yaskota

984 928 S (US) L-Jet...

Not sure what the particulars are of the current brakes on Eleonore, but I think I'm hearing something potentially troubling. Searching forum has yet to yield anything close (except, maybe, burn in guide & cleaning...).

(1) Apply brakes (regular stop)- hear squeal @ rear
(2) Pull away from stop- w/o applying brakes- hear squeal @ rear; squeal ceases/fades away at or above 45 mph...
(3) Round a corner (regardless of speed & occurring when turning or cornering to the right more than left) w/o applying brakes (at any point before/during turn)- hear squeal @ rear

#1 started happening (intermittently) & had checked while in for other work- found uneven wear (right vs left) at rear (I need more info & will follow up w/shop)

Then #1 started happening more often & #2 started to sneak in. Same pattern with #3 which is where things are at currently.

Cleaned wheels today (exterior surface) and noticeably more brake dust at rear. Will get specifics on currently installed brakes from shop Monday & from PO Tuesday evening.

I'm familiar with normal brake sounds indicating wear, but this doesn't seem the same. Can't tell you if I am feeling anything through the brake pedal as I'm numb- especially to details- from about the waist down. But (gross) movement- when applying brakes- seems smooth w/no obvious irregularities (like one might feel with worn rotors or pulsing for whatever reason.

My first guess is that brake pressure (in lines) is not reducing significantly enough after normal application. (Check levels, pressure, lines, etc.) But... squeal when rounding a corner? I'm at a loss... (Hmmm...) Could be two (or three?) different issues though...

Also- no perceived changes in stopping power and if I do brake hard- no squeal or other than normal feedback. I should add that my current braking technique is more of a steady, slow & gradual application until stopped than a pumping or any other style or technique- as lifting my foot off the brake pedal (when stopping) is something- due to my current condition- I am trying to avoid. (Lol!)

Btw- been screened and cleared to drive as my reaction time and reliability w/pedals is above average even a normal person!

So... is this just regular brake squeal or something perhaps more serious?

joejoe

My '81 had similar problem. My cure was to remove wheels, disassemble brakes (as to replace pads), and clean all sliding parts (floating caliper parts) This allowed brake pads to release after braking and squeal went away.

Bilal928S4

In addition to above.

If the brake hose to the calipers are original they can also be contributing to your problem. Old brake hoses tend to swell internally and do not allow the pressure to release.

The Forgotten On

I have the same issue in my 81. Except worse because in my case the front passenger's side caliper sticks when the brakes get hot and makes the same noise and feel as a flat tire.

My fuel economy also suffers because of this. You are not alone in this issue.

Petza914

It probably doesn't it more in turns because you may have a wheel bearing that's becoming worn and the side loads when turning allow just enough angle change of the rotor disc inside the pads to where they touch like you're starting to apply the brakes. The squeal you hear is a harmonic between the back of the brake pad and the piston, not usually between the front of the pad and the rotor. When you take everything apart and are putting it back together apply some brake anti-squeal to the backs of the pads before putting them into caliper. This will stick the piston to the back of the pad and eliminate the harmonic that causes the squeal. Sounds to me like you may have a couple things contributing to the noise though, especially swolen rubber lines. Replace them with braided stainless versions while you're doing all the brake work and you'll have a firmer pedal with better feel too. Get stainless lines that have a coating over the actual braided stainless part so if untouched anything it won't abrade what it's touching or conversely the brake line itself.

yaskota

[UPDATE]

My local shop verified sometime between posting and now that my right rear disc was wearing more than in any other spot AND my brake hoses need or will need replacing.

Since then (for rears):
* EBC Redstuff ordered and received
* Zimmerman drilled & slotted rear discs ordered and arriving soon.
* More parts (such as Goodridge lines) yet to order...

Wear pattern & original symptoms continue and, of course, squeal is now accompanied by a cringe-inducing grinding sound specifically at right rear with nice grooves to match. (Oh the fun of a 928 DD Project car!)

So looking forward to closing this out and will do after Eleonore's next spa day... ;-)

RKD in OKC

Had a horrible noise like that on my Boxster. Turned out to be a coat hanger caught up in the suspension and it was cutting a groove in the rotor.

I would also check the condition of the parking brake stuffs.