Most of the equipment I use in my profession is equipped with timing
belts....from extruder drives to servo driven down stream equipment.
I still have belts in service that have been installed for 10 years
and more that are fine (visually inspected every 6 months). Some of
them run 24 hours a day, 5-6 days a week (much more than one would
drive a car though at a lower RPM, of course). This is the norm,
though I have seen 2 of them go within 12 months. Those were from
poor installation (that guy didn't last long after that).
I'm at 7+ years now on my Honda, but only 92k miles. Even with what
I've experienced in an industrial setting, I'll probably change it out
sometime this year.
I did have an older '82 accord that had the belt break (bought it used
as a used clunker just as a temp get around vehicle), but that belt
was the original and it was at 15+ years old when it broke.
there may be some difference between auto and industrial use - the belts
used on cars don't have the same load throughout their usage speed, and
their speed varies a lot.
most vehicle timing belts break at or close to idle, not at freeway
speeds. reason is that at low speed, the hydrodynamic oil film on the
cam lobes breaks down and allows metal-to-metal contact. once that
happens, the force required to rotate increases significantly as you get
micro-welding of surface asperities. if the motor were to constantly
run at higher rpm's it would undoubtedly last longer.
it's also worth noting that modern auto timing belts are typically much
better than the stuff that was available 20 years ago. hence they last
longer even in an identical application.
The industrial belts that have been supplied over the past 10 years
are nitrile units with fibers (some fiberglass, some kevlar) and are
standard lengths that can be bought at auto supply stores for the most
part (aside from the double sided timing belts).....
I was taking off from a light in first gear, hit about 3500 rpm and
then nada. Knew what it was right away......
kevlar is not typically used in automotive belts because it's
susceptible to moisture, particularly at elevated temperatures. there
are other aramid fibers out there that are better suited - twaron being
the most common.
forgive the pedantry, but a toothed belt is not automatically a "timing"
belt. the term "timing belt", in correct usage, is when there is a
specific gear synchronization function, like syncing an engine's cam to
its crank. the kind of drive belt you get for a final drive on a harley
is simply a "toothed belt". and that's what the majority of industrial
sure, it happens. but as i said, the majority break at or close to idle
- for the reasons given.
Our servo systems do quite a bit of syncronized movements with other
drives/digital and analog IO. These all use timing belts where direct
drive is not available. The extuders themselves used toothed belts,
though they all use closed loop vector regen drives for our control
I can cite 3 instances:
1972 Ford Pinto, at a stoplight (my car 95,000 miles)
1984 Honda Accord, at a stoplight (friend, 28,000 miles)
1985 Honda Hatchback, at a stop sign at the end of a highway off
ramp after 60 miles at 60mph. (father, 61,000 miles)
I never understood before why all three of these failed while
at idle. I don't know of any that failed while moving.
On 6/7/2012 12:45 AM, email@example.com wrote:
Hamilton Honda, located in Central NJ, advertises $390. for a complete
job. http://www.hamiltonhonda.net/ go to service, then service
coupons. Even includes water pump, but I agree with Jim Beam and
would not let them replace.
Perhaps you can take that coupon to your local guy and ask them why
they are so much higher.
I have no connection to Hamilton except I bought one car there.
The facility is modern and the service dept seems efficient and attentive.
for the "replace" advocates, its their inconsistency that irks me.
apart from the damage that things like seal replacement can cause, why
do these guys get so up-tight about replacing stuff that's observably
not defective just because they can access it when they change the
timing belt? i /never/ hear the same people bleating about a much more
commonly problematic issue - the seal on the flywheel end of the engine.
why? because it's a pita to get to, that's why. so they completely
doing stuff just because it's there [particularly when accounting for
damage risk] is simply superstition and witchcraft. particularly when
it's not in the service manual/specified by the manufacturer!!!
it's just like people that change their oil every 3k miles, even though
modern oils are significantly different to those of the 1950's and
[readily and cheaply accessible] testing will put the facts right in
front of their eyes.
