The squeak from hell

[FunElan]

Hi all,

Recently did a front end "renovation," with all new bushings, powdercoated suspension arms, new wheel bearings, refreshed axles, etc. My car already had the PNM front brakes, and I kept all of that as it was and reinstalled. You can see what it all looks like here: https://youtu.be/xhyC5VGjKks

Upon completion of the car and my first drives, a squeak and pulsation (from the RHS of the car) in the brake pedal developed. Link to squeak, you can hear it chirp as the rotor comes around, and as I slow to a stop, it sounds like more of a scraping sound: https://youtube.com/shorts/2E3fer6L7bM?feature=share

The first thing I tried was installing new Centric pads. The squeak persisted. Here's the rabbit hole I went down:

1. New Centric pads
Squeak persisted
2. Resurfaced front rotors
Squeak persisted
3. resurfaced REAR rotors and PNM rear caliper install (just to rule out the rear)
Squeak persisted
4. Removed pads, noticed a bit of a 'rough' surface on the top/bottom edges, regreased and lubricated everything and reinstalled with the pads on the opposite side of the caliper
Squeak was gone for maybe 10-15 miles and then came back

At this point, I'm starting to wonder if this is something 'behind' the rotor, in the driveline. Something like the hub having runout or the new wheel bearing I installed being faulty. I plan on inspecting the caliper again just to ensure that it's evenly situated on the disc, but we did reinstall the way it came out, and this was not an issue prior to all of the work we did. The only other footnote to add, which you can see in the first video linked, is that the RHS axle is about .25inches short, but there was still enough thread and the hub nut is secure on it and hasn't come undone at all.

Would love to solve this before I decide to just drive the car into the ocean

[Tuga2112]

gotta say im pretty clueless.

my suggestion, is to lift the side of the car where the noise is coming from. spin the wheels by hand and try operate the brakes, just to try see if any of the noises appear while your staring at it.

if it only happens with the weight of the car on it. i would be re-inspecting all the suspension bolts.

[RonR]

My Twopenny-worth:

I would be suspicious of your 'short' axle, it looks like the end hasn't been tampered with, so maybe something's trapped between the CV joint and the bearing or carrier and is scraping? Another thing to check is that the circlip on the inside of the bearing is fully home in it's slot.

BTW - Nice S4 Elan!

[FunElan]

My Twopenny-worth:

I would be suspicious of your 'short' axle, it looks like the end hasn't been tampered with, so maybe something's trapped between the CV joint and the bearing or carrier and is scraping? Another thing to check is that the circlip on the inside of the bearing is fully home in it's slot.

BTW - Nice S4 Elan!

Good thoughts, I'll definitely have to take a peek to make sure the axle is seated properly. I believe I peeked at the circlip and it was fine upon install, but who knows now.

The S4 was apart when I bought the M100. Now that it's together, keeping both is a hard prospect, that S4 has been in the family since 1984!! It's just so pure.

gotta say im pretty clueless.

my suggestion, is to lift the side of the car where the noise is coming from. spin the wheels by hand and try operate the brakes, just to try see if any of the noises appear while your staring at it.

if it only happens with the weight of the car on it. i would be re-inspecting all the suspension bolts.

With it in the air, I definitely feel a "tight" spot in the rotation where this would occur. But typically I'd just assume that would be a rotor problem, which it doesn't seem to be (at least in theory). I think my next step is to actually drive it in the air and have someone (or a camera) watching the axle/hub to see if anything is out of the ordinary.

[Simon_P]

I'd be suspicious of the cv joint being seated properly if it isn't it might pull the two halves of the bearing together unevenly or not tight enough. it doesn,t look like the cv joint is in far enough - I'm saying that looking at the back of the hub not the short end.

There is a small screw that holds the disc on the hub can burr which means that the disc will be out.

And nice S4!

[FunElan]

I'd be suspicious of the cv joint being seated properly if it isn't it might pull the two halves of the bearing together unevenly or not tight enough. it doesn,t look like the cv joint is in far enough - I'm saying that looking at the back of the hub not the short end.

