Replace Bearings in Pairs?

[gathermewool]

Vehicle: 14 Subaru Forester XT
Miles: ~80k
Symptom: Low-pitch humming from the rear that grows louder with vehicle (NOT engine) speed. It sounds similar to having meaty all-terrain tires, though it’s a constant hum.

Tire rotation did not change magnitude nor general location of the noise.

I originally associated the noise with wearing tires, but my wife came back from a road trip recently and I immediately noticed that the noise was something like double the magnitude it was not too long before the trip. Before, wind noise would drown out the bearing noise at highway speeds. Now, the low-pitched hum is obtrusive.

NO change in noise while turning or while driving windy roads.

Tires were rotated again a couple of days ago. No change.

Diagnosis: The noise was confirmed by a trusted mechanic to be a rear left wheel bearing. He recommends that I replace both rear bearings at the same time, though he admitted that I wouldn’t save on labor charges by doing both at the same time.

Questions: should I do both at the same time?

How hard is this job? Unfortunately, I don’t have access to a lift any longer and my garage is on the tight side, which is why I’m willing to shell out $2-300/axle for this job.

Money is a little tight, but we can afford this without issue.

My main concern is that I’m not sure I want to risk fixing what ain’t broke on the other side.

Finally, the shop is letting me supply my own Subaru OE part, since I had a 20% off coupon to burn.

Parts: $290 for two hub assemblies and two axle nuts. Did I miss anything the shop can’t reuse during the R&R???

 

[Nick1994]

Do it yourself, looks really easy.

 

[mclasser]

I'd only replace the known bad one and leave the good one alone, especially since you're hiring out the job.

I had a bad rear bearing and only replaced that one. That was like 40k miles ago and the other one is still quiet.

 

[bozo66]

I second only replacing the bad one. That's all I've ever done on a Civic and Honda Accord.

 

[Silverado12]

FWIW I had a 1999 Jeep Cherokee and both went bad at about the same time. I would change both but DIY. Check Rockauto and NAPA.

 

[ABN_CBT_ENGR]

If it aint broke- don't fix it

Just for specifics, you say he recommended to replace both BEARINGS not hubs so to be clear he was recommending you replace both hubs?

If so, I see no reason or benefit to replace a functioning component with another functioning component

 

[Chris142]

Leave the good side alone. I replaced a bad one on our old Tahoe. The other side was still good 90K later.

 

[Silverado12]

I'll say again but you trust your mechanic; listen to his good advice.

 

[newtoncd8]

On our RX330, had the right rear replaced and inquired with repair shop about doing the other; they advised leaving it alone. That was 60k ago and the left side is still fine.

I would only change the bad one.

 

[2010Civic]

Only change the bad one. Maybe he wants you to change both because he isn't 100% sure what side is bad.

 

[Lubener]

The good bearing would be of higher quality than the replacement which is why I would only do the bad side.

 

[92saturnsl2]

The good bearing would be of higher quality than the replacement which is why I would only do the bad side.

I agree with this. Often the replacement parts are foreign made and lesser quality than OEM. This is true of many aftermarket replacement car parts.

I only repair the wheel bearing that is bad and I can't remember ever having to go back and do the other side soon after. Since you don't save on labor, it really is not helping you to do both, instead you're just replacing a perfectly good part.

 

[t1snwrbrdr12]

Those Subaru’s are typically hard to hear in the air, so figuring out which side while the wheels are spinning in the air with no load will occasionally fool the mechanic. He could be unsure. But he could also know how prone to failing that era of Subaru rear wheel bearings are.

They extended their warranty coverage on them (if they didn’t make it a recall...I can’t remember which it is) because they are so problematic. But it’s worth asking a Subaru service advisor if it’s covered by any type of warranty or recall before you get it done.

You can DIY it. It’s a bolt in unit. We never replace the axle nuts. They can be good and stuck into the brake backing plate but it’s simple besides dealing with the corrosion.

 

[oldhp]

Unless you were stuck and both front or rear wheel bearings were under water. Nope just the bad one. That good one could go further than you own the car...............or..................it could go 15 miles. Roll the dice.

 

[gathermewool]

Do it yourself, looks really easy.

I think I will actually t

Do it yourself, looks really easy.

Thanks. I saw that video and may try it myself if I can find the time and the bearing doesn't get worse.

My main question was whether to do both at the same time, which many have answered.

