300M: Turn/re-surface rotors (or replace)

Am going to bring my M (non-PHP) into a dealer soon to look at
rotors. Have recently developed a very noticable shudder being felt
in the brake pedal (and steering wheel) upon application of braking
force. Car ('00) has about 47k miles (mostly city driving), front
pads have plenty of meat on them (front rotors had no measurable wear
at the time), rear pads replaced a few months ago.

(I took the wheels off and looked at all rotors - no nasty gouges or
scores on any surfaces, no stones caught in the pads, etc. This
couldn't be some problem with ABS - could it?)

When I asked service dept (over the phone) about resurfacing or
turning the rotors, I sensed some resistance to the idea. Guy even
went so far as to say that the rotors are "throw-away". I'm
definately getting the vibe that they'd rather replace the rotors
rather then turn them.

Is rotor replacement one of those things that dealer service garages
push unnecessarily or am I over-estimating the durability (or
re-workability) of factory rotors?

And if I'm going to spring for new rotors, are there better
aftermarket types available for the M? Mopar Performance vs oem
replacement?

 

Whether or not the rotors are a throw-away item will depend on a few
factors:

1) There is a minimum thickness allowable (I think even by law???).
And there is a "machining thickness" (amount of material which is
removed during the machining process).

As a theoretical example... Let's say your rotors measure 0.900
inches, and are warped. The mechanic puts them on the lathe and
machines them "flat", and to do this, he has to take of 0.010 inches
on each side of the rotor. This leaves your rotors with a measurement
of 0.880 inches. If the minimum allowablw thickness is specified at
0.875 inches, then the mechanic can re-install the rotors on your car.
However, you wont be very happy! Since there is so little meat left on
them, the thinner they get, the worse they are at disappating the heat
that is generated while braking. This will tend to cause them to warp
again - and fairly soon. Most shops would recommend replacing the
rotors at this point because if you dont, you will be paying them the
labour to do the job again soon anyways!

But if the minimum thickness allowable is 0.890 inches, then you have
no option - they must be replaced.

2) The other major factor is design. I used to own a 1987 Olds. The
"Heavy Duty" brakes in that car were so thin to start with, that by
the time you detected shudder due to the rotors being "out of flat",
that they were already past the point of no return! This contrasts
with my 1979 Chev that went 250,000 kms on the factory rotors! But
these babys were HUGE, and the car was rear wheel drive.

It has been my experience that many of the rotors in todays cars are
deliberately designed to be throw away.

Now on my GM car, GM wanted almost $200 PER ROTOR to replace them!!!
What complete and utter horse shit! The local brake shops varied
between $80 and $130 depending upon brands.

But I found a "jobber" who carried "United Brake Parts", and ony
wanted $25! ???!!

When I asked the shops about them, I was told they "were not good
quality, and would wear out quickly!"

Well let's do some quick math... My brakes were only lasting about 1
year. So at $25 for a rotor, presuming I replaced them with NEW ones
EVERY YEAR, then I could buy new rotors for EIGHT YEARS at dealer
prices, or FOUR YEARS at "brake shop" prices.

I put in the cheap ones. They lasted TWO YEARS, just like the factory
ones!

Now I do not have extensive experience with Chrysler on this issue,
but I do have a 1994 Grand Caravan with the 3.3l engine. As cars go
these days, it is fairly heavy. I do NOT have ABS. But the brakes work
very well. I purchased the van with about 130,000 kms, and now have
about 150,000 kms. When the wheels were off recently at my favorite
shop, they looked at the brakes (they also inspected the vehicle
before I purchased it). They said that the brakes had hardly worn at
all! )))

Before I went in to a dealer with a blank cheque, I would have the car
inspected by at least two reputable brake shops. Most of them will
provide an inspection/estimate for free. THEN go in to the dealer. You
can then decide if your dealer is gouging you or not. There are some
very reputable good quality brands of rotors - such as Wagner - which
should be as good or better than Dealer parts (Keeping in mind that
companies like Wagner often do "OEM" parts for companies like
Chrysler!).

As to the specifics for your model, I have to defer that to others
with direct experience.

hth

 

Mine has had a slight shudder for many miles. I ignore it. New rotors may
do the same fairly quickly. Apparently pad material can leave residue
embeded in the surface that can cause the shudder according to posts here
last year.

 

New thickness is 1.019- 1.029". Minimum thickness (stamped on the
rotor, and yes it is by law - it is illegal to turn them if they are
below that thickness) is 0.960".

