Transfer case skipping

cp2295 · Dec 20, 2017

Hey everyone, swapped a bw1354 into the bronco 2, and on my first test run everything worked good. However this last time I went out and played in the snow whenever i was in reverse and 4 low and had to put the throttle down I heard a massive bang, I have heard this same noise before on my buddies jeep when his t case chain skipped. I was able to also get it to do it in 4 hi (not near as bad) I thought I was able to get it to do it in 2wd but not too sure. So I got it home threw it on jack stands and proceeded to put it in 4 lo, reverse, and loaded it with the brakes but unfortunately couldn’t duplicate the issue.

I had one issue with it though, why only reverse? You would think any tooth wear would be on the forward rotation and therefore skip when moving forward. I have heard these fm145s are known to just grenade randomly.

So I drained all the fluids, popped the covers off both differentials. Didn’t find any missing teeth on either ring or pinion. The transmission had metal in it, but really it wasn’t all that much, pretty normal to me. The t case was very dark (much like when a auto trans has lots of clutch material in it). But not really any metal to speak of.

What I did find was that through the fill hole (I’d say it’s about halfway between the sprockets) I was i able to move the chain up and down a good 3/8”. Lots of slop, now I don’t know transfer cases all to well but it seems extremely excessive. Like if my timing chain had that much play I’d be surprised it was running lol. Anyways anybody with much knowledge on t cases chime in I’d greatly appreciate it.

Also I’m a pretty handy guy, I can rebuild diffs and set gears, rebuild motors etc. if the t case is in need of a rebuild, is it something I should tackle myself or would you guys just recommend pulling it and taking it down to a local transmission shop?

Thanks, chris.

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Doofy · Dec 20, 2017

I miss the old Intl Scout. That puppy had beveled gears instead of a chain and was indestructible. I've always wanted to put a Ranger or ElCamino body on a Scout running gear.

cp2295 · Dec 20, 2017

Also, If anyone has input on a doubler question of mine let me know. I have the old 1350 laying around and have found lots of info on how to do a doubler, however I’m not a huge fan of the press fit/welded intermediate shaft. Has anyone ever had the two shafts splined where they connect? And then welded, Seems like this would be the strongest solution, idk if it’s possible though. Even if it had coarse splines I would think it would add strength, I’ve read about too many failures to want to do the mod using just the pressed/welded shaft.

Also, the threads I have read are old, and all of the companies mentioned no longer make the kits for a doubler, does anyone know of a company that makes a kit now?

And one more thing, can I see reverse through the back of the trans once the t case is off, to confirm that reverse itself isn’t the issue?

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4x4junkie · Dec 20, 2017

It seems that most of the doubler shaft failures I have come across were situations where the user had tried to drive with the doubler unit in LO, but with the T-case in 4-HI. This puts EXTREME stress on the shaft (which I'd question whether even a machined one-piece chromo shaft could handle well). The t-case should ALWAYS be in 4-LO before you shift the doubler inline.

That said, I have not run a pressed/welded shaft myself, so I can't comment surely on just how strong they actually are. Splining the parts together sounds like an excellent idea (though welding them afterward would defeat the purpose). You'll have to call up some machine shops and see if anyone can do it for you (finding someone locally to spline the female side might be difficult, you may have to send it off somewhere).

Duffy @ D.D. Machine is who I got my doubler kit from (360-649-4465), did you call to verify he actually doesn't have any? I know Duffy was back & forth a number of times on their availability, it couldn't hurt to give him a call. Maybe at the least he can do the internal splines on your old shaft if you send it in.

As for the skipping, 3/8" of chain movement doesn't sound that excessive to me (3/4" would be more cause for concern). It only happening in reverse seems to point more toward a shift fork or shaft misalignment issue (maybe a bad bearing?). If it does it in both 4-LO and 4-HI, it might be with the 2WD/4WD shift fork or collar. But if you can also get it to happen in 2WD too, then it might not the t-case at all (it could be the transmission, though I'm not sure I understand your Q about seeing reverse through the trans, nothing internal to the trans should be visible with the t-case removed, at least not on a FM146 or M5OD... not sure about the others... I would think all are like that, as all the trans fluid would dump out if you removed the t-case otherwise)

adsm08 · Dec 20, 2017

If the t-case was removed recently double check the alignment of your shift gate. I had a similar issue, only in 4-hi, and it was my shift gate plate was not lined up right. Basically (IIRC) you need to have it loose, push the shifter as far forward as you can, then tip it back until it just touches the shifter, and then clamp it down.

cp2295 · Dec 20, 2017

adsm08 said:
If the t-case was removed recently double check the alignment of your shift gate. I had a similar issue, only in 4-hi, and it was my shift gate plate was not lined up right. Basically (IIRC) you need to have it loose, push the shifter as far forward as you can, then tip it back until it just touches the shifter, and then clamp it down.

Thanks, I’ll have a look. I figure I can put in 4 low and remove the shifter assembly and make sure I can’t move the actual lever on the t case itself down anymore (basically make sure it’s actually in 4 low). If it was the case that it was not fully engaged in 4 low what your basically saying is the planetary gears weren’t lined up all the way or what?

Also that huge amount of slack in the chain still has me concerned, I talked with a reputable transmission shop and the guy told me that it would take a huge amount of slop for the chain to actually skip teeth. I’m surprised that these chains can even stretch given how thick they are.

