Then the guy says he'll loop around and come back. Yeah that happened 
Summit had everything to do the swap? Do you mind telling us how much you had to spend? I’m sure others will do the same down the road. I’m also curious about your diff drop. Is there a kit?So I thought Summit Racing was going to be faster... Ordered 11/24, shipped 11/28, scheduled for delivery next week. Not sure if its a Black Friday thing but this is the longest I have ever waited for an in-stock item.
1) Shaft Material
Initially I was focused on improving the strength of the shaft. 300M or some other chromoly steel that would yield a higher strength. Twisting of the splines is the text book failure and weakest point, example is Blanco Bronco. If your twisting shafts, your just exceeding the material strength. Twisting shafts at the clip like Blanco Bronco you had a failure at the place with the lowest cross sectional area. An improved housing would have not benefited this failure as the force was transmitted correctly.
2) Bearings support
When I changed my passenger side seal I noticed excessive play in the bearings. When you have excessive play you get more force transmitted latteraly (see exaggerated diagram below). The extra deflection puts more stress on the housing which could be one of the reason we are seeing a failure of the housing. The axle rides directly on needle bearing with no race. This means no machine fit tolerances so you naturally get some play. We are talking 1-2mm of movement which should not be catastrophic. This does add lateral forces and does contribute to the possibility of housing failure. Now if you add in some force from the cv movement on the end and you can really add some force. Example would be landing off a jump and the shock load transmitting from the cv axle movement into the housing. This force can actual go all the way into the differential as the support bearings do nothing to dampen the force (see 2nd crappy diagram).
3) Housing design and material
Next is the material of the housing and cast aluminum is just weaker than other material. Being weaker is not a bad trait but if its cast to conservative it can be thin and to weak. Housing is not designed to prevent the intermediate shaft from moving.
Hypotheses
That the m190 part time disconnect housing makes the diff stronger. There are bigger bearings and higher tolerances. The actuator assembly helps prevent shock loads from from entering the the differential. The extra material helps with housing strength. This might be an upgrade part if you machine a spacer/disconnect eliminator(100% logical but impossible to prove).
Fix!
Would need an upgraded shaft, to improve the strength of the splines. New bearings with a tapper to transmit the shock load to the housing. Upgraded housing to mount bearings and add support. See crap paint picture below (I use paint because CAD gives me nightmares, like flashbacks to my worst job ever). Draw backs are cost, most likely going to need to be 2 piece to get the factory seal and bearings to work with upgraded tapper bearings. Custom cut shaft with machined races for bearings.
Moral is the factory piece is the way it is because it has worked forever. Spicer upgraded unit is doing the lets beef up everything but not reinvent the wheel. I could see buying into something that fixes 2 out of the 3 issues (shaft and housing) but just tackling one issue doesn't alleviate the problem.
Dana publishes the data on torque load limits etc.
Agreed, which is another example of why you need to stay within manufacturer approved angle ranges.
Agreed and likely a cast iron case vs cast aluminum would have better support.
I believe you meant spider gear.
Lol yes
Don't forget to dress up as krampus!!Bronco got left behind today! Went to Truckee and got a tree 2" taller than my house.
