Vibration when decelerating Help!

[jbyrd89]

First time caller here.... about 2 months ago I purchased a "certified pre owned" 2022 ram 1500 classic 2wd crew cab with the 3.6, 850re transmission and 38,000 miles on the odometer.

Just a few days after closing the deal, I noticed a strange vibration on deceleration between approximately 40 and 20 miles per hour that feels somewhat like running over the rumble strip on the side of the road and a constant, slightly less noticeable vibration cruising at around 55. It's a fast vibration that is felt in the seat, not the steering wheel which leads me to assume that it's driveline related and occurs both during braking and coasting without any brake application. The vibration goes away when the transmission is put into neutral and is not present during acceleration.

So far I've made 4 trips to the dealers service department to try to get the issue resolved with no real improvement.

Trip#1- they visually inspected the driveshaft and carrier bearing but did not find a smoking gun. They roadforce balanced all 4 tires to find that the right rear was defective. (The dealership put 4 brand new Goodyear sra tires on it before the sale) they had to order a new tire and said to come back at a later date for installation.

Trip#2- new tire was mounted, balanced and installed. I noticed no improvement in the vibration on the trip home

Trip#3- the transmission control module was re flashed and the tech said it was good to go. Again, the vibration was still there on the trip home

Trip#4- a star case was opened with chrysler, chrysler had them install a new valve body in the transmission which did not fix the vibration, which led them to replacing the entire transmission, torque converter and transmission cooler...... the vibration was still there on the trip home.

I have no hard feelings towards the dealership, I feel like they are doing what that can to work with chrysler's warranty process and try to come to a solution but I'm about to bring it back for trip number 5 and they have had the truck more than I have in my 2 months of ownership. So far I'm struggling to keep my hands off for warranty purposes but have slid under the truck to put my eyes on everything. There's no powdery rust on any u joints or slack that would indicate a bad u joint, Carrier bearing looks and rotates fine, there does not appear to be any balance weights missing, no loose hardware on the yokes, no slack in the pinion bearing. I'm at a loss here, has anyone had any experience with bad bushings on The rear suspension links causing a bad pinion angle or something similar? 38,000 miles doesn't seem like enough wear and tear to be having this sort of problem and the bottom of the truck is clean and shows no obvious signs of abuse. Does anyone have any experience with a similar situation and know of a fix?
(Sorry for the novel of a post, I'm just trying to be thorough)

 

[tron67j]

I read your post last night and reread it again this morning. This is an interesting one especially since the transmission was replaced and the vibration goes away in neutral. My only guess is a bad motor mount because the stress on engine is removed in neutral and acceleration would continually strain the engine against a bad mount and eliminate the ability to vibrate, maybe.

Hopefully someone else has an idea to share. Good luck.

 

[jbyrd89]

It's definitely interesting. One detail that I failed to include in my original post is that the vibration at around 55 is the same in 8th gear as it is in 7th gear, which again makes me lean towards the driveshaft and rear end area. Motor mounts are definitely worth looking at though.

 

[Huliodude]

Jbyrd,

I too have a 2022 Ram 1500 Classic v6 with the 850RE, however I'm 4WD.

My truck has the exact same issue as you describe, except without the "slightly less noticeable vibration cruising at around 55". It too goes away when I decelerate in neutral. I bought the truck brand new and it has done it since day 1, and the truck now has 34,000km on it, and it's gotten no worse or better.

I took it to the dealer when the truck had less than 1000km on it and they all claimed to not hear or feel it. My sons who are total gear heads both do feel it however. I knew that if I pressed it with the dealer, it would start a process not different from what you've been going through, and I decided the issue was small enough to just live with it. I didn't like the idea of them tearing apart my drive train on a brand new truck for a problem that is pretty minor. Perhaps your vibrations are worse than mine or your tolerance for it is lower. Either way, I commend you for getting the dealer to do all they can to try to fix it.

My guess is it is either the transmission, or the rear differential. For context, I had a 2019 Ram 1500 Classic V6 with the 845RE and 4WD, and it had this problem as well, though not as bad, and you would feel it from 20mph down to 0.

Because these trucks are ridiculously quiet and smooth (especially the V6) with low road noise, it's very easy to hear and feel other issues with the truck. Every car I've ever owned has some annoyance, so I decided to live with it, and now I don't even pay attention to it anymore. It's otherwise a fantastic truck.

If you do figure out the problem, I'd love to know the remedy as perhaps I could tell the dealer to start there in case I ever decide I want it fixed.

Lastly, I had a 2021 Ram 1500 Classic with the 5.7 Hemi and the 8HP70 and 4wd, no vibrations at all. However the MDS created more vibrations than your issue ever will!

