[Vwdiesel] Quantum Milage pre & post re-ring

[Erik Lane]

Oh yeah, the couple that I've see had problems with 4th gear more so
than 2nd, although I saw some wear there as well.

On Fri, Oct 8, 2010 at 2:24 PM, Erik Lane <eriklane at gmail.com> wrote:
> I'm sorry, but you misunderstood me. I was talking only about the
> synchro clutches. Replacing the engine clutch is not nearly the job
> that rebuilding the transmission is.
>
> Yes, if the car is really using no fuel when engine braking then the
> MPG should be infinite, not even any just normal large number, so
> those numbers are somewhat suspect. But they're just being reported by
> the computer, so maybe the engineers programmed the computer to report
> some large, but not excessive number.
>
> I also wasn't trying to say that engine braking was never a good idea.
> My point was supposed to about using it as the default. I will use it
> on long grades, or especially if you're already in a gear at high RPM
> as the default, but I don't downshift just for stop signs, etc. In
> general I'm easy on my brakes and hardly ever have to work on them.
> But I see some people downshifting as fast as they can every time they
> stop so the car ends up revving super high over and over and that's
> what I argue against. Every time you downshift the cone clutches need
> to speed the input shaft up to whatever RPM it is (could even be
> 5000-10,000RPM if it's a gasser.)
>
> But again, if this isn't for you then it isn't. I just wanted to make
> sure that it was at least considered before tossed out. But heck, it's
> your money and your car and I have nothing to lose even if you
> purposely destroy your car. (Which I am not at all saying is the
> extreme that we are talking about here. Just emphasizing that I'm not
> trying to cause a big mess or anything because it doesn't matter that
> much to me other than trying to help out someone if I can.)
>
> Erik
>
> On Fri, Oct 8, 2010 at 1:58 PM, Tad <tadc at europa.com> wrote:
>> Just my two cents/experience - after 9 years and almost 160k miles of fairly
>> extensive downshifting on my 01 Golf TDI I changed the clutch, and it still
>> had some life left in it.  In that time I've changed the rear brakes 3 times
>> (once due to a stuck caliper) and front brakes are *still original* with
>> maybe 40-50% left!  I think that's pretty good proof for me that the
>> wear-on-the-clutch argument doesn't hold much water.  Does it cause
>> additional wear?  Yes, but very, *very* little.  I'm far enough from my
>> college physics that I can't actually do the math, but I would bet dollars
>> to doughnuts that the amount of friction required between the clutch and
>> flywheel in order to spin a warm engine from 1000 to 3000 RPM (or so) is an
>> order or magnitude less than what it takes to, say, start out in 1st on
>> level ground.
>>
>> Also I wonder about the accuracy of the JC Whitney MPG unit - I don't recall
>> what car Bill drives but my understanding is that any electronically fuel
>> injected car (gas or diesel) will totally cut fueling when in "overrun" -
>> the condition where the engine is being driven by the wheels such as when
>> coasting down a hill.  Logic would dictate that burning any fuel to idle the
>> engine while coasting would be greater than burning zero fuel while in
>> overrun - the only question would be whether you'd then use more fuel
>> regaining any lost momentum vs not engine braking.
>>
>> As far as worn synchros go, I have also seen that on some worn-out beaters
>> (usually on 2nd gear, probably because that's the most-often-downshifted
>> gear), but I remember reading somewhere that VW reinforced the 2nd gear
>> synchros on the 02M tranny for that very reason.
>>
>> Now as for which is "better" - it's just personal preference really.  For
>> me, it's "just the way I was taught" by my truck-drivin' daddy. :)  One
>> could certainly argue that it's safer to downshift - any emergency maneuver
>> requiring acceleration (or deceleration for that matter, if your brakes
>> happen to fail) is a second or two further away if you're in neutral vs in
>> gear and technically (at least in Oregon) it's actually illegal to operate
>> your car in neutral.
>>
>> On Thu, Oct 7, 2010 at 11:03 AM, Erik Lane <eriklane at gmail.com> wrote:
>>
>>> Yes, by downshifting you're saving wear on your brakes, but you're
>>> increasing wear on the clutches inside your tranny. They are metal
>>> cone clutches, so they will generally last pretty well, but it's
>>> really a good idea, in my opinion, to use the brakes for what they
>>> were made for. Sure, if you have a very long downhill you can
>>> downshift and use the engine, but in general downshifting puts extra
>>> wear on tranny parts. It's much easier and cheaper to do brake work
>>> than tranny work!
>>>
>>> So I would suggest using the brakes as the default, but using the
>>> engine for prolonged things. But when you do downshift it is nicer to
>>> double-clutch it to put less wear on the internal transmission parts.
>>>
>>> Just something to think about.
>>>
>>> Erik
>>>
>>> On Thu, Oct 7, 2010 at 2:45 AM, William J Toensing
>>> <toensing at wildblue.net> wrote:
>>> > Since 1996, all new cars sold in the USA have to be OBD 2 compliant which
>>> means that any car must have a standardized plug that you can plug in an OBD
>>> 2 reader to find any problems stored on the car's computer. Mark, I don't
>>> know if this applies to cars sold in the UK. The reason I mention this is
>>> that I bought an MPG meter that plugs into the OBD 2 port on my 2001 Focus
>>> from JC Whitney. The brand of the meter is Kiwi & it is made in Calif., not
>>> China. It has several functions, of which one reads average MPG & another
>>> reads instant MPG. It is interesting to watch MPG readings while
>>> decelerating. If I put the car in neutral & use the brakes to stop I get
>>> readings of 150 MPG. If I slow down while in top gear or 5 th gear, MPG will
>>> run from 90 to 120 MPG. If I shift into 3rd using the engine to slow down,
>>> which I often do, MPG is around 45 MPG. Observation: For maximum MPG, when
>>> braking, put the gear box into neutral & use the brakes to slow down.
>>> Shifting the gear box into a lower gear to avoid using the brakes results in
>>> a lower MPG, but does save on brake pads. I can see how a Prius gets 50 MPG
>>> (USA) because it can recapture energy used in braking.
>>> > Bill Toensing
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