whining rear

[roadrunnerh]

So for my 8.75 swap in my '75 Scamp, I purchased a used 741 open case with 3.55's. I replaced the pinion seal, the gears looked good, I measured the backlash and came up with .010" (not bad for used gears).
After installation, the rear whines. :brickwall: Not a howl and no grinding sounds, just a high pitch whine.
At highway speeds it stops when coasting and when I apply the gas pedal it starts. This is behind a 225/904 currently, with plans for a 383/727 in the near future.

Someone suggested that this was a pinion bearing noise. Any other thoughts? Is this carrier going to scatter? I was going to drive this to Carlisle this summer 180 miles from Pittsburgh. Now I'm not so sure.
Any input is appreciated.

 

[abodybill]

Harry,
Yep you got a bad bearing in the case.

When you let up on it and coast the load is off and when putting aload on it makes it whine.

Only get worse how long never know.

Would I drive it yep play the odds

But,
I know I would not just put in new bearings.

I would have the whole unit rebuilt gears,bearings and seal and be done with it :cents:

 

[ACME A12]

But, I know I would not just put in new bearings. I would have the whole unit rebuilt gears, bearings and seal and be done with it :cents:

And add a SG while you're at it.

 

[moparchris]

So for my 8.75 swap in my '75 Scamp, I purchased a used 741 open case with 3.55's. I replaced the pinion seal, the gears looked good, I measured the backlash and came up with .010" (not bad for used gears).
After installation, the rear whines. :brickwall: Not a howl and no grinding sounds, just a high pitch whine.
At highway speeds it stops when coasting and when I apply the gas pedal it starts. This is behind a 225/904 currently, with plans for a 383/727 in the near future.

Someone suggested that this was a pinion bearing noise. Any other thoughts? Is this carrier going to scatter? I was going to drive this to Carlisle this summer 180 miles from Pittsburgh. Now I'm not so sure.
Any input is appreciated.

A high pitch whine is a gear issue. If you dont get the pinion depth set up right then it will whine. It has to do with the gear contact (the pattern is running off the end of the tooth). More than likely it was noisey before you ever bought it. Bill is right about the pinion bearings but it would be a groaning low pitch. I wouldn't spend much on a 741 case. I would buy a 489/742 core and go for it. The 741 is actually a good case but cores are cheap and you can sell of this 3rd member to recoup your costs.