Shuddering from somewhere at the back of the truck when turning- 2018 ram 1500

[corneileous]

First off, not sure if this is the right part of the forum to put this but anyways, on my 2018 ram 1500 that has the 392 rear end with limited slip, I’ve noticed now for a couple months that while making a right or left turn from a stopped position that I’ll feel a shudder from back there at the back of the truck kind of like I’m driving over a rumble strip but it only lasts for barely a second and it doesn’t always do this depending on how aggressively I go to take off.

If I’m sitting at a red light going straight or even stopping at a stop sign, but still going straight, it doesn’t do this. Any ideas what this might be? Oh, and by the way, the truck was bought brand new, the fluid has never been changed in either one of the differentials and the truck now has about 62,000 miles.

Don’t laugh, but when I asked ChatGPT about this and was very thorough explaining what was going on, it said that what most likely was going on was that it’s just time to change the fluids because I guess overtime when the fluid starts to wear out that the clutches in the limited slip will stick and won’t let whichever tire turn slower or faster than the other one being that it only does this while taking off from being stopped making a turn.

So does that sound about right? I don’t have the manual in front of me but last time I looked at it, I think it still says I have a ways to go before it’s time to change the fluid in there.

 

[nlambert182]

Diff fluid changes are usually around 30k miles. It's easy to change. I'd start there.

 

[jws123]

yea change the rear diff fluid make sure it has the limited slip addative in it

 

[corneileous]

Diff fluid changes are usually around 30k miles. It's easy to change. I'd start there.

Yeah, but isn’t that only under like severe conditions for frequent trailer towing and off-roading and such? I mean, I’d have to wait until I get home to see what it says in my book, but I don’t think it really has any kind of a maintenance interval that soon from what I remember. I’m not contesting what you’re saying, I’m just saying.

 

[corneileous]

yea change the rear diff fluid make sure it has the limited slip addative in it

Yeah, I think it’s time no matter what because even though I don’t do a lot of trailer towing or even heavy trailer towing, or even that much off-road at all but I do drive it hard. You think I’d be all right to just use an oil pump to suck all the oil out or actually pull the differential cover?

 

[Wild one]

Yeah, but isn’t that only under like severe conditions for frequent trailer towing and off-roading and such? I mean, I’d have to wait until I get home to see what it says in my book, but I don’t think it really has any kind of a maintenance interval that soon from what I remember. I’m not contesting what you’re saying, I’m just saying.

Instead of quoting the manual,just change the diff fluid.It's easy and cheap to change the fluid,and if it still acts up,then ask questions.
Go with a 75W-140 even though your manual will tell you 75W-85 or something stupidly light like that.
75W-140 acts the same as 75W-85 when cold,but when the diff gets hot it has a better cushioning effect and will handle the load between the pinion and ring gear bearing better,especially if you like to drive it hard or fast for long distances

 

[Wild one]

Yeah, I think it’s time no matter what because even though I don’t do a lot of trailer towing or even heavy trailer towing, or even that much off-road at all but I do drive it hard. You think I’d be all right to just use an oil pump to suck all the oil out or actually pull the differential cover?

There's a drain plug on the bottom of the diff,no need to pull the cover.Change it after a fairly decently long drive while the diffs hot.

 

[corneileous]

Instead of quoting the manual,just change the diff fluid.It's easy and cheap to change the fluid,and if it still acts up,then ask questions.
Go with a 75W-140 even though your manual will tell you 75W-85 or something stupidly light like that.
75W-140 acts the same as 75W-85 when cold,but when the diff gets hot it has a better cushioning effect and will handle the load between the pinion and ring gear bearing better

And I’m not contesting that, I was just simply stating, more of kind of excuse of why I haven’t done this sooner because a heavy right foot is the only part of the severe driving that my truck sees.

 

[Wild one]

And I’m not contesting that, I was just simply stating, more of kind of excuse of why I haven’t done this sooner because a heavy right foot is the only part of the severe driving that my truck sees.

