8 3/4 housing crack

[joes68340s]

Has anyone ever seen a crack through the weld on an 8 3/4 center section. looking at the rear of the round center at 12 Oclock going counter clockwise to 10 Oclock. Its cracked through the weld about 3 inchs. This is on a Narrowed 8 3/4 with ladder bars.

 

[Oldmanmopar]

The main weakness with a 8 3/4 is the housing. Housing flex causes the axles to crack the carrier caps by pushing/prying back on the side gear/carrier on a launch when the tires pull the axles forward. Back bracing the carrier is a must with 8 3/4 rears. Usually they are braces to the u-bolts. We are going to brace ours to the backing plates and put tubes in for the u-bolts.

 

[Dana67Dart]

The welds on these housings are pathetic.

It could have been a metal fatigue issue or just a bad weld.

 

[RustyRatRod]

Take a magnifying glass and find each end of the crack. Drill a hole at each end. This will stop the crack from migrating further. Then grind the weld and re-weld it and weld the drilled holes up.

 

[Demonracer]

If it is a narrowed housing with ladder bars as you say, I'll bet that it was probably given a lot of stress with the bars not set correctly. That is why when 8 3/4 rears are used in race applications, most of the time there is a brace welded across the back side of the housing.

 

[justinp61]

I had a 75 D100 that the weld on the 8 3/4 cracked from 4 to 6 o'clock. I tried JB weld to stop it from leaking, didn't work. I cleaned and welded the crack it and it would crack the weld. It was cracked and leaking when I sold the truck. Maybe I didn't use the proper technique.