While driving my truck, I get a hum sound at around 45 mph while in the gas, not coasting. You loose the noise when you go below 40 or over 50. Any thoughts on what it could be? It’s going to the dealer in the morning to be checked out. I will take the mechanic for a spin so he can hear the hum. Thanks, Red

’07 ram 1500 regular cab with hemi and auto trans with 2,000 miles.

 

Yes. I have replace the ring and pinion gear set six trucks with the same problem that you are having. And set the back lash justunder factory specs. specs is .04 to .06. I set back lash to .03.

 

It is going in on Monday to have the ring and pinion gear replaced. The noise is starting to drive me nuts because I usually drive at 45 mph going to work. Thanks for the feedback. Red

 

Just dont drive 45 mph

 

Just to update, they replaced the ring and pinion gears but it did not fix the “hum” even with the backlash adjustment stated above. Today they ordered me a new factory complete rear axel to replace the old one. They say it may be warped or just defective. I’m cool with a new factory axel. Just fix the darn thing so I can enjoy my truck. Red

 

Hmm, my new truck has this too. The hum is not loud at all and it only occurs when under light throttle at 45mph. I figured it was the MDS system. I didnt notice it coming home this evening and my truck has only 200 miles.

My guess is that since it is only at 45mph, and that both of our trucks have this, that its not a mechanical part causing the noise. If it was a mechanical problem in the motor or tranny, then it would be rpm related, not speed related, and the motor hits the same rpms at other speeds in differnt gears.

I think when you are cruising at 45mph, the truck doesnt need as much power and it can go into MDS cutting off 4 cylinders.

Let me know if the dealer does something to fix the problem. Dealers are happy to do warranty work because they get paid, doesnt mean they know what the problem is or that there is even a problem. The suggested ring/pinion gear didnt fix the problem and the mechnic says he has done this on a handful of trucks.

 

Do you have the anit-spin rear axle? I do.

 

Hopefully this is the final update to my truck differential hum. Today they replaced the entire rear housing assembly with a brand new factory assembled unit. It’s just like driving a new truck all over again. She is still new, only 2,500 miles since March. So far she is nice and quiet like she should be. Now I can enjoy my truck without the noise. Red

 

My rear end blew at 45,000 miles. They replaced it with a new one also a Posi (anti-spin). Now around 40 I get a slight hum aswell. Idk what it is but I dont really want to bring it back unless it becomes a big problem, I have the powertrain warranty until 70K and 2010. I would like to know what the problem is though.

But I only hear the noise when im not on the gas.

 

Thanks for letting us know what it is. I'm going to see the dealer about this.