Vibration/Rumble from MDS or something else?

[Want to Drive]

I have a 2014 Ram 1500 Quad Cab Sport with 73,000 miles and for several years I've noticed a vibration/rumble that feels to be coming from under the driver side foot rest area. The vibration/rumble is actually something I can hear as much as I can feel. It's most notable around 35 to 40 mph when I've been off the accelerator and then re-apply the accelerator. For example, I'll approach a sweeping curve around 35 mph, lift off the accelerator into the curve (low rpms) and then apply light acceleration out of the curve. As soon as I apply the accelerator I can both hear and slightly feel the vibration under my feet. If it's happening in any other scenarios, it's not something I've noticed.

I bought the truck in 2018 with approximately 43,000 miles. I'm not sure when exactly I began to notice it, but for the last several years I've solved the vibration/rumble by quickly "stabbing" the accelerator causing the transmission to downshift, which raises the rpm's and cleans up the issue.

A few months ago I was searching the forums and came across mention of MDS (didn't even know these trucks had it). There was a suggestion that using the gear limiter turns off MDS. For the past few weeks I've been selecting the gear down and then gear up until "8" shows on the dash and leaving it there. This does seem to really help the vibration/rumble.

Does anyone have any experience with this? Is my issue related to MDS or possibly the transmission? I'm trying to figure out what's causing the vibration/rumble and if there is a permanent fix for it.

 

[04fxdwgi]

4x4? check your front drive shaft and axle(s). Or maybe wheel bearings.

Very much more likely than MDS, especially since where it is felt

Yes, MDS can be turned off by pressing the (-) button on gear selector then pushing the (+) to any gear. Do it all the time.

 

[XCELLR8]

I feel its the MDS. My 22 4x4 has done this since day one (bought new). While driving at about 40MPH, light throttle, I get the slight rumble. I also get a surging of about 300RPMs also. If I turn off MDS by the gear buttons or tow/haul it goes away. I never noticed this on the other 3 4Gen Rams I had.

I have the 5.7/ 8speed and 3.21 gears in my truck.

 

[Bigskyroadglide]

My 14 RT RCSB RWD does something similar going down hill in 4th gear. It is my opinion it's the torque converter, not mds. I've employed a number of attempts to fix, from turning off Hill assist, tuning, both engine and transmission, to locking out mds to adjusting various transmission parameters, selecting different shift sequences and adjusting shift parameters. It is better but still happens.

I don't really want to drop the transmission to change the converter, as that may not fix it either, so I'm living with it. It does not do it all the time and I've learned when it happens and know in these situations it's going to occur. At speed or in normal freeway operation it is not present.

My experience may be greatly different than yours. As I'm supercharged, tuned, lowered and highly modified. My truck has done this from day one of ownership till now. I'm at 78k miles.

I have changed the fluid (@ 60k) with ZF fluid and new pan with no change.

My thoughts

 

[Jeepwalker]

Try repeating your same driving routine where you'd normally feel the rumbling (vibration), but with the MDS turned 'off' ...or not in 'Eco Mode'. Or just manually put in high gear (it'll still downshift if needed...just won't go beyond selected gear).

This is an oft-repeated complaint of the Ram MDS for many yrs. With my truck it is particularly noticeable when the road has been mostly flat and then gradually inclines..right about at the point before the truck has to kick in more cylinders or downshift for that extra needed power. But on most driving it's pretty seamless. Let us know what you find.

 

[Want to Drive]

4x4? check your front drive shaft and axle(s). Or maybe wheel bearings.

Very much more likely than MDS, especially since where it is felt

Yes, MDS can be turned off by pressing the (-) button on gear selector then pushing the (+) to any gear. Do it all the time.

Truck is 4x2. Is there any known long term issue with using the (-) and (+) selector to turn off MDS? I've been doing it the last few weeks and not having the vibration/rumble has made the truck much more enjoyable to drive. Most of my driving is around town/city driving at less than 50 MPH so that's where the vibration/rumble is felt.

 

[Want to Drive]

I feel its the MDS. My 22 4x4 has done this since day one (bought new). While driving at about 40MPH, light throttle, I get the slight rumble. I also get a surging of about 300RPMs also. If I turn off MDS by the gear buttons or tow/haul it goes away. I never noticed this on the other 3 4Gen Rams I had.

I have the 5.7/ 8speed and 3.21 gears in my truck.

I'm inclined to believe it's the MDS as well. Using the gear buttons eliminates the rumble for me also. I have the 5.7/ 8 speed. Unsure of rear end gear however.

 

[Want to Drive]

Try repeating your same driving routine where you'd normally feel the rumbling (vibration), but with the MDS turned 'off' ...or not in 'Eco Mode'. Or just manually put in high gear (it'll still downshift if needed...just won't go beyond selected gear).

This is an oft-repeated complaint of the Ram MDS for many yrs. With my truck it is particularly noticeable when the road has been mostly flat and then gradually inclines..right about at the point before the truck has to kick in more cylinders or downshift for that extra needed power. But on most driving it's pretty seamless. Let us know what you find.

I've been testing this the last couple of weeks in areas I drive frequently. I've been selecting gear 8 and as you mentioned, it downshifts as needed. Doing this has eliminated the rumble in areas of my drive where I notice the issue.

I wasn't sure if using the gear selector turns off MDS, but it seems it does.

Is the rumble caused by an issue with the MDS or is the rumble a symptom of a perfectly functioning MDS?

 

[Want to Drive]

My 14 RT RCSB RWD does something similar going down hill in 4th gear. It is my opinion it's the torque converter, not mds. I've employed a number of attempts to fix, from turning off Hill assist, tuning, both engine and transmission, to locking out mds to adjusting various transmission parameters, selecting different shift sequences and adjusting shift parameters. It is better but still happens.

I don't really want to drop the transmission to change the converter, as that may not fix it either, so I'm living with it. It does not do it all the time and I've learned when it happens and know in these situations it's going to occur. At speed or in normal freeway operation it is not present.

My experience may be greatly different than yours. As I'm supercharged, tuned, lowered and highly modified. My truck has done this from day one of ownership till now. I'm at 78k miles.

I have changed the fluid (@ 60k) with ZF fluid and new pan with no change.

My thoughts

Appreciate your input.