Besides true warpage, the problem could also be pad material not filmed
evenly on the rotor surface, as Art mentioned, causing different
friction at different points. Also, it could be uneven wear so that
there is a thickness variation rather than a true warping. If the
latter is the cause, then having the rotors slightly thinner (from wear
and turning) will not contribute to the recurence of the problem.
Thinner rotors would contribute slightly to tendency to warp because
there's less mass to absorb a lot of heat at one time (but surface area
for cooling is, for all practical purposes, not diminished more than a
fraction of a per-cent).

It is a gamble either way re: get new vs. turn the existing ones
(assuming the thickness is not down close to the legal limit). On the
same car, one person may have the warped rotors turned and they do fine,
another person may buy a new pair and the new pair give problems.

If you get new rotors, I suggest NAPA's P/N 86777, which is the PHP
rotor, at $47 each. For some reason, the non-PHP is $60 (they are
physically interchangeable). But I can't promise you they won't warp
too. It's a design issue. The best you can do is get a replacement
that has as good a materials and manufacturing proceses as you can get -
but that in itself can't fix a marginal design issue (and as has been
pointed out, many manufacturers are grossly guilty of that on brakes
these days). Short of going with come exotic mod which would cost
several thousand dollars for the M, there has not been a magic bullet
aftermarket solution on these cars, that is, a brand that has been found
to be problem free (because it is a design issue). There has been some
discussion on the 300M ezBoard about some available stainless steel
rotors, but even they cost over $700 the pair - IOW - forget it (and I
don't know that they solve the problem either).

BTW - don't worry about the rear rotors on your M - they may last the
life of the car due to not much heat and wear on them. Your problems
are the front - focus on doing the best you can for those. IOW - don't
get the rear rotors turned or replaced - put your money in the fronts -
that's where the problems are.

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

When/if you replace your rotors, make sure you get QUALITY rotors.
Buy CANADA/USA parts ONLY. The China/Japan/India/etc. parts that are
on the market do not hold up the same.

 

I see that many have responded and provided excellent advice so I will only
add a couple of new thoughts. First, if you do not have one already, invest
in a good torque wrench and use it to reset the torque evenly on all your
lug nuts after you have removed the wheels or had work done by others. From
my personal experience, this seems to help reduce/eliminate warped rotors
and brake pulsing. Second, you got advice to buy quality US/Canadian made
rotors. I've had very good luck with the Raybestos brand as opposed to the
Chinese imports in the generic "white box". Lastly, do either re-surface or
replace the rotors whenever you are changing your pads as this helps to
increase pad wear life.

Bob

 

Good points, Bob.

BTW - The NAPA rotors that I recommended (NAPA P/N 86777) are the
Raybestos rotors boxed and labeled as NAPA's in-house United Brake
brand.

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

Some rotors are now so thin from the factory that after you turn them
once they will quickly warp again. Combine this fact with the cheap
price of rotors these days (they can be had for about $35 each for
your car (your cost from the parts store)) and you see why they
hesitate to turn them. Cost you a little more up front but then they
don't have to deal with you coming back unhappy.

If you can't do the work yourself you might want to consider taking it
to a couple of other brake places to get estimates first. Dealer
charges are higher than other places for brake work and there really
isn't anything that they can do better than your average shop in this
case.

Steve B.

 

Could be just bad luck but the only good brake jobs I've gotten were at my
Chrysler dealer. Whenever I go to a brake shop I have to bring the car back
for one reason or another and the brakes never feel as good as new.

 

I just had my rotors turned on my '03 300M. I have 43K miles and my
rotors were doing the same thing as yours. I went to my local brake guy
and had them turned for $20. The brakes feel better than they did when
the car was brand new.

 

I verified that the new thickness is 1.019 and the min. thickness is
..960 (verified by independant brake shop - not the dealer garage).

Measured one of mine - 1.0165. Based on conversations with
independent brake shops, seems they take .004 off each side normally.

Paul Adams said:

Around here, the going rate (independant shop) is about $60 ($44
USD). The dealer wants more like $80.

I was thinking that taking the rotors off was a pain (involving taking
the big nut off the hub, releasing the bearings, etc). Guess I was
thinking it was a lot like taking off the front drums off an old
MoPar. Now that I realize the rotors basically slide off, I'll call
around and see what the cost is if I bring them in somewhere.

Was looking at aftermarket rotors on the net (only Brembo seems to
come up). Stainless steel ($700!) and cryogenic rotors (?).

Around here, Crappy Tire has them at $80 each (unknown brand) - would
rather buy Brembo for $60 US. Will try other parts outlets next week.

Did '98 and '99 300M's come with 15" wheels? (saw this many times on
various parts-charts on the web). Based on the charts - seems that
different years have different rotors (yes?).

