Brake Shudder

On Tue, 26 Oct 2004 15:05:00 +1000, D Walford <walford@iprimus.com.au>
wrote:

>Gono wrote:
>>
>?
>> My belief is that the bloody things should be bedded in by the
>> mechanic or brake specialist !!
>
>Probably the best method.
>
>> Next problem of course is finding a bloody road where you can
>> efectively do this , Fairly hard in the burbs
>> I'm lucky where i live in the west of melbourne i have a few quiet
>> roads where i can do this ( the road to the womens prison is my usual
>> haunt for this proceedure)
>
>If we don't here from you after the next set of new pads I'll assume you
>got run over by a very large green and yellow gravel truck:-)
>
>
>
>
>Daryl
Thats the one Daryl i always try to avoid the trucks better after
about 7.00 pm
Gono

I've been suitably educated now!
Thankyou all for you input.

Cheers, Kay

John_H wrote:
> If they really must be machined, find someone who grinds them, then go
> out and bed your pads in properly.
>
> Have a look at...
> http://www.stoptech.com/whitepapers/...otors_myth.htm
>
Hmm, sounds like crap. My Subaru brakes just keep vibrating, and have had
a few! machinings, so figured it couldn't be warped discs again. My
mechanic friend said it probably is, so we got it up on his hoist and put a
dial on the outer edge, and sure enough, rotating the sucker showed quite a
bit of variation, something like 10thou. Due to the orientation I
couldn't do the inner surface, but guessing the results would be the same.
If you don't call this a warping, I suppose you could call it an uneven
wearing or something!

Regards
Tony

--�
http://tonyspage.abock.de for some Topfield info including turning
those recordings into DVDs, adding features with the open source TAP
environment etc...

On Mon, 25 Oct 2004 13:46:45 +1000, John_H <john4271@hotmail.com>
wrote:


>>Just like to visit the machanic a little knowledgable :)
>
>Firstly -- my views on the subject aren't mainstream and would no
>doubt raise the ire of those who'd want to machine them.
>
>I'd start by banning brake lathes, which destroy more rotors than
>braking ever did but are a nice little earner to those who have 'em.
>
>If you use the correct pads and bed them in properly from new (almost
>no one ever does) your brakes aren't likely to develop shudder...
>which is almost always due to pad material building up on the rotors.
>Your mechanic however will almost certainly know better (he'll reckon
>they've warped) and isn't likely to be interested if he doesn't get to
>use his lathe.
>
>FWIW I can almost always wear my own rotors down to minimum thickness,
>without their developing even the slightest hint of shudder and still
>have them within the manufacturer's spec for runout. It usually takes
>three sets of pads, sometimes only two, to wear out a rotor.
>
>If they really must be machined, find someone who grinds them, then go
>out and bed your pads in properly.
>
>Have a look at...
>http://www.stoptech.com/whitepapers/...otors_myth.htm
>
>Your brake 'specialist' will no doubt be pissed if you tell him. Nor
>should you ask him why brake lathes didn't appear on the scene until
>disc brakes became mainstream.... In the ten years prior to that,
>those who had 'em never felt the need to machine them.
>
>So there, I probably haven't helped one bit. :))
John i agree with your post completely and always bed my brakes in
after any pad replacement etc
But the discs will still need machining if they have a cementite build
up on them
Next question do you think that a mechanic or brake specialist should
explain to the person who has had this work done to their vehicle the
proceedure of pad bedding ??? especially to a woman
next problem just how soon after the replacement does this need to or
can be done effectively ??? can the woman drive the car 50 kilometers
home and explain what needs to be done to the husband that night ???
My belief is that the bloody things should be bedded in by the
mechanic or brake specialist !!
Next problem of course is finding a bloody road where you can
efectively do this , Fairly hard in the burbs
I'm lucky where i live in the west of melbourne i have a few quiet
roads where i can do this ( the road to the womens prison is my usual
haunt for this proceedure)
Regards Gono

tony_h wrote:

>John_H wrote:
>> If they really must be machined, find someone who grinds them, then go
>> out and bed your pads in properly.
>>
>> Have a look at...
>> http://www.stoptech.com/whitepapers/...otors_myth.htm
>>
>Hmm, sounds like crap.

Did you catch the author's name by any chance? One of the most
respected in the business -- try googling *carroll smith gt40*.

