Front brakes on old Nissan - wheel bearing?

[Svashtar]

Doing the brakes on my daughters ancient 2000 Nissan Sentra. She complained there was a loud metal to metal sound underneath the car when she stepped on the brakes, and the car was slow to stop. Sight unseen I bought brake parts all around for $100. That was a mistake it turns out.

Did the drums in back, but they were still looking ok. At least drum brake parts are dirt cheap.

Fronts surprised me by only being down about half as well. Bottom line I can move the rotor back and forth anout 3/8” each way. Huge lateral wobble to the wheel. Only thing I can think is the wheel bearing. Not sure if this has front and back bearings or just a single one.

Thanks for any info. Hopefully this won’t be too much of a hassle to change.


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[Svashtar]

Answered my own question, thanks. Has to be the bearing. Hopefully it didn’t damage the tiny axle. (The only time I saw axle damage was on my MM, because the bearing ate it up, after the dealer told me it was fine and didn’t need to be replaced under warranty.)
I think the grinding sound is the bearing eating into the race, not the axle.

The only thing I can’t figure is why she said the car was harder to stop, the brakes were less effective, and the grinding only happened when she braked going in reverse?




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[justbob]

I “think” the early Nissans had a replaceable bearing/race for the hub if not chewed up too badly. Been quite awhile since I did one however. If it’s as bad as your describing I wouldn’t hesitate to just get the hub assembly, plus that would save you having someone press the bearing on if you don’t own a press.

Hopefully the engine mounts are up to par and saving the axle shaft from the additional stresses they are currently seeing. As for wearing into the axle I doubt it. I don’t think a normal person would be willing to pilot the car with the scary noises that would create..


*This is a general procedure for most front wheel drive cars.*

1) Remove wheel, caliper, and rotor.
2) Have a drink
3) Remove large nut from axle shaft w/impact and then thread it back on a few threads to protect the them from the hammer you will use to unseat it from the steering knuckle.
4) Eat a sammich.
5)Remove nuts from lower ball joint & outer Tie rod (sometimes the tie rod can remain if there is enough room for the axle shaft to slide out)
6) Take a brake but look busy.
7)Pickle fork the lower ball joint and tie rod and separate them from the steering knuckle.
8) Grab a drink to wash down sammich from step 4.
9)While pulling the bottom of the knuckle towards you, give the axle shaft a few light blows with a 4# sledge (increasing blows as needed)
10) Install bandaid on the finger that got pinched between steering knuckle and lower control arm.
11) Remove shaft and lay to the side
12) Remove hub mounting bolts and hub (I’ve had some come right out and others I’ve had to get medieval on..)
13) Remind owner just how much they owe you before proceeding.

Reinstall in reverse order.



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[Grimrepairman]

The only thing I can’t figure is why she said the car was harder to stop, the brakes were less effective, and the grinding only happened when she braked going in reverse?

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The worn wheel bearing allows the hub and rotor to move excessively perpendicular to the axle, as a result the caliper gets pushed in. Requires extra pedal travel to push the caliper back out before appropriate pressure is applied to the brakes. Will feel like drum brakes way out of adjustment.
Not sure why it only made noise in reverse.

Bob, excellent instructions. I would only add be careful with the pickle fork, easy to tear the boots on tie rod or ball joint.
I'm not familiar with the specific model, some wheel bearings press directly into the knuckle. If that's the case, I usually hammer the guts out of them and then run a few beads of weld around the inside of the outer race. As the welds cool they will shrink the race and make removal much easier. Can generally use the old outer race as a driver for installation.
Hopefully it's a bolt on hub, and none of that will be necessary.
SKF has a downloadable chart of torque specs for all wheel bearings by make and model.
Good luck.

[Svashtar]

I “think” the early Nissans had a replaceable bearing/race for the hub if not chewed up too badly. Been quite awhile since I did one however. If it’s as bad as your describing I wouldn’t hesitate to just get the hub assembly, plus that would save you having someone press the bearing on if you don’t own a press.

Hopefully the engine mounts are up to par and saving the axle shaft from the additional stresses they are currently seeing. As for wearing into the axle I doubt it. I don’t think a normal person would be willing to pilot the car with the scary noises that would create..


