc.

It' not IMPOSSIBLE that ALL of the shops that have looked at this are all wrong....but it's not LIKELY, either. The ONE SOLD clue that I have in all of this is this pausing in Neutral thing...and that is why I am trying to get an answer from other AW4 owners about this one specific thing.
 
Probably already been done... But how do the motor mounts look?

How does it respond to the initial P to R? And P straight to D?

The ONLY way to cause the clunk/lurch is to pause in Neutral before shifting to Drive (at a standstill, from any other gear, or Park). There is NO other way to cause the clunk/lurch.
 
Driven a lot of xjs that exhibit this. Never once thought it was bad to address. A lot of the problem I notice too is worn/soft springs. In reverse the axle rotates down, effectively flattening the springs (and the axle trying to move rearward from reverse) and slightly lowering the vehicle. Going to drive the opposite happens and the springs unload slightly, giving a little bit of clunk/lurch. Seems worse cold when the idle is high as it's exaggerated slightly.

Wouldn't be bad to make sure all your suspension is in good order.

I totally agree tho, one person's horrible clunk is another's...eh.

If that were my problem then pausing in Neutral (releasing the reverse tension on the drivetrain) would lessen the clunk/lurch, not increase the clunk/lurch, correct?

On mine, pausing in Neutral INCREASES the clunk/lurch.
 
Do you have stock axles? Gears? Lockers in either axle?

Can you take a video?
Its hard to guage your clunk vs mine... with your use of caps and the tone in your posts, its like some catastrophic bang that is about to kill everyone in a ten mile radius!?? :D
Seriously though- make a video? Post to youtube and share the link. Lets hear it?

Fwiw mine does the same thing. It's a new to me jeep, and Im not done with my maintenance yet. If I try to eaze it into D from P to R to N to D its the worst. Straight shot from R to D and its much less if at all.

I haven't stressed nearly as much about it as you have about yours though. So, I'd be hesitent to call it "the same". I checked U joints and suspension. All seems to check out so far. Ball joints up front have a little play, so that's on the short list, but not the culprit imo.
2 things-
1. I "inspected" my motor mounts... And they looked pretty good. I got a header to install, and with the drivers mm exposed decided it was one of those "while your in there" parts, so I got both sides. The drivers side was shot to all hell and fell apart after I got it completely out. Having been a flat rate mechanic, I can say its something I could've missed, if i were trouble shooting a clunk in the tranny/ rear end. Also, I dont know how else I would've known since visually it looked ok and with the pass side being pretty good, it didnt display the characteristics of SHOT motor mounts. Its still a few pieces from starting so I will have to report back.

2. I'm wanting to check backlash in the rear end, and thats not easy to do without tearing in to it. My visual and hand-on-drive-shaft-shake-violently inspections didn't reveal any lose ujoints or anything out of the norm. However, I can't put it "under load" with my bare hands. Only way to check the internals of the rear end, is to pull the shafts and crack her open. Have you paid the shop to do so?
 
A bit of background on this topic, this isn't the first time the OP has posted on this alleged transmission issue. In the previous postings there has been a lack of basic diagnostics, (differential, engine/trans mounts, rear suspension bushings) and some stubborn clinging to assumptions that do not seem to be supported either with data or basic common sense. Inspection of the gear pattern, internal parts wear and condition, and measurement of backlash of the rear differential by a differential specialist, not a general shop technician, or transmission specialists, has also been suggested more than once.

It has been explained by people that have owned more than one XJ, that the transmission behavior is within the range of "normal" for the 1980's Aisin Warner transmission technology, and that the 1980's technology XJ Cherokee is a somewhat crudely designed vehicle that tends to transmit noises though the first generation uni-body, not to mention that all XJ's are nearing or well past 20 years of age/wear/usage. Noise/vibration/harshness were not the primary AMC design features for the XJ.
 
Do you have stock axles? Gears? Lockers in either axle?

Can you take a video?
Its hard to guage your clunk vs mine... with your use of caps and the tone in your posts, its like some catastrophic bang that is about to kill everyone in a ten mile radius!?? :D
Seriously though- make a video? Post to youtube and share the link. Lets hear it?