Or, if you're referring to the grinding comment... that's how
reputable manufacturer's do it. You'll only ever see rotors
manufactured in Oriental gaols that have been turned (finished on a
lathe). Bedding in is also highly desirable if you want long lasting
trouble free brakes.

>My Subaru brakes just keep vibrating, and have had
>a few! machinings, so figured it couldn't be warped discs again. My
>mechanic friend said it probably is, so we got it up on his hoist and put a
>dial on the outer edge, and sure enough, rotating the sucker showed quite a
>bit of variation, something like 10thou. Due to the orientation I
>couldn't do the inner surface, but guessing the results would be the same.
>If you don't call this a warping, I suppose you could call it an uneven
>wearing or something!

Hardly likely to be wear if you clocked the (unworn) outer edge.
Distorted by some mechanical means no doubt. Warped by heat generated
from braking... never!

FWIW I've seen discs come off a brake lathe with 10 thou runout -- and
they didn't even shudder at the time.

--
John H

OK, I'll ask the question that all the lurkers are asking themselves - just
how do I bed in new brake pads?

"Gono" <gono@atozworld.com> wrote in message
news:qkqqn090csj41ogd4k6rct25qrnq0ogee0@4ax.com...
> On Mon, 25 Oct 2004 13:46:45 +1000, John_H <john4271@hotmail.com>
> wrote:
>
>
> >>Just like to visit the machanic a little knowledgable :)
> >
> >Firstly -- my views on the subject aren't mainstream and would no
> >doubt raise the ire of those who'd want to machine them.
> >
> >I'd start by banning brake lathes, which destroy more rotors than
> >braking ever did but are a nice little earner to those who have 'em.
> >
> >If you use the correct pads and bed them in properly from new (almost
> >no one ever does) your brakes aren't likely to develop shudder...
> >which is almost always due to pad material building up on the rotors.
> >Your mechanic however will almost certainly know better (he'll reckon
> >they've warped) and isn't likely to be interested if he doesn't get to
> >use his lathe.
> >
> >FWIW I can almost always wear my own rotors down to minimum thickness,
> >without their developing even the slightest hint of shudder and still
> >have them within the manufacturer's spec for runout. It usually takes
> >three sets of pads, sometimes only two, to wear out a rotor.
> >
> >If they really must be machined, find someone who grinds them, then go
> >out and bed your pads in properly.
> >
> >Have a look at...
> >http://www.stoptech.com/whitepapers/...otors_myth.htm
> >
> >Your brake 'specialist' will no doubt be pissed if you tell him. Nor
> >should you ask him why brake lathes didn't appear on the scene until
> >disc brakes became mainstream.... In the ten years prior to that,
> >those who had 'em never felt the need to machine them.
> >
> >So there, I probably haven't helped one bit. :))
> John i agree with your post completely and always bed my brakes in
> after any pad replacement etc
> But the discs will still need machining if they have a cementite build
> up on them
> Next question do you think that a mechanic or brake specialist should
> explain to the person who has had this work done to their vehicle the
> proceedure of pad bedding ??? especially to a woman
> next problem just how soon after the replacement does this need to or
> can be done effectively ??? can the woman drive the car 50 kilometers
> home and explain what needs to be done to the husband that night ???
> My belief is that the bloody things should be bedded in by the
> mechanic or brake specialist !!
> Next problem of course is finding a bloody road where you can
> efectively do this , Fairly hard in the burbs
> I'm lucky where i live in the west of melbourne i have a few quiet
> roads where i can do this ( the road to the womens prison is my usual
> haunt for this proceedure)
> Regards Gono

On Tue, 26 Oct 2004 07:35:15 +1000, John_H <john4271@hotmail.com>
scribbled thusly:

>tony_h wrote:
>
>>John_H wrote:
>>> If they really must be machined, find someone who grinds them, then go
>>> out and bed your pads in properly.
>>>
>>> Have a look at...
>>> http://www.stoptech.com/whitepapers/...otors_myth.htm
>>>
>>Hmm, sounds like crap.
>
>Did you catch the author's name by any chance? One of the most
>respected in the business -- try googling *carroll smith gt40*.

John. he says he's "never" seen a warped disc!

I've seen dozens on road cars, very few if any on race cars...maybe
drums were the go when he was servicing his own road cars.


Oz1...of the 3 twins.

