Waking The Dead

Try Disc Brake quiet applied to the back of the pads (Permatex)

As Mike mentioned, if you're getting squeal apply brake pad anti-squeal to the back of your pads. 

Thanks, Mike and Ron.

When I pulled the pads, there was already some grease on the back of the pads, so it looks like that's not it.

This isn't normal brake squeal. They do that VERY slightly when they're first applied, but it's very slight and the normal high-pitched squeal.

This is a very loud low-pitched 'moaning' sound - the kind Vince would comment about.

Mike's right.  Disk Brake Quiet is a type of silicon gel that is applied between the pads and the piston or between the pads and the caliper to reduce noise.  That should do it, along with chamfering the leading edge of the pads (both) at a 45 degree angle for about 1/2 to 2/3'rds of the thickness of the pad.  IOWords, if the pad material is 3/8" thick you would be chamfering it about 1/4" through the thickness and along the flat pad area.  You can use an angle grinder and just eyeball it.  Wear a mask and avoid breathing the powder.  Oh, and there should be absolutely NO "grease" on either side of the pads.  None.  Quiet gel, yes.....Grease, no.

And get rid of that Acetone - it leaves a residue the pads might not like.  Go to NAPA or Autozone and get some "Braklene" brake cleaner and liberally spray it on the rotors and pads, then buff the surfaces of both with 150 grit sandpaper to remove the gloss, then assemble everything bed them in:

Bedding in process:

Take the car out on a back road and get it up to about 50-60mph.  

Push on BOTH the brake and the gas so that it starts to slow down to around 30, but bring it back up to 50 while pushing on the brake.  The idea is to get the brake pads quite hot to cure them in and make them hard (and stop better).  

The engine will be working hard to keep you there.  Hold this for 30 seconds, then let off the brake and let it cool for 30 seconds, then reapply both brake and gas for 30 seconds, then let them cool for 30 seconds.  Do this three or four times.  Make it work hard.

On the final pass, let it cool down for 30 seconds and then simply drive home.  The brakes should be bedded in and (hopefully) will no longer moan.

Gordon, thanks for the detailed reply.

I'd already done most of what you suggest.

- chamfered the leading pad edges pretty much as you suggested, with a hand file

- sanded the pad faces down to new material

- bedded in the brakes much as you described

I figured the 'grease' behind the pad was some kind of 'quieting' gel deliberately placed there when the kit was installed by VS. It's only on the piston where it contacts the pad, not slathered all over. I did pick up a Permatex product for this purpose at NAPA. Guess I can clean off what's on there and replace with the Permatex.

I hadn't heard of sanding the rotor face, though. Guess I can try that, too. It looks and feels pretty smooth and clean.

What I'm wondering is why, after driving cars with disc brakes for over 40 years, I've never heard one make a sound like this.

Oh, one other thing.

When it starts making this noise, if I get off the pedal and apply the rear brakes lightly with the handbrake lever, it never makes the sound. But it's definitely coming from the rear brakes.

Well, since you've already done everything I can think of, try applying the brakes and when it starts making the noise, keep your foot on the brake and gently pull on the e-brake lever.

If it stops, I would suspect something going on with the e-brake actuator cam.  I'm also assuming (since I can't see your calipers installed), that there is a lever/cam that pushes against part of the pad when the e-brake is pulled and I would start looking there to see what's going on.  

If possible, I would get it up on four jack stands or (more preferably and mucho safer) a frame lift, start it up, get it going in 2'nd gear or something more appropriate and gently apply the brakes to make it moan while some brave soul is under there seeing what the heck is going on.  Once you see what's causing it, I suspect that you'll also see how to correct it.

I had something similar to this on a LeBaron GT, once, and it turned out to be a larger-than-normal gap between the caliper and the caliper hanger (mount) allowing it to vibrate until the brake pressure was high enough (harder pedal pressure) to overcome the looseness and stop the noise (which, on mine, was more of a rattle).  Might be something similar, but not seeing it doesn't help.

I suggested sanding the rotors because you said you used Acetone for cleanup and that leaves a residue.  Use Braklene and THEN lightly sand them to insure a squeaky-clean surface.  Can't hurt......

OH!....And the "Click and Klack" guys on "Car Talk" would probably suggest strapping  a neighbor onto the rear of the car so they can hang down under there and see what's going on while you drive the car around putting on the brakes.  They would suggest that, but I would go for the lift......

gn

Or, since the Speedie is about being old school, maybe I should forget about these new-fangled hydraulic brakes and go with a tried and true cable system and be done with it.

