NP241 Cracked case

[KallyI]

Has anyone else on the forum had any cracks develop in these Transfer Cases? It is cracked about 2" aft and below of where the 2wd/4wd shifter comes through the case. The crack is about 1 1/2" long. I have no idea how the crack was caused. I have not used the truck as a true 4X4 since August 2000, and I don't run in 4wd mode on dry pavement for any distance. The skid plate protects this area of the Transfer Case fairly well, and I don't recall getting any direct hits under the truck at any rate. At this point, Devcon has been applied to the outside of the crack, and it is no longer leaking, but I am keeping a close eye on it.

[BobND]

One cause of transfer case cracking is worn splines on a driveshaft, especially the front one. When the shaft is under load (torque), and the suspension and powertrain mounts flex, the driveshaft splines need to slip in or out to accommodate to movement. If the splines are worn or damaged, and "hang up", case breakage can result.

[dieseldummy]

I had one break completely in half on my '93. Suspiciously one of the CV joints was going out at the same time.

[GMCfourX4]

The first time I pulled the front driveshaft on my truck, I wondered if my t-case would crack from all the pressure required to compress it enough to get it out (with LOTS of grease in the joint, PB Blaster, etc...). It took a LOT of work to get the slip joint apart, and get it cleaned up enough that it worked properly. It is entirely possible that your front d/s slip joint has seized, and that sufficient frame flex could have caused the t-case to crack.

-Chris

[DA BIG ONE]

Parts & cases http://www.drivetrain.com/transfercasesparts.html#New%20Process%20Model%2024 6

or

http://www.transfercases.com/

[NH2112]

If you find the cause and rectify it, but don't want to spend the money for a new transfer case, you can repair cracks "relatively" easy by the following process.

1: First of all, stop-drill the ends of the crack. This will prevent the crack from getting longer. Start small (1/8", maybe) and finish with a 1/4" bit.

2: Tap the holes to 1/4"-20, and install 1/4"-20 allen-head setscrews using Loctite 262. The green "bearing mount" Loctite will work as well.

3: Drill and tap 2 more 1/4"-20 holes along the crack, approx 5/16" from the centers of the setscrews that are already installed.

4: Repeat step 3 till there's no more room to drill. Let the Loctite set completely according to the label.

5: Now drill & tap 1/4"-20 holes in between the setscrews, and loctite setscrews into these holes. Do this in between all the setscrews until the crack is completely repaired.

You may want to check the thickness of the aluminum and insert the setscrews just to a depth where they won't protrude inside the case and possibly interfere with something.

[DA BIG ONE]

MIG or TIG will work to weld the crack on an aluminum case, however the cause of the crack needs to fixed first!

[NH2112]

Duh! I forgot that the 241 is aluminum while I was writing that post, then edited it a minute later and it dawned on me but not completely! I guess that's what happens when you're a Dana 20/NP203/NP205 guy LOL

[DA BIG ONE]

Originally posted by NH2112:
Duh! I forgot that the 241 is aluminum while I was writing that post, then edited it a minute later and it dawned on me but not completely! I guess that's what happens when you're a Dana 20/NP203/NP205 guy LOL My case the NP246 is magnesium as in fireball if a torch is put to it.

[rjschoolcraft]

Magnesium can be welded...with the right procedures, skill and tools. While I've never personally done it, I've spec'd magnesium welds hundreds of times on helicopter gearboxes.

Magnesium fires are quite scary, though... :eek:

[DA BIG ONE]

Originally posted by ronniejoe:
Magnesium can be welded...with the right procedures, skill and tools. While I've never personally done it, I've spec'd magnesium welds hundreds of times on helicopter gearboxes.

Magnesium fires are quite scary, though... :eek: OH-6 gearboxes, or?