I welcome you to crackerbox palace,We've been expecting you.

On Tue, 26 Oct 2004 07:12:29 +0800, "clockmeister"
<no-one@nowhere.com> wrote:

>
>"Alky" <newsantispam@iprimus.com.au> wrote in message
>news:417d76de_1@news.iprimus.com.au...
>> OK, I'll ask the question that all the lurkers are asking themselves -
>> just
>> how do I bed in new brake pads?
>>
>
>Like asking the meaning of life that is, but as a guide...
>
>http://www.bendix.com.au/_products_t..._performax.asp
>
>
I've had "brake shudder" at times on my last 4 commodores VT-VY

I dont believe any of them had warped discs.

When I first depress the peddel they may shudder a little... but if I
modulate the peddle a little the shudder stops and I can break
smoothly....

Calipers exerting uneven pressure?

clockmeister wrote:

>
>"John_H" <john4271@hotmail.com> wrote in message
>news:mk2rn0tm4aei92tpdi5bakv4tkisbf1idt@4ax.com.. .
>> clockmeister wrote:
>
>> Maybe my own Dunny's a bit too old to qualify. It's now on it's
>> second set of front rotors (DBA replacements). The first set saw out
>> a mere 2 sets of replacement pads (Metal Kings at the time) -- because
>> those older Dunnies have a habit of tapering their rotors at the
>> outside. Otherwise they were well within the service spec for runout
>> and groove depth (which doesn't cause brake shudder either).
>
>Groove depth doesn't, runout does. How old is your Commodore?

Mine's a VN, which has never had the brake problem that's apparently
perplexed the Holden engineers, although it has had a few other
problems they never managed to solve. ;-)

Nor does runout by itself cause shudder, in my limited experience.
There are three separate problems encountered with disc brakes...
pedal feedback, wheel/suspension shimmy under brakes, and brake
shudder. The first two are more likely to be caused by runout.

I've also assumed that the original poster knows the difference.

--
John H

Gono wrote:

>But the discs will still need machining if they have a cementite build
>up on them

The way I understand what Carroll Smith has said (he's no longer with
us) is you won't have cementite if you use the right pads and bed them
in correctly.

>Next question do you think that a mechanic or brake specialist should
>explain to the person who has had this work done to their vehicle the
>proceedure of pad bedding ??? especially to a woman

Not the way I do 'em (I wouldn't wish to be sued)!.. Noting that the
procedure recommended by Bendix (see OzOne's post) is about the limit
of what anyone's likely to recommend in these litigious times. :)

>next problem just how soon after the replacement does this need to or
>can be done effectively ??? can the woman drive the car 50 kilometers
>home and explain what needs to be done to the husband that night ???

So long as they don't get overly hot prior to bedding in it should be
OK.

>My belief is that the bloody things should be bedded in by the
>mechanic or brake specialist !!

If I were a brake specialist, which I'm not, I'd insist on doing the
bedding in myself!

>Next problem of course is finding a bloody road where you can
>efectively do this , Fairly hard in the burbs
>I'm lucky where i live in the west of melbourne i have a few quiet
>roads where i can do this ( the road to the womens prison is my usual
>haunt for this proceedure)

I'm even luckier. I live a fair way out of town and there's a bitumen
road past my gate which is almost never policed. I do the last bit on
the return run, which involves a 160 kph crash stop (just short of
lock up -- or ABS intervention) which has 'em smokin' -- literally.
Definitely not recommended for the burbs. :)

--
John H

"John_H" <john4271@hotmail.com> wrote in message
news:u7qqn05i82e4pulhtglqrbpts6d633tm4b@4ax.com...
> tony_h wrote:
>
>>John_H wrote:
>>> If they really must be machined, find someone who grinds them, then go
>>> out and bed your pads in properly.
>>>
>>> Have a look at...
>>> http://www.stoptech.com/whitepapers/...otors_myth.htm
>>>
>>Hmm, sounds like crap.
>
> Did you catch the author's name by any chance? One of the most
> respected in the business -- try googling *carroll smith gt40*.
>
> Or, if you're referring to the grinding comment... that's how
> reputable manufacturer's do it. You'll only ever see rotors
> manufactured in Oriental gaols that have been turned (finished on a
> lathe). Bedding in is also highly desirable if you want long lasting
> trouble free brakes.

