[s-cars] BBK issue

Mon Jul 7 18:01:51 PDT 2008

Yeah man, similar symptoms here.  Identical setup also.  I think what 
you're describing is what I have come to describe as a "groan."  It 
happens frequently at times of low speed and no pedal application.  It's 
more likely to happen if I'm actually turning the wheel either direction.

Speaking of hoping, I'm hoping it's not a big deal, but I've had the 
setup and the symptom for over a year now with no tangible difficulties 
whatsoever.  I've come to believe it's one of two things.  More likely 
to me, the DS2500 just makes some weird sounds in general and it's 
nothing to worry about.  In the back of my head is the possibility that 
it has something to do with the rotor offset being 1mm off compared to 
the RS2 package.  Both theories are easy to test, but for one reason or 
another I haven't gotten around to other.  I'm willing to tolerate the 
noise in exchange for sheer athleticism of the package, and that 
overrules the fact that I don't have an easy way of milling down the 
brackets that precisely.  I'd reluctantly consider trying a different 
pad, but not before my current ones wear out.  So...  If I do make the 
dubious decision of trying another pad, I'll get back to everyone on the 
results.  At this rate of pad wear, I'm estimating about five to seven 
years on that.  Seriously.

-Cheers!
Mike

jpb3 wrote:
> Hi Randy, hope you had a good rally and better luck with your tandem
> than with the S!  I am going to copy the S car list with our train of
> correspondence. (If any lister wants to read through from the bottom
> up any feedback or advice is greatly appreciated!)
>
> This problem we are both dealing with seems to have gotten somewhat
> worse for me over the holiday.  I was running the OEM Avus 16" wheels
> which have very small clearance with the caliper so I was hoping that
> perhaps some sort of resonancy was happening between that rim and the
> caliper when the caliper warmed and expanded a slight bit.  Note I
> have been using "hoping" far too much in our conversations!  I put my
> 17" Bolero's on this weekend with mucho clearance but as you know it
> makes no difference!  As I have said before if it was not for the
> direct correlation with the brake pedal and the noise I would believe
> that the wheel bearing is bad, but seeing how that if you just barely
> tap the brake pedal the noise goes away momentarily (until you let
> off) I cannot bring myself to that conclusion, yet.
>
> So that we are on the same page I will list what is on my car and when
> the noise started happening.  I made a close visual inspection of
> everything when I did the wheel swap this weekend and nothing looks
> out of place, nothing looks like it should be making this noise!
>
> 95 S6, 928GTS calipers from Benson Porsche, brand new.
> OEM RS2 caliper brackets from VAG Parts UK, not machined.
> A8 (323mm?) Brembo rotors, brand new from PartsQuick.
> Ferodo DS2500 pads, brand new.
> Paragon braided hoses, banjo fitting.
> Porsche OEM caliper bolts.
> *034 bracket bolts* (note, these are standard metric head Vs. the OEM
> Hex head bracket bolts I have seen elsewhere)
> Super Blue, pressure bled.
>
> My braking system did not make any noise (other than pad squeal) for
> the first hundred or so miles.  I bedded everything in properly
> according to Mov-it instructions on their website.  As I have stated
> before my brakes immediately started making this groaning noise after
> a very hard stop to avoid a collision with someone who pulled out in
> front of me.  At the time I thought I may have bended something
> (bracket?) when I did that stop though that doesn't make sense.  I
> drove another 10 miles and pulled over and inspected b/c I thought
> that I was rubbing the caliper against the wheel or something of that
> nature.  Nothing looked amiss.  Noise then became intermittent and not
> too bad, only occasionally making itself known.  Turning left induced
> the noise, turning right quieted it or if I tapped my brakes it would
> stop for awhile.  It was only doing this for about two weeks before I
> was hit and my car than sat at a body shop for 5 weeks............that
> about brings us up to present.
>
> On the way home from body shop the noise returned, only this time
> worse. (More grinding sound, vibrations in the steering wheel.)  Put
> my 17" Bolero's on and now the noise is present every time I drive.
> It use to take some driving time (10-15 minutes) before the noise
> would appear, this has been reduced dramatically to about 3-5 minutes
> as evidenced on the way to work this morning.  It is now very loud and
> once it starts the only thing that makes it stop is turning right or
> tapping the brakes, and only momentarily when performing one of these
> actions.  Suspension deflection also seems to have an impact.  I live
> in very rolling terrain, with lots of hills and dips.  When the
> suspension loads up the noise is there, when it unloads (cresting a
> hill) it subsides somewhat for a second.
>
> ALL of the above sounds like a wheel bearing to me. HOWEVER, there is
> no play whatsoever when I have the wheel off the ground and do the
> Up/down, forward/back check for play.  Also, why would even the
