- First Name
- Nate
- Joined
- Jul 14, 2020
- Threads
- 54
- Messages
- 2,690
- Reaction score
- 5,845
- Location
- Sac-a-tomatoes
- Vehicle(s)
- Bronco, F150
- Your Bronco Model
- Black Diamond
- Thread starter
- #1
Updates
Post 31 CV Axle photos
I guess this is the next step in my journey into Bronco failure points. This is something I have been digging into since my CV Axle failure. I am thinking the front end weakness for the bronco is how power gets transmitted from the cv through the intermediate shaft to the center differential.
Some of the first real catastrophic failures are the passenger side tube. We have had several other front failures but when people warranty the bronco all hope is lost on getting any real info. The documented history off youtube as follows was observed on Trail Militia Video and second was Blanco Bronco. There have been other failures, please if you have info on them post them.
Key critical points at this stage are that you can physically see the stock cv-axles, other words aftermarket cv are not the solution. Blanco was a shaft failure, Trail Militia was a complete failure. I am going to focus on the intermediate shaft as the point of weakness.
Resource Link to diagrams
https://media.spicerparts.com/cfs/files/media/gKvvL6ujMaD8b5GND/LAXIP-0002-52022.pdf?token=eyJhdXRoVG9rZW4iOiIifQ==&store=original
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.
Post 31 CV Axle photos
I guess this is the next step in my journey into Bronco failure points. This is something I have been digging into since my CV Axle failure. I am thinking the front end weakness for the bronco is how power gets transmitted from the cv through the intermediate shaft to the center differential.
Some of the first real catastrophic failures are the passenger side tube. We have had several other front failures but when people warranty the bronco all hope is lost on getting any real info. The documented history off youtube as follows was observed on Trail Militia Video and second was Blanco Bronco. There have been other failures, please if you have info on them post them.
Key critical points at this stage are that you can physically see the stock cv-axles, other words aftermarket cv are not the solution. Blanco was a shaft failure, Trail Militia was a complete failure. I am going to focus on the intermediate shaft as the point of weakness.
Resource Link to diagrams
https://media.spicerparts.com/cfs/files/media/gKvvL6ujMaD8b5GND/LAXIP-0002-52022.pdf?token=eyJhdXRoVG9rZW4iOiIifQ==&store=original
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.
Sponsored
Last edited:
.
