Sean Allan

Hiya everyone,

I'm trying to find out some more information about a worry-some clunk that I have in my truck (details of my truck are in my sig). Ever since I've owned the truck I've had a clunk while driving in 4LO.

>>THINGS I'VE CHECKED<<
U-joints (I've inspected and greased 'em all!)
Vacuum shift mechanism (all working fine)

I suspect the transfter case chain or something else in the transfer case. The clunk kinda does sounds like a loose chain engaging. Can the transfer case chain get loose over time? Can it be adjusted or replaced without removing the transfter case?

Does anybody out there in DODGE RAM land have a service manual for the transfer case that they can e-mail me? A diagram or schematic would be awseome.

I've read and searched through the forum and there are a few others that have had similar problems, but the didn't follow up with how they fixed it. I'm heading on a long surfing roadtrip to Baja soon and I don't want to get stuck somewhere remote!

Any help is great help.
Sean.

TxDiesel007

Basic help on this

how much fluid does the t case have? Mine used to clunk and rattle, and i use that as an indicator that my fluid level is low.. All is well now...

Rick

stock03

Mine rattles and clunks in 4-lo too. But so does my old ScoutII.

torquefan

The most common failure I have seen several times has to do with the disconnect in the front axle. It is common for the intermediate axle shaft to wear the splines off into a "ramp" shape where the sliding collar engages them. 4WD will keep working fine until a large load is put on it, then the worn splines will push the sliding collar off the shaft (against the vacuum pressure) until 4WD momentarily disengages with a loud clunk, then the collar will spring back into place on the shaft, just to do it all over again whenever the load becomes too great.

Just remove the vacuum disconnect cover, and have a good look at the splines on the shafts. If they are worn on an angle, that's probably your problem.

'pants

But...isn't the vacuum disconnect cover topside of the tranny, where you'd have to start with a Sawzall at the transmission tunnel in order to be able to see into it? (If not, where is it?)
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I had my transmission rebuilt a couple of years ago, and prolly put 10 or 20K miles on it since. The guy who did the repair is honest and likeable longtime-shop-owner, but I also discovered he's got an appalling mess of a shop. He used a "sometimes does side jobs for me" guy to do the actual rebuilding, and it looked like one or two DIFFERENT other people pulled/reinstalled the tranny, leaving me with this "oh, NO..." feeling when I got underneath it after finally getting it back from his shop. Any mechanic with an eye for detail could have seen that lines hadn't been bolted back in as they were before, had been re-bent to force them in place, the battery ground-strap barely re-attached, and everything was still filthy, like it didn't matter to them to clean up the chronic residue buildup while things were out on the bench. Bummer. OK, clearly he's not as ****-retentive as I, but...hopefully his mechanical work was good...

The reason I'd gotten under it was that a secondary problem I'd reported to him at the time of the transmission rebuild still remained: when I shifted into 4WD/reverse to back up my scary-steep dirt/gravel driveway, the truck would often go up a ways with expected zest, but sometimes, all in a fraction of a second, lose-drive/CLUNK/lurch-forward/take up the drive again, as if it had been trying to test my brake-pedal reflex (which is nowhere near fast enough). When I called about this, Shop Guy told me he'd asked Guy 2 to look at that, since he's the Dodge truck expert, but apparently Guy 2 had forgotten this. A few more calls from me, and at some point, when Guy 2 comes in next, he tells Shop Guy that this problem was the result of a deteriorated vacuum-fitting/tubing connection at the top of the tranny, where it's all but impossible to see. Shop Guy says he'd try to find me one (with me wondering whether this was going to be additional cost for parts/installation, despite the fixed-price package that he'd quoted, and the hassle of having to bring the truck in and leave it again).

He also says something about the 4WD light still being a reliable indicator of whether I'm really in 4WD - because I'd noticed that the light would go out at each CLUNK experience, and I'd definitely feel a loss of traction.

A couple of weeks and a few calls (always by me) later, Shop Guy says he can't find that vac fitting, and even the dealer didn't have any available special-order, etc. He sent me off to get one from ebay, which I did, but damned if the only one I could find (anywhere online) was used.

Recalling that I'd already brought the truck back to Shop Guy at least once to get him to fix some sloppy mis-assembly underneath, and the "get a ride home" problem, while he kept the truck far longer than should have been necessary, I decided to just deal with this myself. Doing it, I seem to recall using lots of lights and maybe a mirror to see what was going on, but I did get the replacement fitting in place. And it WORKED. No clunking anymore. That was in late 2013; the old fitting had been prematurely turning into goo from biodiesel leaking onto it, so I figured I'd probably be OK with the used one as long as the leak didn't recur.

