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Grinding Noise From Rear of Car When Turning

Started by Bentley, October 24, 2014, 01:21:14 PM

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Bentley

Hello Everyone,

I have a '68 DeVille and lately I've noticed a grinding noise coming from the rear of the car when turning a corner. It only happens when I turn right, and it's more pronounced when turning and going up an incline, such as pulling into a driveway. Does anyone have any idea what could be causing this? Thanks.


Wes
Wes Bentley
CLC # 30183

Dave Shepherd

#1
Tough to diagnose noises remotely, barring something like the exhaust hitting the body or more likely the driveshaft, could be an axle beaing.

mgbeda

Could be the drum brakes.  When turning the side load moves the wheels very slightly and could cause parts not usually in contact to grind.  Also could be differential gears, driveshaft bumping something, exhaust bumping something, etc.

-mB
-Mike Beda
CLC #24610
1976 Sedan DeVille (Bessie)

Steve Passmore

Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

Fred Pennington 25635

If you have a limited slip also called posi-trac differential you must add a friction modifier to the oil to keep it from making noise.
The additive loses it's effectiveness over time.  If you have this type of rear end, change the oil and replace the additive.
DON"T let the fast lube places change the oil. They will tell you they have oil that either has the additive in it or doesn't need it, BS.
Good parts stores carry it, even Autozone. About 4 oz will do it.
Fred Pennington, CLC 25635
1940, LaSalle 5019
1940 LaSalle 5019 parts car
1968 Ford Bronco
1973 Mustang Convertible
2012 Shelby GT500

harry s

I'd pull the other brake drum just to be sure it is not telegraphing to the other side. If no luck there could be the diff.    Harry
Harry Scott 4195
1941 6733
1948 6267X
2011 DTS Platinum

Jay Friedman

I agree with S Passmore that it could very likely be a rear axle bearing. 
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

Scot Minesinger

Mileage might be helpful and history too.  If you do not have "controlled differential" (limited slip/posi and etc.) then we can rule that out, but if you do it is something to strongly consider.  I think if you have this option their is a sticker in the trunk explaining it, certainly VIN would let you know.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Dave Shepherd

I do not think the vin shows what type of diff you have.

Mike Josephic CLC #3877

When a posi-traction differential was put on the car, didn't they have a metal
tag on the "pumpkin" that stated so?  I remember GM did that on Chevy's so
I expect Caddy would have also.

Mike
1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

35-709

#10
For 1973 there will be a "G" in front of the ratio code stamped on the front of the differential if it has a controlled differential.  We might be able to assume it is the same for a '68, it is in the shop manual.

If it DOES have a controlled differential, I am with Fred Pennington.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

Dave Shepherd

If you can jack up the rear turn one wheel forward the other wheel will also go forward if controlled diff is in place.

The Tassie Devil(le)

One way of checking for a bad axle race is to drive turning left then right, and loading up the suspect bearing.

Most every time, the bad bearing will be the one that is under the most load.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Bentley

I'll check if I have a controlled differential, and then change the oil. I haven't done that since I've owned the car, which has been 14 years now. So it's probably a good idea anyway. Do the 68's have a differential gasket, or do you just use the Permetex stuff?


Thanks,

Wes
Wes Bentley
CLC # 30183

Scot Minesinger

You will need a special oil if it is a posi, so find out first.  Easy way to tell jack up rear of car (both wheels).
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

cadman56

The oil fill plug on a 68 will have a special tag indicating it is a controlled differential.  The ratio code will also have a 'G' in front of the number.  If it is a controlled differential make sure to get the special additive.  I have 4 68s & 3 are the controlled differential marked as I mention.  The shop manual verifies the information.  Larry
1956 Cadillac Coupe deVille (sold)
1956 Cadillac Convertible (sold)
1956 Cadillac Eldorado Seville (sold)
1967 Cadillac Eldorado (sold)
1968 Cadillac Convertible (Sold)
1991 Cadillac Fleetwood Brougham dElegance
Larry Blanchard CLC #5820