Any tips for pinpointing brake squeal?

[jana519]

This has been an on/off again issue for my 2002 Honda Odyssey. Whenever I remove the wheel on the front driver side and reinstall it, sometimes there is squealing coming from the brakes. It worsens if I turn the wheel. The sound is intermittent and can't be reproduced reliably.

Any tips on pinpointing where this is coming from? Is there a way to reproduce brake squealing while the vehicle is on jacks?

 

[mindless1]

I assume the pads aren't completely worn out and it's not just the wear indicator starting to rub against the hub.

First the quicker easier check, make sure your wheel seats fully on the hub and that the lug nuts completely tighten it down. Any play moving the wheel by hand when jacked up is either insufficient seating of the rim, or tightening of the lug nuts, or a bad bearing/hub. I mean wheel to hub play, obviously if it's the front you will get movement from the fact that it has to rotate left and right to steer.

It's not realistically possible to produce brake squealing on jacks. "Maybe" you could lift the whole end of the vehicle if it's on the driven wheel end, spin the wheels using the engine and apply the brakes, but I wouldn't count on it and wouldn't bother trying even if you have very sturdy jack stands (is risky on poor or poorly placed jack stands).

If you can't see anything with the wheel off, is it near time for new pads? If so get some, and do both sides. If not, essentially do a brake pad service minus new pads, where you take the caliper off, lube the slider pins if needed (clean rust off if present), clean the rails the pads slide on. Before you start taking anything apart, check the caliper bracket bolts to make sure they haven't loosened.

If using abutment clips aka slider shims they may need removed to clean rust under them if present, and in some cases removing those can mangle them and require replacement, put silicone grease under where they attach to retard rust, and put the clips back on, then grease the area where they contact the pads.

Look at the dust shield in case it's slightly rubbing. While the caliper is off, either apply some tacky goop (aka brake quiet) or some silicone brake grease to the back of the pad where the caliper piston sits, or on the lip of the piston (grease only, no tacky goop). Brake quiet or silicone grease type products are often sold near the counter at auto parts stores for a buck or two for a one time use packet if you don't want to buy a larger quantity, but if everything needs greased again you might need a couple packets.

 

[jana519]

I assume the pads aren't completely worn out and it's not just the wear indicator starting to rub against the hub.

First the quicker easier check, make sure your wheel seats fully on the hub and that the lug nuts completely tighten it down. Any play moving the wheel by hand when jacked up is either insufficient seating of the rim, or tightening of the lug nuts, or a bad bearing/hub. I mean wheel to hub play, obviously if it's the front you will get movement from the fact that it has to rotate left and right to steer.

It's not realistically possible to product brake squealing on jacks. "Maybe" you could lift the whole end of the vehicle if it's on the driven wheel end, spin the wheels using the engine and apply the brakes, but I wouldn't count on it and wouldn't bother trying even if you have very sturdy jack stands (is risky on poor or poorly placed jack stands).

If you can't see anything with the wheel off, is it near time for new pads? If so get some, and do both sides. If not, essentially do a brake pad service minus new pads, where you take the caliper off, lube the slider pins if needed (clean rust off if present), clean the rails the pads slide on. Before you start taking anything apart, check the caliper bracket bolts to make sure they haven't loosened.

If using abutment clips aka slider shims they may need removed to clean rust under them if present, and in some cases removing those can mangle them and require replacement, put silicone grease under where they attach to retard rust, and put the clips back on, then grease the area where they contact the pads.

Look at the dust shield in case it's slightly rubbing. While the caliper is off, either apply some tacky goop (aka brake quiet) or some silicone brake grease to the back of the pad where the caliper piston sits, or on the lip of the piston (grease only, no tacky goop). Brake quiet or silicone grease type products are often sold near the counter at auto parts stores for a buck or two for a one time use packet if you don't want to buy a larger quantity, but if everything needs greased again you might need a couple packets.

Thank you kindly. The pads are good, so just replacing the shims, dust covers, and lubrication as you suggested should make quite a difference. I'm going to torque the 2 push pin bolts on the caliper properly, also. I think just a light "tune-up" is all it needs.

 

[dave_the_nerd]

Are you torquing the lug nuts to spec? Sometimes if they're over/undertightened things can flex just a smidge and you'll get a bit of rubbing somewhere.

 

[jana519]

I removed the caliper and installed brand new shims and pin boots. Turns out the 2 shims on the interior pad were completely missing, and the lubrication on the bottom pin was mostly gone.

Unfortunately it's still squealing. I'm beginning to wonder if the suspension needs to be aligned.

Are you torquing the lug nuts to spec? Sometimes if they're over/undertightened things can flex just a smidge and you'll get a bit of rubbing somewhere.

I don't have a torque wrench, so I guesstimate 80 ft lbs. I believe it's part of the issue at hand. Thing is I've never used a torque wrench on lug nuts on any car my whole life, and I haven't had a problem so far. Don't really want to drop $100 or however much a torque wrench costs for lug nuts.

 

[mindless1]

If the lug nuts seem to be tightening down evenly then it's probably not the problem but you can get a loaner tool torque wrench at Advance Auto Parts, Autozone, etc by putting down a deposit.

Normally if a vehicle suddenly went out of alignment you would notice in the handling, or if it got there slower you would see uneven tire wear, but nothing should be loose enough to squeal from a misalignment unless whatever is squealing was shot anyway and needs replaced regardless of whether an alignment is needed.

