Center Diff/transfer case/axle damage

[Colby Murphy]

Have what is probably a stupid question for all of you out there, but you don't know what you don't know. Yesterday during the great Dallas blizzard of 2021 I was in some ice and snow trying to make it back home and I hit the center diff lock button stupidly right before making a left turn and as soon as I started into the turn, probably 2 seconds after hitting the CDL button, the front passenger side area drivetrain popped/pow'd a good 3-4 times very loudly (enough to scare me and cause for concern) before I was able to straighten the wheels back up and then it stopped. CDL stayed on and no more noise came from any part of the vehicle but.... DID I DO SOME DAMAGE/BREAK SOMETHING I DONT KNOW ABOUT YET?????

Thank you in advance for any input on this

 

[RET2]

Anti Lock braking activated?

 

[Colby Murphy]

Anti Lock braking activated?

man I want to think that was it but it sounded wayyyy diferent than ABS activating. They were loud audible pops like something was trying to rotate and catch but was binding or missing

 

[TeCKis300]

I would find it hard to believe that CDL on icy/snowy roads could damage the vehicle in that fashion. (or was it dry roads?) Even then, the driveline is pretty robust and able to take some serious abuse.

Were you able to turn off the CDL and continue on without any issues? Binding would be normal and expected and perhaps the sound was just ice frozen up in the driveline and it just worked itself out?

 

[Colby Murphy]

I would find it hard to believe that CDL on icy/snowy roads could damage the vehicle in that fashion. (or was it dry roads?) Even then, the driveline is pretty robust and able to take some serious abuse.

Were you able to turn off the CDL and continue on without any issues? Binding would be normal and expected and perhaps the sound was just ice frozen up in the driveline and it just worked itself out?

It was on ice and snow for sure. Yeah I was able to turn it off and back on fine. It was after driving around all day and had already been functioning so it wasn't any I've build up

 

[linuxgod]

The CDL would lock the transfer case, which is under the gear shifter/coolbox area), but doesn't engage anything in the front wheels. Unless you had an aftermarket front locker engaging the CDL shouldn't lock anything in the front. I wouldn't expect any noise from either side of the vehicle from that. Our front and rear differentials are "open diffs", so when turning power goes to the faster spinning wheel (typically the outer wheel in a turn, unless maybe the inner one is slipping on ice). Using the CDL on dry pavement can cause the center diff inside the transfer case to bind up and basically force one set of wheels to spin/lose (some) traction when they normally have grip.

I think there's a relay for the CDL in the passenger footwell or glovebox area. I haven't checked the wiring diagrams, but whenever I enable my CDL I can tell when it has activated because I can hear a click come from that area. It's possible that relay was clicking trying to activate. Mine is quiet though, not a loud pop or pow just a click, but if you've never used the CDL maybe it's related?

I did once have 4Lo cluck into engagement on dry pavement, so it's possible the actuator for the CDL was sticking/not fully engaging, and when you made the turn the stress caused the actuator to come loose and re-engage until it lined up correctly. I would think the noise would be under the coolbox, but who knows how sound might transmit along the drivetrain?

Personally I'd make sure 4Lo and the CDL engage/disengage correctly a few times the next time you're out on snow (or gravel). If they do then I wouldn't necessarily worry. If you've got some miles on your truck and/or tow with it you might want to flush the transfer case. I do mine every 30k, but I also tow a lot... normal folks could go 100k+

 

[Colby Murphy]

The CDL would lock the transfer case, which is under the gear shifter/coolbox area), but doesn't engage anything in the front wheels. Unless you had an aftermarket front locker engaging the CDL shouldn't lock anything in the front. I wouldn't expect any noise from either side of the vehicle from that. Our front and rear differentials are "open diffs", so when turning power goes to the faster spinning wheel (typically the outer wheel in a turn, unless maybe the inner one is slipping on ice). Using the CDL on dry pavement can cause the center diff inside the transfer case to bind up and basically force one set of wheels to spin/lose (some) traction when they normally have grip.

I think there's a relay for the CDL in the passenger footwell or glovebox area. I haven't checked the wiring diagrams, but whenever I enable my CDL I can tell when it has activated because I can hear a click come from that area. It's possible that relay was clicking trying to activate. Mine is quiet though, not a loud pop or pow just a click, but if you've never used the CDL maybe it's related?

I did once have 4Lo cluck into engagement on dry pavement, so it's possible the actuator for the CDL was sticking/not fully engaging, and when you made the turn the stress caused the actuator to come loose and re-engage until it lined up correctly. I would think the noise would be under the coolbox, but who knows how sound might transmit along the drivetrain?

Personally I'd make sure 4Lo and the CDL engage/disengage correctly a few times the next time you're out on snow (or gravel). If they do then I wouldn't necessarily worry. If you've got some miles on your truck and/or tow with it you might want to flush the transfer case. I do mine every 30k, but I also tow a lot... normal folks could go 100k+

Good info, thank you! I was mainly concerned due to the little card insert on my visor that says "to avoid damage to transfer case/cdl don't hit button while turning" which in essence is exactly what happened

 

[bloc]

I think the splined CDL collar tried to engage and bounced off the splines a few times due to the mismatch in front/rear driveline RPMs while turning, and this could be a somewhat violent event. That probably transmitted torque to the front wheels, resulting in the perception of the problem being up there.

Frankly? I wouldn’t worry about it too much. These things are robust. Maybe change your transfer case fluid, but in all honesty I doubt it is even needed.

 

[Colby Murphy]

I think the splined CDL collar tried to engage and bounced off the splines a few times due to the mismatch in front/rear driveline RPMs while turning, and this could be a somewhat violent event. That probably transmitted torque to the front wheels, resulting in the perception of the problem being up there.

Frankly? I wouldn’t worry about it too much. These things are robust. Maybe change your transfer case fluid, but in all honesty I doubt it is even needed.

oh that makes sense!! thanks man! All i could do was sit there and think to myself... what did i just do?? but your explanation sounds pretty spot on