> slightest (resting foot) on the brake pedal have any impact on the
> noise if it was a wheel bearing?  I can quiet the noise completely if
> I ride the pedal.
>
> I am at a loss and await to hear if your swapping of the rotors and
> brackets makes any difference.  If it does I am going to order new
> slotted rotors from Apikol but I just can't see the rotors being the
> issue. I re-read your original email and the theory of brake fluid
> expansion leading to pad dragging is interesting but my fluid is fresh
> and blue, no old left in the system and pressure bled.  Noise is
> getting progressively worse which again points to a wheel bearing.
> But is doesn't feel like a wheel bearing, it definitely feels like
> something is going on with the braking system on the passenger side.
>
> Thanks,
>
> John
>
>
>
>
>
>
>
>
> ----- Original Message ----
> From: "McCall, Randy" <rmccall at nexant.com>
> To: jpb3 <jpb3wvu at yahoo.com>
> Sent: Friday, July 4, 2008 6:35:09 PM
> Subject: RE: posts on groaning big brakes
>
> Yep, if I tap the brakes the noise stops momentarily (until, of course
> I let off the brakes...)
>
> One thing I'm going to try (before I pronounce it the caliper), is to
> swap the brake brackets and rotors from side to side and see if the
> noise also migrates.  Mine made no noise prior to installation of the
> new brackets, A8 rotors (in place of the slotted ECS 314 mm rotors)
> and brake pads.  I just don't believe its brake pads, and I also don't
> hold a strong opinion on the caliper sticking.  Would have done so
> before is my thought.
>
> Have company for the weekend and a tandem (bicycle) rally this weekend
> in McMinville, so not until the beginning of the week...
>
> -Randy
>
> From: jpb3 [mailto:jpb3wvu at yahoo.com]
> Sent: Friday, July 04, 2008 8:48 AM
> To: McCall, Randy
> Subject: Re: posts on groaning big brakes
>
> Hi Randy,
>
> Looks like you have covered your bases there with the pads.  Forgot to
> mention that I have the factory vibration dampers installed as well
> and have since the initial install.  My brakes never did this prior to
> a ultra hard stop (to avoid a T collision on a 2 lane rd).
>
> Mine is also the right side that sings.  If you chamfered the pads and
> greased everything with no results I am not going to go down that
> path.  The scenario about the hanging piston seems right to me, though
> my calipers are brand new so that is discomforting.  When the brakes
> start singing if I just barely tap the brakes it will interrupt the
> noise, does yours do this as well?  If it wasn't for this fact I would
> point to the wheel bearing as that is what it sounds like but I know
> it cannot be that b/c of the complete correlation with the brake
> pedal.
>
> I am going to look and perhaps try some things today, will let you
> know if I come across anything.
>
> John
>
> ----- Original Message ----
> From: "McCall, Randy" <rmccall at nexant.com>
> To: jpb3 <jpb3wvu at yahoo.com>
> Sent: Friday, July 4, 2008 9:01:17 AM
> Subject: RE: posts on groaning big brakes
>
> Hey John,
>
> I chamfered the brake pads, and put on the OEM vibration dampers last
> week.  I also lightly lubed the edge of the pad where the metal
> contacts the caliper with a special silicon caliper grease.  (also
> checked the axle bolt).  No go....  Still sings like a canary (one
> note though) after the brakes are warm.  I talked with 034 who sold me
> the brackets and bolts - they had no ideas; talked with Scott Mockry
> at SJM; same story.  He thought that maybe one of the calipers wasn't
> retracting - seems as though mine is the right side that is singing.
>
> So not answers yet on the resolution, and sounds like there are at
> least two of us with the problem!  Do you have the Euro A8 rotors ie,
> non-slotted, non-drilled?
>
> My previous 314mm rotors from ECS were slotted, and made no noise with
> these calipers and same brake pads.
>
> -Randy
>
> From: jpb3 [mailto:jpb3wvu at yahoo.com]
> Sent: Friday, July 04, 2008 5:50 AM
> To: McCall, Randy
> Subject: Re: posts on groaning big brakes
>
> Hi Randy,
>
> Thanks for your insights.  I just got my car back from the body shop
> yesterday and on the way home the brakes started singing like they
> never have before!  So much for my axle bolt theory (that was a bit of
> a stretch to begin with). It definitely sounds as though it is a
> harmonic resonance from the brakes, if I just lightly tap the brakes
> it stops completely.  As soon as I lift my foot off the pedal it
> begins again.  It only happens after the braking materials are warm as
> well.  Never heard it in the first few miles of the day when
> everything is still cold.
>
> This points to the caliper assembly and not much else IMO. I am going
> to throw my summer wheels on today and will make a close inspection of
>  the front left caliper assembly.  Is that the same side yours is
> making noise as well?
>
> Any updates on your progress solving this noise?
>
> Thanks,
>
> John
>
> ----- Original Message ----
> From: "McCall, Randy" <rmccall at nexant.com>
> To: jpb3 <jpb3wvu at yahoo.com>
> Sent: Monday, June 23, 2008 9:18:15 AM
> Subject: RE: posts on groaning big brakes
>
> Hi John,
>
> Thanks for the detailed reply.  Sorry to hear about the accident -
