My 7 1/4” diff makes a rumbling sound. It’s not too loud, but slowly gets louder as speed increases. I don’t think it’s coming from the center, but who knows for sure. Seems smart to change out the axle bearings and proceed from there. Thoughts? 1970 Duster, 7 1/4 diff, never been touched other than me changing fluid a year or so ago.
Axle bearings??
- Thread starter dddDuster
- Start date
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You can(might) locate the sound with a mechanics stethoscope or a dowel
Get the rear axle up on jack stands, chock the front tires front and back.
Put your foot on the brake and put the car in gear.
Take your foot off the brake and let the rear wheels spin.
CAREFULLY touch the stethoscope to the left axle housing that the axle bearing goes into.
Do the same for the right and for the diff.
On the diff listen to the pinion bearing area and the rear cover.
( be sure to apply the brake till the wheels come to a stop before you put it back in park)
This will point you in the right direction.
Side note...
My 323,000 mile 7 1/4 sounded horrible till I added just shy of a quart of gear oil.
If the spider gear shaft wasn't as warm as it was I would have kept using it.
New video by Dana Nance
Get the rear axle up on jack stands, chock the front tires front and back.
Put your foot on the brake and put the car in gear.
Take your foot off the brake and let the rear wheels spin.
CAREFULLY touch the stethoscope to the left axle housing that the axle bearing goes into.
Do the same for the right and for the diff.
On the diff listen to the pinion bearing area and the rear cover.
( be sure to apply the brake till the wheels come to a stop before you put it back in park)
This will point you in the right direction.
Side note...
My 323,000 mile 7 1/4 sounded horrible till I added just shy of a quart of gear oil.
If the spider gear shaft wasn't as warm as it was I would have kept using it.
New video by Dana Nance
Last edited:
66 Valiant wagon
Well-Known Member
Do you have any sign of a bad seal on the inside of the drum backing plate? I had a bad axle bearing on my 66 Valiant wagon. It howled pretty good until I changed it.
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