Is the noise definitely coming from the brakes area or at least definitely from one side? If not the brakes I would inspect the boot on the CV axle for tears, though usually a bad CV starts making a clicking noise when you turn, and fairly regularly, not an intermittent squeal.

Is it possible your power steering pump is going out or just low on fluid? I'd check the fluid.

 

[jana519]

So I was able to narrow down the issue to something specific.

1. I rented the torque wrench and torqued the lugs down to 80 ft lbs each. Didn't fix it.

2. Even though the old pads still had about half the pad left, I went ahead and installed brand new pads, just to be sure.

While working on the brakes, when I tightened the lugs and rotated the wheel backwards and forwards, I was able to reproduce the groaning/harmonics that I was hearing inside the vehicle. So I took the wheel off and rotated just the rotor backwards and forwards to see whether I could hear the noise... nothing. The pads were absolutely quiet.

Now I'm thinking tightening the wheel is making the noise. So I shove my entire body weight into the rotor and rotate. Sure enough, that causes it. Seems there is some contact between the rotor/hub and the "knuckle"???

I sprayed Liquid Wrench around the rotor and knuckle where they meet the wheel hub. This quieted the noise. I don't know what's causing the noise, but I've figured out a "solution" of sorts. What do you guys think?


@dave_the_nerd
@mindless1

 

[mindless1]

If you have rotor-knucle contact, you either have loose bolts or a substantial impact-damage to bend the parts enough to rub, and should see fresh abraded metal on the knuckle.

I don't know where you sprayed liquid wrench but hope you didn't get it on the brake pads. If you did, flush it off with massive amounts of brake cleaner.

I'm leaning towards your putting weight on it to mean the bearing in the hub is shot, but it's hard to diagnose these things remotely. It could be that you have a (truly, not what most call it) warped rotor and tightening the wheel against it makes a difference, but this would tend to result in a pulsating sensation while braking rather than a squeal (unless the pads were so far worn that it caused the wear indicator to scrape).

I suppose it depends on how much labor you want to put into it. The cheap but high labor way would be swap the left rotor to the right and vice versa, switching them back right away so they don't wear the pads excessively to match the different rotor wear.

The higher shotgun cost but lower labor way would be to either replace the rotor or the hub, or just the bearing if you have a press to do bearings... I mean if you are capable of doing a hub with a new bearing already in it, this may be cheaper than paying a shop to put a new bearing in your existing hub, assuming the two, hub and bearing are separately replaceable which for some reason I though was true on your vehicle.

How many miles are on this '02 vehicle? I'm thinking you probably already had the rotors replaced at least once if not multiple times, and that doesn't mean they can't be bad but what about the hubs? I mean you could easily be at a mileage where it is typical to need new hubs, and if it's not the problem at the moment, it might be the more prudent thing to shotgun repair with the expectation that they are about due for replacement, but don't get cheap generic hubs or you may not have a long term solution if that is even the problem...

It's hard to take interpretations, over the internet, and make assumptions, and spin the bottle to see where it lands. I would take the rotor off and see if there is any movement in the hub that is less than tight and smooth.

 

[jana519]

If you have rotor-knucle contact, you either have loose bolts or a substantial impact-damage to bend the parts enough to rub, and should see fresh abraded metal on the knuckle.

I don't know where you sprayed liquid wrench but hope you didn't get it on the brake pads. If you did, flush it off with massive amounts of brake cleaner.

I'm leaning towards your putting weight on it to mean the bearing in the hub is shot, but it's hard to diagnose these things remotely. It could be that you have a (truly, not what most call it) warped rotor and tightening the wheel against it makes a difference, but this would tend to result in a pulsating sensation while braking rather than a squeal (unless the pads were so far worn that it caused the wear indicator to scrape).

I suppose it depends on how much labor you want to put into it. The cheap but high labor way would be swap the left rotor to the right and vice versa, switching them back right away so they don't wear the pads excessively to match the different rotor wear.

The higher shotgun cost but lower labor way would be to either replace the rotor or the hub, or just the bearing if you have a press to do bearings... I mean if you are capable of doing a hub with a new bearing already in it, this may be cheaper than paying a shop to put a new bearing in your existing hub, assuming the two, hub and bearing are separately replaceable which for some reason I though was true on your vehicle.

How many miles are on this '02 vehicle? I'm thinking you probably already had the rotors replaced at least once if not multiple times, and that doesn't mean they can't be bad but what about the hubs? I mean you could easily be at a mileage where it is typical to need new hubs, and if it's not the problem at the moment, it might be the more prudent thing to shotgun repair with the expectation that they are about due for replacement, but don't get cheap generic hubs or you may not have a long term solution if that is even the problem...

It's hard to take interpretations, over the internet, and make assumptions, and spin the bottle to see where it lands. I would take the rotor off and see if there is any movement in the hub that is less than tight and smooth.

Great suggestions thanks. I'll take the rotor off an inspect the hub to see if it tells me more. Might find fresh wear on the interior rotor if indeed it does rub against the knuckle. The key is the rubbing is very light, enough for some light groaning but not consistent. I don't know how deep the wear will be.

I don't think the wheel bearing is bad, as nothing indicates it would be. I don't know what part in the hub could go bad such that it allows contact between parts. This whole experience has been humbling, made me realize I don't know as much as I thought I did.