AutoBanter - View Single Post - What are some car-repair jobs you always wished you could do but have never done?

**Xeno**

On 6/11/2017 6:57 PM, wrote:
> On Mon, 6 Nov 2017 04:48:28 +0000 (UTC), RS Wood >
> wrote:
>
>> wrote:
>>
>>> Some of the best rotors out there are Chinese - but also some of the
>>> worst. Consistency is the problem
>>
>> I can't argue but my point is that I've heard everything.
>> The problem is that the advice has to be both logical and actionable.
>>
>> Saying "buy only Brembo or Meyle" is actionable, but not logical.
>> Saying "don't buy Chinese crap" is logical but not actionable.
>>
>> For advice to be useful, it has to be both actionable and logical.
>> I've never heard that in rotors other than buy solid and don't buy
>> drilled/slotted rotors.
>>
>> Other than that, there's no way for a person to tell if one rotor is gonna
>> be better than another.
>>
>> Hence pragmatically ... a rotor is a rotor is a rotor is a rotor.
>>
>>> In some instances (virtually never normal street use) grooved and
>>> slotted rotors DO provide better braking. We are talking competition
>>> use, where the rotors are glowing red hot half the time, and the pads
>>> are off-gassing like crazy - where even 100% dry DOT4 brake fluid
>>> boils in the calipers. Under those conditions, rotors can warp - and
>>> even fracture (in Rallye use I've seen red hot rotors hit an icy
>>> puddle and totally fracture)
>>
>> I'm never talking racing.
>> They drive on bald tires for heaven's sake in racing!
>>
>>
>>> Actually, on SOME cases you can. Look at the consistancy of the fins
>>> in the rotors, and the even-ness of the thickness of the braking
>>> surfaces on both sides of the fins.
>>
>> I'm not gonna disagree that we all can see the mark of good quality on some
>> things when we have two to compare in our hand, but it's too late if you
>> order on the net.
>
> And only a total fool buys everything on the net. I can generally buy
> off the shelf for close to the same price, with no hassle returns and
> I get to see-feel EXACTLY what I'm buying.
>>
>>>> How are you gonna know the metallurgy?
>>>
>>> You don't - that's the hard part - but when you are in the business
>>> you get to know which suppliers stand up, and which don't. If you
>>> know the suppliers well, they will tell you which ones they have
>>> trouble with, and which ones they don't.
>>
>> Yup. I have nothing against good suppliers. I use Brembo and Meyle but if
>> someone else gave me a rotor at a better price, I'd consider them too.
>
> Can't even BUY Brembo for my daughter's car.
>>
>>> And some rotors DO WARP. Not many - but I've had at least a bushel
>>> basket full of genuinely warped rotors in my 25 year carreer. Most
>>> "warped" rotors are not warped - but some are. Some DRASTICALLY - to
>>> the point the caliper moves visibly when the wheel is turned - and if
>>> the sliders stick the pedal jumps and the steering wheel twitches.
>>
>> That's not the measure of warp.
>> Warp is measured on a flat bench.
>> Just like head warp is measured.
>
> Not in the real world. On a large percentage of rotors doing it your
> way is totally impossible. And my way (the industry standard) I can
> measure warpage/runout ON THE CAR and know if it's a problem before
> taking ANYTHING apart beyond moving the rim.
>>
>>> More often than not though, they are either pitted or have deposit
>>> buildup, ot they have "hard spots" due to metalurgical inclusions
>>
>> The only person who says their rotors warped that I will ever trust is one
>> who measured the warp just like you'd measure head warp.
>>
>> If they haven't measured it, it's not happening.
>> And nobody measures it.
>> So it didn't happen.
>>
>> It "could" happen. But it doesn't (on street cars).
>> The problem is the temperature never gets hot enough.
>>
>> Now they can be "warped" from the factory; but that's different (and rare).
>>
>>> Wrong tool. The one I'm talking about has tabs that fit into the
>>> notches on the piston face to "thread" it in as you squeese. Can
>>> sometimes get away with the $17 "cube" but the kit you KNOW is going
>>> to work starts at about $35 for one of questionable quality, and goes
>>> up very quickly from there (and IT won't turn back Mazda rear calipers
>>> - they use a different system
>>
>> I think we're talking about two different kinds of disc brake systems.
>> I had the Nissan 300Z which had the rear disc also as the rear parking
>> brake, but my bimmer has the rear disc and a separate rear parking brake.
>
> Really crappy system - sorry.
>
>
> I've worked on everything from a moskovitch to a Rolls, with Jags,
> Rovers, Toyotas, Fiats, Ladas, VWs, Nissans as well as just about
> every North American brand
>>
>> The piston arrangement is different as is the way to retract them.
>>
>> You don't *twist* pistons in disc brakes that I own that don't have the
>> parking brake as part of the disc brake itself.
>
> I'm talking in general - not the limited vehicles of your experience.
>>
>> At least I don't.
>>
>>
>>>> Never once in my life have I found a single person who has *measured* the
>>>> warp.
>>>
>>> I have. many times.
>> How?
>>
>>>> You know why?
>>>> They don't even know *how* to measure rotor warp.
>>>> They don't have the tools to measure rotor warp
>>> A somple dial indicator tells the tale
>>
>> Nope.
>> How you gonna tell runut from warp with a dial gauge?
> \Measure in more than 2 places -
>>
>>> - and sometimes one side is
>>> straight, and the other side is not - parallelism warpage - where some
>>> fins collapse and one side of the rotor "caves in" - 1 inch thick on
>>> one "side" of the rotor, and .875 or something like that diametrically
>>> across the rotor. - and sometimes virtually deead flat on both
>>> surfaces - other times with about hald paralel and the other half
>>> "sloped"
>>
>> Now you're straining credularity.
>
> No I'm not. Seen it many times
>>
>>>> (Hint: It requires a flat benchtop and feeler gauges and it's not hard -
>>>> but they don't know that because they didn't measure a single thing.)
>>>
>>> That won't necessarilly tell you anything. The only way to KNOW is to
>>> use a dial indicator properly.
>>
>> How you gonna tell runut from warp with a dial gauge?
>
> Watch the needle move.
>>
>>> And that is where YOU are WRONG.
>>> Many technicians measure brake rotors virtually every day of their
>>> working lives.
>>
>> On the entire freaking Internet, find *one* picture (just one) of a
>> technician actually properly measuring brake rotor *warp*.
>
> The internet doesn't show EVERYTHING. What you know comes from the
> web. What I know comes from tears in the trade (including teaching the
> trade)