Also seems that PHP rotors are a tad (sometimes 15-20%) cheaper than
non-PHP. Can someone explain the differences in the PHP/non-PHP
rotors? (ie will PHP rotors _really_ fit on a non-PHP car?)

Dealer wanted $340 (CDN) plus tax for new rotors, installed, with new
pads (pads have "lifetime" waranty - free replacement (parts+labor)).
This is a "package" price. Rotors only (installed) is $10 or $20
cheaper.

Dealer says that in the last couple of years the minivans are coming
with rotors that are good for 1 turning so I guess they don't exactly
treat them as "throw-aways".

 

The numbers I posted are out of the Chrysler FSM.

....For 0.008" total. Obviously if they are truly warped, they may have
to take off more. But what they told you is probably typical.

Yes - once you remove the wheel and caliper (remove two bolts, and hang
caliper on strut spring).

I think some of the earlier 2nd gen 300M's did in fact come with 15"
wheels - not sure what percentage.

After '99, there were only two types of front rotors on the M - the PHP
and the non-PHP - physically 100% interchangeable. Other than that
there is only the third (smaller diameter) rotor for the 15" wheeled LH
vehicles (different steering knuckle to locate the calipers/pads further
in or out to accommodate the two different rotor diameters).

The only difference is that the non-PHP's are vented on the inside,
i.e., they pull air in from the engine side of the rotor, and the PHP's
are vented on the outside...they pull air in from the curb side. The
visible difference is that there is an open groove for air entrance on
the curb side of the rotor, where the non-PHP is solid in that area and
has an open groove on the opposite (engine) side. I know there are some
photos showing the difference linked from the 300M ezBoard - I will try
to find them and provide the URL (ezBoard search engines suck big time).

The factory engineers would probably tell you that the PHP (outside
venting) should only be used if the wheels are open construction (i.e.,
alloy wheels) vs. the more closed off steel wheels. Whether it makes a
difference in reality, I can't say for sure.

That's typical of most rotors these days. And if you accept the common
line that the risk of warping goes up tremendously because they're
thinner after you turn them, then you can be convinced to throw then
away without turning even though they could be just fine. I'm not sure
it is as drastic an issue as some claim it is. In one sense, you could
argue that a rotor that's already warped and truned already has the
distortions settled out of it from its earlier history (stress relief
from heat). (This also ties in with the possibility that what is often
blamed on warping could really be due to uneven wear, i.e., varying
thickness, which is not a true warping and therefore not related to heat
dissipation issues, and would therefore not be made worse by turning and
making a few thousandths of an inch thinner). To replace or turn is a
gamble either way. Buying new costs more but takes out some (not all if
it's an inferior product) risk.

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

Crappy tire??? You a Canuck too???

Whereabouts are you??? If you live close, I can put you onto some
parts leads for those rotors.

 

I do 'em myself so I KNOW what's been done and how. Helps that I was
trained as a mechanic and made my living at it for 20 some years.

 

As promised (link to photos of rotors of Donn Scruggs, a contributor to
the 300M ezBoard with normally-aspirated M in the low 14's quarter
mile): http://public.fotki.com/ScouterDon/carstuff/300mods/brake_rotors/

(Single left-click on thumbnails to enlarge individual photos. "Regular
Rotor" = non-PHP.)

Here's another photo showing the groove on the curb side of the PHP
rotor (these happen to be drilled and slotted rotors, but the venting is
the same on OEM PHP rotor):
http://community.webshots.com/photo/90612228/90614052hfTSzs
That photo is by SD Mike (San Diego Mike) - another contributor to, and
moderator on, the 300M ezBoard). The vent groove is perhaps a little
more obvious in this photo.

I know there's another photo somewhere that shows someone sticking their
finger in the groove to make it even more obvious, but by now you should
have the "picture" (literally). 8^)

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

Took the rotors off and had them turned at crappy tire ($30 plus tax
for the pair).

New thickness = 1.019"
Thickness @ turning = 1.0165"
Minimum legal thickness = 0.960
Thickness after turning = 0.972 / 0.975 (!)

So they took about 43 thou off them (about 1.1 mm).

One thing I noticed was that although the outer surface was pretty
flat and had a uniform texture, the back side had pits or depressions
that were from 1/8" to 1/4" in area. Basically it looked more like a
thin chrome-plated surface that was flaking off and forming pits. The
mechanic said that the inner side of rotors typically do degrade more
than the outer side.

Can someone tell me what those spring clips (shaped like a "W") are
for? They seem to act like springs that hold the brake pads apart but
they're a bitch to keep in place when putting the caliper back on.

