i have a 2004 reg cab 2wd with the 9.25 rear end, the rear end is whining from 30mph to 65mph. it only does it when im on the gas. as soon as i let off it goes away. its definatley in the rear end as i had to replaced the whole thing at one point cause my pinion gear snapped in half and caused lots of damage, i also had to replace all the bearings and seals in the second axle. the noise didnt start untill the replacement axle was installed, i have adjusted the backlash and used different oils, the whine will change a little but never goes away. any ideas on what else i could check or do would be greatly appreciated, this noise is driving me nuts

 

If the bearings were fresh in the replacement diff, and your pinion pre-load has been set correctly, then it could be your gear mesh causing the noise. You can have correct backlash and incorrect gear alignment! Did you put marking compound on the teeth and see how the pinion is making contact with the ring gear? Most gear whine on Accel, is from incorrectly meshed gears and/or backlash at the speeds you have stated.

What about the pinion angle? Is it possible with the new rear end installed the pinion angle has changed?
Just some ideas. I'd get some other opinions before you tear back into things.

 

yea i marked the teeth on the ring and it looked like a good contact pattern, gonna tear it back down today and see if there's anything i haven't checked like pinion preload and other stuff like that, ive looked through this forum and this seems to happen alot on this generation of ram with the 9.25. hopefully i can get it figured out so that that i know what to tell the rest of the guys with this problem. if i cant get it then i hate to say it but I'll have to take it to a rack and axle shop

 

Well, the pinion pre-load must be set and checked with the axles out. So, unless your willing to tear off both side brakes/calipers/axles, checking the pinion pre-load isn't going to be correct since the axles add additional drag to the carrier.