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Username Post: '79 Monte Carlo differential "whine"        (Topic#363685)
Mincom79 
Newbie
Posts: 3

Loc: South Carolina
Reg: 12-10-20
12-19-20 08:36 AM - Post#2810341    

Hello to All,
As a new member, thanks for inviting me to join ChevyTalk. I would appreciate your advice regarding my first post as follows...
After my 40K mile, bone stock '79 Monte Carlo had its limited-slip rear end rebuilt, a "whine" recently developed at 38-45 mph.
A reputable local garage replaced pinion bearings and both axles, yet the whine remains.
They think it's the ring & pinion gear set that would need replacement to stop the whine (and erratic wear on the gears). Any thoughts ?
Thanks in advance !
Martin (Mincom79)



 




wagonman100 
Site Ambassador
Posts: 15003

Loc: Baltimore, MD
Reg: 11-27-04
01-01-21 12:00 PM - Post#2811122    
    In response to Mincom79

Whines are usually caused by the ring and pinion having the wrong spacing. You probably don’t need them replaced, just correct the spacing by changing the shims to move the ring gear further away or closer to the pinion gear. The contact pattern should be checked with marking compound or bluing. The backlash should also be checked and the pinion bearing preload should have been checked when the bearing was replaced.
https://www.youtube.com/watch?v=dAqAqODmcj4


Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
sz0k30 
"12th Year" Gold Supporting Member
Posts: 523
sz0k30
Loc: Oakland Co., Michigan
Reg: 10-12-08
01-13-21 10:46 AM - Post#2812011    
    In response to wagonman100

I've always heard that you can't adjust the whine away. The only way to get rid of it is to replace the gears.



 
wagonman100 
Site Ambassador
Posts: 15003

Loc: Baltimore, MD
Reg: 11-27-04
01-14-21 03:05 PM - Post#2812086    
    In response to sz0k30

It may depend on how many miles have been put on the gears while they were whining. But I am certainly no ring and pinion expert. Whining at certain speeds can also be a bearing failure. Here’s another good article:
https://fuelandfriction.com/weekend-warrior/under s...

Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
Mincom79 
Newbie
Posts: 3

Loc: South Carolina
Reg: 12-10-20
01-18-21 11:00 AM - Post#2812330    
    In response to wagonman100

Thank you all for your replies !

We found (today) that the ring & pinion gear set had a wear pattern, requiring an original GM replacement, specific for 1979 "G body" Monte Carlo, Malibu, or El Camino as follows:

- 10 bolt, limited slip differential
- 48 spline (teeth) ring gear
- 21 spline pinion gear (stamped ID: GM3pu)

While I search salvage yards, does anyone suggest an OEM parts source other than Summit ?
Please advise. Thank you !




 




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