Strange squeal/squeak when pressing brake pedal

**Matt Devo** · 01-21-2010 05:33 AM

I recently noticed that when pushing on the brake pedal while already stopped, I can hear what sounds like a squeaky spring being compressed. It's coming mainly from the front right side, but is also somewhat audible from the left as well. It doesn't sound like squeaky pads (Hawk HPS, installed with anti-squeal gel on back of pads), but I'm not sure what else it could be. Thoughts?

edit: added audio clip below. sound is audible from the 10s-20s mark

MP3 clip

TIA

**schmally** · 01-21-2010 05:41 AM

Its just the flux capacitor activating. It needs warm up time before you reach 88mph!!

**schmally** · 01-21-2010 05:53 AM

No but seriously.. Im trying to look up somethings to help you out, but im finding nothing.

**Matt Devo** · 01-21-2010 06:31 AM

added audio clip to first post above

**Dan1969** · 01-21-2010 05:14 PM

Sounds like the caliper is getting stuck or being difficult to move in the body... IDK, stumped on this one.

**Matt Devo** · 01-22-2010 07:58 AM

bump, anyone? I'll take a closer look at the calipers today while I'll throwing on my COs :)

**CyberPMG** · 01-22-2010 08:54 AM

What brake fluid are you using? Is this a noise that's heard inside the car, or is this coming directly from the front brakes outside?

**SpacemanSpiff** · 01-22-2010 09:00 AM

That sounds horrible... I have a slight squeak coming from the pedal area when I pump them, but it's nothing like yours (which I'd classify more as a creaking). I just assumed mine was from the piston being pushed in on the master cylinder.

Spiff, no help

**MikeWire** · 01-22-2010 09:28 AM

you have the ST-40 right?

I would say take a look at the dust seals and see if they are OK. If they are torn they could be letting in brake dust and dirt which would make the piston seal dry up and could cause a squeak like that.

I would also check the TQ on the caliper bridge bolts and the carrier bolts, just to be sure.

**Matt Devo** · 01-22-2010 10:14 AM

Originally Posted by CyberPMG

What brake fluid are you using? Is this a noise that's heard inside the car, or is this coming directly from the front brakes outside?

Valvoline DOT4 synthetic. Noise is coming from the wheel well, not the MC

Originally Posted by MikeWire

you have the ST-40 right?

I would say take a look at the dust seals and see if they are OK. If they are torn they could be letting in brake dust and dirt which would make the piston seal dry up and could cause a squeak like that.

I would also check the TQ on the caliper bridge bolts and the carrier bolts, just to be sure.

yup, ST40s. I'll take a look today and update the thread later. Thanks for the input.

**schmally** · 01-22-2010 10:22 AM

The brake fluid has to be a mineral based fluid. Im not sure of the valvoline is or not..

**MikeWire** · 01-22-2010 11:47 AM

Originally Posted by schmally

The brake fluid has to be a mineral based fluid. Im not sure of the valvoline is or not..

You might be confusing the power steering fluid with brake fluid - any DOT 4 brake fluid will work in any system requiring DOT 4.

Audi PS system needs to have a mineral based VW/Audi fluid, not generic PS hydro fluid.

**Matt Devo** · 01-22-2010 06:30 PM

Originally Posted by MikeWire

you have the ST-40 right?

I would say take a look at the dust seals and see if they are OK. If they are torn they could be letting in brake dust and dirt which would make the piston seal dry up and could cause a squeak like that.

I would also check the TQ on the caliper bridge bolts and the carrier bolts, just to be sure.

I took a look at the seals today and there wasn't any obvious signs of damage, but it could just be it wasn't visible. I cleaned/re-lubed the back sides of the pads without any improvement, so I'm guessing a rebuild is the next step. The noise is definitely coming from the caliper.