But now 3+ years later, the clunk is back, yet the 4WD light does NOT go out now, and I don't notice (other than for that fraction of a second) a loss of traction.

It's the *identical* sound as before, though, so being fairly unfamiliar with my drive system innards, I'd expect it to be the same cause.

Anything ELSE to check out here?

Thanks - Dave

Sean Allan

Hey Guys/Gals,

I ended up discovering that the problem was a broken shift fork inside the transfer case. I had a shop completely rebuild the case, and now the clunk is gone (along with some hard earned $$$).

I just thought I would put a end to the thread.

Cheers,
Sean.

John Faughn

If you could catch it soon enough , I had a clunk and was a few blocks from home so parked & started looking , it was in the transfer case .
Dropped out & split the case , the snap ring holding the output bearing snapped .
There is a upgrade for this , a large slit washer , and keeps the snap ring from getting beat up .
Called a local trans parts place and they had in stock , this was some yrs. ago and I may have had more details so as to ask the parts place , as I remember they did not now what I was talking about in the beginning but with enough push from me , they went and found one on the self .

And now I have a 2001 GMC Sierra 2500HD from a shop that thought there noise / symptoms were electrical , got it home and the same thing R. output bearing snap ring had been bad soo long that the case was ready to just explode one of the shift forks was worn through and high/low would jump randomly .

'pants

My "CLUNK" persists, worse than before, probably worsened as the result of my hauling a 2-ton load of coral chips home, backing up my funky driveway a few weeks back.

The shop that rebuilt trans/transfer case a few years back kept the truck all day yesterday, dropping the pans on both units, reporting no metal or other signs of problems that I assume would support a diagnosis of a broken selector fork. Even on the steepest of city streets, they can't replicate the noise, and it's frustrating to me that they haven't (yet) been willing to just head up to my place to witness, but I'm not sure "witnessing" is going to make much difference.

I'm at a big disadvantage because of my lack of usable "truck-servicing" space, so I've never had the chance to see within the transfer-case or the transmission...thus I *still* don't know what it takes to follow Torquefan's recommended check/fix (below). Can someone please fill in some details on what he described?

Mostly, I need to know this: isn't the "vacuum disconnect cover" inaccessible without dropping the trans/transfer case first?

Lately, I can barely start backing up the driveway before the scary !clunk! happens, always accompanied by a lurch forward. 4WD light remains on. Repeating the 4WD selection sometimes will re-engage it, but not always, and it's never dependably willing to stay in 4WD.

I'll repeat 4WD selection until I get up enough off of the road to park, and in doing so, curb the wheels, of course. Then, even in park with the e-brake fully engaged, once I take my foot off the brakes, the truck will roll or maybe slide forward for a foot or two, apparently until the curbed wheels bite into the upslope to the right, leaving me parked at an angle that suggests I was drunk when I did so...and always leaving me with a "***?" bubble above my head...

'pants

In case this is still of interest to someone, I heard back from Torquefan after PM-ing him, and he clarified: "Hi, the cover I was referring to is on the front axle, on the passenger side. It houses the vacuum diaphragm and the switch for the 4wd indicator lamp. 4- 1/4 inch bolts hold it on. Here's a link to a diagram: https://www.google.ca/url?sa=i&rct=j...66649923449259" I will get into that at first light, because this hasn't fixed itself for me. (Thanks, Torquefan Dave...)

Adding to woes and confusion, turns out the shop that did the transmission & transfer-case rebuild 2-3 years back, somehow left all four bolts on my transfer-case output flange at "finger tight." Yeah. Even in my dangerous and crappy (and ONLY) at-home place to get under my truck, it wasn't more than a minute and a half before I noticed that - and that was while lying in the dirt on a 25% slope. So I'd been running around that way for a few YEARS, and the threads on the loose bolts were badly beaten, with one having long since dropped onto the brush-guard below, and staying there, miraculously. I was able to run a die down each one to get the threads working again.

The shop owner's response, though somewhat apologetic, left me again wondering what the hell else they'd missed on doing the original rebuild & replacement, and whether that Saturday when I'd left it with them to check the recurring "CLUNK" had merely been about "customer-service theatre," and not so much, as he told me, about his having pulled off the pan and inspected the transmission (I thought he also said this about the transfer-case, but there IS no pan for that...)