Fwiw mine does the same thing. It's a new to me jeep, and Im not done with my maintenance yet. If I try to eaze it into D from P to R to N to D its the worst. Straight shot from R to D and its much less if at all.

I haven't stressed nearly as much about it as you have about yours though. So, I'd be hesitent to call it "the same". I checked U joints and suspension. All seems to check out so far. Ball joints up front have a little play, so that's on the short list, but not the culprit imo.
2 things-
1. I "inspected" my motor mounts... And they looked pretty good. I got a header to install, and with the drivers mm exposed decided it was one of those "while your in there" parts, so I got both sides. The drivers side was shot to all hell and fell apart after I got it completely out. Having been a flat rate mechanic, I can say its something I could've missed, if i were trouble shooting a clunk in the tranny/ rear end. Also, I dont know how else I would've known since visually it looked ok and with the pass side being pretty good, it didnt display the characteristics of SHOT motor mounts. Its still a few pieces from starting so I will have to report back.

2. I'm wanting to check backlash in the rear end, and thats not easy to do without tearing in to it. My visual and hand-on-drive-shaft-shake-violently inspections didn't reveal any lose ujoints or anything out of the norm. However, I can't put it "under load" with my bare hands. Only way to check the internals of the rear end, is to pull the shafts and crack her open. Have you paid the shop to do so?

My XJ with this problem is a 1999 XJ 4WD, 100% stock, 98K easy (street-only) miles, 4.0L, AW4, Chrysler 8.25, open differentials, never has towed, nor been towed.

From my original post, here are the two videos of my differential while being shifted mostly back and forth from Reverse to Drive with an ~4 second PAUSE IN NEUTRAL each time. First video is with TC in 2H, second video is with TC in 4L:

https://www.youtube.com/watch?v=yLV5XDG1J90&t=28s

https://www.youtube.com/watch?v=99t7lKHlUqw

If I do NOT pause in Neutral, then all shifts are ALWAYS gentle and smooth.

You are the first person that I have found whose XJ MAY have the same problem that mine does. If so, that could be extremely helpful to one or both of us. Before I waste any more of your time here though, I should confirm with you that your "clunk" noise is coming from your differential...as if someone is striking your differential ring gear with a hammer. If your clunk noise is coming from anywhere else, then unfortunately (for me) we don't have the same problem.

Reason for my ALL CAPS is because I have been trying to diagnose this problem for over a year now in multiple forums (in addition to the numerous trips to local repair shops), and it is hard to get responders on these forums to just answer the question that I am asking, and also difficult to get responders to actually read my XJ's symptoms and history. Most responses are responding to a problem that has nothing to do with my XJ's problem. I write that my clunk/lurch only happens at a standstill and only when shifting into Drive from Reverse with pausing in Neutral, and I always get multiple responses such as "mine used to do that when my XJ was downshifting at around 10 mph...I greased the slip yoke and it solved the problem". I do appreciate that people are trying to help, but unless they have experienced the exact same problem, their responses just don't help me with my problem. So I finally resort to ALL CAPS to try to get responders to just answer my question...doing this test takes all of about 10 seconds. The bottom line is that unless a reader's clunk can be totally 100% avoided by simply not pausing in Neutral, then it is not the same problem that my XJ has, unfortunately.

I stress over this problem because I'd like to sell my XJ, but it is difficult to sell it for any kind of a reasonable price with a seemingly undiagnoseable problem like this. The person who sold it to me over a year ago either didn't know that this was not normal, or they did and just were lucky enough to have an inexperienced buyer like me show up. At the time, I just assumed that the idle speed was too high...I learned later that that was not the case. I am honest when I sell a vehicle, and so I'd have to sell this XJ for about $2500-$3000 less than normal price to compensate for the fact that I am going to have to tell the buyer that "it may need a new transmission, or maybe even also a new differential, and maybe also god-knows-what" because of this mystery clunk/lurch. I could just keep it and avoid pausing in Neutral, but for various reasons an XJ is no longer is the vehicle that I need.