Definitely go with something like a Redline 140 if you drive it hard

 

[corneileous]

There's a drain plug on the bottom of the diff,no need to pull the cover.Change it after a fairly decently long drive while the diffs hot.

I guess I can just look when I get home, but is there also a drain plug on the front differential? But aside from not remembering about the drain plug, I was only asking just because I’ve never noticed a differential to do this before, and I have had quite a few limited slip rear ends over the years but yeah, if I can keep from having though pull the cover, that would make me happy, especially on the front one.

 

[Docwagon1776]

Does your rpm briefly fluctuate as well when the shudder happens?

 

[corneileous]

Does your rpm briefly fluctuate as well when the shudder happens?

Well, I don’t know, because I’ve never watched the tach when this happens but this evening when I go to drive home from work, I’ll definitely watch it this time.

But like I said in my opening post, it just feels like a light shudder that’s really not even as intense as driving over an actual rumble strip like on the side of the highway, but it is definitely there that you can feel it and I think a couple times I’ve noticed where it feels like, I’m assuming, that the limited slip is trying to engage when I’m really not even that hard on the throttle as I go to make my turn from being stopped. But don’t get it twisted, I don’t know if the LS is trying to engage or not when it’s not supposed to, I just know that a couple times that fought crossed my mind like the limited slip was trying to engage even on bare, dry asphalt, and not even trying to take off hard.

 

[Docwagon1776]

Well, I don’t know, because I’ve never watched the tach when this happens but this evening when I go to drive home from work, I’ll definitely watch it this time.

But like I said in my opening post, it just feels like a light shudder that’s really not even as intense as driving over an actual rumble strip like on the side of the highway, but it is definitely there that you can feel it and I think a couple times I’ve noticed where it feels like, I’m assuming, that the limited slip is trying to engage when I’m really not even that hard on the throttle as I go to make my turn from being stopped. But don’t get it twisted, I don’t know if the LS is trying to engage or not when it’s not supposed to, I just know that a couple times that fought crossed my mind like the limited slip was trying to engage even on bare, dry asphalt, and not even trying to take off hard.

I had a Jeep that had a similar feeling, only around curves, never on the straight. It got progressively worse, but slowly. Turns out I had a very slow seep of transmission fluid and it had gotten *juuuust* low enough to slightly reduce flow when the fluid sloshed in the pan from turning at low speed. Topping off the transmission fluid fixed it.

Now, this is a low percentage chance it's your issue, but figured I'd ask. I wouldn't be hung up on it just being the rear end, though it's certainly a suspect.

 

[corneileous]

I had a Jeep that had a similar feeling, only around curves, never on the straight. It got progressively worse, but slowly. Turns out I had a very slow seep of transmission fluid and it had gotten *juuuust* low enough to slightly reduce flow when the fluid sloshed in the pan from turning at low speed. Topping off the transmission fluid fixed it.

Now, this is a low percentage chance it's your issue, but figured I'd ask. I wouldn't be hung up on it just being the rear end, though it's certainly a suspect.

Well, I hope it’s not my transmission and the last time I was under there, I didn’t see any kind of oil leaks, which, I don’t have any oil leaks anywhere that I know of, but since I have that eight speed, I’m not touching that thing because of my lifetime warranty….lol.

But I’m definitely gonna start with changing the oil in both my front and rear diff and go from there and eventually getting that expensive Mopar **** that goes in that auto transfer case I have.

 

[Wild one]

Well, I hope it’s not my transmission and the last time I was under there, I didn’t see any kind of oil leaks, which, I don’t have any oil leaks anywhere that I know of, but since I have that eight speed, I’m not touching that thing because of my lifetime warranty….lol.

But I’m definitely gonna start with changing the oil in both my front and rear diff and go from there and eventually getting that expensive Mopar **** that goes in that auto transfer case I have.

