98 Ram 2500 Auto Trans, 5.9 Gas, 3 inch lift, 35s

Need a little help trying to figure out what this might be. There is a hum/whine coming from what I believe to be the tranny or the rear dif maybe? It only happens when you're cruising and take your foot off the gas, as your coasting. If you give it gas again it goes away. And no, its not the tires for you wise guys.

 

Have a look at the fluid in the rear diff. Also check for pinion slop.

 

ditto...I had the same noise and it was my pinion bearing that had failed in the rear differential... had it rebuilt along with new clutchpack for the LSD and its been quiet ever since. now would be a good time to correct the gearing in the differetials to match the 35" tires while your in there...(If you havent already) Your transmission and gas mileage will thank you as well as make the truck more fun to drive. (Nice truck, my truck looked just like yours when I bought it minus the bumper being all black...)

 

thanks for the input guys Ill have to check it out. auggiedoggy thanks you've got a sweet rig there yourself. how much was it to have it rebuilt? Gears are defintley in the works soon but unfortunately my tires are bald right now so tires have to come first=/(Sigh) Im an 18 year old in college right now so my budgets pretty tight, I'm assuming you have the 4:11s? how much did that setup cost?

 

Go 4.56's with 35's.

 

Does it do it at all speeds, or just at certain speeds? Mine makes a noise similar to what you describe, but it is only noticable when I get above about 70 mph, and then coast. Less then 70 and I don't hear anything. Mines been doing it for over 3 years now too. Started about the same time I got my new limited slip and 4.56 gears installed back in 2008. I had the shop that did my gears look into it, but they said they didn't see anything wrong. Since I rarely drive over 65, it hasn't really been a problem for me, and so much time has passed since I first noticed it, I kinda just haven't worried about it.

 

Silver_Dodge, it doesn't do it at low speeds but above like 30 id say and it does. and do either of you know how about how much 4.56s would run? and how does it affect gas mileage both low end and top end

 

Expect about $1500 parts and labor. It will help you fuel economy if you are running 35's with stock gears today because your engine and trans will not have to work as hard to get things moving. I had 4.10's when I first installed my 35's. Power and fuel economy improved when I went to 4.56's.

 

ditto .... I have 4.56 gears too... it cost me like $400 in labor and close to that in parts for a master rebuild kit for both the diff and the LSD..

 

pretty steep, worth it though so guess its time to start saving up once i get tires haha. thanks a lot for the input guys