New rear end whinning, why?

[Go Hogs Go]

I've got a 3:23 sure grip with new gears, bearings, and it's set up to the proper specs. We've been in this thing twice and cannot get it to stop whining above 45 mph with the power on. It's quiet under 45 and whines above 45 with power on only. The wear pattern on the gears is perfect, ruling out the pinion depth and the back lash on the ring gear is set to 8 thousands. We don't know what else to do. Are the gears just breaking in, or do these things just whine sometimes? We've got about 500 miles on the car. There is absolutely no mechanical reason for it to whine.

[Ghoste]

Could be breaking in, how loud is it and how many miles are on it now?

[Go Hogs Go]

It's not really all that loud. It's probably got 500 miles on it.

[Ghoste]

I know it's hard to diagnose a noise this way but in this case it may not be a cause for concern.  All the same, if there is a good gear guy in your area who can give it a listen, it would only take a minute.

[Dans 68]

There is absolutely no mechanical reason for it to whine.

If there is noise then there probably is a mechanical reason. Did you add MOPAR Hypoid Gear Oil Additive Friction Modifier? Since it occurs above 45 mph the rotating mass may just be singing a bit due to harmonics. Give it another 500 miles to set-in and re-examine it. You may want to change the brand/amount of lube also. What is now in it?

Dan

[firefighter3931]

Some gearsets are known to be noisy. It's possible that it's still breaking-in.  I like to use 85/140 gear oil with the friction modifier...what are you using for lube in yours ?

I've also found that doing figure 8's in a parking lot will help loosen things up....especially if the suregrip unit is fresh....might be worth a try 


Ron

[Dans 68]

I've also found that doing figure 8's in a parking lot will help loosen things up....especially if the suregrip unit is fresh....might be worth a try 

Ron

Good idea. When I've changed my lube i've done figure eights, in both directions, to force the additive into the nooks and crannies. Do about 8 laps.

Dan

[Corellian Corvette]

That's funny - my tranny guy just gave me the same advice (do figure 8's). Seemes to have really helped (mine car is like JUST on the road so I have maybe 50 miles on)

[tecmopar]

Just curious, what brand of gears are they.

[Challenger340]

If no noise occurs generally only in 1 load direction;

On "coast", the pinion is pushed "out of mesh".
On "Drive" the Pinion is pulled "into mesh".

It would seem to be the Front Pinion Bearing.

[426HemiCharger]

Did you try "Sure-Grip" Lube?

It may be Hypoid Gear oil but I have never heard it called that name.

If lube doesn't do anything then check the clearance between the pinion and ring gears.  Did you modify it because it may whine of there is a locker kit installed.

[Go Hogs Go]

I'll check the front pinion bearing, we haven't done that. I can't remember what gear oil we used off hand. I'll check it out and try some figure 8's

[Hemidog]

I'll check the front pinion bearing, we haven't done that. I can't remember what gear oil we used off hand. I'll check it out and try some figure 8's

Did it work itself out? or did you find a problem?

I have the exact same symptoms as you, but my rearend have not been rebuilt while I've owned it.

[Nacho-RT74]

Some gearsets are known to be noisy. It's possible that it's still breaking-in.

well in my case, I don't think is STILL breaking in since is my driver. plus the whinning is from 0 to any speed, acelerating and releasing the pedal acelñerator... so EVERYTIME.

and yes, it has enough backslash