If it aint broke- don't fix it

Just for specifics, you say he recommended to replace both BEARINGS not hubs so to be clear he was recommending you replace both hubs?

If so, I see no reason or benefit to replace a functioning component with another functioning component

I was using bearing and hub assembly interchangeably, sorry. The hub assembly has to be replaced in this case.

I'll say again but you trust your mechanic; listen to his good advice.

I may attempt to do it myself. Combine that with the fact that the mechanic won't be able to offer any sort of discount (no common parts from left to right), so there's no benefit besides reduced downtime to replacing both, I think.

The good bearing would be of higher quality than the replacement which is why I would only do the bad side.

That may be the case, but I feel like the OE hug assembly (from Subaru Parts Warehouse) may be more durable than some aftermarket assembly. Thoughts?

Those Subaru’s are typically hard to hear in the air, so figuring out which side while the wheels are spinning in the air with no load will occasionally fool the mechanic. He could be unsure. But he could also know how prone to failing that era of Subaru rear wheel bearings are.

They extended their warranty coverage on them (if they didn’t make it a recall...I can’t remember which it is) because they are so problematic. But it’s worth asking a Subaru service advisor if it’s covered by any type of warranty or recall before you get it done.

You can DIY it. It’s a bolt in unit. We never replace the axle nuts. They can be good and stuck into the brake backing plate but it’s simple besides dealing with the corrosion.

My wife said he drove the car with his brother (partner) in the back, listening for which side the noise was coming from. I should do the same thing with my wife driving (me in the hatch area) to see if I can confirm the side easily.

Corrosion is my biggest concern. I'm worried that I'll not be able to get the assembly out, and that I'll be stuck with it halfway out. It would really suck if I had to tow the vehicle to the shop after getting a quote (with my tail between my legs).

Now that I've been thinking about it a while, I guess the four bolts that attach the assembly should provide enough torque to pull the assembly back to where it's supposed to be, either helping to break it loose further or putting it into a condition where I could drive it to the shop if worse came to worst.

Unless you were stuck and both front or rear wheel bearings were under water. Nope just the bad one. That good one could go further than you own the car...............or..................it could go 15 miles. Roll the dice.

I think this is the consensus and what I'll be doing. I want to confirm for sure that the rear left bearing is the culprit, so I'll have to take a drive while riding in the trunk. If so, I'll try to take a shot at this job myself.

The only thing I'll need to purchase is a higher-rated torque wrench. Any recommendations there for something that won't be used often? I just purchased a Husky 50-250 ft-lbs click-type for $90 due to the Lifetime warranty, but I can always return it.

 

[t1snwrbrdr12]

Torque isn’t that important for anything in this job except the axle nut. What is that spec? I’d think it’d be under 250.

Do you have a socket big enough for the axle nut?

Once you get the hub unbolted, the whole backing plate and hub assembly can be removed from the knuckle and worked on a little away from the car. We usually just held them by band and whack them from behind with a hammer till the hub works it’s way out. If you disconnect the brake cable you’ll really be able to remove it and take it to a bench if you feel that’s easier.

 

[supton]

I vote to do in pairs. Only had two cars that had bad bearings. One I elected to have both done at the same time--once on the lift, it was clear that both were indeed bad (105k, early death, but well known on MkIV's it seemed). The other car, one bearing went bad and six months later the other went. That was double the downtime as a result on that vehicle, which was approximately twice as annoying as being in the shop only once.

I could not R&R the job myself on either car. Now if I could the job myself, maybe one at a time.

 

[SwampSurvivor]

If it aint broke- don't fix it

Just for specifics, you say he recommended to replace both BEARINGS not hubs so to be clear he was recommending you replace both hubs?

If so, I see no reason or benefit to replace a functioning component with another functioning component

These cars use unit bearings, so you're replacing both either way .

 

[ABN_CBT_ENGR]

These cars use unit bearings, so you're replacing both either way .

I understood that, read my post very carefully and in context with the commentary in #15

 

[philipp10]

I had a Forester. Same issue. Funny thing is, I went to the shop and told them. it's the right side rear. Mechanic insisted it was coming from the left. So he does the left, noise stil there. So in the end, ended up doing both anyway. I would probably do just the one. Apparently these bearing are undersized for the vehicle. I'm old.....I remember a time when replacing wheel bearings was un-heard of.