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- Jake
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- #1
I've wondered from time to time how Ford was planning to pay for all the expected warranty damage claims from IFS and a front locker, especially when they will be having a lot of locker newbees (myself included) and having the front locker in so many models/trims.
It occurred to me that they had to have a way to measure and limit torque (based on steering angle) and since they obviously require the 4A when getting a front locker, I figured that is where the magic happens.
Ideally someone will know and let us know, otherwise conjecture is all we have. Steering angle, input/output torque sensors are easy, the mechanical connection is where I am fuzzy in my two theories. I am thinking that the 4A has the ability in both 4 low and 4 high (if it lets you lock the front in 4 high) to release the lock (at say...75% of a dangerous torque level, so as to almost always be really locked and to give it time to unlock before hitting the actual danger level) and hold with the clutch (and allowing calculated clutch slip in the 4A to limit torque to the front axle) to keep it below the theoretical calculated worst case with the angle of the wheels. I favor this theory because it is the fastest response time of the two and explains the 4A requirement. Would minimize use of the clutch and attendant heat generation. (Plus that is how I would have designed it.)
Theory two is that they release the front locker using the same calculations and as soon as it can tell which wheel is spinning, uses the brakes to limit that wheels rotation to the other. It would be slower to release the lockers then the clutch in the 4A and thus not give as much protection. Modulating the electronic throttle is also relatively slow and would take away torque from the rear axle, so I don't see that as a viable strategy.
I would be interested in people's thoughts on the subject and my theory. The possible warning would be if I am right. If the 4A is being used to protect the front moving bits, it would be using calculated loads and steering angle data. Changing wheel diameter, weight, gearing maybe even some ultra grippy tire (am sure safety margins are very high and grippy tire scenario is not really a problem), lifting the suspension, changing the geometry, etc. Might throw those calculations out the window and allow more damage to occur. Same thing using a hack to get the front to lock when the truck normally won't allow it. Mansquatch might need some extra programming beyond speedo correction to account for the larger tires, could be a reason for the delay. Anyway, that is my theory, feel free to bolster or shoot it down, either way I think it will be a fun conversation.
It occurred to me that they had to have a way to measure and limit torque (based on steering angle) and since they obviously require the 4A when getting a front locker, I figured that is where the magic happens.
Ideally someone will know and let us know, otherwise conjecture is all we have. Steering angle, input/output torque sensors are easy, the mechanical connection is where I am fuzzy in my two theories. I am thinking that the 4A has the ability in both 4 low and 4 high (if it lets you lock the front in 4 high) to release the lock (at say...75% of a dangerous torque level, so as to almost always be really locked and to give it time to unlock before hitting the actual danger level) and hold with the clutch (and allowing calculated clutch slip in the 4A to limit torque to the front axle) to keep it below the theoretical calculated worst case with the angle of the wheels. I favor this theory because it is the fastest response time of the two and explains the 4A requirement. Would minimize use of the clutch and attendant heat generation. (Plus that is how I would have designed it.)
Theory two is that they release the front locker using the same calculations and as soon as it can tell which wheel is spinning, uses the brakes to limit that wheels rotation to the other. It would be slower to release the lockers then the clutch in the 4A and thus not give as much protection. Modulating the electronic throttle is also relatively slow and would take away torque from the rear axle, so I don't see that as a viable strategy.
I would be interested in people's thoughts on the subject and my theory. The possible warning would be if I am right. If the 4A is being used to protect the front moving bits, it would be using calculated loads and steering angle data. Changing wheel diameter, weight, gearing maybe even some ultra grippy tire (am sure safety margins are very high and grippy tire scenario is not really a problem), lifting the suspension, changing the geometry, etc. Might throw those calculations out the window and allow more damage to occur. Same thing using a hack to get the front to lock when the truck normally won't allow it. Mansquatch might need some extra programming beyond speedo correction to account for the larger tires, could be a reason for the delay. Anyway, that is my theory, feel free to bolster or shoot it down, either way I think it will be a fun conversation.
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