*This is a general procedure for most front wheel drive cars.*

1) Remove wheel, caliper, and rotor.
2) Have a drink
3) Remove large nut from axle shaft w/impact and then thread it back on a few threads to protect the them from the hammer you will use to unseat it from the steering knuckle.
4) Eat a sammich.
5)Remove nuts from lower ball joint & outer Tie rod (sometimes the tie rod can remain if there is enough room for the axle shaft to slide out)
6) Take a brake but look busy.
7)Pickle fork the lower ball joint and tie rod and separate them from the steering knuckle.
8) Grab a drink to wash down sammich from step 4.
9)While pulling the bottom of the knuckle towards you, give the axle shaft a few light blows with a 4# sledge (increasing blows as needed)
10) Install bandaid on the finger that got pinched between steering knuckle and lower control arm.
11) Remove shaft and lay to the side
12) Remove hub mounting bolts and hub (I’ve had some come right out and others I’ve had to get medieval on..)
13) Remind owner just how much they owe you before proceeding.

Reinstall in reverse order.



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Thanks very much for the info. No idea what I’m doing here so may have to take it to my mechanic. I’ll get everything apart and see how it’s put together. I was naive enough to think I would just pop the damaged bearing off the axle.

By the way, that large nut on the axle shaft just inboard of the cotter pin is easily turned, so I’ll have to look at everything in light of your directions.

(The only things I’m comfortable with right now are the drink, sandwich and taking a break...!)

In reading your post for the third time, I’ll keep my fingers crossed and just replace the entire hub. If I understand it, all I would need for that is a torque wrench, everything would be included.

Thanks again.

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[Svashtar]

The worn wheel bearing allows the hub and rotor to move excessively perpendicular to the axle, as a result the caliper gets pushed in. Requires extra pedal travel to push the caliper back out before appropriate pressure is applied to the brakes. Will feel like drum brakes way out of adjustment.

Not sure why it only made noise in reverse.



Bob, excellent instructions. I would only add be careful with the pickle fork, easy to tear the boots on tie rod or ball joint.

I'm not familiar with the specific model, some wheel bearings press directly into the knuckle. If that's the case, I usually hammer the guts out of them and then run a few beads of weld around the inside of the outer race. As the welds cool they will shrink the race and make removal much easier. Can generally use the old outer race as a driver for installation.

Hopefully it's a bolt on hub, and none of that will be necessary.

SKF has a downloadable chart of torque specs for all wheel bearings by make and model.

Good luck.



Got it, that makes sense. Damn, I thought for once I had the diagnosis perfect: brakes are not as effective in slowing the car, grinding noise when applying them, and was congratulating myself for getting drums, rotors, shoes, pads, wheel cylinders and hardware for just over a hundred bucks. Should have waited for her to show with the car, but wanted to save time.

It would cost me $25 to ship the $55 worth of front brake parts back, might as well install everything.

Thanks for the good input.


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[Svashtar]

Just checked, and just my luck. The rears are a bolt on hub, but the fronts are press on bearings. I only have a small one ton bench mounted press, so I’ll have to take it to my mechanic. He says 2.4 hours so that’s like $275, plus about $50 for the bearing.

He also wanted to do the other front, but if it ain’t broke... plus the plan is to keep the car only another 6 months.

Talk about perfuming a pig! although I have to say this car is very well built. About 230,000 and it still runs great.


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[Grimrepairman]

May as well do the front brakes too. They'll be apart to access the bearing, so labor shouldn't change. Also the photo that was in the post earlier looked like there may have been metal to metal contact on the rotor. Could have just been from the caliper bracket. Hard to tell without having my hands on it.

[Svashtar]

May as well do the front brakes too. They'll be apart to access the bearing, so labor shouldn't change. Also the photo that was in the post earlier looked like there may have been metal to metal contact on the rotor. Could have just been from the caliper bracket. Hard to tell without having my hands on it.


Thanks, I’ll ask if he’ll throw that in, good idea. I have the parts so was just going to do it myself once I got the car back.

There’s about half the front pad left, but when the brakes are off there’s so much movement of the rotor side to side into the pads, that I don’t know what got boned.

I could follow Bob’s instructions and work to get the old bearing off, then take it somewhere to have the new bearing pressed on; I’d like to learn how to do it, but figure the difference of about $225 is worth paying my mechanic.