Jap brakes hardly ever suffer from warpage causing brake shudder although
older Subaru's had a bit of an issue if they get very hot.

>>My Subaru brakes just keep vibrating, and have had
>>a few! machinings, so figured it couldn't be warped discs again. My
>>mechanic friend said it probably is, so we got it up on his hoist and put
>>a
>>dial on the outer edge, and sure enough, rotating the sucker showed quite
>>a
>>bit of variation, something like 10thou. Due to the orientation I
>>couldn't do the inner surface, but guessing the results would be the
>>same.
>>If you don't call this a warping, I suppose you could call it an uneven
>>wearing or something!
>
> Hardly likely to be wear if you clocked the (unworn) outer edge.
> Distorted by some mechanical means no doubt. Warped by heat generated
> from braking... never!

You should spend a day at a Holden dealer where low KM cars have discs
shaped like bananas. They are routinely replaced under warranty. Ford are no
different from what I hear.

> FWIW I've seen discs come off a brake lathe with 10 thou runout -- and
> they didn't even shudder at the time.

It's a miracle. Discs ain't what they used to be...

"Alky" <newsantispam@iprimus.com.au> wrote in message
news:417d76de_1@news.iprimus.com.au...
> OK, I'll ask the question that all the lurkers are asking themselves -
> just
> how do I bed in new brake pads?
>

Like asking the meaning of life that is, but as a guide...

http://www.bendix.com.au/_products_t..._performax.asp

John_H wrote:

>
>Noting that the
>procedure recommended by Bendix (see OzOne's post) is about the limit
>of what anyone's likely to recommend in these litigious times. :)

Oops -- 'Twas Clocky's post.

--
John H

Gono wrote:
>
?
> My belief is that the bloody things should be bedded in by the
> mechanic or brake specialist !!

Probably the best method.

> Next problem of course is finding a bloody road where you can
> efectively do this , Fairly hard in the burbs
> I'm lucky where i live in the west of melbourne i have a few quiet
> roads where i can do this ( the road to the womens prison is my usual
> haunt for this proceedure)

If we don't here from you after the next set of new pads I'll assume you
got run over by a very large green and yellow gravel truck:-)




Daryl

"Toby Ponsenby" <toby@privacy.net> wrote in message
news:1c2qnaahtwr7l$.p4pb05ffsrlw$.dlg@40tude.net.. .
> <| clockmeister |> did write on 26Oct2004 at 11:20:07 AM
>> Nah, brake pulsation which may be fixed by measuring runout of the disc
> and
>> the hub and matching them to cancel each other out.
>>
>> That may work if it's a slight pulsation at low speed.
> Jesus! Runout in the hub? Still using conical races and bearings may mean
> you're right:-)

The hub is a sealed unit, but there will always be a slight runout as
nothing is made perfect. The best you can do is to try and cancel them out.
We used to have to do this under warranty but now this is done at
production.

> Erk!
>
> How about unbolting the stuff , wire-brushing all mating surfaces and
> replacing it all using a <gasp>TORQUE WRENCH rather than a rattle gun may
> cure the problem.

Wheels don't get rattled on without the use of a torque stick at the very
least at dealerships and the fix was what you said plus cancelling the
runout.

> Possibly that car will allow a series of differing mounting positions for
> the rotors, and therefore a runout test in each of the available rotor
> positions may yield good results.
> Bear in mind that the workshops that do this sort of work won't like
> spending the time necessary to get things right.
> And yes, even the wheel nuts may require the treatment.

That is what is required these days and the dealerships do it that way on
complaint vehicles.

> Then there are the slide pins on floating calipers. Maybe they're made of
> putty or somethin.

They're not the problem.