 

[jbyrd89]

Huliodude,
The vibration on deceleration is just about 1/2 as severe as hiting the ruble strip and it's driving me nuts. It's a real shame too because the truck checks all of the boxes when it comes the reasons why I bought it. I already had a v8 4x4 truck at home to cover pulling the tractor and boat around so I didn't need another one, I just wanted something comfortable for the kids in the back seat, decent fuel mileage for back and fourth to work and good reliability with no turbos and over the top technology. We've got 2 of the same trucks at work with the same drive trains as mine, same year, just the tradesman package and they have given no trouble whatsoever. Hopefully the dealer hangs in there and gets to the bottom of the issue, I know they are just as frustrated as I am.

 

[Racer9]

Try manually downshifting and see what happens with the vibe. If it increases the issue is with the motor, if it remains the same regardless of rpm it is in the driveline.
Also, just because parts are new or low mileage, doesn't mean they are not bad. I would be looking real hard at the drive shaft, U-joints, and carrier bearing. Might even try shimming/adjusting the carrier to see if it affects anything.

 

[jbyrd89]

Try manually downshifting and see what happens with the vibe. If it increases the issue is with the motor, if it remains the same regardless of rpm it is in the driveline.
Also, just because parts are new or low mileage, doesn't mean they are not bad. I would be looking real hard at the drive shaft, U-joints, and carrier bearing. Might even try shimming/adjusting the carrier to see if it affects anything.

The steady vibration around 55 remains the same no Matter if the trans is in 7th or 8th which is why I lean towards a driveline issue. It's tough to keep my Hands off for the sake of not voiding the warranty while the dealership is still willing to continue take the truck in and try different things under warranty but I'm being good for now lol. I sure wish I could find a buddy with a similar vibration free truck that would let me borrow the drive shaft for a test drive. It may be normal but my driveshaft sure seems to have a lot of balance weights on it from the factory. I also find myself wondering if strapping a go pro under the truck would capture the driveshaft rattling around during the vibration events or show any other clues.. ..

 

[Daw14]

I’m with you on thinking it’s the driveshaft out of balance ,or something to do with it. Carrier or u-joints possible also. But if there is an excessive amount of weights that’s even more likely imo.

 

[Jeepwalker]

I would take it to another dealership. But before you do, swing by and talk to the servicee manager. Find out who their "good" or even 'best' mechanic is. Within each dealership you have a range of Techs from 'Excellent' to 'Mediocre -- at best'. Find out who their 'good' tech is, and make sure you get him scheduled to do your truck. And make sure he's there (and actually working on it) the day you drop it off. With your own eyes. Or contact RamCares, here on the forum.

Most likely, it sounds like driveline issues. Could be a center bearaing, U-joint, bent driveshaft (has anyone put a dial indicator on it?!), or a bad/incorrect/missing rear output bushing. Or could be a torque converter issue or something within the rear diff, like a loose yoke, or maybe a wearing pinion bearing, or wheel bearing (allowing wheel hop). Or even a bad shock! Or possibly something within the front steering ...since you say the steering wheel shakes bad. It's 2WD so that removes a lot of the issues which come with a 4wd.

This is one of those issues which is going to require basic inspection and testing. It's exactly the kind of job which "parts-replacers" are no good at.

 

[Jeepwalker]

Your tk has electric parking brakes, no?? This won't work with electric brakes I don't think ...but if it's manual parking brakes, try gently applying them part-way when the shaking starts. The shoes within the rotors will 'center' the rear wheels...let's say.. if the wheel bearings were sloppy. But wheel bearings are pretty easy to determine 'free-play' on a hoist. That ought to be part of basic testing ...as should checking for a bent axle. But if the guys looking at your truck before were in a hurry, or chronic 'parts-replacers' ...they'd probably skip over some of the basics.

 

[jbyrd89]

Your tk has electric parking brakes, no?? This won't work with electric brakes I don't think ...but if it's manual parking brakes, try gently applying them part-way when the shaking starts. The shoes within the rotors will 'center' the rear wheels...let's say.. if the wheel bearings were sloppy. But wheel bearings are pretty easy to determine 'free-play' on a hoist. That ought to be part of basic testing ...as should checking for a bent axle. But if the guys looking at your truck before were in a hurry, or chronic 'parts-replacers' ...they'd probably skip over some of the basics.