> I've got another 95.5 S6 in my woodshop still being dismantled after
> getting rear-ended at about 50mph.....Engine went to Mahoney, Tranny
> and ECU to Canada, and lots of other parts have been scattered across
> the country.
>
> And thanks for the tip on the axle bolt - I do have the torque wrench
> big enough to check that, and that's an easy one to try.  I ordered
> the anti-vibration dampers this weekend from SJM, so I'll throw those
> in whenever they arrive also.  I don't think the wheel bearing is a
> problem with this car, but you never know.  In my case, before I
> retrofitted the new brackets and rotors and went from the ECS stage II
> BBK to the full RS2 brackets, 323 rotors, and 928GTS calipers, there
> was no singing brakes!  The old rotors were the slotted ECS rotors
> (314mm I think).
>
> The noise now isn't so much a groan as it is a single pitch hum - a
> resonance type noise from rubbing.  It happens in straight line, but
> also increases on left hand turns; that could point to the loose axle
> bolt...  I'll sure as heck try the easy stuff like axle bolt torque
> first!
>
> I'll let you know the outcome on my various remedies...
>
> Thanks,
>
> -Randy
>
> From: jpb3 [mailto:jpb3wvu at yahoo.com]
> Sent: Monday, June 23, 2008 5:16 AM
> To: McCall, Randy
> Subject: Re: posts on groaning big brakes
>
> Hi Randy,
>
> Unfortunately my car was rear ended and has been at a body shop for
> about a month now and I did not completely solve the "groaning" issue
> with the brakes before it went in.  I originally thought it was a
> wheel bearing, as the noise originally appeared after I did a hard
> stop to avoid a collision.  This was from about 75mph to
> lock-antilock.   I thought that since I had just installed the BBK
> that perhaps this braking event might have put enough force on the
> wheel bearing that it made a weak or almost ready to fail bearing
> apparent.
>
> The problem was that there was literally no movement of the wheel when
> I tested it while it was jacked up off the ground.  No side to side or
> top to bottom movement whatsoever.  I have had bead wheel bearings
> before and usually you can almost always feel the bearing going out
> but tugging on the wheel in all directions.
>
> What did happen was I had to order a special 17mm hex socket for the
> Wheel bearing R&R for the axle bolt.  To my surprise when I went to
> loosen the axle bolt I found it already loose!  It wasn't finger loose
> but pretty close to it.  This was odd since the required torque for
> that monster is somthing like 168 ft/lb!  Since I do not have a torque
> wrench that goes that high I took my 3/4 drive ratchet and a small
> section of pipe and tightened it as much as I thought I should.  The
> "groaning" all but dissapeared!  It has not completely gone away but
> was infrequent and not any where near as loud or continuos as before.
> In fact it has probably only happened 2-3 times since I tightend that
> axle bolt and only for a second or two.   In my opinion it probably
> isn't quite tight enough but I will fix that once I get my car back as
> I have large torque wrench now and am curious as to how tight that
> bolt really is.  I probably only had it a week or so in this condition
> before I was hit so my results are not conclusive.
>
> So..check that axle bolt first and see if it is tight.  I am
> interested to know.  If yours is tightend to spec it I would then take
> the wheel and brake disc off and check that guard behind the disc,
> just to make sure it is not the culprit. ( i dont think it will be )
>
> I am not yet convinced that it is NOT a wheel bearing issue, though as
> I said I all but eliminated the noise by tightening up my axle bolt.
> Let me know if your is loose as well.
>
> John
>
> ----- Original Message ----
> From: "McCall, Randy" <rmccall at nexant.com>
> To: jpb3wvu at yahoo.com
> Sent: Saturday, June 21, 2008 12:59:59 PM
> Subject: RE: posts on groaning big brakes
>
> Searching the archives, I saw your post on AW from March of this year
> regarding your PS groan after installing a BBK.  I had an existing BBK
> on my 95.5S6A when I bought the car, found out when I went to change
> the pads and rotors that it was a Stage II ECS kit with smaller
> rotors...  Put in new machined RS2 brackets from 034 (for corrected
> side-side rotor position)and reinstalled the new 323 rotors, stock
> Textar Porsche pads.  Since that time I have been getting a "groan"
> that happens a lot like what you described.  Hard to tell if its from
> one side or the other, but it is fine until you drive 10 minutes or
> so, then you can hear it on straight line driving, and even feel it a
> bit in the steering wheel.
>
> I was thinking this was a pad dragging after brake fluid warmed and
> perhaps a small bit of air in the caliper, so I recently power-bled
> all the corners and flushed the Super Blue fluid (came out clean); the
> car came without pad dampers, so I've ordered those to see if that
> might help.
>
> Question after this long explanation is:  was your problem a wheel
> bearing, or do the brakes continue to "sing" at a kind of resonant
> frequency like mine now are.  Not a squeal, but a light groan like you
> described.
>
> Thanks
>
> -Randy
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