Car Rear End Gear Whine???

[trailrider894]

Hey guys, I have a 1979 Chevy Monza Spyder with a 5.7l Vortec V8, 5-Speed t-50 Burg Warner Tranny, Posi Rear End, w/ CAI, Shorty Headers( long tube wasn't an option because of the car size... :eek2:), Single 3" to a Cherry Bomb Glasspack ( soon to be replaced with a different muffler just haven't chosen yet), Edelbrock Thunder Series Carb w/Edelbrock Intake and Edelbrock Cam, ( i can't find the specs on the cam, anymore i forgot them. )

ANYWAY.... I changed the rear end gears from 2.57's to Richmond 3.23's and now the rear end whines a little but when you aren't acceleration, just when cruising or de-accelerating. It could just be the way its gonna sounds since the differnt processes in making it. Its is just annoying because people outside can hear it, also there is alittle slop in the axle and it makes a chunking noise when you are just riding in a low gear, for instance when looking for a parking spot, everytime the cam lopes it makes the car lurch forward and then it makes a chunk noise like something is hitting something else... This car is one heck of a engineering feat for me. Lets just say a 350 isn't supposed to fit in a car that barely weighs 2900lb's.

[CJM]

Could be the following:
More likely
-Rear wheel bearings
-Gears in the rear could be going
-You mention you have a posi, do you have a true locker where both wheels spin with no differentiation around turns OR do you have a limited slip. If its a limited slip you may need some limited slip oil (I forget the proper name), add it to the oil in the diff-see if it goes away.

Less likely
-Bad/Bent axleshafts-but that would cause a definite vibration
-Bad u joints-but that would also cause vibration.

Do this:
1. Take the tires off the while its jacked up. Grab the axle shaft-might have to remove the drum or disc (whichever you have) and yank on the shaft a bit. It should have very minimal if any play. If it does have play you may have a bad bearing. Also might as well pull the shafts and check for wear on the end of the splines if you can.

2. Pull the cover off the rear (if you can on this thing) and check the gears, look at the teeth-are they chipped/messed up? Does the gear oil appear shiny like flakes of metal are in it?

To me it sounds as if the rears bad, you note clunking and a high whine. The clunking would be the teeth on the gears hitting each other.

[wild250rman]

did you change the whole rear end or just the gear set. sounds to me the backlash is to loose on the coast side causing the winning noise. remove the diff. cover and inspect the teeth for wear and see were the teeth are riding on the pinion and ring they have a paste at your local auto parts to check the tooth pattern set up, you also need a mic. set up to check your back lash clearances and an inch pound torque wrench to check the pinion out put shaft play also did you use a new crush collar on the pinion or did you use the old one. maybe it is not crushed properly and the pinion is still to far back on the ring gear.

[wilkin250r]

I'm kinda with wild250rman on this one. The combination of the whining, plus the clunking, it sounds like you've got slop somewhere in the ring and pinion.

The clunking is likely because the teeth of the gears aren't meshing properly, they don't fit tightly, there's a gap between them. When you lurch, the teeth move across that gap and hit each other.

[HondaPohl]

Check backlash. Also when you put on the yellow paint or shoe polish or whateva you use to check your wear pattern, you have to put torque on the pinion.

[8secnotch]

I'm also kinda with wild250rman to a point. What carrier are you useing? How did you set up the gears and to what specs did you go by? What did you use to set back lash and pinion depth. Also what did you torque your crush sleeve with and to what ftlbs. I set up alot of rears and most of the time the person who builds the rear just uses a 1/2'' inpact to set the pinion and crush sleeve and most of the time the ring gear depth is way off and most think the shims that come out to shim the carrier have to go back in the same way not the case, but that will give you what your explaining. If it was me I would just take it all apart and start from scratch. Gear are pretty tough but if you keep driving it like that your going to be putting in new gear sooner than later. Your going to need a dial indicator and a back lash gauge. It has nothing to do with the diff fluid your useing.

[trailrider894]

Well here is the deal, I checked the backlash and everything. It all comes down perfect within the margins. My dad who is a GM Master Tech of 25yrs who has rebuild 100's of rear ends helped me put it back together and he used his MIC setup for rear ends and he said it was all perfect, even the tooth wear on the gears are PERFECT. Everything is exactly to spec. All the torques and everything. The magnet on the cover is clean and the oil ran clean also.

