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Loud humming noise coming from rear end


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You guys and gals. I have a question. I recently started noticing of a loud roaring or humming noise coming from the rear end at higher speeds. I replace both rear wheel bearings, so that's not the culprit. Is there a carrier bearing that can be replaced on that Driveline? Or do I just have to order a whole new driveshaft as I've heard that the drive shafts are non-serviceable? Neil would be greatly appreciated. FYI, I have a 2005 Subaru Legacy GT

 

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See post # 298, https://legacygt.com/forums/showthread.php/idea-web-links-saved-various-parts-219238p8.html

 

 

When my carrier bearing went, I could feel it under my right elbow on the center arm rest.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

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See post # 298, https://legacygt.com/forums/showthread.php/idea-web-links-saved-various-parts-219238p8.html

 

 

When my carrier bearing went, I could feel it under my right elbow on the center arm rest.

Yes, as do I. Strange thing is, I don't see a carrier bearing anywhere on the drive line coming from the transmission to the differential in the rear? I see from the parts diagram where it's supposed to be, but I don't see it on my drive shaft? Doesn't it bolt up to the frame of the car somehow?? I will see if I can take some video footage of it maybe I'm just overlooking it.. so am I correct in presuming that this is a non replaceable item or a non-service item? Or did you find a way to replace yours?

 

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Yes, as do I. Strange thing is, I don't see a carrier bearing anywhere on the drive line coming from the transmission to the differential in the rear? I see from the parts diagram where it's supposed to be, but I don't see it on my drive shaft? Doesn't it bolt up to the frame of the car somehow?? I will see if I can take some video footage of it maybe I'm just overlooking it.. so am I correct in presuming that this is a non replaceable item or a non-service item? Or did you find a way to replace yours?

 

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The OEM Subaru driveshaft is one piece that isn't user-serviceable. The carrier bearing is surrounded by a donut-shaped rubber thing. Mine has a decent amount of play with 215K on it now.

https://driveshaftstore.com/Subaru-Legacy-Driveshaft-2005

 

These driveshafts have replaceable parts, and I'd recommend replacing your OEM one with this if your driveshaft needs to go.

 

Before that goes into your car though, make sure your wheel bearings are in good shape first. Those break far more on Subarus and will create a humming noise. You can jack the car up on all four wheels, leave the car in neutral/park with the handbrake off, and then spin each wheel while you hold the spring in your suspension with your free hand. If, while the wheel is spinning, you feel vibration in the spring, then your bearing is likely gone.

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The OEM Subaru driveshaft is one piece that isn't user-serviceable. The carrier bearing is surrounded by a donut-shaped rubber thing. Mine has a decent amount of play with 215K on it now.

 

https://driveshaftstore.com/Subaru-Legacy-Driveshaft-2005

 

 

 

These driveshafts have replaceable parts, and I'd recommend replacing your OEM one with this if your driveshaft needs to go.

 

 

 

Before that goes into your car though, make sure your wheel bearings are in good shape first. Those break far more on Subarus and will create a humming noise. You can jack the car up on all four wheels, leave the car in neutral/park with the handbrake off, and then spin each wheel while you hold the spring in your suspension with your free hand. If, while the wheel is spinning, you feel vibration in the spring, then your bearing is likely gone.

Once again, the Subaru forum has provided me with a wealth of knowledge that is proving to be very very very helpful. I can't thank you enough for your input and the time you spent responding to my query. I will advise as to what I find out. I recently replaced both rear wheel bearings oh, so I do not suspect that to be the culprit. But you never know. I will verify that before I replace a drive shaft

 

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What type of wheel bearing did you use when you replaced them?

Some aftermarket wheel bearings are junk and don't last long at all.

I used an aftermarket one from orielys. That might have been the problem. I'm putting it up on jack stands now and I'll let you know when I find out2f74cd7eac86d5f0080dfb41c4a75708.jpg

 

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The OEM Subaru driveshaft is one piece that isn't user-serviceable. The carrier bearing is surrounded by a donut-shaped rubber thing. Mine has a decent amount of play with 215K on it now.

 

https://driveshaftstore.com/Subaru-Legacy-Driveshaft-2005

 

 

 

These driveshafts have replaceable parts, and I'd recommend replacing your OEM one with this if your driveshaft needs to go.

 

 

 

Before that goes into your car though, make sure your wheel bearings are in good shape first. Those break far more on Subarus and will create a humming noise. You can jack the car up on all four wheels, leave the car in neutral/park with the handbrake off, and then spin each wheel while you hold the spring in your suspension with your free hand. If, while the wheel is spinning, you feel vibration in the spring, then your bearing is likely gone.

Wheel bearings all checked out okay. Also wiggled the tire quite a bit to see if there's any play in the bearings and there wasn't any. So my presumption would be at this point it is, in fact, the driveshaft. I wish it would have been the wheel bearing though. Those are a lot easier to get to than this driveshafts going to be. It kind of looks like a pain in the ass

 

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The Prop shaft is much easier then the hub's. Spray the mount bolts with PB Blaster and let it do its work. Don't over tighten the four nuts at the rear diff joint.

 

Grab the shafts on either side of the carrier bearing and see how much play you have, there shouldn't be to much, may be 3/8"

 

If you contact the Drive Shaft Store let them know we sent you. The Customer Rep I talked with was named Steve.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

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  • 4 weeks later...
The Prop shaft is much easier then the hub's. Spray the mount bolts with PB Blaster and let it do its work. Don't over tighten the four nuts at the rear diff joint.

 

Grab the shafts on either side of the carrier bearing and see how much play you have, there shouldn't be to much, may be 3/8"

 

If you contact the Drive Shaft Store let them know we sent you. The Customer Rep I talked with was named Steve.

Great info! I will let Steve know

 

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The Prop shaft is much easier then the hub's. Spray the mount bolts with PB Blaster and let it do its work. Don't over tighten the four nuts at the rear diff joint.

 

Grab the shafts on either side of the carrier bearing and see how much play you have, there shouldn't be to much, may be 3/8"

 

If you contact the Drive Shaft Store let them know we sent you. The Customer Rep I talked with was named Steve.

You guys are all geniuses in my book. So, upon further investigation, I found that I had, in fact, over tightened the 2 carrier bearing bolts and the 4 bolts at the rear. I backed the torque off to 15 ftlbs at the rear/25 ftlbs at the carrier and everything is perfect.

 

I also noticed that the 4 rear bolts have a "flat" milled into the outer circumference of the head of the bolts. It would appear that the flat is designed to rest against the U joint assembly. However, in this new drive shaft, it doesn't do that. The outer face of the "boss" features of the U joint assembly are not wide enough. That flat part of the head never engage's and it will just Spin and spin and spin. To keep things consistent, I held the bolt in place and tightened up the other side.

 

But the moral to the story is, don't over tighten the bolts on a propeller shaft- just like you guys advised. Cheers!

 

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