You could still check the fluid level in your 8 speed,they're famous for being shipped slightly low on fluid,if that does happen to be your issue,highly doubtful it is,but it's still worth checking it's fluid level,you could top it up with mopar 8/9 speed fluid,and you won't affect your warrenty

 

[corneileous]

You could still check the fluid level in your 8 speed,they're famous for being shipped slightly low on fluid,if that does happen to be your issue,highly doubtful it is,but it's still worth checking it's fluid level,you could top it up with mopar 8/9 speed fluid,and you won't affect your warrenty

Yeah, but doesn't that require having a diagnostic tool plugged in and all that stuff so that the transmission is at the proper temperature when you go checking the fluid level?

 

[Wild one]

Yeah, but doesn't that require having a diagnostic tool plugged in and all that stuff so that the transmission is at the proper temperature when you go checking the fluid level?

You've been around long enough to know you can use the evicc for checking the temperature,and i'm guessing you've also seen the green sheet several times that tells you how to check the fluid level in the trucks transmission.
Here it is again,the only hard part is getting the rear tires roughly 9" in the air to level the transmission pan rail.The ideal checking temp is between 100F and 105F which you can access through your evicc.
Start with a cold transmission,by the time you go through the gears /procedure,you'll be getting close to the ideal temp

 

[corneileous]

You've been around long enough to know you can use the evicc for checking the temperature,and i'm guessing you've also seen the green sheet several times that tells you how to check the fluid level in the trucks transmission.
Here it is again,the only hard part is getting the rear tires roughly 9" in the air to level the transmission pan rail.The ideal checking temp is between 100F and 105F which you can access through your evicc.

No, I can honestly say that I've never seen that little green piece of paper you shared. Yes, I know that my dash gauge does tell me the temperature of the transmission but since I have lifetime warranty on my truck, I've never paid attention to that stuff about servicing the transmission like a lot of y'all have because whenever my transmission decides it doesn't wanna shift anymore, I'll be taking it in and be paying them 100 bucks for them to put me a new transmission underneath it.

 

[Wild one]

No, I can honestly say that I've never seen that little green piece of paper you shared. Yes, I know that my dash gauge does tell me the temperature of the transmission but since I have lifetime warranty on my truck, I've never paid attention to that stuff about servicing the transmission like a lot of y'all have because whenever my transmission decides it doesn't wanna shift anymore, I'll be taking it in and be paying them 100 bucks for them to put me a new transmission underneath it.

They won't install a new transmission under warrenty,you'll get a rebuilt,and fyi ma Mopar farms their rebuilds out to the cheapest bidder.Good luck with you're theory though,me i'd rather check the fluid level and keep a good working transmission well maintained and topped up on fluid. With the parts supply issue these days,you could be waiting quite awhile before they get the parts to repair your truck. Just my 02

 

[corneileous]

They won't install a new transmission under warrenty,you'll get a rebuilt,and fyi ma Mopar farms their rebuilds out to the cheapest bidder.Good luck with you're theory though,me i'd rather check the fluid level and keep a good working transmission well maintained and topped up on fluid. With the parts supply issue these days,you could be waiting quite awhile before they get the parts to repair your truck. Just my 02

You're right, it probably won't be new, but I didn't mean new in the literal sense. I meant new as in something else other than what's underneath there right now.

And there's nothing wrong with what you say and if I didn't have this warranty, I would agree with you 110% but if there's evidence that I cracked open a "sealed" transmission, I'm screwed as soon as something happens. I've already talked to the warranty people about this and even asked them if they're going to replace my transmission basically due to lack of maintenance whenever this happens and they assured me I'd be covered. I didn't ask, but I think it's pretty well assumed that I'm not supposed to touch it if I want them to pay for it when its all the sudden stuck in park, won't shift into park or just won't shift at all.

And yeah, because warranty will be paying for this, I'll probably be waiting for a while to get my truck back as soon as my transmission starts showing signs of lack of maintenance just like if I ever do become a victim of a chewed up camshaft lobe from a seized lifter, it won't be just a couple of weeks and then get my truck back.

I'm not arguing with what you're saying, I'm just saying I'm not in the same boat as you are.