CJM, it is a Limited Slip, not a true posi. The rearend was rebuilt completely less than 200 miles ago. I just finished rebuilding the car with my father, on my weekends back from college. I was told by him that it could just be needing a break in as far as the whining, and he said that the chunking noise could be caused by the Gears because they are made using a differnt process, and thats the same thing a friend of mine who has dragged raced for years told me. ( he was on Pinks All-Out)

[CJM]

Hmm.

You did add a LSD additive tho when you put the gear oil in tho, right? I had an old F truck that made all kinds of whining, checked the axle code (fords makeit easy lol), found it had the LSD, put the additive in and no more noise.

Id say if everything is clean inside, no wear or noticeable issues with the teeth, Id try some additive to be sure. Cant really hurt.

[wilkin250r]

I'm not the best driveline mechanic, so I don't know for certain, but I HAVE seen different ring and pinion brands advertised as having more noise than others. Maybe that's what you've got.

[trailrider894]

Originally posted by CJM
Hmm.

You did add a LSD additive tho when you put the gear oil in tho, right? I had an old F truck that made all kinds of whining, checked the axle code (fords makeit easy lol), found it had the LSD, put the additive in and no more noise.

Id say if everything is clean inside, no wear or noticeable issues with the teeth, Id try some additive to be sure. Cant really hurt.

Can you give me some brand nmes that make this stuff?

[CJM]

Thing is tho, the clunk/[oping your getting indicates bad backlash imho. The additive would only cure whining.

Try some amsoil slip lock if you can find it, but generally any parts store should have "lsd additive" by the oil, I know pepboys does. It also goes by the name (finally remember) "friction modifier"

[trailrider894]

Originally posted by CJM
Thing is tho, the clunk/[oping your getting indicates bad backlash imho. The additive would only cure whining.

Try some amsoil slip lock if you can find it, but generally any parts store should have "lsd additive" by the oil, I know pepboys does. It also goes by the name (finally remember) "friction modifier"

Thanks man!! I'll try to get my dad out here with his MIC again to measure that again...

[8secnotch]

Im also a GM tech and if your explaining whats going on correct with it clunking around and its not set up right. Alittle whining is normal untill you get a wear pattern set in the gears but it should go away in a few miles or so. Have you checked the u joints in the drive shaft? If you have and there both good disconnect the drive shaft from the rear and twist the rear driveshaft yoke and see how much free play you have there. If you have anything more then like a 1/2'' max your not set up right. If its nice and snug and feels smooth I would look else where for the noise.

[trailrider894]

Originally posted by 8secnotch
Im also a GM tech and if your explaining whats going on correct with it clunking around and its not set up right. Alittle whining is normal untill you get a wear pattern set in the gears but it should go away in a few miles or so. Have you checked the u joints in the drive shaft? If you have and there both good disconnect the drive shaft from the rear and twist the rear driveshaft yoke and see how much free play you have there. If you have anything more then like a 1/2'' max your not set up right. If its nice and snug and feels smooth I would look else where for the noise.

Well, i put about 50 miles on the gears today of just street driving and what not. The whining sound went away all nearly all together. The clunking is much less often than it was. I did change the gear oil from a 75w90 to a 75w140 Synthetic, so that might have helped. The drive shaft is smooth and has hardly any play, it is almost non-existant. And CJM, just an FYI I talked to my Father about the Limited Slip, and he said " its an older style Posi-Track, so its not a true Posi-Track, because sometimes the wheels don't track like they should around corners because the design of the posi doesn't always work. " So maybe that helps...

[CJM]

Sounds like its more of a locker than a posi then. Do you notice if you gun it off the line while trying to turn it wants to keep going straight?

This would explain why it clunks as well-thats your locker in the rear unlocking/locking back up.

[trailrider894]

Originally posted by CJM
Sounds like its more of a locker than a posi then. Do you notice if you gun it off the line while trying to turn it wants to keep going straight?

This would explain why it clunks as well-thats your locker in the rear unlocking/locking back up.

Yes... It definetly doesn't like powersliding. lol

[CJM]

Thats why your getting that clunk then, its the locker unlocking/locking.