Well I looked through all of the old posts and have found contridicting statements. This is the question I have a 7.5/7.625
I installed Richmond 3.73 gears on my series 2 factory posi, I used the old bearings because they looked fine. I also installed a solid pinion spacer. I get a whining when i let off the gas (coasting in drive or neutral). I took the rear back apart and checked everything out. Everything looks cool, (No abnormal gear wear or bearing pitting/wear) I noticed that my backlash was a little bit too much so I tightened it up. It is about .006". The rear still whines. I read some post that say that the gears are set up improperly, and some say that they have the same problem. Whats the deal? Should I be concerned?

 

Mine done the same thing. Dont be concerned. All richmond gears whin. Its the way they are made. The whin will slowly go away after you break the gears in.

 

richmonds tend to make more noise because of the way the gears are cut for more strength. running more or the max back lash will/might help. did you follow the break in procedure?

 

You'll never get them quite. Either deal with the noise or switch brand of gears.

 

I just got my Richmond 3.73 gears and Eaton Posi installed and it whines too......everyone has told me it is normal.

 

yeah, my friend has richmond 3.90's in his 76 355 camaro and it whines...

 

Im Glad to know that I am not the only one with this problem. Thanks Guys!

 

The gears ARE NOT cut any different than anybody else's gears.

The reason for the noise associated with Richmond Gears is related to the material hardness. All of Richmonds gears, with the exception of thier high impact gearsets used for racing, rockwell out really, Really hard. That in itself changes the resonate frequency of the metal.

You either get lucky or you dont when you install Richmonds, and changing lash is about the only way you will be able make a difference. But you will not get rid of the noise, by changing lash it will just change amplitude or the frequency (or the harmonics thereof).

The best gearset to use in a 7.5, or any other differential, IMO is USGear/Strange....or Precision Gear. USGear is the OE manufacturer for GM since the 50's and Precision bought all of USGears earlier manufacturing equipment, so the product is virtually the same. The are quite, easy to set-up and the only thing that I found that will live in a 7.5" in the cars you drive.