I called around to see who had new rotors, and found brands like
Wagner, Gardian, Dana (Napa) "Trustop" and "Application Engineered".
The Wagner brand had listings for 282 and 297 mm diameter rotors, and
seemed to refer to one or both of those as "European". The original
rotors measure 11 5/8" (295 mm) so I'm not sure what the smaller
rotors are for (15" wheels perhaps?). Prices ranged from $58 to $84
and, if I remember correctly, when PHP and non-PHP were both
available, the PHP rotors were less expensive. (and yes Bill I did
see the links showing the difference being which side the rotors were
vented on).

Went out for a test drive and the vibration/shakes were completely
gone. But there's still a problem. I suspected I was applying too
much pedal during braking and it's still the case. Brakes are too
spongy, and during a hard brake when I'm practically standing on the
pedal the brakes simply don't bite and the ABS doesn't even kick in.

Either I put on some bad pads when I changed the brakes the last time,
or I've got some air in the brake line. Which leads to my next
post...

 

Wow! Must've been really bad.

Possibly way overheated for some reason. There's a term for the
condition of the metal, but it slips my mind for the moment. There have
been a few posts over the years on the 300M ezBoard of that happening to
the front 300M rotors. Sticking/dragging caliper?

Yes - they're pad spreaders. Most so-called "professional" mechanics
throw those (your personal property) away without even asking when doing
a brake job. Some LH's come with them, but most do not - I have not
figured out a rhyme or reason as to which options or years they come
with - I snooped around a Chrysler lot one time and some new LH's had
them, most didn't even though the calipers are the same for all.

You can't buy replacements thru the dealer. The only place I have ever
seen posted for a source for those was with a certain brand of pads that
someone bought from Pep Boys. I'm not sure how effective they are -
possibly they help a little on the CAFE numbers (by reducing brake
drag), but Chrysler has no interest in making sure they are available to
the customer after the sale.

Dana is the parent corp. for Raybestos and United Brake (which is a
Raybestos boxed as United Brake for NAPA).

My guess is "European" = PHP (for the autobahn)

Yes - the Ø282mm are for LH vehicles that came from the factory with 15"
wheels (mostly the base model Intrepids and Concordes - possibly later
years came with only 16" or larger wheels and the larger brakes). I
though I covered that before in this thread.

That can be just needing to wear in a little - but I'll read your other
post to see what you say there. Or perhaps your pads are
overheated/toasted - not surprising if the rotors were as bad as they
apparently were.

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

Stop working on your own brakes. Change your oil, change your plugs,
heck, even rotate your own tires but brakes are too important!

If you don't know what these parts are, don't know about bleeding
brakes, and have only this ng as a font of knowledge, you are putting
yourself and others in danger.

If you can find somebody that really knows what they are doing, then
learn from them, otherwise it is just too dangerous!!!

Dan

 

The rotors on the LH cars are bit undersize for the weight of the car.
Theoretically if you remove metal, they'll dissipate heat worse, and
warp sooner the next time. However I have had no problems turning the
rotors on my Intrepid; have done each once, with no recurrence of the
warpage. If you work on your own car, taking them off and having them
machined at Pep Boys is just fine, costs about $20 and an afternoon's time.

If you have to pay $90/hour for removal of the rotors and machining
them, the price of the parts is less important.

It is very important to torque the wheel nuts evenly to prevent rotor
warpage. A torque wrench, a six inch extension and the correct socket
costs about $20 at Sears. Any time, after having new tires put on ANY
car, I drive away slowly, loosen every wheel nut, and retorque to specs.
Most times the tire store guys will have most of them too tight and a
few too loose, which invites rotor warpage.

 

Looking back at the situation, I don't think that my rotors were
warped. I think that pitting and crater-ing on the back side caused
uneven brake grab which caused brake pedal and steering-wheel
shudders. Rotor surface was probably more glazed than it should be.

I think that the set of pads I put on a few months ago (crappy tire)
are partly to blame. They have about 1/2 dozen deep rivit holes in
the pads where (salt) water can site and maybe corrode the surface
when the car is sitting for a long time (like at airport parking lots
for 3 to 10 days at a stretch). Just a theory.

Anyways, I bought a set of "Performance Friction" pads (carbon metalic
- made in SC) and they are doing much better than the relatively new
unknown-brand. The new pads were $80 for the pair. I could have
gotten Napa brand organic pads for $120, but actually the guy at the
parts counter talked me out of it. The organic's are supposed to be
easier on the rotors, but they dust (or dust more?) and they tend to
squeel.

When you look at a rotor and see how thick the central portion is that
the studs go through, I don't think you're going to be warping that
plate, especially when you tighten the lug nuts with a cross-type tire
iron.