Grinding Sound at Specific RPM/Speed

Question

I have a 2011 Ram 1500. For about a month I thought I was hearing a clunk between 2nd and 3rd gear. I finally decided to listen carefully by turning my radio off. I now certainly notice it, but it is very specific. It is more of a grind than a clunk when I listen closely and comes from the front of the truck. It is not between 2nd and 3rd gear, it was just a coincidence (I think). It happens before shifting as well.

That is when I noticed it only happens when I am accelerating very slowly and maintaining a low RPM. (I would guess around 1500 RPM). The constant seems to be the speed. It seems to happen between 24-26 MPH, which just happens to be when it shifts sometimes. If I accelerate too hard I never hear it. If I don’t accelerate at a constant speed, then I do not hear it. So at a constant RPM, right around 25 MPH, I hear the grinding sound. It only lasts for a split second. I can almost always repeat the sound if I accelerate correctly.

The only thing is, today, I heard the same noise at about 17 MPH while accelerating after a turn. I also thought (not 100% sure) I have heard it at faster speeds a couple times (40+ MPH), but the traffic/wind is too loud to know for sure.

Does anyone know what this sound could be? This is my first question, so let me know of any edits or information you guys need. I am just guessing the motor or transmission. All I know is it is coming from the front of the truck.

Answer 1

Your best bet would be to have someone in the truck (in park, with e-brake on) to hit the gas while you are under the truck. Make sure they know what sound to look for first, and when the sound happens, have them try to keep it going so you can determine where it is coming from. Since it seems to happen at a specific RPM range, you should be able to replicate it while it's in park.

Also, if it happens while it's in park, you can pretty much discard the transmission as the source. It could quite possibly just be something loose under there that only rattles when a certain pitch resonates (this happens with heat shields a lot), but again, it's impossible to tell until you get under there to determine the origin of the noise.

Answer 2

Definitely not caused by the cold air intake. This sounds like a tranny issue. Your truck is a 2011 ram 1500, which I believe was the last year using the 545RFE tranny. My 2004 Dakota has the same transmission, a 545RFE, and I have the EXACT same issue, quiet grinding on acceleration, always at about 1500RPM, ONLY in 1st and 2nd gear, then a “clunk” into 3rd sometimes. Very rough sometimes, and sometimes quite smooth. Varies a lot. I personally think Dodge has sold a faulty transmission as many Durango’s and Jeeps with the same 545RFE, have the same problem. I think Dodge really screwed up bad when they built and designed this tranny. Could just be a design defect, but I think they should have issued a recall on it.

The 545RFE was in use from something like 02 or 03 until 2011 or 2012, but your 2011 Ram 1500 definitely uses the 545RFE, basically identical to the one in my 04 Dakota. I personally think it is a poor design of the tranny, not sure what is causing it, but they messed something up when designing it. Always have plenty of fluid in my tranny too, fluid is still a good colour, I think it may just be a poor design and they refuse to acknowledge their own failure on building the 545RFE.