Then, I could move the spark advance to the steering wheel and...

I take it this is a new install.  This may be a long shot, but a number of years ago I installed a similar brake kit in my IM and found the rotors were not centered correctly between the calipers.  I ended up centering the rotors by adding some washers to the caliper brackets.  Again, this is a long shot, but it will only take you a few minutes to check. 

Are the pads showing any sign of uneven wear between the two sides of the caliper?

When you apply the brakes, does the slider portion move as expected or are they siezed up?

Is the caliper square to the rotor? If it sits at an angle, it can cause vibration because the whole pad doesn't make initial contact.

What master cylinder are you running, and do you run any residual valves? The brakes moaning with the pedal but not with the handbrake could mean that not enough fluid is getting to the rear brakes. So when the pedal is lightly pressed, the front brakes make contact with the disc normally, but the rears still sit a small distance away letting them vibrate against the disc. The slightly larger MC sold for disc brake conversions or perhaps a 2 pound residual valve in the rear line may help if you've run out of other ideas.

Here's the procedure we used when I was in charge of our fleet. 
We called it burnishing the pads but bedding also works.   This is the same procedure that engineers from Ford, Chevy and Chrysler followed during our developmental sessions with each of the manufacturers.

Find a clear stretch of highway and accelerate up to 70 MPH and bring the car to a complete stop as fast as you can without locking up the brakes. Immediately do two more stops from the same speed. 

Let the car sit (with your foot off the brake pedal ) for 3 minutes and do 3 more stops from 60 MPH 

Let the car sit (with your foot off the brake pedal) for 1 minute and do 3 more stops from 40 MPH. 

By now, the brakes should be smoking and stinking up the place but that's good. It's burning all the resins from the pad and they will last longer and stop better. 

I might add that there are several other ways of performing the burnishing (bedding) but this method worked for us.

Larry.....   That was the method the TOYOTA mechs. told me they used back in the '80s.....

Works like a charm.....

I have no idea where there is a stretch of road here in Southern CA where I can get to 70mph and then come to a complete stop without being asspacked. 
lol

All of this is my 1st notion as well.  I believe it has to do with the installation and not just the pads squealing.

When you step on the brake and it starts to make the low drone, do you hear an oscillation?   Is it a steady 1 long woooooooooooo noise or is it a wooowoooowooowooowooo noise.  Do you hear a decibel/octave change?

If it oscillates, then something is not centered or your discs from the manufacturer are not concentric or surfaced properly.  You may need to take them to a machine shop and have the rotors surfaced.  It might be a bad batch from china.

If it doesn't oscillate, then I would suspect it may be a master cylinder issue and you are not getting a smooth even pressure or enough pressure to the rear of the car.

Did you re-bleed the rears???  You could also have air in the rear lines which will cut down on pressure...could be a bubble.  Did Vintage give you a "new" master cylinder or did they cannibalize one off of a donor vehicle???  Master cylinder may be dying if not new or at the bare minimum rebuilt...

Don't think that sound is a pad issue.  Pads make a high pitch whine...a low drone means it is mechanical/pneumatic.

For sure try bedding 1st...but i don't know...

Zulu

I was just typing up a reply which referenced 'bedding in the pads'. When I had my old 3 series, My mechanic used to charge me for this process each time he did the brakes on the car.

It's worth a shot. Good luck finding an open road in LA.

Ted

It's not that tough to find a long stretch, I've used truck terminal parking lots on the weekends when they're closed or large warehouse complexes.   Another option is a large shopping mall early in the morning or late at night.

You don't need a longer road, you need a bigger engine!

Right on, Justin!

I've got the VS standard 1915cc - dead stock except for bigger jugs.

If I have to get to 70 mph to bed in the brakes, that's half the morning gone right there.

I should also mention that EMPI makes two mounting brackets for the same kit - a stamped steel one and a 'deluxe' cast bracket.

I'd been wondering why they went to the trouble of making the 'deluxe' bracket for a budget-priced kit. Maybe I've discovered why?

Does anyone have any experience with the 'deluxe' bracket?

I think I remember that Jerry Freeman had this same problem just before his VS was totalled. I wonder if Dr. Clock will run into this once he gets the car back on the road.

I don't think it matters what caliper bracket you use.  What's important is that the rotor is centered in the caliper.  Take the wheel off.  Take the pads off.  Is the rotor in the middle of the caliper?  Then, spin the rotor.  Do you notice any side movement (warped rotor)?  Finally, as Justin mentioned, is the rotor parallel to the caliper?

