The Stovebolt Site Forums The Shop Area Driveline rear end noise

I have a 62 chev 1 ton panel with a ho 72 rear end. I've tried a number of different 3rd members to try to eliminate a whine from the rear that happens when the engine is working hard, the harder it works the louder it whines. When I back of the gas the whine decreases . I'm not sure if this is normal but accentuated by the fact it's a panel letting the noise resonate in the empty space in back.
I've had one 3rd member checked by a shop , who reported all was well with the unit, and spun the 2 others I tried while on the work bench and could hear nothing weird, even using a stethoscope .
I've tried deep purple rear end oil as well as conventional 80 weight with assorted mixtures of Lucas oil treatment. When the rear end was out I checked the wheel bearings as well and all was well there. None of these rear ends are positrac. I don't think it the tranny , a t 5 as the whine increases as I go through the gears.
Any input would be appreciated .
Thanks John

If it is a high pitched, it is pinion bearings, low pitched like wheel rpm is carrier or wheel bearings.

Ed

Sure it's not coming from the transmission or drive line? Hard to believe you have three third members with bad bearings. I had a '85 dodge pickup with a bad tail shaft bearing, I had the pinion out looking for bad bearings and found nothing. The driveshaft can transfer noise pretty good!

Did you pull the covers on the rear ends and check the bearing, check for funky gear wear pattern, missing teeth, back lash check and pinion depth check ???????

The very used HO52 with 4.11s I bought had a bit of pitting in the ring gear. It's a little noisy, not a lot but annoying just the same. I originally filled it with 85/140 (as I recall), then after a couple hundred miles drained a quart and added a quart of Lucas. That helped but the rearend was still making noise so I added a small blue bottle of STP one of the original viscosity additives....better but not as quite as I'd like.

I think I'm going to drain the above cocktail out and try this, Swepco 203 Moly XP Gear Oil 250 wt./ISO 1000 1 Gallon (New XP Formula). It's used in lots of high hp transmissions and rearends. The moly additive should help cushion the ring gear and quiten things. We'll see.

Of course in a perfect world I'd change the ring gear and pinion, but that's not gonna happen.

RonR

Grab the pinion flange & check for any looseness. Pry the carrier assembly side to side & check for any play in the brgs. If that is OK check the tooth contact pattern. It does seem strange to have 3 different ones & still get noise. If it has has a driveshaft carrier brg. make sure it is good.

r
Thanks for the input, While trying to eliminate the whine which sounds similar to the old trannys with straight cut gears I'm also messing with different ratios. When I finally decide on a ratio, I'll have the 3rd member disassembled and see what I can find

The HO 72 is a great, rugged rear end, but the ones I've dealt with all seemed to have a little gear whine. There is an adjustable side thrust bearing on most of the ones I've seen, with a brass disc that bears against the side of the ring gear with an adjusting screw and a locknut on the driver's side of the carrier housing. It's there to prevent the ring gear from deflecting when pulling a heavy load. To minimize ring gear flex under load, loosen the locknut and very gently turn the adjuster clockwise until you can feel the thrust button contact the ring gear, then back off ever so slightly so it's not rubbing the gear all the time. Tighten down the locknut and you're good to go!
Jerry

You may be hunting a ghost that doesn't exist. As you stated in your fourth sentence, the sound may just be resonating in that giant empty metal box. Every bare boned delivery type van I have ever driven made a loud rear differential gear whine sound when the cargo area was empty.

I agree with Paul. I had a 66 C-20 that had a moderate amount of rear end noise with regular driving. It was however much louder with a camper and crawl through boot installed. I thought mine was loud until I drove one owned by my father in law. He had it "fixed" but It still sounded like a fire truck was following it. He put about 250K miles on it and it still worked when he sold it.
Fred