"John_H" <john4271@hotmail.com> wrote in message
news:65arn0llct0lq8dh70picftgak2dlq0m2u@4ax.com...
> clockmeister wrote:
>
>>
>>"John_H" <john4271@hotmail.com> wrote in message
>>news:mk2rn0tm4aei92tpdi5bakv4tkisbf1idt@4ax.com. ..
>>> clockmeister wrote:
>>
>>> Maybe my own Dunny's a bit too old to qualify. It's now on it's
>>> second set of front rotors (DBA replacements). The first set saw out
>>> a mere 2 sets of replacement pads (Metal Kings at the time) -- because
>>> those older Dunnies have a habit of tapering their rotors at the
>>> outside. Otherwise they were well within the service spec for runout
>>> and groove depth (which doesn't cause brake shudder either).
>>
>>Groove depth doesn't, runout does. How old is your Commodore?
>
> Mine's a VN, which has never had the brake problem that's apparently
> perplexed the Holden engineers, although it has had a few other
> problems they never managed to solve. ;-)

Original rotors or aftermarket ones? I think you got lucky ;-)

> Nor does runout by itself cause shudder, in my limited experience.
> There are three separate problems encountered with disc brakes...
> pedal feedback, wheel/suspension shimmy under brakes, and brake
> shudder. The first two are more likely to be caused by runout.
>
> I've also assumed that the original poster knows the difference.
>

Runout was deemed a big enough problem for Holden to start cancelling out
runout of hubs/discs in production. I don't know if it worked, I left.

Hi,

My TH Magna has slowly developed wheel shudder when braking, more
noticeable at higher speeds.

I've done 55,000km without any problems whatsoever - great car.

Am I on the right track thinking the chances of the front disks
requireing machining are good rather than a simple disk pad
replacement?

Just like to visit the machanic a little knowledgable :)

Cheers,
Kay

"KC" <kaye_see@yahoo.com.au> wrote in message
news:n0non0pjndkueltir20g265a08j305rhca@4ax.com...
> Hi,
>
> My TH Magna has slowly developed wheel shudder when braking, more
> noticeable at higher speeds.
>
> I've done 55,000km without any problems whatsoever - great car.
>
> Am I on the right track thinking the chances of the front disks
> requireing machining are good rather than a simple disk pad
> replacement?
>
> Just like to visit the machanic a little knowledgable :)
>
> Cheers,
> Kay

Yep. Machined, or replaced if they are not thick enough.

KC wrote:

>
>My TH Magna has slowly developed wheel shudder when braking, more
>noticeable at higher speeds.
>
>I've done 55,000km without any problems whatsoever - great car.
>
>Am I on the right track thinking the chances of the front disks
>requireing machining are good rather than a simple disk pad
>replacement?
>
>Just like to visit the machanic a little knowledgable :)

Firstly -- my views on the subject aren't mainstream and would no
doubt raise the ire of those who'd want to machine them.

I'd start by banning brake lathes, which destroy more rotors than
braking ever did but are a nice little earner to those who have 'em.

If you use the correct pads and bed them in properly from new (almost
no one ever does) your brakes aren't likely to develop shudder...
which is almost always due to pad material building up on the rotors.
Your mechanic however will almost certainly know better (he'll reckon
they've warped) and isn't likely to be interested if he doesn't get to
use his lathe.

FWIW I can almost always wear my own rotors down to minimum thickness,
without their developing even the slightest hint of shudder and still
have them within the manufacturer's spec for runout. It usually takes
three sets of pads, sometimes only two, to wear out a rotor.

If they really must be machined, find someone who grinds them, then go
out and bed your pads in properly.

Have a look at...
http://www.stoptech.com/whitepapers/...otors_myth.htm

Your brake 'specialist' will no doubt be pissed if you tell him. Nor
should you ask him why brake lathes didn't appear on the scene until
disc brakes became mainstream.... In the ten years prior to that,
those who had 'em never felt the need to machine them.

So there, I probably haven't helped one bit. :))

--
John H

<| Mug Punter |> did write on 25Oct2004 at 12:16:10 PM
> "KC" <kaye_see@yahoo.com.au> wrote in message
> news:n0non0pjndkueltir20g265a08j305rhca@4ax.com...
> > Hi,
> >
> > My TH Magna has slowly developed wheel shudder when braking, more
> > noticeable at higher speeds.
> >
> > I've done 55,000km without any problems whatsoever - great car.
> >
> > Am I on the right track thinking the chances of the front disks
> > requireing machining are good rather than a simple disk pad
> > replacement?
> >
> > Just like to visit the machanic a little knowledgable :)
> >
> > Cheers,
> > Kay
>
> Yep. Machined, or replaced if they are not thick enough.

Make that
Yep - machined or replaced if *you* are thick enough.

At that distance travelled, I doubt the disks would be down to their (don't
sue us, we specified it on the disk) minimum thickness.


--
Toby
quidquid latine dictum
sit, altum viditur