What inconsistency - many shops always recommend easy services that make
lots of money. I can understand why shops suggest replacing the water pump
when they do the timing belt - more dollars for them for little actual extra
effort. There were certain vehicles in the past (80's Escorts with original
CVH engine) where it was a reasonable idea. Not only was the water pump
likely to fail before the belt needed replacing a second time, when it
failed it was likely to take out the timing belt and valves/head when it
did. For those Escorts the water pump was cheap and easy to replace when you
did the belt, so I think it was a reasonable thing to do. In fact for those
early Escorts, I think it was more import to replace the water pump at
regulalr intervals than to replace the timing belt. After Ford eliminated
the potential valve interference, the need for replacing the water pump when
you did the timing belt was eliminated - at least in my mind (second year,
or third?). For other vehicles, I agree it is not something worth while -
particualrly if it is a noninterference engine.
Old habits are hard to break - especially when so many Toyota enthusiasts
continue to blame all the sludged up engines from the late 90's on
insufficient oil changes. I've finally broken the habit but one thing
worries me. We have two I4 RAV4s in the family. They both have oil change
indicators (5000 mile fixed interval indicators) which is good. - except,
they both use more than a quart of oil in 3000 miles. So if the drivers
don't check the oil, I worry thay might end up with less than 2 quarts of
oil in the pan at 5000 miles when it is changed. My Sister is particualry
lax about checking oil - the last time I changed her oil I only got around
2.5 quarts in the drain pan (I know some was in the filter and I spilled a
little, but I am afraid the engine was over 1.5 qt low). Both my Sister and
SO think the oil change indicator light relieves them of the need to check
the oil at least occasionally. I hope they don't learn why this is a bad
Maybe the handsome markup on the cost of parts is also a factor in this.
I've heard from a good source that they use a 2.25 multiplier for
markups. The manufactureres only wish to make that much profit on those
same parts. But I'm just saying ... I've already brought up this subject
before and did't end up well with it. :-(
The dealer adds about a 60% markup to the original purchase price when they
buy OE parts from Honda. That's where your full-retail price comes from.
Independent garages generally get between 10% and 25% off full-retail when
they buy from the dealer. They add that back when they resell to you, so
they can stay competitive with the dealer for parts while still making some
money on those parts.
Well, then how is it that Majestic Honda can sell a heater core for
about $300 that my local dealer sells for around $470? They both sell
the same OEM core and I assume even Majestic makes some money on their
I've got that 2.25 multiplier from a local radio show host who is
himself the owner or head mechanic of a large repair shop. You could
tell he was rather uncomfortable by the question and was trying to move
to other subject on the air real fast.
$470 retail suggests a $282 purchase at a 60% markup, leaving a margin of
$18 if they sell to you at $300. Perhaps Majestic's volume with Honda is
higher than most, so they get a discount?
Volume-shippers also get /substantial/ discounts from their carriers, so
they may be making the margin back by marking up their shipping. One of our
(commercial) customers pays much less than half to ship stuff what you'd
pay if you walked in off the street. Or did you pay $300 /total/, excluding
A 60% markup equates to a multiple of 1.67.
A multiple of 2.25 suggests they're buying the part for $209. Possible, but
I think unlikely.
That 2.25 may be true for aftermarket parts, but my experience says it's
unlikely for OE parts, especially those sold by an independent garage. With
a few exceptions, independents can't get hold of OE except through a
Oops, I just realized that my local Honda dealer's part store does
indeed charge about 60% above Majestic's online price though I seem to
recall some $625 from my last call to them.
This, however, was certainly different with my last mechanic who pretty
much wanted to charge the same price as the dealer. That's what caused
me to look for another mechanic.
I still don't know then how to interpret the 2.25 multiplier I've heard
from that radio show host. He did wave me off by saying that it was a
pretty complicated formula but was the industry norm. It's clearly not a
subject mechanics like their customers to inquire about.
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