There is no vibration in the steering wheel and i have jacked up all 4 wheels and checked bearings and joints, I did not notice any slack or strange noises on any corner. I've put the rear axle on jack stands, turned traction control off and ran the truck all the way up to 80 and back down to 0 with no signs of vibration. (I also understand that this does not put much if any dynamic load on the driveline and does not change pinion angle and flex bushings like the truck would if it was accelerating and decelerating on the ground). My truck is a 22 classic SLT, so no fancy bells and whistles like an electric parking brake. I did just try to apply the parking brake while the truck was vibrating and it makes no difference.
I work in experimental jet engine testing, and instrumentation calibration. Before that I spent many years running a service truck across 3 states doing commissioning, diagnostics and repair on diesel and gaseous fueled standby generators from 5 to 3,250kw, That being said I've never had the luxury of using the parts cannon and don't understand how so may people are proud to use it, most customers would just refuse to pay for it but luckily Chrysler and the dealer have been footing the bill so far. The other dealer in my area said that they were booked up for 2 months with diagnostic work and I got "sorry about your bad luck" vibes from them.

 

[Jeepwalker]

Ok..that's good info. Sounds like you've already dug in a lot. Maybe reach out to these guys would be a good idea:

RamCares

www.ramforum.com

 

[jbyrd89]

The truck went back to the dealer for trip number 5 today... the service writer decided it was time to put another set of eyes on my my truck so he assigned a different tech that he described as well seasoned. I spoke with the tech and gave him the same rundown as what you guys have read above then we went for a test drive. Almost immediately he acknowledged that he felt the vibration and that he believes that the driveshaft is the culprit. He mentioned that chrysler has had their fair share of driveshaft issues, especially the 2 piece shafts and as a matter of fact he just had to put one on a brand new wagoneer. When I told him that I didn't notice any of the 3 balance weights missing off of the front shaft and the 4 on the rear shaft were sill there as well his eyes got big and he said that 7 weights on a 2 piece drive shaft is an abnormal amount and that most likely indicates that they had trouble balancing the shaft from the factory. He also mentioned that while the rear end seemed quiet, its not impossible to get some odd vibrations from there too, but his money was on the driveshaft and that would be the next step. The tech gve me the impression thay he's very knowledgeable as we spoke about other short comings and strong points of ram trucks, the pentastar 3.6 and chrysler transmissions for the remainder of the test ride. They began the process of ordering a new driveshaft as soon as we returned to the dealership so here's to hoping that trip number 5 provides some positive results.

 

[Huliodude]

Let us know if it turns out to be the driveshaft. I’m thinking it may not be the culprit as the vibration would continue in neutral, and during acceleration as well.

I was thinking it could something in the differential, perhaps the ring gear or carrier, as there is some engine braking when decelerating and the backside of those gears are being engaged at that time. A simple poor finish or backlash tolerances too wide can cause vibration issues.

 

[Jeepwalker]

Hopefully that does it.. I would think a tech would inspect the U-joints, look where weights were previously welded on (and may have fallen off), or even put a dial indicator on it (although granted that sucks up a lot of time). But hopefully that does the trick.

Are you getting charged for all these parts?

 

[RamInfo]

I’m with you on thinking it’s the driveshaft out of balance ,or something to do with it. Carrier or u-joints possible also. But if there is an excessive amount of weights that’s even more likely imo.

Back in the 70s I drove a late model stock car with an LS 454, Grand National QC rear end, etc.etc. When we first started running the car, on 12” wide tires, we kept breaking driveshafts. Finally went to a custom driveline guy whose position was that “any time you see a weight on a driveshaft it’s a crooked or off-center shaft” and will cause problems. So, in his giant lathe setup he built us up a shaft, fine trued it with torch and water, and sent us on our way. We never broke another driveshaft, but then started breaking the mounting ears on the Muncie 4speed (aluminum case) we were running so ended up with a cast iron 3speed from a Pontiac.

So, my point is, were this my truck it’d be digging into the carrier, u-joints, pinion bearing, and looking for another propeller shaft for test purposes. And on 2-pc shafts the condition and lubrication of intermediate splines should be checked, also.

Good luck to the OP!
Best,
RI

 

[Marshall]

Years ago on a large truck, I think it was a 3 ton IHC that the drive shaft would bounce when letting off the gas at speed, The joints felt good while on the truck, but when I pulled it ,the u joints where very rough and dry. New joints fixed it. Those trucks used a rubber mounted center bearing and it was also a bit poor as well. 2 piece shaft.
the only time you noticed it was on a coasting in gear, sometimes you will hear a clicking sound.

 

[jbyrd89]

Hopefully that does it.. I would think a tech would inspect the U-joints, look where weights were previously welded on (and may have fallen off), or even put a dial indicator on it (although granted that sucks up a lot of time). But hopefully that does the trick.

Are you getting charged for all these parts?

Luckily, so far all parts and labor have been covered under the powertrain warranty