Regarding your motor mounts, it seems to me that the looser the motor mounts would be, the less the clunk/lurch there would be. To use the hammer/anvil analogy, where the engine is your hand on the hammer, the transmission/driveshaft is the hammer, and the differential ring gear is the anvil, a loosely held hammer will have a weaker blow to the anvil than a tightly held hammer would. Similarly, looser rear axle mountings should cause a lesser clunk coming from the differential, just as a loosely held anvil will create less of a clunk than a firmly held anvil would. Looser rear axle mountings would increase the "lurch", but not the differential "clunk". This analogy isn't perfect, I admit, but regardless, no amount of looseness or tightness anywhere would explain why the clunk/lurch only occurs when you pause in Neutral. That behavior is either normal for an AW4, or it isn't, regardless of how loose or tight the rest of the XJ is.

Regarding rear differential play, you can use a long screwdriver to test the play under pressure as I did...

https://www.youtube.com/watch?v=WRZIZmRVL0s

...but it really doesn't prove much as you can see, because you do need the impact of the driveline suddenly shifting into gear in order to really see and hear any noticeable possibly excessive play in the rear differential.
About 10 experts in shops have checked the differential play without removing the differential cover, and I certainly could pay a shop to remove the cover and check the play, etc., but regardless of the outcome, it still wouldn't explain why there is only a clunk/lurch when shifting with a pause in Neutral. The differential is either loose or it isn't...it can't be loose when I pause in Neutral and then tight when I don't pause in Neutral. Only the transmission could cause this difference, and that is why I am trying to determine whether all AW4's behave this way or not. If they do, then my transmission is fine and I need to have my differential rebuilt. If they don't, then my transmission still has a problem and I need to have my transmission fixed (again). For me to invest more money in either the transmission or the differential without knowing if my transmission is behaving normally or not, when the answer to that question can be determined by a simple 10 second test by other people who have AW4's, wouldn't make any sense. These forums are to get answers to our questions, right? I don't really want to be walking up to perfect strangers on the street with XJ's, asking them to do this test for me, but if I can't get answers from these online forums then I'll have to do that, I guess.

Back to your problem vs. mine, my first question for you would be if your "clunk" noise is coming from your differential...as if someone is striking your differential ring gear with a hammer. If your clunk noise is coming from anywhere else, then unfortunately (for me) we don't have the same problem.
On the other hand, if your "clunk" noise IS coming from your differential, then perhaps one of us can figure out what the problem is and share it.
I'm taking my XJ into yet another shop (a different transmission shop, this time) on Tuesday, and I'm going to ask them specifically about the "pausing in Neutral is the problem" thing, but it wouldn't surprise me at all if their answer is "depends upon the transmission...don't know about the AW4...we'd have to tear the transmission apart to give you an answer...that will cost $300, and then we can tell you how much more the actual repair will be, if it needs any repair at all". A lot of shops seem to just use their customers to pay for their on the job training.
 
A bit of background on this topic, this isn't the first time the OP has posted on this alleged transmission issue. In the previous postings there has been a lack of basic diagnostics, (differential, engine/trans mounts, rear suspension bushings) and some stubborn clinging to assumptions that do not seem to be supported either with data or basic common sense. Inspection of the gear pattern, internal parts wear and condition, and measurement of backlash of the rear differential by a differential specialist, not a general shop technician, or transmission specialists, has also been suggested more than once.

It has been explained by people that have owned more than one XJ, that the transmission behavior is within the range of "normal" for the 1980's Aisin Warner transmission technology, and that the 1980's technology XJ Cherokee is a somewhat crudely designed vehicle that tends to transmit noises though the first generation uni-body, not to mention that all XJ's are nearing or well past 20 years of age/wear/usage. Noise/vibration/harshness were not the primary AMC design features for the XJ.

Forgive me if I am misinterpreting your post above, but am I incorrect in feeling that your purpose in posting it was to:

1. Warn other readers that this I am not following advice, am stubbornly clinking to illogical conclusions, and so I will just waste readers' time if they are foolish enough to respond to my posts,

and

2. The so-called "problem" that I am describing is within the range of "normal" for an AW4?

Please correct me if the above interpretation is incorrect.
 
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