Topic: Dual Case Failure

[rockymtn89]

Hi All. I have a 4runner with dual cases, using a variety of fairly old parts, both Marlin and TG. I know the answer to my question is to "dig in and find out" but I am curious what experience others have had. Today while driving home in 2wd, I stopped at a light. When I went to accelerate, I heard a big bang (I thought I hit something) and then grinding noise coming from the transfer case. No matter what gear I put it in (4wd/2wd or Hi/Lo) I have no power to either front or rear driveshafts. What parts in the t-case could fail that would give absolutely no power going to the front or rear? I've heard of some situations where the case blows up and it can be driven in front wheel drive, but right now I have nothing. Input shaft on the rear case? I'll tear into it at some point but would like to know what I might be up against. Thanks!

[lone walker]

More likely you lost one of the two input would be my guess.

[OVRAROK]

Are the rear gears TG? If so I'm guessing broken input shaft

[05sport4x4]

I had something similar happen about 10 years ago. Was lightly 4 wheeling in low range and when I started to move from a stop heard a big bang. No idea what it was but thought something in the t-case broke. No power to either front or rear drive shafts in any gear position. 100 mile tow home and removed the t-case and manual trans. The friction material from the clutch had separated from the disk and that was the cause. New clutch and was back to working.

[rockymtn89 [OP]]

The adapter is TG but the 4.7 gears in the rear case are MC total spline, all 23-spline. I'm pretty sure it's not the clutch because there is very clear grinding coming from the t-case area. I'm going to tear them and figure it out this week. I haven't had them out without the tranny as one big unit. Is it reasonable to just unbolt the crawl box from the tranny and drop them down (still supporting the tranny, of course)? I can't remember what's easiest...

[a1gemmel]

When I've done it I support the tranny with a ratchet strap across the frame or a jack underneath it and drop the crawl box and transfer case together. Fair bit easier than taking it all out together in my opinion.

[rockymtn89 [OP]]

Sounds good. That's my plan.

[rockymtn89 [OP]]

Looking through some other posts, it looks like OVRAROK has a lot of experience building these cases. In your opinion, paper gaskets, RTV, or a combo of both to seal them back up? Thanks! Anyone else's opinion is welcome, too, of course...

[OVRAROK]

Looking through some other posts, it looks like OVRAROK has a lot of experience building these cases. In your opinion, paper gaskets, RTV, or a combo of both to seal them back up? Thanks! Anyone else's opinion is welcome, too, of course...

I'm a paper OEM gasket guy if bench building. However, never opposed to using sealant on the trail.
On a different note, I have quite a few parts for the rf1a laying around. Don't mind helping on the parts side. Let me know if I can help in any way

[rockymtn89 [OP]]

Thanks! I appreciate it. The vehicle is in my driveway (and soon garage) so it will be a bench build. Hopefully I never have to do this on the trail. I have everything from my current duals and will be rebuilding, so hopefully I won't need too many parts.

[rockymtn89 [OP]]

I'm getting ready to order parts tomorrow. Is there any reason to upgrade to a 2.28 MC total spline input gear on the crawl box (not the second case)? Right now, it's just OE 2.28 or TG 2.28.

[OVRAROK]

Ordering parts...
 What ended up being the problem?

[rockymtn89 [OP]]

Looks like the TG coupler wore out and slowly took the MC Total Spline input with it. It was build with a mismatch of parts. I have an MC-08 adapter ready to go in and am just waiting on the other parts. I plan to do a total rebuild. Do you have any experience with the 3209 coupler bearing having issues? I've read a few posts online about the balls getting spit out periodically, but that was from a few years ago. Apparently, someone on TTORA found a better replacement bearing, but if it's not an issue I won't worry about it. I think the adapter I'll be using is from 2018. I'd like to have the most reliable setup possible. 

[rockymtn89 [OP]]

I assume that the step down in the input isn't normal...and the coupler wasn't pretty either.

[rockymtn89 [OP]]

Case coupler pic.

[Gnarly4X]

.... The friction material from the clutch had separated from the disk and that was the cause. New clutch and was back to working.

Geezz...I've never heard of that failure.  What was the manufacturer of the clutch disc?

Gnarls.

[rockymtn89 [OP]]

Finally getting parts to put it back together. What do you put on the coupler splines/input shaft to help prevent fretting? I've read anti-seize; any particular type or recommendation?

[rockymtn89 [OP]]

Well, this stinks. When replacing the cage bearing for the front output, I discovered that someone had cut out a race at one point and subsequently cut into the aluminum housing. See image. It's not too deep and isn't close to going all the way through, but I don't know how much stress this area sees once it's covered with the bearing race. Is there a way to repair this? Should I leave it and run it? Do I need to replace that whole part of the t-case? Thanks for your opinions.

[OVRAROK]

I'd smear a little jb weld in there, and run it. Just in the Crack. If you want to replace housing, I'm sure I have a few lying around

[rockymtn89 [OP]]

I was thinking JB weld, too. Just a bit and the run it. I'll keep your extra housings in mind if it doesn't work. Thanks!

[rockymtn89 [OP]]

Too much wear on the output shaft teeth? (See photo). Anyone have one in better shape or is this what I should expect from 34 y/o parts?? Thanks.

[Gnarly4X]

Well, this stinks. When replacing the cage bearing for the front output, I discovered that someone had cut out a race at one point and subsequently cut into the aluminum housing. See image. It's not too deep and isn't close to going all the way through, but I don't know how much stress this area sees once it's covered with the bearing race. Is there a way to repair this? Should I leave it and run it? Do I need to replace that whole part of the t-case? Thanks for your opinions.

That damage is not repairable.

JB weld will just be cosmetic, not strong enough to create structural support.

Once the race is inserted the centrifugal forces will be contained to the surface area of the race.

Aluminum alloy has some elasticity, so the forces required to actually cause a crack from the damaged area would have to be very high or very hot.

I'd definitely run it.

Gnarls.

[rockymtn89 [OP]]

Got it back together and installed thanks to Ovrarok sending me some parts. I have about 200 miles on the setup and there seem to be no issues. I'll put in new synthetic oil in about 600 miles or so. I swapped out all the bearings and it's much quieter. Thanks for the help and feedback as I worked on my first dual case rebuild!