Teaching the trade, yes, bound to cause tears at times.
>>
>> Just find a *single* picture please. Just one.
>> On the entire freakin' Internet.
>>
>> Find one.
>>
>>> Dealerships were then REQUIRED to buy an "on-the-car lathe" to true
>>> up rotors.
>>
>> That's not warp.
>> Nothing on this planet is going to fix warp.
>> There's not enough metal to remove.
>
> That is totally dependent on how much warp. And what, other than
> "warp" will cause a rotor to develop "runout" if it is totally true
> when installed.
>>
>>> A wize man learns from the mistakes of others - a fool never learns
>>> because he "never makes mistakes"
>>
>> Which is why I wish I had done these half-dozen jobs:
>> 1. Alignment
>> 2. Transmission
>> 3. Engine
>> 4. Tires
>> 5. paint
>
> Ond I've dome them all at least once.

Done hundreds and hundreds of alignments.
>>
>>> Yes - you are right to the extent that MOST "warped rotors" are not.
>>> But you are absolutely WRONG when you say they never warp in
>>> street/highway use and anyone who says they have had a warped rotor is
>>> lying and hasn't measured the rotor to prove it.
>>
>> I never once said "never" but "almost never" which is different, and we're
>> only talking street, and I have references that back up everything I say
>> whereas you provided zero references for what you said.
>
> You have references I have experience.

Ditto. Been there, measured that. ;-)
>>
>> I'm not here to argue opinions.
>> I only argue using logic.
>
> Reality defies logic.
>>
>> Just read the references I provided and then provide some references that
>> back up your point of view.
>>
>> The "Warped" Brake Disc and Other Myths of the Braking System
>> <http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths>
>>
>> The 'Warped Rotor' Myth
>> <http://www.10w40.com/features/maintenance/the-warped-rotor-myth>
>>
>> Warped Brake Rotors - Vibrating Reality or Internet Myth?
>> <https://blog.fcpeuro.com/warped-brake-rotors-vibrating-reality-or-internet-myth>
>>
>> Stop the +IBg-Warped+IBk- Rotors Myth and Service Brakes the Right Way
>> <http://www.brakeandfrontend.com/warped-rotors-myth/>
>>
>> Raybestos Brake Tech School, Part One: Rotors Don't Warp
>> <http://www.hendonpub.com/resources/article_archive/results/details?id87>
> Only the stop-tech article is written by a pro (Can't open the
> raybestos link so it's useless)
>
> The rest could be written by you - same level of cred. They are
> written by enthusiasts who have read articles.
>
> They are correct in most of what they say - but real warpage DOES
> exist, because not all rotors are properly manufactured and stress
> relieved and heat treated - like the problem Toyota had in the early
> '80s, and many of the "crap" rotors in the aftermarket - as I have
> explained before. In the "ideal world" they would never warp. Also,
> not all rotors spend their life in "normal" conditions - other
> problems in the braking system, or abuse, can cause a lot more heat
> than normal driving - which is why the accurate stement is:

Overtightening wheel nuts or uneven tightening of same will cause
warpage of discs.
>
> "Under normal operating conditions, properly manufactured and
> installed brake rotors very seldom actually WARP. Poor quality rotors
> can warp, as can rotors that are severely overheated due to abuse or
> certain braking system falures. When you experience brake pulsation,
> actual brake rotor warpage is UNLIKELY to be the problem - but
> stranger things HAVE happened. Uneven friction material transfer due
> to either poor intial bedding of the pads or improper use of the
> brakes is much more likely, and some brake pads are more prone to
> causing these issues due to their composition. In areas where winters
> are more severe and salt is used on the roads some pad compostions are
> more likely to cause problems - particularly the hard-spotting and
> pitting of rotors due to localized overheating caused by uneven
> friction material transfer. Many brake problems tend to be regional in
> nature for this reason. Rustout of cooling fins of a rotor, for
> instance, would be unheard-of in arizona or alabama, but fairly common
> in the northeat and the "rust belt".
>
>
> NEVER say never and ALWAYS avoid always.
>

--

Xeno