Tow Vehicle Rearend Noise 3500 Chev Dually
 

Chevrolet 3500 series dually, 2000 year model 7.4 engine---GM rearend 4.10 ratio---owners manual says it requires synthetic rear end grease when replacing. I'm hearing a high pitch "sing" between 60 and 65 mph...just enough to get your attention if the CD player is not loud enough, 40,000 actual miles, is there an additive that might help this and is there any need for alarm outside of just an annoyance ????

Rusty anytime you here a noise that wasn't there before it is a cause for concern. You can do a little diagnosis yourself first. Try driving the truck at the speed the noise is most noticeable than moving the streering wheel back and forth and see if you can change the noise . That will indicate a wheel bearing or side carrier bearing problem. Then left off on the throttle and accelerate if the noise changes you may have a pinipn bearing or ring and pinion concern. I don't believe in snake oils to fix noises. Better off and have it looked at.

it makes this "singing" during "load" or acceleration periods.

If luck is on your side it sounds like the front pinion bearing. Get the rear cover off and look for any signs of metal flakes in the oil. Do a disassemble of the differential looking at the races and bearings closely. Replace them as necessary. Make sure you use the correct synthetic oil upon completetion. As far as noises in rear axles go, it won't get any better by ignoring them.

Re: Tow Vehicle Rearend Noise 3500 Chev Dually
 

I have a 96 GMC 3500 and I had the exact same problem. The small pinion support bearing went south. Never knew there was a problem with it until I got to approx. 72 - 75 mph and was getting a strange small vibration. I believe all those rear ends in that time period had a small whine to them anyway. I know a few guys that have complained about the same deal. If you catch it quick enough you havent ruined any of the other bearings in the housing. I didnt take mine to a dealer to have it fixed. The prices were outta sight. Went to a truck repair shop. Freightliner dealer took care of it nicely and saved some bucks!

Re: Tow Vehicle Rearend Noise 3500 Chev Dually
 

Do yourself a favor, if you are going to do the repair yourself, check and record the backlash so the ring and pinion will go back into the same wear pattern. If you don?t set the backlash to the original number that you had before disassembly you will end up with a VERY NOISY rear end.

Use the same pinion shim so you also have the correct location for the pinion in relation to the ring gear.

Just a heads up,
Bob