[cleary524]

The old silver Mag Wag is still alive and well. This car has been through so much over the last 15 years! Following my timing disaster back in 2016 car has pretty much run flawlessly for the last 35k miles. Back around the beginning of September we had some really heavy rains I had to drive the car through and shortly there after around 9/20-9/25 or so, I started noticing a little pulsing in the drivetrain under low RPM, light throttle load while going 40-50 mph.

Then around the first week of October it started becoming a little more pronounced. The low RPM shudder seemed to occur mostly between 5th & 4th gear, while driving in the 35 mph to 50 mph speed with light throttle. At those conditions the shuddering seemed to surge the car while driving, making it feel like it is bucking. Put down on the throttle and make the gear shift, engine responds find and smooths right out.

So poking around here on the forum, I see the MAP sensor, the Cam Position Sensor and the Crank Position Sensor as all possible suspects. So I replaced all three sensors with only a little bit of improvement with the Cam Position Sensor (car starts a lot easier/quicker now). Changed the oil & filter, then changed the plugs (was overdue on the plugs by 95k miles...opps). Plugs looked great, just worn down some, but all clean, no oil, not unusual observation of detonation or fouling. As mentioned, aside from the low RPM range (1,000 to 1,600 RPM), runs as it should....great!

Looking a little more into what could be causing this, I've never had the following TSB performed:

TSB#: 21-011-05

Date: April 23, 2005

Models: 300/Magnum/Charger/Grand Cherokee (WK w/3.7L, LX w/ 5.7L, or LX AWD w/3.5L) equipped with a NAG1 (W5A580) transmission (sales code DGJ).

Model year: 2005

SUBJECT: NAG1 (W5A580) Transmission - Shudder When Torque Converter Clutch Engages

So, thinking back to early September when we had a lot of rain, it is possible that the O-ring around the tranny fill tube has let some water in? I'm due for a trans fluid change and I never had this TSB completed. I did a full 13-quart trans fluid & filter change at 60k miles like 12 years ago and I'm 136k on the clock now. Fingers crossed this is the culprit for the low idle shuddering/surging that is occurring?

Anybody older members on here still, that have experienced this condition in the past?

Cheers, hope everyone is well!

Long live the Magnum!!!

 

[Hemihackman]

Yes, that is the most likely cause. Drop the trans pan and see if pink film is there. May need many trans flushes to correct.

 

[RobsSXT]

Mr. Cleary524- I've been around a minute so I'll chime in. Any fluid in the transmission is going to be a separate issue from the transfer case TSB (which I had done years ago). They are not connected or intertwined in any way. The TSB is a design change inside the transfer case that stopped or prevented a low speed shudder when turning at a tight angle, for example parking lots.

You need to check your transmission fluid. ONE. SINGLE. DROP of water will exhibit those symptoms. Absolutely any moisture in there is bad news. I'm really, really leaning towards water getting in there last September.

Ok, there is good news though. Get that water out now and you'll be able to save the transmission.

 

[cleary524]

Yes, that is the most likely cause. Drop the trans pan and see if pink film is there. May need many trans flushes to correct.

Mr. Cleary524- I've been around a minute so I'll chime in. Any fluid in the transmission is going to be a separate issue from the transfer case TSB (which I had done years ago). They are not connected or intertwined in any way. The TSB is a design change inside the transfer case that stopped or prevented a low speed shudder when turning at a tight angle, for example parking lots.

You need to check your transmission fluid. ONE. SINGLE. DROP of water will exhibit those symptoms. Absolutely any moisture in there is bad news. I'm really, really leaning towards water getting in there last September.

Ok, there is good news though. Get that water out now and you'll be able to save the transmission.

Having the transmission serviced on Thursday (11/10), fingers crossed!

Rob, I had the transfer case shudder problem years ago. Got that taken care of. This is different. Hopefully the trans service fluid flush & filter will remedy it. Otherwise, she runs pisser!

 

[cleary524]

Had the transmission fluid flushed (13-qts), filled and filter replaced today. Improved the condition considerably, but unfortunately still ever so slightly present. Wonder if there's still some remnant water possibly still in the transmission?

Had them do the TSB for the dipstick tube gasket/RTV sealant too.

Little concerned, if this condition will do damage over time?

 

[Jim McVeigh]

I had that problem on my Ram SRT-10. It was the driveshaft center bearing.

 

[cleary524]

After more than a week of adding some miles the condition stayed about the same, 80% better after the fluid exchange & filter.

So after a little research here on the forum, I found an old thread that mentioned use of a friction modifier to the trans.

So I gave it a try. I bought a 4-ounce bottle of the Mopar differential friction modifier, pumped out 3 ounces of trans fluid from the fill tube and added just 2 ounces of the modifier. Low and behold the shuddering smoothed right out. Topped off the trans fluid with another ounce of tranny fluid and we're good to go.

Fingers crossed! Trans feels nice and smooth again.... Amazing.