There is a small screw that holds the disc on the hub can burr which means that the disc will be out.

And nice S4!

How could the CV joint not be "in" the hub far enough with the nut tightened to 200 ft lbs? we definitely have enough thread.

Well either way.... we have conclusive evidence that this is NOT a brake problem now. First we used a dial gauge on both discs, noting the crazy runout on the RHS and virtually none on the LHS. So then we swapped the discs and tried again. Then used the indicator on the hub surface as you can see in this video:

SO...I'm wondering if there IS indeed something wrong with using that shortened axle....or of the shop that pressed my wheel bearing in for me messed something up. Either way....I have a spare axle I will have rebuilt this week ($50 well worth it) that hasn't been cut short. If I have to pull the hub off, I might as well put the better axle on.

[Tuga2112]

what would happen if the wheel bearing was pressed in but there was a bit of dirt in one side ?
could something like that make it be at an angle ?

[RonR]

Still seems to me that your CV joint isn't sitting in the bearing and hub correctly. If it isn't fully home the two halves of the bearing inner won't close up properly and you'll have run-out and noise as the ball bearings wouldn't be seated properly.
Your first video at 27 seconds in shows the CV joint with more of the outer housing visible than I remember on mine. Try comparing the left & right, as the CV joints are identical and should sit in the carriers/hubs the same amount.

CV in Video.jpg

Drawing from the Maintenance manual:

Bearing-Hub-Carrier-Diagram.jpg

The other possibility is that you have a bent hub or CV joint outer shaft, which might also explain the noise. Was the car in an accident, or was the driveshaft from a crashed car?

[FunElan]

Still seems to me that your CV joint isn't sitting in the bearing and hub correctly. If it isn't fully home the two halves of the bearing inner won't close up properly and you'll have run-out and noise as the ball bearings wouldn't be seated properly.
Your first video at 27 seconds in shows the CV joint with more of the outer housing visible than I remember on mine. Try comparing the left & right, as the CV joints are identical and should sit in the carriers/hubs the same amount.

CV in Video.jpg

Drawing from the Maintenance manual:

Bearing-Hub-Carrier-Diagram.jpg

The other possibility is that you have a bent hub or CV joint outer shaft, which might also explain the noise. Was the car in an accident, or was the driveshaft from a crashed car?

Fantastic detective work Ron! Thank you. You have a good point. That axle is from a parts car. Unknown history. It stands to reason that perhaps the original would fit better, I'm going to get that redone anyway and inspect the hub/bearing at the same time. Is there anything that would prevent a theoretically not bent axle from fitting "all the way" into the hub?

Either way, it feels good to know that the problem ISN'T in the brakes, and that I have a starting point.

We've set the car back down without the center cap so it's easier to crack the big nut come the next free day (which isn't for a while )

[RonR]

Is there anything that would prevent a theoretically not bent axle from fitting "all the way" into the hub?

From my POV there's 2 possibilities: A foreign body between the CV joint and the bearing/hub, or some damage to the splines on either CV shaft or hub.

BTW if the bearing inners have been loose and as you've driven on it I'd replace the bearing as well, as you couldn't be sure what shape the internals are in.

[FunElan]

Is there anything that would prevent a theoretically not bent axle from fitting "all the way" into the hub?

From my POV there's 2 possibilities: A foreign body between the CV joint and the bearing/hub, or some damage to the splines on either CV shaft or hub.

BTW if the bearing inners have been loose and as you've driven on it I'd replace the bearing as well, as you couldn't be sure what shape the internals are in.

I bought a new bearing yesterday from RockAuto - $20 shipped! I'm also going to drop off the other axle today. Either way, the RHS is getting a better axle and a new bearing and I hope that will solve everything.

[FunElan]

Hub removed today - the bearing had a TON of movement. This is a brand new bearing. Now we try and figure out how to get that massive circlip out...

[FunElan]

Never updated here what the solution was - one of my axles had been cut short by a PO for some reason. Had enough thread to engage the hub nut and torque it down, but I guess it was still allowing hub runout. New axle and the squeak was gone.