Here’s that photo again. Thanks to you and Bob for the help.

https://uploads.tapatalk-cdn.com/20180502/5275dc5b7b2223df1dfd114f8d29bd b9.jpg

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[justbob]

I’d be really surprised if you couldn’t get a new hub with the bearing already installed.

As for doing the other side, I tend to disagree. All it takes is hitting the same pothole in your daily commute over a period of time and that is the difference of getting a 100,000 miles or more out of a suspension piece. Or like here in the rust belt, since the salt collects on the shoulder of the road it’s very common to see the right side of the vehicle in need of parts quicker than the left. Why waste money? Especially on something soon for sale..

Replace brakes? Definitely. You already purchased them and you have to remove anyways.


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[Svashtar]

I’d be really surprised if you couldn’t get a new hub with the bearing already installed.

As for doing the other side, I tend to disagree. All it takes is hitting the same pothole in your daily commute over a period of time and that is the difference of getting a 100,000 miles or more out of a suspension piece. Or like here in the rust belt, since the salt collects on the shoulder of the road it’s very common to see the right side of the vehicle in need of parts quicker than the left. Why waste money? Especially on something soon for sale..

Replace brakes? Definitely. You already purchased them and you have to remove anyways.


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Thanks Bob; the service writer for my mechanic says only the backs have a removable hub, and that the fronts have to be taken apart as you describe and have a new bearing pressed on. I'll go to the guys at NAPA today who seem to know what they're talking about and check with them and see if I can just get the hub.


You make a good point, and despite their recommendation I wasn't going to do the left side bearing. It seems tight and I only have to get 4-6 months out of it. Believe it or not this old Nissan will sell like hot cakes here in the Salinas valley to some of our undocumented friends. :D


Two quick questions:


1) Back in the 70's when I worked for Chevron we would always sell wheel bearing repacks to folks, recommended (too much probably) every 15K miles. Are these pressed on bearings not meant to be repacked then?


2) Would the synthetic chassis lube I use for the Metco control arms and suspension fittings on my wife's older car be suitable for a wheel bearing? Things have changed beyond the standard chassis grease we used to use for everything 40 years ago.


Thanks again for the good info.

[Grimrepairman]

Just did a quick Google. The front is a sealed bearing, unable to repack or lubricate. The bearing is pressed directly into the knuckle and probably has a large snap ring for good measure. The hub has a shaft which is then pressed into the center of the bearing. The axle nut really just holds the axle in place as opposed to setting bearing preload or endplay.

Not all grease is created equal. I don't know the specific science involved, but some are not to be used for "high speed bearings" due to certain additives. I personally use regular old wheel bearing and chassis grease that comes in a small tub. Lucas "red and tacky" is an acceptable equivalent as far as I know.

[Svashtar]

Just did a quick Google. The front is a sealed bearing, unable to repack or lubricate. The bearing is pressed directly into the knuckle and probably has a large snap ring for good measure. The hub has a shaft which is then pressed into the center of the bearing. The axle nut really just holds the axle in place as opposed to setting bearing preload or endplay.

Not all grease is created equal. I don't know the specific science involved, but some are not to be used for "high speed bearings" due to certain additives. I personally use regular old wheel bearing and chassis grease that comes in a small tub. Lucas "red and tacky" is an acceptable equivalent as far as I know.

Thanks, so won't be able to just replace the hub and be done with it.

In the case we were hoping for, the hub and the bearing were one unit that would press (or be driven) directly onto the axle?

Thanks for the info on the grease. I know the stuff you're talking about, but have regular black lithium grease for general use and synthetic chassis lube from Mobil and Valvolene in tubes, so am used to those. Was just curious for future applications.

[Grimrepairman]

In the case we were hoping for, the hub and the bearing were one unit that would press (or be driven) directly onto the axle?

In that case the hub and bearing have their own housing and bolt directly to the knuckle. The axle passes through the center with a "close" fit as opposed to an interference fit which would require pressing or hammering.

Happy to help.

[Svashtar]

In that case the hub and bearing have their own housing and bolt directly to the knuckle. The axle passes through the center with a "close" fit as opposed to an interference fit which would require pressing or hammering.



Happy to help.


Good to know! Wish I had been in that situation here.


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