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4x4junkie · Dec 21, 2017

cp2295 said:
Thanks, I’ll have a look. I figure I can put in 4 low and remove the shifter assembly and make sure I can’t move the actual lever on the t case itself down anymore (basically make sure it’s actually in 4 low). If it was the case that it was not fully engaged in 4 low what your basically saying is the planetary gears weren’t lined up all the way or what?

If it was only skipping in 4-LO, then it could be very likely be the planetaries or the HI/LO range fork, but you said it did it in 4-HI too, which I think lessens (if not eliminates) the chance it's anything to do with those.

More diagnostics are probably in order. ×2 on the shifter gate adsm mentions, though another thing you may want to check for is worn shift fork friction pads. This can cause incomplete engagement and therefore the slipping.

I have a 1350 case here with a hair over ½" of chain movement checked how you checked it on yours. It was working 100% and made no abnormal noises whatsoever when it was pulled for a 1354.

cp2295 · Dec 22, 2017

4x4junkie said:
If it was only skipping in 4-LO, then it could be very likely be the planetaries or the HI/LO range fork, but you said it did it in 4-HI too, which I think lessens (if not eliminates) the chance it's anything to do with those.

More diagnostics are probably in order. ×2 on the shifter gate adsm mentions, though another thing you may want to check for is worn shift fork friction pads. This can cause incomplete engagement and therefore the slipping.

I have a 1350 case here with a hair over ½" of chain movement checked how you checked it on yours. It was working 100% and made no abnormal noises whatsoever when it was pulled for a 1354.

Cool, thanks for the input. Inspecting the pads would obviously mean splitting the case, right? All that dark material in the fluid would leave me to believe the pads are wearing (are they of a clutch/brake pad material?) as far as the shift gate you guys are referring to the alignment of the linkage itself? Nothing inside the case or? I’ll still check that the linkage is aligned properly, if it’s not I’ll start there refill all the fluids and retry. If it’s aligned just fine then I guess I’ll be pulling the case and inspecting the pads chain sprockets etc.

What am I looking for with the pad wear? A measurement of some sort? I guess at that point a full rebuild would be in order to make sure its good. Any pointers when splitting the case apart-so guts don’t come flying at me like the first time I split a 2 stroke case hahaha [emoji23].
From what I can picture in my head I’d wanna lay the front down flat and pull the rear case off and out, leaving the chain sprockets etc laying down on the front case...?

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4x4junkie · Dec 22, 2017

Splitting a t-case apart is easy-peasy. Nothing should go "SPROINNNNGGGG!!!" and fly across the garage when you pull the rear case half off. You will need to remove the rear output yoke to get the cover off though.

What you are looking for are two small plastic (nylon or delrin) pads near the ends of the shift fork where it rides within the groove of the shift collar. If the case has ever been run with only partial engagement (or with low fluid), the shift collar rubbing hard against the fork might have worn the pads down (or caused them to fall off), leaving a bunch of play between the fork & the collar. I haven't had to replace a set of pads yet myself, but it looks like a very quick & easy replacement.
Some t-cases I know also had a plastic 2W/4W fork that can become worn or deformed if the case is allowed to get extremely hot or undue pressure put on the internals (the plastic forks I recall don't have friction pads). I have not tried it yet, but there might be a possibility you can swap the metal fork (with pads) from an earlier 1350 case into a later 1354, since the two cases are so similar. That said, the plastic fork is not a common trouble spot in normal operation.

The shifter gate is the piece around the base of the shift lever. You adjust it by loosening the two bolts (one big, one small) on the side of the trans.

I strongly suggest picking up a factory service manual set for your truck if you don't already have one, especially if you plan to keep the truck for awhile. Manuals from dealerships are all over Ebay for around $30-50 for the set (often two big books each about 1.5-2" thick). This is one of the best cheap investments you can make if you do most of your own work (I occasionally see free manuals floating around online that you might be able to download too, though I VERY much prefer to have a material item (book) in front of me that I can just flip a page and go straight to whatever info it is I need while working on something).

cp2295 · Dec 26, 2017

I’m with ya on a hardcopy, much easier to skip through the pages. Haven’t been able to work on it recently due to the holidays but I went to adjust that linkage and noticed that the square bushing that the linkage rides on was off, but luckily still just barely hanging onto the rod. Wondering if 4 low and high weren’t engaging properly since that thing was missing, I’m gonna pull the lever off today and drill a hole and throw a cotter pin in it so it can’t come out and see if that does anything for me.

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cp2295 · Dec 27, 2017

Well, it looks like I’m gonna be rebuilding the t case. Cant see what else it would be, still just doing it in reverse, 4 low and high.

The used auto locker I installed today is also banging popping and clicking... all sorts of fun for me this week! Haha

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cp2295 · Jan 23, 2018

Well haven’t screwed with it at all since adjusting the tcase linkage. today I got it to make the noise in 2wd in reverse, so I’m thinking transmission! Time for a 4.0 and m5r1 I guess lol.

I am wondering if it wouldn’t do it in 2wd because there wasn’t as much load on it vs 4wd. Now that it’s getting worse it’s beginning to do it in 2wd too.

Anyone ever heard of a trans skipping like this? Thinking about pulling the pan on the trans and seeing there’s any chunks hanging out in there. Unfortunately I won’t be able to see the reverse gear/idler but if it’s broken enough chunks i should see some..

I cant imagine it being the t case since it does it in 2wd now. And doesn’t do it in any forward gears.

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Transfer case skipping

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