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1997 Dodge Ram 1500 slt Laramie 2wd
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Discussion Starter · #1 · (Edited)
So I bought a 1997 Dodge Ram 1500 slt Laramie 2wd. It has the 318 small block, 46RE trans, and 9.25" differential. I don't have much experience with differentials, and all the shops in my area are backed up pretty bad. At any speed above 20 mph, the rear end makes a god awful sound. I can't tell if it's the ring and pinion out of alignment, or if the pinion bearing has excessive clearance. Any tips or tricks of how to make a definite diagnosis?

UPDATE:
First off, thank you all for the recommendations and pointers. Second, I managed to find a local shop to take a look, and they're saying it started as pinion bearing failure, which then progressed to destroy other bearings and eventually damage the ring, as well as the spider gears. Thanks previous owner for driving a few hundred miles on bad bearings...
 
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So I bought a 1997 Dodge Ram 1500 slt Laramie 2wd. It has the 318 small block, 46RE trans, and 9.25" differential. I don't have much experience with differentials, and all the shops in my area are backed up pretty bad. At any speed above 20 mph, the rear end makes a god awful sound. I can't tell if it's the ring and pinion out of alignment, or if the pinion bearing has excessive clearance. Any tips or tricks of how to make a definite diagnosis?

I’d suggest not driving the vehicle and checking the rear differential fluid. When you remove the top fill plug (a rubber plug on some), the fluid should be level with the bottom of the fill hole (when parked on level ground). You can use your little finger tip to see if the level is below the fill hole opening.

If the fluid is low, you will have to determine if there is a leak - which should be visible. You may have already had damage done to the gears if the fluid level is low.

If the fluid is low, you could fill the differential with the correct fluid and drive it a short distance, to determine if the noise is eliminated by the fluid.
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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Welcome to Allpar. If you have a rear axle noise, the wear or damage has already been done. Gears tend to howl or sing, bearings tend to growl. The pinion bearings turn 3 or 4 times faster than the carrier bearings. Make sure that the noise isn't from a rear wheel bearing first.
The pinion bearing noise will be audible once the vehicle starts moving. The carriers and wheel bearings come in around 20 mph.
If there is a 'glitter' or 'sheen' in the old fluid under light, a rear axle overhaul may be suggested. The chip magnet will capture larger particles.
If you will be towing with the truck, use a synthetic 75w-140 GL-5 hypoid meeting Chrysler MS-8985.
Add a friction modifier if it is a limited-slip.
Did it have a trailer hitch when you bought it? If the previous owner pulled a boat, was the axle submerged?
 
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Virginia Gentleman
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Imperial is spot on. It's either the pinion bearings or the carrier bearings or both or the gear lash is not correct. Don't ask how I know. Been there, done that.

It won't be inexpensive to fix. Only real way to know for sure is to remove the pumpkin cover.
 

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Sadly the once indestructible 9.25" rear axle started to have problems in the late 1990s.
Like metioned the damage is done. It's time for a rebuild or replacement. You may find a good salvage rear if you try www.car-part.com
 

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1997 Dodge Ram 1500 slt Laramie 2wd
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10 Posts
Discussion Starter · #6 ·
I’d suggest not driving the vehicle and checking the rear differential fluid. When you remove the top fill plug (a rubber plug on some), the fluid should be level with the bottom of the fill hole (when parked on level ground). You can use your little finger tip to see if the level is below the fill hole opening.

If the fluid is low, you will have to determine if there is a leak - which should be visible. You may have already had damage done to the gears if the fluid level is low.

If the fluid is low, you could fill the differential with the correct fluid and drive it a short distance, to determine if the noise is eliminated by the fluid.
Fluid was at the proper height, and I can't see any leaks. I went ahead and replaced the fluid anyway and I couldn't see any metal shavings in it.
 

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1997 Dodge Ram 1500 slt Laramie 2wd
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10 Posts
Discussion Starter · #7 ·
Welcome to Allpar. If you have a rear axle noise, the wear or damage has already been done. Gears tend to howl or sing, bearings tend to growl. The pinion bearings turn 3 or 4 times faster than the carrier bearings. Make sure that the noise isn't from a rear wheel bearing first.
The pinion bearing noise will be audible once the vehicle starts moving. The carriers and wheel bearings come in around 20 mph.
If there is a 'glitter' or 'sheen' in the old fluid under light, a rear axle overhaul may be suggested. The chip magnet will capture larger particles.
If you will be towing with the truck, use a synthetic 75w-140 GL-5 hypoid meeting Chrysler MS-8985.
Add a friction modifier if it is a limited-slip.
Did it have a trailer hitch when you bought it? If the previous owner pulled a boat, was the axle submerged?
The previous owner did tow with it, but never a boat. It is not a limited slip sadly, it's an open gear set. The old fluid did not have any metal shavings or "glitter", and it was replaced with synthetic 75w-140. All wheel bearings were replaced by the previous owner about 15k miles before parked.
 

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2017 Ram 1500 3.6 Crew
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Or, it could be wheel bearings. My 2008 had wheel bearing failure at 118k. If sound changes easily with throttle variance, more likely ring and pinion. Wheel and differential bearings most often change with speed.
 
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