4WD/Transfer Case/Front diff Banging and Grinding Noise

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The Car Stereo Company

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Is that not the same thing as an IWE?
theres some elecreonic component regarding the 4wd. i had no 4wd for the first 96k miles i had my truck. nobody could fix it until i finally found a competent dealer. they fixed it just as my warranty was about to expire. they told me it was a 4wd actuator and referred to the iwe as a different part. said it was an electrical issue with an actuator..... how true it is, i dont know, but they fixed mine. the loud bang you are hearing is the transfer case most likely. i have had the same noise. almost like a gunshot sound.
 
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theres some elecreonic component regarding the 4wd. i had no 4wd for the first 96k miles i had my truck. nobody could fix it until i finally found a competent dealer. they fixed it just as my warranty was about to expire. they told me it was a 4wd actuator and referred to the iwe as a different part. said it was an electrical issue with an actuator..... how true it is, i dont know, but they fixed mine. the loud bang you are hearing is the transfer case most likely. i have had the same noise. almost like a gunshot sound.
Interesting.... You don't happen to have paperwork for that service still, do you? I would be very curious about that.

I got around to thinking about whats going on with my truck and if both IWE's just happened to have failed in the same way where vacuum will not disengage them, I am essentially running an unwanted IWE delete kit?? Maybe its not causing as much damage as i initally thought?
 

FordTechOne

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I would start by re-checking the work that was done. You mentioned that the driver’s side knuckle was replaced; that requires removal and re-installation of the wheel bearing and IWE. When the IWE is installed, it is important that it is collapsed with a vacuum pump prior to installation. It is also crucial to verify that the axle stub is completely through the hub by taking a measurement.

My guess is the shop didn’t follow the required procedures and damaged the IWE on the drivers side. Partial engagement will result in a lot of noise and damage to both the hub and IWE.
 
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I would start by re-checking the work that was done. You mentioned that the driver’s side knuckle was replaced; that requires removal and re-installation of the wheel bearing and IWE. When the IWE is installed, it is important that it is collapsed with a vacuum pump prior to installation. It is also crucial to verify that the axle stub is completely through the hub by taking a measurement.

My guess is the shop didn’t follow the required procedures and damaged the IWE on the drivers side. Partial engagement will result in a lot of noise and damage to both the hub and IWE.
Lets say it is partially engaged... Would that cause the other CV and transfer case driveshaft to spin as well? If it is engaged when its not supposed to be?

Should I be concerned with damage to the transfer case or frony diff?

Also I still cannot explain why Neither one if the IWE's will disengage from that respective CV when 27 poundsof vacuum is applied and the pressure holds?
 

FordTechOne

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Lets say it is partially engaged... Would that cause the other CV and transfer case driveshaft to spin as well? If it is engaged when its not supposed to be?
Yes, because they’re connected through the differential.
Should I be concerned with damage to the transfer case or frony diff?
Not likely, as the front driveshaft spins freely in 2WD. So no transfer case engagement.
Also I still cannot explain why Neither one if the IWE's will disengage from that respective CV when 27 poundsof vacuum is applied and the pressure holds?
So that’s definitely an issue; the axle should spin freely with vacuum applied. However, if one IWE is damaged and stays engaged, it may cause drag on the other axle.
 

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For one thing, you should NOT engage in 4WD at highway speeds on hard-surface roads, PERIOD! This is per the manual, which explicitly states that it "can produce excessive noise...". So you've got two significant factors that could cause the mechanical issues you're describing by driving at excessive speeds beyond the design of the 4WD system, and while driving on dry pavement. Sounds may be more pronounced when turning the steering wheel, even the the slightest turn. Remember: we have 4WD and NOT AWD, which the latter is designed to operate at all times and conditions, on all types of surfaces.

Secondly, the front axle on a Raptor is a limited slip, which would explain why if one hub is engaged, this may lead to the opposite axle shaft spinning when its hub is not engaged.

I, too, had problems with 4WD: namely, that I did not have 4WD when I was on the trails, even though the dash showed it was in 4WD. So I had to school myself on how the how F-150 4WD system works. The main culprit was a solenoid valve that would not release vacuum.

When engaging 4WD HI via the cabin selector switch, the first operation that occurs is a motor in the transfer case engages the front driveshaft. This will get the front axles moving at the same speed as the rear axle if the truck is actually driving on a surface (i.e. this does NOT work properly when you have all four wheels suspended on jack stands and troubleshooting this system in drive--trust me, I learned this the hard way). The purpose of this is to synchronize the axle/IWE rotation to the wheel rotation, which allows the next operation to occur. The solenoid vacuum release vacuum to the IWE whereupon the spring tension in the IWE will re-engage the gear on the wheel hub, which should occur with no grinding of the gears since the wheel and axle rotations should now be in sync due to the xfer case engagement previously.

Having said all this, yes, it could be the case of one or both bad IWE's on your Rap. I seemed to experience the loud bangs and grinding as you, but at slow, several miles per hour speeds on dry pavement and replaced the suspect IWE and it seemed to resolve the issue completely, even though I could not find anything wrong with the replaced IWE.
 

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The Car Stereo Company

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ford states you can engage 4wd at any speed. however its best to not be moving when you do it. much leass chance of the grinding banging into 4wd. but you are correct in not wanting to turn on tarmac due to excessive traction which can/will break an axle.
 

K1LDZR2

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Alrighty, so some interesting findings.

Decided to go for a drive with a camera mounted to the underside of the truck to see if I could capture what was going on. I was monitoring the live video feed on my hour plus drive and the entire time, both CV shafts were spinning at wheel speed as well as the transfer case drive shaft.

No noise on the freeway, about 40 miles one way. I got to my destination and as soon as I hit uneven ground (gravel patch on the side of the road) the noise comes back.

Looking back at the video, the passenger IWE / CV seems to disengage at the time of the noise, and noise goes away after re-engaging (Big clunk noise).

Immediately I am thinking IWE after seeing video. I go back home and jack up the front of the truck to begin my vacuum test. Here are my readings starting from the beginning of the system and working my way down:

- Vacuum reservoir pulls vacuum - 25 inch pounds
- Check valve works (Brand new installed yesterday)
- Solenoid works (Brand new installed yesterday)
- Vacuum pressure measured at solenoid - 25 in pounds
- Used the hand pump to create 25 in pounds of vacuum at the top of the vacuum line where it connects to solenoid. Held 25 pounds for 2 minutes. Checks out, moving on.
- Turned truck back on. Pulled the vacuum line from both IWEs and it measured 25 in pounds on both sides.

Heres where it gets interesting.
Hooked up the vacuum to the IWE directly and maxed out the hand pump at 27 pounds. Both IWEs will hold that pressure for 2 minutes BUT when I try to spin the wheel on both sides, the CV shaft still spins with the speed of the wheel, even with vacuum applied.


How in the hell do BOTH IWE's fail at the exact same time and have the exact same problem where seemingly no amount of vacuum will disengage them from the axles?
This makes more sense as to why both CVs and the transfer case drive shaft were all spinning in unison for my entire drive but I am extremely concerned with how much damage this may have caused.

Anyone hear of this happening before? @FordTechOne any ideas?


Heres the video


I'm really new to all this, but I'm having a similar but less violent issue. Could it be that the IWEs aren't properly engaging and disengaging even with the right amount of vacuum just because they (or something connecting to them) needs to be lubricated?
 
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