Lastly, are the caliper bracket bolts torqued as per Empi instructions?

Harmonic caused by the stamped steel brackets?

That's what I was wondering. Could there be another explanation for why EMPI offers two different quality brackets of the same geometry for the same brakeset?

The cast will be lighter, for less unsprung weight.  I'd be very surprised if the brackets were your problem, but having said that, I can't remember the last time I came across steel caliper brackets.

Maybe I should ask if anyone here is using the EMPI rear wheel disc kit with no problems? I'd guess yes because that's what VS is installing as their four-wheel disc option. But EMPI switched from Varga calipers to these Chinese no-names sometime in the past few years.

What other types of rear-wheel discs are people here using?

My Beck came with AC Industries disc brakes front/rear from SoCal Imports.

I upgraded to rear discs two winters ago. I did not do the work, my mechanic did.

EMPI's were our only choice due to scarcity of AC Industies kits at the time. As I recall, my mechanic got the kit through Carey (not certain on that issue) and I am not certain WHICH kit I have. The first season was all good, late last summer (second season) I started to experience a drone like noise maybe similar to what you describe (something akin to a "Car Talk" episode comes to mind here). I would get it coming down a hill that would also have a left hand curve to it. It appeared to emanate from the driver rear wheel area. I would get a repeat of this on the very same hill each time I took that route. Last September while doing the Corn Daze Fall run, I heard it again on several down hills with turns in them and something as simple as turning into a gas station stall. My car is at Special Editions's for the winter and I asked Carey to check it out. Earlier this week (and earlier in the winter) he thought it might be the outside rear bearing...well, he has now replaced that and says he has not heard the noise in the little bit (weather has not allowed for much testing) of testing so far. Perhaps if Carey sees this he could pipe in on the problem...same as mine? Maybe? Prior to Carey's diagnosis, Stan Galat mentioned he had replaced his spring plate bushings for a similar sound, but Carey seemed to think the bearing was the problem...some more warmer weather testing in Bremen will hopefully prove out that the bearing is the culprit. 

Photos of my EMPI rears, I can't tell if they are the same kit or not?

Rich, that Tangerine racing exhaust it fricken awesome

Amen on that exhaust!! Someone else mentioned bleeding rear brakes and that also seems like a good idea.  That would mess up the brake balance a lot and not apply the rear brakes completely.  Just another thought.

I don't hear this when I'm hard on the brakes, only easing off - very light on the pedal - and almost stopped. So, it's not that the calipers aren't gripping hard enough. It happens when I'm purposely applying the brakes very lightly.

It seems like hard application (or using the handbrake cable) applies enough force to steady the brake and keep it from vibrating.

I'll try to post a video of what it sounds like, but it can be hard to predict when it will happen. It also never seems to happen when the brakes are cold - only when they've warmed up.

I don't feel or hear any pulsing as you would with a warped rotor. The discs seem flat and centered between the pads. Judging if the pads are really parallel to the rotor is tough. The calipers are 'floating' freely and not seized.

Did I hear someone say Tangerine...Love My Exhaust!!! 

Hey Dan, put a camber compensator on your car (unless it just had not yet been installed in the pic).  It'll greatly improve handling.

Lane, it is on my list! I actually talked to Carey about it, but he wasn't sure if it would be blocked by the exhaust, but after seeing that Rich has one installed, I think I will be definitely ordering one.

Ya, it fits fine with the exhaust. Carey has a favorite brand which escapes me at the moment...about $75 as I recall. It does help.

Rich, he said it was the one from CB Performance with the straps  Looking at the pic of yours, it looks like the same one I had put on my previous VS.

That sounds about right, Dan.

The wheel bearing theory makes sense to me. 

Looking further into my brake problem, I discovered this today:

I'd noticed rear suspension travel kind of short and a pretty abrupt stop at the limit. Also, I've started to notice the same 'droning' sound from the rear when hitting a sharp bump at low speeds with my foot off the brakes.

So, a closer look revealed this. The return spring for the e-brake has been hitting a frame member. There's only about 3/4 inch clearance between the two with no load in the car, and about 1/2 inch with me in the driver's seat. So, the brake caliper is now the bump stop in my rear suspension with a total suspension travel of 1/2 inch. There doesn't appear to be any way to adjust this.

This is how VS installed the brakes on a new build. Has anyone with EMPI rear discs in a VS noticed the same?

Whoa. Very nice picture and explanation of what looks like a vexing problem.