Seriously, if I employed a mechanic who put a vehicle up even on a JACK and didn't notice a bolt having dropped out of a drive-flange with three others gapped open to where another 1/4" of threads would have let them drop away too, and while working a foot away to drop the transmission pan, I'd have to fire him as a liability concern.

I really, really, really need a place to work on my own vehicles...

Mickeyblueyes

You can go to one of those rent a space places,rent a spot the size of a garage,leave your tools there,the money that you pay for storage space has got yo be way less than paying crack head mechanics to butcher your ride.

'pants

Heard that.

I think this place (Hawaii) is maybe the only place in the US where it doesn't work like that...storage places are only for storage, and they're super-expensive, so they're an even worse "investment" vs somehow dealing with your overflow or lack of space at home. Back in the 90s on a trip through California I was amazed that a dirt-poor friend had a "shop" that he stuffed into a rollup-door "storage" place...I kept thinking he would get in trouble with the management if they knew, but obviously they really DID.

But yeah, having a place like that nearby would be a godsend. I was actually hoping that they'd overbuilt them (there are at least three national chains here, plus several local versions) and maybe they'd have to consider allowing that kind of tenency, but no, not yet. Stuff, along with rent and everything else, is uber-expensive here.

'pants

Hmmm...if only that were the end to MY thread...

I don't think there ARE any shift-forks in the transfer-case, are there? I think you meant the "CAD" (center axle disconnect), which is at the backside of front axle, on the pass. side, as detailed at Diagnosing 4WD Engagement Problems on Dodge Ram pickups

And while that device DOES have a shift-fork in it, I can't imagine it being bent under any circumstances, because there can't be a bending force on the fork beyond the strength of the vac diaphragm actuator, which slides the "shift collar" across the gap between the two shafts, engaging or disengaging them. The shafts can't exert any force on the fork, either (other than as the result of a horrendous accident, I suppose...)

I found out where the CAD is from Torquefan, took the cover off this afternoon, and...

Witnessed the Fugliness. The outermost edge of the "intermediate shaft" (inboard of the CAD) splines are now ragged, with sharp metal on the bottom of the housing (can be felt with fingers). Surprisingly the "shift collar" can still move over onto those splines, but apparently it doesn't move over much - and maybe that's the whole problem: it's just a case of "not enough" to fully engage. I gotta see if there's some spec for how far over it's supposed to move; I'd guess it should move until it overlaps each shaft's splines equally...? (Anyone?) Since my 4WD light does come on, I was tempted to think it was moving the right distance, but quite possibly the switch gets triggered before the shift collar is really far enough across to securely bridge the two spline sets.
CAD housing with cover off...right splines OK, left splines hosed.

patdaly

Oh yea, the TC has shift forks..............

'pants

I stand corrected - thanks, Pat.

Is that parts view something I can get my hands on? Well, not that one in particular...really I need one for the CAD. (Or maybe I should go with some aftermarket substitute?)

I got the cover/fork/vac-motor assembly out and on the bench today, and found that:
a) there's 1/4" of wobble at the end of the fork (apparently the shaft/boring in the fork are worn) which means the shift-collar won't be kept fully engaged - certainly contributing to my spline-ripping problem
b) thick oil of some sort kept drizzling out of the vac ports, which made me wonder if there's a leak, or if it's just the low-point, where that stuff would end up

Minimally I need the vac motor/shaft, and would just assemble them into my original cover and keep my fingers crossed.

I edited this to not be too lame by not at least having tried to do part-number research... seems like the vac motor assembly is relatively cheap on ebay ("Dodge Ram / Jeep Axle 4x4 4WD Shift Actuator # 4882682") but the fork (Mopar 04137727) is not so common and costs a bit more, over $100, anyway. So I may just get a new actuator here and check to see if the sloppy fork slip-fit is still bad with the new shaft in place...if so, I'm thinking I could probably just fit a setscrew, since it doesn't have to move along or spin on the shaft anyway?

I need to drive the truck while waiting for parts. I figure I can just zip-tie around the splines on the outboard axle-shaft so as to keep the shift-collar from wandering left into the 4WD position, and then bolt up the hollowed-out cover, w/plugs in any open holes to keep grit & water out of the CAD gallery for the next week or so until the new vac-actuator gets here...

--Dave